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  • 1.
    Almeida, Roseley
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Fed Bahia, Inst Fis, Campus Univ Ondina, Salvador, BA, Brazil.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Almeida, Jailton
    Univ Fed Bahia, Inst Fis, Campus Univ Ondina, BR-40210340 Salvador, BA, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Theoretical Evidence behind Bifunctional Catalytic Activity in Pristine and Functionalized Al2C Monolayers2018In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 1, p. 148-152Article in journal (Refereed)
    Abstract [en]

    First principles electronic structure calculations based on the density functional theory (DFT) framework are performed to investigate hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on two-dimensional Al2C monolayers. In addition to the pristine Al2C monolayer, monolayers doped with Nitrogen (N), Phosphorous (P), Boron (B), and Sulphur (S) are also investigated. After determining the individual adsorption energy of hydrogen and oxygen on the different functionalized Al2C monolayers, the adsorption free energies are predicted for each of the functionalized monolayers in order to assess their suitability for HER or OER. The density of states and optical absorption spectra calculations along with the work function of the functionalized Al2C monolayers enable us to gain a profound understanding of the electronic structure for the individual system and their relation to the water splitting mechanism.

  • 2.
    Anversa, Jonas
    et al.
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil.;Fac Meridional, Escola Engn Civil, BR-99070220 Passo Fundo, RS, Brazil..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Piquini, Paulo
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    High pressure driven superconducting critical temperature tuning in Sb2Se3 topological insulator2016In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 21, article id 212601Article in journal (Refereed)
    Abstract [en]

    In this letter, we are reporting the change of superconducting critical temperature in Sb2Se3 topological insulator under the influence of an external hydrostatic pressure based on first principles electronic structure calculations coupled with Migdal-Eliashberg model. Experimentally, it was shown previously that Sb2Se3 was undergoing through a transition to a superconducting phase when subjected to a compressive pressure. Our results show that the critical temperature increases up to 6.15K under the pressure unto 40GPa and, subsequently, drops down until 70 GPa. Throughout this pressure range, the system is preserving the initial Pnma symmetry without any structural transformation. Our results suggest that the possible relevant mechanism behind the superconductivity in Sb2Se3 is primarily the electron-phonon coupling. Published by AIP Publishing.

  • 3.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Unveiling the charge migration mechanism in Na2O2: implications for sodium-air batteries2015In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 12, p. 8203-8209Article in journal (Refereed)
    Abstract [en]

    Metal-air batteries have become promising candidates for modern energy storage due to their high theoretical energy density in comparison to other storage devices. The lower overpotential of Na compared with Li makes Na-air batteries more efficient in terms of battery lifetime. Additionally, the abundance of Na over Li is another advantage for Na batteries compared to Li batteries. Na2O2 is one of the main products of sodium-air battery reactions. The efficiency of air cells is always related to the charge transport mechanisms in the formed product. To unveil these diffusion mechanisms in one of the main products of the cell reaction Na-O-2 we systematically investigate the mobility of charge carriers as well as the electronic structural properties of sodium peroxide. The framework of the density functional theory based on hybrid functional approach is used to study the mobility of charge carriers and intrinsic defects in Na2O2. Our calculations reveal that the formation of small electron and hole polarons is preferentially occurring over the delocalized state in the crystal structure of Na2O2. The migration of these small polarons displays activation energies of about 0.92 eV and 0.32 eV for the electron and hole polarons respectively, while the analysis of the charged sodium vacancy mobility reveals an activation energy of about 0.5 eV. These results suggest that the charge transport in sodium peroxide would mainly occur through the diffusion of hole polarons.

  • 4.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Faraday Mat Lab, Mat Res Ctr, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni): towards high-voltage sodium battery applications2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 14, p. 9658-9665Article in journal (Refereed)
    Abstract [en]

    Sodium-ion-based batteries have evolved as excellent alternatives to their lithium-ion-based counterparts due to the abundance, uniform geographical distribution and low price of Na resources. In the pursuit of sodium chemistry, recently the alluaudite framework Na2M2(SO4)(3) has been unveiled as a high-voltage sodium insertion system. In this context, the framework of density functional theory has been applied to systematically investigate the crystal structure evolution, density of states and charge transfer with sodium ions insertion, and the corresponding average redox potential, for Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni). It is shown that full removal of sodium atoms from the Fe-based device is not a favorable process due to the 8% volume shrinkage. The imaginary frequencies obtained in the phonon dispersion also reflect this instability and the possible phase transition. This high volume change has not been observed in the cases of the Co- and Ni-based compounds. This is because the redox reaction assumes a different mechanism for each of the compounds investigated. For the polyanion with Fe, the removal of sodium ions induces a charge reorganization at the Fe centers. For the Mn case, the redox process induces a charge reorganization of the Mn centers with a small participation of the oxygen atoms. The Co and Ni compounds present a distinct trend with the redox reaction occurring with a strong participation of the oxygen sublattice, resulting in a very small volume change upon desodiation. Moreover, the average deintercalation potential for each of the compounds has been computed. The implications of our findings have been discussed both from the scientific perspective and in terms of technological aspects.

  • 5.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Islam, Muhammed Shafiqul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Natl Univ Bangladesh, DSHE, Dhaka 1000, Bangladesh..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Predicting electrochemical properties and ionic diffusion in Na2+2xMn2-x(SO4)(3): crafting a promising high voltage cathode material2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 2, p. 451-457Article in journal (Refereed)
    Abstract [en]

    Sodium ion batteries have emerged as a good alternative to lithium based systems due to their low cost of production. In this scenario, the search for higher voltage, sodium cathodes results in a new promising alluaudite structure Na2+2xMn2-x(SO4)(3). The structural, electronic and Na diffusion properties along with defects have been reported in this investigation within the framework of density functional theory. A band gap of 3.61 eV has been computed and the average deintercalation potential is determined to be 4.11 V vs. Na/Na+. A low concentration of anti-site defects is predicted due to their high formation energy. The biggest issue for the ionic diffusion in the Na2+2xMn2-x(SO4)(3) crystal structure is revealed to be the effect of Mn vacancies increasing the activation energy of Na+ ions that hop along the [001] equilibrium positions. This effect leads to activation energies of almost the same high values for the ionic hop through the [010] direction characterizing a 2D like ionic diffusion mechanism in this system.

  • 6.
    Banerjee, Amitava
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Bromination-induced stability enhancement with a multivalley optical response signature in guanidinium [C(NH2)(3)](+)-based hybrid perovskite solar cells2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 35, p. 18561-18568Article in journal (Refereed)
    Abstract [en]

    Guanidinium lead iodide (GAPbI(3)) has been synthesized experimentally, but stability remains an issue, which can be modulated by the insertion of bromine (Br) into the system. We have performed a systematic theoretical investigation to see how bromination can tune the stability of GAPbI(3). The optical properties were also determined, and we have found formation enthalpy-based stability in the perovskite systems, which are active in the visible and IR region even after bromine insertion and additionally more active in the IR range with the transition from GAPbI(3) to GAPbBr(3). The spin orbit coupling effect is considered throughout the band structure calculations. The ensemble of the primary and secondary gaps in the half and fully brominated hybrid perovskites leads to the phenomenon of a multipeak response in the optical spectra, which can be subsequently attributed as multivalley optical response behaviour. This multivalley optical behaviour enables the brominated guanidinium-based hybrid perovskites to exhibit broad light harvesting abilities, and this can be perceived as an idea for natural multi-junction solar cells.

  • 7.
    Banerjee, Amitava
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rashba Triggered Electronic and Optical Properties in De Novo Designed Mixed Halide Hybrid PerovskitesManuscript (preprint) (Other academic)
  • 8.
    Banerjee, Amitava
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jena, Naresh K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Scrupulous Probing of Bifunctional Catalytic Activity of Borophene Monolayer: Mapping Reaction Coordinate with Charge Transfer2018In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 8, p. 3571-3576Article in journal (Refereed)
    Abstract [en]

    We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on two-dimensional (2D) noble metal free borophene monolayer based on first-principles electronic structure calculations. We have investigated the effect of Ti functionalization on borophene monolayer from the perspective of HER and OER activities enhancement. We have probed the activities based on the reaction coordinate, which is conceptually related to the adsorption free energies of the intermediates of HER and OER, as well as from the vibrational frequency analysis with the corresponding charge transfer mechanism between the surface and the adsorbate. Ti-functionalized borophene has emerged as a promising material for HER and OER mechanisms. We believe that our probing method, based on reaction coordinate coupled with vibrational analysis that has been validated by the charge transfer mechanism, would certainly become as a robust prediction route for HER and OER mechanisms in coming days.

    Keywords: borophene; hydrogen evolution reaction; oxygen evolution reaction; reaction coordinate; vibrational frequency

  • 9.
    Banerjee, Hrishit
    et al.
    SN Bose Natl Ctr Basic Sci, Dept Condensed Matter Phys & Mat Sci, JD Block,Sect 3, Kolkata 700106, India..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Saha-Dasgupta, Tanusri
    SN Bose Natl Ctr Basic Sci, Dept Condensed Matter Phys & Mat Sci, JD Block,Sect 3, Kolkata 700106, India..
    Cationic Effect on Pressure Driven Spin-State Transition and Cooperativity in Hybrid Perovskites2016In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 28, no 22, p. 8379-8384Article in journal (Refereed)
    Abstract [en]

    Hybrid or metal organic framework (MOP) perovskites of general composition, ABX(3), are known to show interesting properties that can lead to a variety of technological applications. Our first-principles study shows they are also potential candidates for exhibiting cooperative spin-state transitions upon application of external stimuli. We demonstrate this by considering two specific Fe-based MOF perovskites, namely dimethylammonium iron formate, [CH3NH2CH3][Fe(HCOO)(3)], and hydroxylammonium iron formate, [NH3OH][Fe(HCOO)(3)]. Both the compounds are found to undergo high-spin (S = 2) to low-spin (S = 0) transition at Fe(II) site upon application of moderate strength of hydrostatic pressure, along with large hysteresis. This spin-state transition is signaled by the changes in electronic, magnetic, and optical properties. We find both the transition pressure and the width of the hysteresis to be strongly dependent on the choice of A-site cation, dimethylammonium or hydroxylammonium, implying that tuning of spin-switching properties is achievable by chemical variation of the amine cation in the structure. Our findings open up novel functionalities in this family of materials of recent interest, which can have important usage in sensors and memory devices.

  • 10.
    Banerjee, Hrishit
    et al.
    SN Bose Natl Ctr Basic Sci, Dept Condensed Matter Phys & Mat Sci, JD Block,Sect 3, Kolkata 700106, India..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Saha-Dasgupta, Tanusri
    SN Bose Natl Ctr Basic Sci, Dept Condensed Matter Phys & Mat Sci, JD Block,Sect 3, Kolkata 700106, India..
    Design and Control of Cooperativity in Spin-Crossover in Metal-Organic Complexes: A Theoretical Overview2017In: INORGANICS, ISSN 2304-6740, Vol. 5, no 3, article id 47Article, review/survey (Refereed)
    Abstract [en]

    Metal organic complexes consisting of transition metal centers linked by organic ligands, may show bistability which enables the system to be observed in two different electronic states depending on external condition. One of the spectacular examples of molecular bistability is the spin-crossover phenomena. Spin-Crossover (SCO) describes the phenomena in which the transition metal ion in the complex under the influence of external stimuli may show a crossover between a low-spin and high-spin state. For applications in memory devices, it is desirable to make the SCO phenomena cooperative, which may happen with associated hysteresis effect. In this respect, compounds with extended solid state structures containing metal ions connected by organic spacer linkers like linear polymers, coordination network solids are preferred candidates over isolated molecules or molecular assemblies. The microscopic understanding, design and control of mechanism driving cooperativity, however, are challenging. In this review we discuss the recent theoretical progress in this direction.

  • 11.
    Bashir, Amna
    et al.
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Lew, Jia Haur
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Shukla, Sudhanshu
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Gupta, Disha
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Baikie, Tom
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Patidar, Rahul
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Indian Inst Sci Educ & Res, Pune 411008, Maharashtra, India.
    Bruno, Annalisa
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Mhaisalkar, Subodh
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Akhter, Zareen
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan.
    Cu-doped nickel oxide interface layer with nanoscale thickness for efficient and highly stable printable carbon-based perovskite solar cell2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 182, p. 225-236Article in journal (Refereed)
    Abstract [en]

    The power conversion efficiency (PCE) of hole conductor free carbon-based perovskite solar cells (PSCs) is restricted by the poor charge extraction and recombination losses at the carbon-perovskite interface. For the first time we successfully demonstrated incorporation of thin layer of copper doped nickel oxide (Cu:NiOx) nanoparticles in carbon-based PSCs, which helps in improving the performance of these solar devices. Cu:NiOx nanoparticles have been synthesized by a facile chemical method, and processed into a paste for screen printing. Extensive X-ray Absorption Spectroscopy (XAS) analysis elucidates the co-ordination of Cu in a NiOx matrix and indicates the presence of around 5.4% Cu in the sample. We fabricated a monolithic perovskite module on a 100 cm(2) glass substrate (active area of 70 cm(2)) with a thin Cu:NiOx layer (80 nm), where the champion device shows an appreciated power conversion efficiency of 12.1% under an AM 1.5G illumination. To the best of our knowledge, this is the highest reported efficiency for such a large area perovskite solar device. I-V scans show that the introduction of Cu:NiOx mesoporous scaffold increases the photocurrent, and yields fill factor (FF) values exceeding 57% due to the better interface and increased hole extraction efficiency. Electrochemical Impedance Spectroscopy (EIS) results reinforce the above results by showing the reduction in recombination resistance (R-rec) of the PSCs that incorporates Cu:NiOx interlayer. The perovskite solar modules with a Cu:NiOx layer are stable for more than 4500 h in an ambient environment (25 degrees C and 65% RH), with PCE degradation of less than 5% of the initial value.

  • 12.
    Bera, Suman
    et al.
    Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India.
    Ghosh, Dibyendu
    Indian Inst Sci Educ & Res, Dept Chem Sci, Kolkata 741246, India;Indian Inst Sci Educ & Res, Ctr Adv Funct Mat, Kolkata 741246, India.
    Dutta, Anirban
    Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India.
    Bhattacharyya, Sayan
    Indian Inst Sci Educ & Res, Dept Chem Sci, Kolkata 741246, India;Indian Inst Sci Educ & Res, Ctr Adv Funct Mat, Kolkata 741246, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pradhan, Narayan
    Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India.
    Limiting Heterovalent B-Site Doping in CsPbI3 Nanocrystals: Phase and Optical Stability2019In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 4, no 6, p. 1364-1369Article in journal (Refereed)
    Abstract [en]

    B-site doping with various metal ions in alpha-CsPbI3 has been proven to be a potential approach in bringing phase stability to these nanocrystals. However, while the doping of various homovalent ions in replacing Pb(II) has been extensively studied, heterovalent doping was observed to be limited. To understand the impact of heterovalent doping, Sb(III) was chosen here as an effective dopant for occupying the Pb(II) position in CsPbI3 nanocrystals. Importantly, it was observed that insertion of Sb(III) also stabilized the crystal phase of these red-emitting nanocrystals, but only with limited doping. However, with more intake, the cube shape turned to platelet and therefore also reduced the stability. Details of the insights of formation of these doped nanostructures are investigated, and further, these were implemented for photovoltaic application and comparable efficiency was recorded.

  • 13.
    Callini, Elsa
    et al.
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland.;Swiss Fed Lab Mat Sci & Technol, Empa, Ueberlandstr 129, CH-8600 Dubendorf, Switzerland..
    Aguey-Zinsou, Kondo-Francois
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Ramon Ares, Jose
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Bals, Sara
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Biliskov, Nikola
    Rudjer Boskovic Inst, Bijenicka Cesta 54, Zagreb 10000, Croatia..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Charalambopoulou, Georgia
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Chaudhary, Anna-Lisa
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Cuevas, Fermin
    UPEC, CNRS, ICMPE, UMR7182, 2-8 Rue Henri Dunant, F-94320 Thiais, France..
    Dam, Bernard
    Delft Univ Technol, Chem Engn, Julianalaan 136, NL-2628 BL Delft, Netherlands..
    de Jongh, Petra
    Univ Utrecht, Debye Inst Nanomat Sci, Inorgan Chem & Catalysis, Univ Weg 99, NL-3584 CG Utrecht, Netherlands..
    Dornheim, Martin
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Filinchuk, Yaroslav
    Catholic Univ Louvain, Inst Condensed Matter & Nanosci, B-1348 Louvain, Belgium..
    Novakovic, Jasmina Grbovic
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Hirscher, Michael
    Max Planck Inst Intelligent Syst Stuttgart, Heisenbergstr 3, D-70569 Stuttgart, Germany..
    Jensen, Torben R.
    Aarhus Univ, Dept Chem, Ctr Mat Crystallog, Langelandsgade 140, DK-8000 Aarhus C, Denmark.;Aarhus Univ, iNANO, Langelandsgade 140, DK-8000 Aarhus C, Denmark..
    Jensen, Peter Bjerre
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Novakovic, Nikola
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Lai, Qiwen
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Leardini, Fabrice
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Gattia, Daniele Mirabile
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Pasquini, Luca
    Alma Mater Studiorum Univ Bologna, Dept Phys & Astron, I-40127 Bologna, Italy..
    Steriotis, Theodore
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Turner, Stuart
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Vegge, Tejs
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Zuttel, Andreas
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland..
    Montone, Amelia
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Nanostructured materials for solid-state hydrogen storage: A review of the achievement of COST Action MP11032016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 32, p. 14404-14428Article in journal (Refereed)
    Abstract [en]

    In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. This Action dealt with the state of the art of energy storage and set up a competitive and coordinated network capable to define new and unexplored ways for Solid State Hydrogen Storage by innovative and interdisciplinary research within the European Research Area. An important number of new compounds have been synthesized: metal hydrides, complex hydrides, metal halide ammines and amidoboranes. Tuning the structure from bulk to thin film, nanoparticles and nanoconfined composites improved the hydrogen sorption properties and opened the perspective to new technological applications. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies. Computational screening methods allowed the prediction of suitable compounds for hydrogen storage and the modeling of the hydrogen sorption reactions on mono-, bi-, and three-dimensional systems. This manuscript presents a review of the main achievements of this Action.

  • 14.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Watcharatharapong, Teeraphat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Rafael Barros
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Current computational trends in polyanionic cathode materials for Li and Na batteries2018In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 30, no 28, article id 283003Article, review/survey (Refereed)
    Abstract [en]

    A long-standing effort has been devoted for the development of high energy density cathodes both for Li-and Na-ion batteries (LIBs and SIBs). The scientific communities in battery research primarily divide the Li- and Na-ion cathode materials into two categories: layered oxides and polyanionic compounds. Researchers are trying to improve the energy density of such materials through materials screening by mixing the transition metals or changing the concentration of Li or Na in the polyanionic compounds. Due to the fact that there is more stability in the polyanionic frameworks, batteries based on these materials mostly provide a prolonged cycling life as compared to the layered oxide materials. Nevertheless, the bottleneck for such compounds is the weight penalty from polyanionic groups that results into the lower capacity. The anion engineering could be considered as an essential way out to design such polyanionic compounds to resolve this issue and to fetch improved cathode performance. In this topical review we present a systematic overview of the polyanionic cathode materials used for LIBs and SIBs. We will also present the computational methodologies that have become significantly relevant for battery research. We will make an attempt to provide the theoretical insight with a current development in sulfate (SO4), silicate (SiO4) and phosphate (PO4) based cathode materials for LIBs and SIBs. We will end this topical review with the future outlook, that will consist of the next generation organic electrode materials, mainly based on conjugated carbonyl compounds.

  • 15.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ghaisas, S. V.
    Relative Localization Prediction in Covalent Clusters: An Ab Initio Theory Driven Quest2012In: Advanced Science Letters, Vol. 18, no 1, p. 208-212Article in journal (Refereed)
    Abstract [en]

    A method to estimate the relative binding energies of atom within a covalently bonded cluster is proposed. The method uses projected density of states (PDOS) for the individual atoms in the cluster. A parameter similar to variance is defined over certain region of PDOS. The value is seen to be inversely related to the local binding energy of the atom. The method is applied to Si<sub>19</sub>O<sub>8</sub> and Si<sub>19</sub>O<sub>10</sub> clusters to determine the relatively weakly bound atoms in these clusters. Fragmentation of the clusters using simulated annealing reveals that those atoms are fragmented which are identified to be weakly bound from the proposed method.

  • 16.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ghaisas, S. V.
    Majumder, C.
    An ab-initio study of silicon adsorption on metallic surfaces (Au/Ag): Novel perspective to explore chemical bonding2012In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 85, no 7Article in journal (Refereed)
  • 17.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ghaisas, S. V.
    Majumder, Chiranjib
    Structure and energetics of silicon clusters adsorbed on the Au(111) surface: a first principles study2010In: International Journal of Nanotechnology, Vol. 7, no 9-12, p. 833-842Article in journal (Refereed)
  • 18.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rajesh, Ch.
    First principles-based adsorption comparison of group IV elements (C, Si, Ge, and Sn) on Au(111)/Ag(111) surface2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 10Article in journal (Refereed)
  • 19.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rajesh, Ch.
    Mahamuni, S.
    Ghaisas, S. V.
    Oxygen impact on quantum confinement effect for silicon clusters in different size regimes: ab initio investigations2011In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 64, no 2-3, p. 331-337Article in journal (Refereed)
  • 20.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rajesh, Ch.
    Mahamuni, Shailaja
    Ghaisas, S. V.
    Quantum Confinement Effect in Pristine and Oxygen Covered Silicon Nanocrystals with Surface States2011In: Journal of Computational and Theoretical Nanoscience, Vol. 8, no 9, p. 1739-1743Article in journal (Refereed)
    Abstract [en]

    Absorption spectra for pristine silicon and oxygen capped silicon nanocrystals (ncs) are computed using time dependent local density approximation (TDLDA) in the size regime of 1.0 to 1.5 nm. These clusters show very small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps. This indicates presence of surface states. The partial density of states (PDOS) for these clusters confirms the presence of surface states when compared to the corresponding ncs with hydrogen passivation. The HOMO&#8211;LUMO gaps do not show any size dependence. However the optical absorption gaps show the quantum confinement effect (QCE) for both the types of clusters. The oxygen capped silicon ncs are prepared following the wet chemical route. The optical absorption spectrum of experimentally prepared ncs is compared with the computed one. Experimental results support the theoretical argument explaining the QCE in these clusters.

  • 21.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rajesh, Ch.
    Mahamuni, Shailaja
    Ghaisas, S. V.
    Structural and Optical Properties of Oxygenated Silicon Quantum Dots2011In: Advanced Science Letters, Vol. 4, no 11-12, p. 3580-3584Article in journal (Refereed)
    Abstract [en]

    Silicon quantum dots of size as small as 1 nm in diameter were prepared by wet chemical route. These clusters are found to be covered with oxygen and hydrocarbon molecules. The optical measurements reveal strong absorption around 4.67 eV and weak absorption at lower energies. The clusters show a broad luminescence around 3.87 eV. These quantum dots are modeled using <i>ab-initio</i> Car Parinello Molecular Dynamics and computational studies explain the absorption spectrum of the clusters over observed energy range. In principle, these quantum dots can be useful as scintillating layer on crystalline silicon solar cells to enhance the photovoltaic efficiency.

  • 22.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Xie, Wei
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Mathews, Niripan
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.;ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Sherburne, Matthew
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Asta, Mark
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Mhaisalkar, Subodh G.
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.;ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Rational Design: A High-Throughput Computational Screening and Experimental Validation Methodology for Lead-Free and Emergent Hybrid Perovskites2017In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 2, no 4, p. 837-845Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells, with efficiencies of 22.1%, are the only solution-processable technology to outperform multicrystalline silicon and thin-film solar cells. Whereas substantial progress has been made in scalability and stability, toxicity concerns drive the need for lead replacement, intensifying research into the broad palette of elemental substitutions, solid solutions, and multidimensional structures. Perovskites have gone from comprising three to more than eight (CH3NH3, HC(NH2)(2), Cs, Rb, Pb, Sn, I, Br) organic and inorganic constituents, and a variety of new embodiments including layered, double perovskites, and metal-deficient perovskites are being explored. Although most experimentation is guided by intuition and trial-and-error-based Edisonian approaches, rational strategies underpinned by computational screening and targeted experimental validation are emerging. In addressing emergent perovskites, this perspective discusses the rational design methodology leveraging density functional theory-based high-throughput computational screening coupled to downselection strategies to accelerate the discovery of materials and industrialization of perovskite solar cells.

  • 23.
    Das, Tisita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol Indore, Discipline Phys, Indore 453552, Madhya Pradesh, India.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Das, Gour P.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India;Indian Inst Technol, Dept Met & Mat Engn, Kharagpur 721302, W Bengal, India.
    Functionalization and Defect-Driven Water Splitting Mechanism on a Quasi-Two-Dimensional TiO2 Hexagonal Nanosheet2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 7, p. 5074-5082Article in journal (Refereed)
    Abstract [en]

    In this work, we have dealt with the functionalization of a newly reported quasi-2D hexagonal nanosheet (HNS) of titanium dioxide (TiO2) for photocatalytic water splitting to generate hydrogen and oxygen. Functionalization has been carried out by creating a single oxygen vacancy defect as well as by incorporating substitutional doping with C, N, P, and S atoms at the O site of TiO2 HNS. The effects of functionalization and vacancy defects on the structural and electronic properties of HNS have been investigated by determining the corresponding projected density of states. It has been observed that functionalization causes a shift in the VBM and CBM of HNS, which in principle influences the catalytic activity. In addition, we have determined the work function for these materials in order to correlate them with the electrochemical activities of different considered HNSs. The catalytic activity has been predicted by determining the reaction coordinate as constructed from the free energies of the different reaction intermediates involved in HER and OER Among all of the systems that we have studied, HNS with an oxygen monovacancy has emerged as the best possible candidate for the water-splitting mechanism.

  • 24.
    Das, Tisita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Das, Gour P.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata, India.
    TiS2 Monolayer as an Emerging Ultrathin Bifunctional Catalyst: Influence of Defects and Functionalization2019In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 20, no 4, p. 608-617Article in journal (Refereed)
    Abstract [en]

    We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two‐dimensional (2D) noble‐metal‐free titanium disulfide (TiS2) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS2 is based on electronic‐structure calculations witihin the framework of density functional theory (DFT). Since TiS2 is the lightest compound among the group‐IV TMDCs, it is worth exploring the catalytic activity of a TiS2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS2 monolayer by determining the density of states, work‐function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects.

  • 25.
    Djouambi, Nadia
    et al.
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Bougheloum, Chafika
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Messalhi, Abdelrani
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Bououdina, Mohamed
    Univ Bahrain, Coll Sci, Dept Phys, POB 32038, Zallaq, Bahrain.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    New Concept on Photocatalytic Degradation of Thiophene Derivatives: Experimental and DFT Studies2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 27, p. 15646-15651Article in journal (Refereed)
    Abstract [en]

    In this study, the photocatalytic degradation of seven sulfur compounds (2-methylthiophene, 3-methylthiophene, 2-phenylthiophene, 3-phenylthiophene, 2,5-diphenylthiophene, 2-(2-thienyl) pyridine, and 2-(3-thienyl) pyridine in semiaqueous medium are compared to thiophene. The apparent-reaction-rate constant (k) is found to decrease in the following order: 2,5-diphenylthiophene > 2-(2-thienyl) pyridine > 2-penhylthiophene methylthiophene > 3-penhylthiophene > 2-methylthiophene > 2-(3-thienyl) pyridine > 3-thiophene. From the data obtained by UV light absorption (lambda(max)) measurements and electronic structure calculations (frontier orbitals energy, global hardness, and global softness), the kinetic parameters of the reaction have been determined. Among the studied compounds, thiophene with a high lambda(max) and low calculated LUMO-HOMO gap energy has showed higher activity under UV irradiation. Interestingly, a lower activity is observed with low lambda(max) and high LUMO-HOMO gap energy. This demonstrates, for the first time, that the reactivity depends essentially on the thermodynamic stability of the sulfur compound rather than on the nature or the position of the substituent on the ring.

  • 26. Dwibedi, Debasmita
    et al.
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shanbogh, Pradeep P.
    Sundaram, Nalini G.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Na2.44Mn1.79(SO4)(3): a new member of the alluaudite family of insertion compounds for sodium ion batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 36, p. 18564-18571Article in journal (Refereed)
    Abstract [en]

    Sodium-ion batteries have been extensively pursued as economic alternatives to lithium-ion batteries. Investigating the polyanion chemistry, alluaudite structured Na2Fe2II(SO4)(3) has been recently discovered as a 3.8 V positive electrode material (Barpanda et al., Nature Commun., 5: 4358, 2014). Registering the highest ever Fe-III/Fe-II redox potential (vs. Na/Na+) and formidable energy density, it has opened up a new polyanion family for sodium batteries. Exploring the alluaudite family, here we report isotypical Na2+2xMn2-xII(SO4)(3) (x = 0.22) as a novel high-voltage cathode material for the first time. Following low-temperature (ca. 350 degrees C) solid-state synthesis, the structure of this new alluaudite compound has been solved adopting a monoclinic framework (s.g. C2/c) showing antiferromagnetic ordering at 3.4 K. Synergising experimental and ab initio DFT investigation, Na2+2xMn2-xII(SO4)(3) has been found to be a potential high-voltage (ca. 4.4 V) cathode material for sodium batteries.

  • 27.
    Dwibedi, Debasmita
    et al.
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Gond, Ritambhara
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Dayamani, Allumolu
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Na2.32Co1.84(SO4)(3) as a new member of the alluaudite family of high-voltage sodium battery cathodes2017In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 1, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Electrochemical energy storage has recently seen tremendous emphasis being placed on the large-scale (power) grid storage. Sodium-ion batteries are capable of achieving this goal with economic viability. In a recent breakthrough in sodium-ion battery research, the alluaudite framework (Na2Fe2(SO4)(3)) has been reported, with the highest Fe3+/Fe2+ redox potential (ca. 3.8 V, Barpanda, et al., Nat. Commun., 2014, 5, 4358). Exploring this high-voltage sodium insertion system, we report the discovery of Na2+2xCo2-x(SO4)(3) (x = 0.16) as a new member of the alluaudite class of cathode. Stabilized by low-temperature solid-state synthesis (T <= 350 degrees C),this novel Co-based compound assumes a monoclinic structure with C2/c symmetry, which undergoes antiferromagnetic ordering below 10.2 K. Isotypical to the Fe-homologue, it forms a complete family of solid-solution Na2+2x(Fe1-yCoy)(2-x)(SO4)(3) [ y = 0-1]. Ab initio DFT analysis hints at potential high voltage operation at 4.76-5.76 V (vs. Na), depending on the degree of desodiation involving a strong participation of the oxygen sub-lattice. With the development of safe organic electrolytes, Na2+2xCo2-x(SO4)(3) can work as a cathode material (similar to 5 V) for sodium-ion batteries.

  • 28.
    Dwibedi, Debasmita
    et al.
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ling, Chris D.
    Univ Sydney, Sch Chem, Bldg F11, Sydney, NSW 2006, Australia..
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Duraisamy, Shanmughasundaram
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Munichandraiah, Nookala
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ionothermal Synthesis of High-Voltage Alluaudite Na2+2xFe2-x(SO4)(3) Sodium Insertion Compound: Structural, Electronic, and Magnetic Insights2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 11, p. 6982-6991Article in journal (Refereed)
    Abstract [en]

    Exploring future cathode materials for sodium-ion batteries, alluaudite class of Na2Fe2II(SO4)(3) has been recently unveiled as a 3.8 V positive insertion candidate (Barpanda et al. Nat. Commun. 2014, 5, 4358). It forms an Fe-based polyanionic compound delivering the highest Fe-redox potential along with excellent rate kinetics and reversibility. However, like all known SO4-based insertion materials, its synthesis is cumbersome that warrants careful processing avoiding any aqueous exposure. Here, an alternate low temperature ionothermal synthesis has been described to produce the alluaudite Na2+2xFe2-xII(SO4)(3). It marks the first demonstration of solvothermal synthesis of alluaudite Na2+2xM2-xII(SO4)(3) (M = 3d metals) family of cathodes. Unlike classical solid-state route, this solvothermal route favors sustainable synthesis of homogeneous nanostructured alluaudite products at only 300 degrees C, the lowest temperature value until date. The current work reports the synthetic aspects of pristine and modified ionothermal synthesis of Na2+2xFe2-xII(SO4)(3) having tunable size (300 nm similar to 5 mu m) and morphology. It shows antiferromagnetic ordering below 12 K. A reversible capacity in excess of 80 mAh/g was obtained with good rate kinetics and cycling stability over 50 cycles. Using a synergistic approach combining experimental and ab initio DFT analysis, the structural, magnetic, electronic, and electrochemical properties and the structural limitation to extract full capacity have been described.

  • 29. Francis, Priya
    et al.
    Patil, Sumati
    Rajesh, Chiranjib
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Mahamuni, Shailaja
    Dharmadhikari, ChandrakantV.
    Ghaisas, SubhashV.
    Electronic and optical properties of agglomerated hydrogen terminated silicon nanoparticles2013In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 67, no 7Article in journal (Refereed)
  • 30.
    Gaikwad, Prashant V.
    et al.
    Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.;Bhabha Atom Res Ctr, Radiochem Div, Bombay 400085, Maharashtra, India..
    Pujari, Pradeep K.
    Bhabha Atom Res Ctr, Radiochem Div, Bombay 400085, Maharashtra, India..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kshirsagar, Anjali
    Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.;Savitribai Phule Pune Univ, Ctr Modeling & Simulat, Pune 411007, Maharashtra, India..
    Cluster assembly route to a novel octagonal two-dimensional ZnO monolayer2017In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 33, article id 335501Article in journal (Refereed)
    Abstract [en]

    To explore the possibility of cluster assembly resulting in a two-dimensional (2D) stable monolayer of ZnO, a systematic study is performed on the structural evolution of bare and passivated stoichiometric clusters of ZnnOn, n = 1-8, using density-functional-theory-based first principles electronic structure calculations. The changes in hybridization are investigated with the aid of the site-projected partial density of states and partial charge density, while the effect of passivation and size on the ionicity of the cluster is studied using Bader charge analysis. The structural and chemical properties are found to be influenced by the coordination number of atoms in the clusters irrespective of the coordinating species. The physical parameters and hybridization of the states for the clusters on passivation resemble those of the bulk. Passivation thus provides an environment that leads to the stability of the clusters. Cluster assembly using the stable cluster geometries of passivated clusters (without the passivating atoms) has been shown to lead to stable 2D structures. This stability has been studied on the basis of binding energy, vibrational frequency, phonon dispersion and thermal properties. A new octagonal 2D monolayer planar geometry of ZnO is predicted.

  • 31.
    Ghosh, Biplab
    et al.
    Nanyang Technol Univ ERI N, Energy Res Inst, Res Techno Plaza,X Frontier Block Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Interdisciplinary Grad Sch, 50 Nanyang Ave, Singapore 639798, Singapore.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Wei, Hao
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.
    Guet, Claude
    Nanyang Technol Univ ERI N, Energy Res Inst, Res Techno Plaza,X Frontier Block Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.
    Li, Shuzhou
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.
    Mhaisalkar, Subodh
    Nanyang Technol Univ ERI N, Energy Res Inst, Res Techno Plaza,X Frontier Block Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.
    Mathews, Nripan
    Nanyang Technol Univ ERI N, Energy Res Inst, Res Techno Plaza,X Frontier Block Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.
    Poor Photovoltaic Performance of Cs3Bi2I9: An Insight through First-Principles Calculations2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 32, p. 17062-17067Article in journal (Refereed)
    Abstract [en]

    Bismuth-based halide perovskite derivatives have now attracted huge attention for photovoltaic (PV) applications after the unparalleled success of lead-based halide perovskites. However, the performances of PV devices based on these compounds are poor, despite theoretical predictions. In this Article, we have investigated the electronic structure and defect formation energies of Cs3Bi2I9 using density functional theory (DFT) calculations. The calculated electronic bandstructure indicates an indirect bandgap and high carrier effective masses. Our calculations reveal a large stability region for this compound; however, deep level defects are quite prominent. Even the varying chemical potentials from the stoichiometric region do not eliminate the presence of deep defects, ultimately limiting photovoltaic efficiencies.

  • 32.
    Guha, Anku
    et al.
    Tata Inst Fundamental Res Hyderabad, Sy 36-P, Hyderabad 500107, India.
    Vineesh, Thazhe Veettil
    Tata Inst Fundamental Res Hyderabad, Sy 36-P, Hyderabad 500107, India.
    Sekar, Archana
    Tata Inst Fundamental Res Hyderabad, Sy 36-P, Hyderabad 500107, India.
    Narayanaru, Sreekanth
    Tata Inst Fundamental Res Hyderabad, Sy 36-P, Hyderabad 500107, India.
    Sahoo, Mihir
    Indian Inst Technol, Sch Basic Sci, Bhubaneswar 751013, Odisha, India.
    Nayak, Saroj
    Indian Inst Technol, Sch Basic Sci, Bhubaneswar 751013, Odisha, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Narayanan, Tharangattu N.
    Tata Inst Fundamental Res Hyderabad, Sy 36-P, Hyderabad 500107, India.
    Mechanistic Insight into Enhanced Hydrogen Evolution Reaction Activity of Ultrathin Hexagonal Boron Nitride-Modified Pt Electrodes2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 7, p. 6636-6644Article in journal (Refereed)
    Abstract [en]

    Enhancing the intrinsic activity of a benchmarked electrocatalyst such as platinum (Pt) is highly intriguing from fundamental as well as applied perspectives. In this work, hydrogen evolution reaction (HER) activity of Pt electrodes, benchmarked HER catalysts, modified with ultrathin sheets of hexagonal boron nitride (h-BN) is studied in acidic medium (Pt/h-BN), and augmented HER performance, in terms of the overpotential at a 10 mA cm(-2) current density (10 mV lower than that of Pt nanoparticles) and a lower Tafel slope (29 +/- 1 mV/decade), of the Pt/h-BN system is demonstrated. The effects of h-BN surface modification of bulk Pt as well as Pt nanoparticles are studied, and the origin of such an enhanced HER activity is probed using density functional theory-based calculations. The HER charge transfer resistance of h-BN-modified Pt is found to be drastically reduced, and this enhances the charge transfer kinetics of the Pt/h-BN system because of the synergistic interaction between h-BN and Pt. An enormous reduction in the hydrogen adsorption energy on h-BN monolayers is also found when they are placed over the Pt electrode [-2.51 eV (h-BN) to -0.25 eV (h-BN over Pt)]. Corrosion preventive atomic layers such as h-BN-protected Pt electrodes that perform better than Pt electrodes do open possibilities of benchmarked catalysts by simple modification of a surface via atomic layers.

  • 33.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Materials and Engineering, Royal Institute of Technology (KTH).
    Metal Functionalized Silicene for Efficient Hydrogen Storage2013In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 14, no 15, p. 3463-3466Article in journal (Refereed)
    Abstract [en]

    First-principles calculations based on density functional theory are used to investigate the electronic structure along with the stability, bonding mechanism, band gap, and charge transfer of metal-functionalized silicene to envisage its hydrogen-storage capacity. Various metal atoms including Li, Na, K, Be, Mg, and Ca are doped into the most stable configuration of silicene. The corresponding binding energies and charge-transfer mechanisms are discussed from the perspective of hydrogen-storage compatibility. The Li and Na metal dopants are found to be ideally suitable, not only for strong metal-to-substrate binding and uniform distribution over the substrate, but also for the high-capacity storage of hydrogen. The stabilities of both Li- and Na-functionalized silicene are also confirmed through molecular dynamics simulations. It is found that both of the alkali metals, Li+ and Na+, can adsorb five hydrogen molecules, attaining reasonably high storage capacities of 7.75 and 6.9 wt%, respectively, with average adsorption energies within the range suitable for practical hydrogen-storage applications.

  • 34.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    De Sarkar, Abir
    Johansson, Börje
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Enhancement of energy storage capacity of Mg functionalized silicene and silicane under external strain2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 12, p. 123903-Article in journal (Refereed)
    Abstract [en]

    The electronic structure, stability, and hydrogen storage capacity of strain induced Mg functionalized silicene (SiMg) and silicane (SiHMg) monolayers have been studied by means of van der Waals induced first principles calculations. A drastic increase in the binding energy of Mg adatoms on both the monolayers under the biaxial symmetric strain of 10% ensures the uniform distribution of dopants over the substrates. A significant positive charge on each Mg accumulates a maximum of six H-2 molecules with H-2 storage capacity of 8.10% and 7.95% in case of SiMg and SiHMg, respectively. The average adsorption energy for H-2 molecules has been found ideal for practical H-2 storage materials.

  • 35.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kang, T. W.
    Johansson, Borje
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    BC3 Sheet Functionalized with Lithium-Rich Species Emerging as a Reversible Hydrogen Storage Material2015In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 16, no 3, p. 634-639Article in journal (Refereed)
    Abstract [en]

    The decoration of a BC3 monolayer with the polylithiated molecules CLi4 and OLi2 has been extensively investigated to study the hydrogen-storage efficiency of the materials by first principles electronic structure calculations. The binding energies of both lithiated species with the BC3 substrate are much higher than their respective cohesive energies, which confirms the stability of the doped systems. A significant positive charge on the Li atom in each of the dopants facilitates the adsorption of multiple H-2 molecules under the influence of electrostatic and van der Waals interactions. We observe a high H-2-storage capacity of 11.88 and 8.70 wt% for the BC3-CLi4 and BC3-OLi2 systems, respectively, making them promising candidates as efficient energy-storage systems.

  • 36.
    Hussain, Tanveer
    et al.
    Univ Queensland, Ctr Theoret & Computat Mol Sci, Australian Inst Bioengn & Nanotechnol, Brisbane, Qld 4072, Australia..
    Kaewmaraya, Thanayut
    Univ Paris 11, Inst Elect Fondamentale, UMR 8622, F-91405 Orsay, France.;Khon Kaen Univ, Fac Sci, Dept Phys, Khon Kaen 40002, Thailand..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Defect and Substitution-Induced Silicene Sensor to Probe Toxic Gases2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 44, p. 25256-25262Article in journal (Refereed)
    Abstract [en]

    Structural, electronic, and gas-sensing properties of pure, defected, and substituted silicene monolayer have been studied using first-principles calculations based on density functional theory. The spin-polarized calculations with van der Waals effect taken into consideration have revealed that the pristine silicene sheet rarely adsorbs the CO2, H2S, and SO2 gas molecules, which restricts the gas-sensing application of this 2D material. However, inducing vacancy defect in silicene drastically changes the electronic properties, and as a consequence it also improves the binding of exposed gas molecules significantly. Our Bader charge analysis reveals that a considerable amount of charge is being transferred from the defected silicene to the gases, resulting in binding energy improvement between silicene and the gas molecules. The change in binding energies has further been explained by plotting density of states. In addition to the vacancy defects, we have also considered the substitution of Al, B, N, and S in silicene. We found that the sensing propensity of silicene is more sensitive to the vacancy defect, as compared with the impurities.

  • 37.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kaewmaraya, Thanayut
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Materials and Engineering, Royal Institute of Technology (KTH).
    Functionalization of hydrogenated silicene with alkali and alkaline earth metals for efficient hydrogen storage2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 43, p. 18900-18905Article in journal (Refereed)
    Abstract [en]

    First principles density functional theory has been employed to investigate the electronic structure along with the stability, bonding mechanism, band gap and charge transfer of metal functionalized hydrogenated silicene (SiH), or silicane, in order to envisage the hydrogen storage capacity. Various metal adatoms including Li, Na, K, Be, Mg and Ca have been doped on the most stable chair like configuration of silicane. The corresponding binding energies and charge transfer mechanism have been discussed from the perspective of H-2 storage ability. The Li and Na metal adatoms have been found to be ideally suitable not only for their strong metal to substrate binding and uniform distribution over the substrate but also for their high capacity for storage of hydrogen. The stability of both Li and Na functionalized SiH has also been confirmed by MD simulations. It was found that both Li+ and Na+ adsorbed four H-2 molecules attaining reasonably high storage capacities of 6.30 wt% and 5.40 wt% respectively with average adsorption energies lying within the range suitable for practical H-2 storage applications, in contrast with alkaline earth metals.

  • 38.
    Hussain, Tanveer
    et al.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Australia.
    Kaewmaraya, Thanayut
    Khon Kaen Univ, Dept Phys, Integrated Nanotechnol Res Ctr, Khon Kaen, Thailand; Nanotec KKU Ctr Excellence Adv Nanomat Energy Pro, Khon Kaen, Thailand.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vovusha, Hakkim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. King Abdullah Univ Sci & Technol, Phys Sci & Engn Div PSE, Thuwal, Saudi Arabia.
    Amornkitbamrung, Vittaya
    Khon Kaen Univ, Dept Phys, Integrated Nanotechnol Res Ctr, Khon Kaen, Thailand; Nanotec KKU Ctr Excellence Adv Nanomat Energy Pro, Khon Kaen, Thailand.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Defected and Functionalized Germanene-based Nanosensors under Sulfur Comprising Gas Exposure2018In: ACS SENSORS, ISSN 2379-3694, Vol. 3, no 4, p. 867-874Article in journal (Refereed)
    Abstract [en]

    Efficient sensing of sulfur containing toxic gases like H2S and SO2 is of the utmost importance due to the adverse effects of these noxious gases. Absence of an efficient 2D-based nanosensor capable of anchoring H2S and SO2 with feasible binding and an apparent variation in electronic properties upon the exposure of gas molecules has motivated us to explore the promise of a germanene nanosheet (Ge-NS) for this purpose. In the present study, we have performed a comprehensive computational investigation by means of DFT-based first-principles calculations to envisage the structural, electronic, and gas sensing properties of pristine, defected, and metal substituted Ge-NSs. Our initial screening has revealed that although interaction of SO2 with pristine Ge-NSs is within the desirable range, H2S binding however falls below the required values to guarantee an effective sensing. To improve the binding characteristics, we have considered the interactions between H2S and SO2 with defected and metal substituted Ge-NS. The systematic removals of Ge atoms from a reasonably large super cell lead to monovacancy, divacancies, and trivacancies in Ge-NS. Similarly, different transition metals like As, Co, Cu, Fe, Ga, Ge, Ni, and Zn have been substituted into the monolayer to realize substituted Ge-NS. Our van der Waals corrected DFT calculations have concluded that the vacancy and substitution defects not only improve the binding characteristics but also enhance the sensing propensity of both H2S and SO2. The total and projected density of states show significant variations in electronic properties of pristine and defected Ge-NSs before and after the exposure to the gases, which are essential in constituting a signal to be detected by the external circuit of the sensor. We strongly believe that our present work would not only advance the knowledge towards the application of Ge-NS-based sensing but also provide motivation for the synthesis of such efficient nanosensor for H2S and SO2 based on Ge monolayer.

  • 39.
    Hussain, Tanveer
    et al.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia..
    Kaewmaraya, Thanayut
    Khon Kaen Univ, Dept Phys, Integrated Nanotechnol Res Ctr, Khon Kaen, Thailand..
    Khan, Mehwish
    Univ Vet & Anim Sci, Dept Pharmacol & Toxicol, Lahore 55000, Pakistan..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Islam, Muhammad Shafiq
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Amornkitbamrung, Vittaya
    Khon Kaen Univ, Dept Phys, Integrated Nanotechnol Res Ctr, Khon Kaen, Thailand.;Nanotec KKU Ctr Excellence Adv Nanomat Energy Pro, Khon Kaen, Thailand..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Improved sensing characteristics of methane over ZnO nano sheets upon implanting defects and foreign atoms substitution2017In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 41, article id 415502Article in journal (Refereed)
    Abstract [en]

    Thanks to the growing interests of metal oxide sensors in environmental and industrial uses, this study presents the sensing mechanism of methane gas (CH4) on recently synthesized two-dimensional form of ZnO, ZnO nano sheets (ZnO-NS). The adsorption energy of CH4 on pristine ZnO-NS, calculated by means of van derWaals corrected first-principles calculations, is found to be insufficient restricting its application as an efficient nano sensor. However, the creation of (O/Zn) vacancies and the substitution of foreign dopants into ZnO-NS considerably intensify the binding energy of CH4. Through a comprehensive energetic analysis, it is observed that among all the substituents, boron (B), sulphur (S) and gallium (Ga) improves the binding of CH4 to 2.75, 6.1 and 7.5 times respectively than its values on pristine ZnO-NS. In addition to the CH4 binding energies falling ideally between physisorption and chemisorption range, a prominent variation in the electronic properties before and after CH4 exposure indicates the promise of substituted Zn-NS as a useful nano sensors.

  • 40.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Maark, Tuhina Adit
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Improvement in Hydrogen Desorption from - and -MgH2 upon Transition-Metal Doping2015In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 16, no 12, p. 2557-2561Article in journal (Refereed)
    Abstract [en]

    A thorough study of the structural, electronic, and hydrogen-desorption properties of - and -MgH2 phases substituted by selected transition metals (TMs) is performed through first-principles calculations based on density functional theory (DFT). The TMs considered herein include Sc, V, Fe, Co, Ni, Cu, Y, Zr, and Nb, which substitute for Mg at a doping concentration of 3.125% in both the hydrides. This insertion of TMs causes a variation in the cell volumes of - and -MgH2. The majority of the TM dopants decrease the lattice constants, with Ni resulting in the largest reduction. From the formation-energy calculations, it is predicted that except for Cu and Ni, the mixing of all the selected TM dopants with the MgH2 phases is exothermic. The selected TMs also influence the stability of both - and -MgH2 and cause destabilization by weakening the MgH bonds. Our results show that doping with certain TMs can facilitate desorption of hydrogen from - and -MgH2 at much lower temperatures than from their pure forms. The hydrogen adsorption strengths are also studied by density-of-states analysis.

  • 41.
    Johansson, Malin B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Phuyal, Dibya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Cameau, Mathis
    Zhu, Huimin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cesium bismuth iodide, CsxBiyIz, solar cell compounds from systematic molar ratio variationManuscript (preprint) (Other academic)
  • 42.
    Johansson, Malin B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Phuyal, Dibya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Cameau, Mathis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Zhu, Huimin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ahuja, Rajeev
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter TRoyal Inst Technol, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cesium Bismuth Iodide Solar Cells from Systematic Molar Ratio Variation of CsI and BiI32019In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 18, p. 12040-12052Article in journal (Refereed)
    Abstract [en]

    Metal halide compounds with photovoltaic properties prepared from solution have received increased attention for utilization in solar cells. In this work, low-toxicity cesium bismuth iodides are synthesized from solution, and their photovoltaic and, optical properties as well as electronic and crystal structures are investigated. The X-ray diffraction patterns reveal that a CsI/BiI3 precursor ratio of 1.5:1 can convert pure rhombohedral BiI3 to pure hexagonal Cs3Bi2I9, but any ratio intermediate of this stoichiometry and pure BiI3 yields a mixture containing the two crystalline phases Cs3Bi2I9 and BiI3, with their relative fraction depending on the CsI/BiI3 ratio. Solar cells from the series of compounds are characterized, showing the highest efficiency for the compounds with a mixture of the two structures. The energies of the valence band edge were estimated using hard and soft X-ray photoelectron spectroscopy for more bulk and surface electronic properties, respectively. On the basis of these measurements, together with UV-vis-near-IR spectrophotometry, measuring the band gap, and Kelvin probe measurements for estimating the work function, an approximate energy diagram has been compiled clarifying the relationship between the positions of the valence and conduction band edges and the Fermi level.

  • 43.
    Kanhere, Pushkar
    et al.
    Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rupp, Caroline J.
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Chen, Zhong
    Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore..
    Substitution induced band structure shape tuning in hybrid perovskites (CH3NH3Pb1-xSnxI3) for efficient solar cell applications2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 130, p. 107497-107502Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic hybrid perovskite compounds such as CH3NH3PbI3 hold a great potential for low cost photovoltaic devices. Though CH3NH3PbI3 possesses fundamental properties favorable for solar energy harvesting, environmentally safe materials with higher energy efficiency are needed for practical applications. Replacement of lead by tin is a promising solution and investigating the fundamental properties of lead and tin mixed halides is essential. In this article, we have reported electronic and optical properties by employing Density Functional Theory based first principles calculations of Sn doped methyl ammonium lead halide, CH3NH3Pb1-xSnxI3 (x = 0, 0.25, 0.5, 0.75, 1.0). Our results reveal that tin doping narrows the optical band gap allowing absorption of visible light up to 850 nm. Tin doping at Pb sites primarily affects the composition and nature of the valence band maximum. Tin 5p induced electronic states are highly delocalized in nature and are likely to improve the mobility and possible exciton diffusion lengths of holes. Based on the results of this study, 50% Sn doping could to be useful for enhanced performance of perovskite based photovoltaics.

  • 44. Kanhere, Pushkar
    et al.
    Shenai, Prathamesh
    Chakraborty, Sudip
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Zheng, Jianwei
    Chen, Zhong
    Mono- and co-doped NaTaO3 for visible light photocatalysis2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 30, p. 16085-16094Article in journal (Refereed)
    Abstract [en]

    Electronic structures of doped NaTaO3 compounds are of significant interest to visible light photocatalysis. This work involves the study of the band gap, band edge potentials, and thermodynamic stability of certain mono-doped and co-doped NaTaO3 systems, using DFT-PBE as well as hybrid (PBE0) functional calculations. Doping of certain non-magnetic cations (Ti, V, Cu, Zn, W, In, Sn, Sb, Ce, and La), certain anions (N, C, and I), and certain co-dopant pairs (W-Ti, W-Ce, N-I, N-W, La-C, Pb-I, and Cu-Sn) is investigated. Our calculations suggest that substitutional doping of Cu at the Ta site, Cu at the Na site, and C at the O site narrows the band gap of NaTaO3 to 2.3, 2.8, and 2.1 eV, respectively, inducing visible light absorption. Additionally, passivated co-doping of Pb-I and N-W narrows the band gap of NaTaO3 to the visible region, while maintaining the band potentials at favorable positions. Hybrid density of states (DOS) accurately describe the effective band potentials and the location of mid-gap states, which shed light on the possible mechanism of photoexcitation in relation to the photocatalysis reactions. Furthermore, the thermodynamic stability of the doped systems and defect pair binding energies of co-doped systems are discussed in detail. The present results provide useful insights into designing new photocatalysts based on NaTaO3.

  • 45.
    Klaa, Kaltoum
    et al.
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria;Badji Mokhtar Univ, Dept Phys, LEREC Lab, Annaba, Algeria.
    Labidi, Salima
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Labidi, Malika
    Badji Mokhtar Univ, Dept Phys, LNCTS Lab, Annaba, Algeria.
    Amara, Abdelaziz
    Badji Mokhtar Univ, Dept Phys, LEREC Lab, Annaba, Algeria.
    Bououdina, Mohamed
    Univ Bahrain, Coll Sci, Dept Phys, POB Box 32038, Zallaq, Bahrain.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat, S-10044 Stockholm, Sweden.
    Composition dependent tuning of electronic and magnetic properties in transition metal substituted Rock-salt MgO2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 475, p. 44-53Article in journal (Refereed)
    Abstract [en]

    Full potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT) is used to investigate the structural, electronic and magnetic properties of Fe and Ni (3d transition metal) substituted Rock-salt wide band gap insulator Mg1-xMxO (M = Fe, Ni). We have performed spin polarized calculations throughout this work with generalized gradient approximation (GGA) type exchange correlation functional. Additionally, the electronic structures and density of states are computed using modified Becke-Johnson (mBJ) potential based approximation with the inclusion of coulomb energy (U = 7 eV). Based on the Vegard's law and structural optimization, the lattice parameter and bulk modulus are found to be in good agreement with experimental values. Moreover, the analysis of electronic band structures reveals an insulating character for Ni substituted MgO while semiconducting and half-metallic character for Fe substituted case. It has been found that the p-d super-exchange interaction provides a ferromagnetic character due to the 3d transition metal impurities and oxygen atom. The observed p-d hybridization at the top of the valence band edge in this investigations could be useful for magneto-optic and spintronic applications.

  • 46. Kotmool, Komsilp
    et al.
    Bovornratanaraks, Thiti
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    The effect of morphology and confinement on the high-pressure phase transition in ZnO nanostructure2015In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, no 11, article id 114309Article in journal (Refereed)
    Abstract [en]

    The transition pressure (Pt) of the B4-to-B1 phase transformation of zinc oxide nanoparticle (n-ZnO) structures was investigated in terms of their size and morphology. Nanorods, nanopencils, nanopyramids, nanowires, and nanotubes of the B4 phase in various sizes were directly built up by accounting for the atomic basis of the core and surface regions. The previously proposed transformation path was performed for constructing shapes and sizes compatible with B1 phases. Using systematic density functional theory, the surfaces were cleaved from the optimized crystal structures at different pressures in both the B4 and B1 phases. A method for calculating the surface energy at different pressures is proposed using an asymmetric slab model. Using the proposed model, the transition pressure of n-ZnO structures was found to significantly depend on their morphology and size, which is in good agreement with the available experimental reports.  

  • 47.
    Kotmool, Komsilp
    et al.
    Mahidol Wittayanusorn Sch, Dept Phys, Nakhon Pathom 73170, Thailand.;Thailand Ctr Excellence Phys, Commiss Higher Educ, Bangkok 10400, Thailand..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bovornratanaraks, Thiti
    Thailand Ctr Excellence Phys, Commiss Higher Educ, Bangkok 10400, Thailand.;Chulalongkorn Univ, Fac Sci, Dept Phys, ECPRL, Bangkok 10330, Thailand..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Role of relativity in high-pressure phase transitions of thallium2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 42983Article in journal (Refereed)
    Abstract [en]

    We demonstrate the relativistic effects in high-pressure phase transitions of heavy element thallium. The known first phase transition from h. c. p. to f. c. c. is initially investigated by various relativistic levels and exchange-correlation functionals as implemented in FPLO method, as well as scalar relativistic scheme within PAW formalism. The electronic structure calculations are interpreted from the perspective of energetic stability and electronic density of states. The full relativistic scheme (FR) within L(S) DA performs to be the scheme that resembles mostly with experimental results with a transition pressure of 3 GPa. The s-p hybridization and the valence-core overlapping of 6s and 5d states are the primary reasons behind the f. c. c. phase occurrence. A recent proposed phase, i. e., a body-centered tetragonal (b. c. t.) phase, is confirmed with a small distortion from the f. c. c. phase. We have also predicted a reversible b. c. t. -> f. c. c. phase transition at 800 GPa. This finding has been suggested that almost all the III-A elements (Ga, In and Tl) exhibit the b. c. t. -> f. c. c. phase transition at extremely high pressure.

  • 48. Kotmool, Komsilp
    et al.
    Kaewmaraya, Thanayut
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Anversa, Jonas
    Bovornratanaraks, Thiti
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Gou, Huiyang
    Piquini, Paulo Cesar
    Kang, Tae Won
    Mao, Ho-Kwang
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Revealing an unusual transparent phase of superhard iron tetraboride under high pressure2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 48, p. 17050-17053Article in journal (Refereed)
    Abstract [en]

    First principles-based electronic structure calculations of super-hard iron tetraboride (FeB4) under high pressure have been undertaken in this study. Starting with a "conventional" superconducting phase of this material under high pressure leads to an unexpected phase transition toward a semiconducting one. This transition occurred at 53.7 GPa, and this pressure acts as a demarcation between two distinct crystal symmetries, metallic orthorhombic and semiconducting tetragonal phases, with Pnnm and I4(1)/acd space groups, respectively. In this work, the electron-phonon coupling-derived superconducting T-c has been determined up to 60 GPa and along with optical band gap variation with increasing pressure up to 300 GPa. The dynamic stability has been confirmed by phonon dispersion calculations throughout this study.

  • 49.
    Krishnamurthy, Shrreya
    et al.
    IISER, Dept Phys, Pune 411008, Maharashtra, India;IISER, Ctr Energy Sci, Pune 411008, Maharashtra, India;Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.
    Kour, Prachi
    IISER, Dept Phys, Pune 411008, Maharashtra, India;IISER, Ctr Energy Sci, Pune 411008, Maharashtra, India.
    Katre, Ankita
    CEA Grenoble, LITEN Grp, 17 Ave Martyrs, F-38054 Grenoble 9, France.
    Gosavi, Suresh
    Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ogale, Satishchandra
    Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.
    Cystamine-configured lead halide based 2D hybrid molecular crystal: synthesis and photoluminescence systematics2018In: APL MATERIALS, ISSN 2166-532X, Vol. 6, no 11, article id 114204Article in journal (Refereed)
    Abstract [en]

    We have synthesized and studied a specific family of disulfide bridge based 2D organic inorganic hybrid perovskites using the cation, cystamine [2,2'-dithiobis(ethylammonium), abbreviated as SS] in the three lead halide (X = I, Br, and Cl) based systems, and explored their unique photo-physical properties. Green, blue, and white emissions are noted in I, Br, and Cl based systems, respectively. The experimental observations are compared with the results of first principles DFT calculations. The role of the halide ion (X) in the [Pb-X-4] cages on the luminescence of the disulfide bridge based hybrid system is elucidated, and the corresponding systematics are analyzed.

  • 50.
    Krishnamurthy, Shrreya
    et al.
    Indian Inst Sci Educ & Res, Ctr Energy Sci, Dept Phys, Doctor Homi Bhabha Rd, Pune 411008, Maharashtra, India;Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.
    Naphade, Rounak
    Indian Inst Sci Educ & Res, Ctr Energy Sci, Dept Phys, Doctor Homi Bhabha Rd, Pune 411008, Maharashtra, India.
    Mir, Wasim J.
    Indian Inst Sci Educ & Res, Ctr Energy Sci, Dept Chem, Doctor Homi Bhabha Rd, Pune 411008, Maharashtra, India.
    Gosavi, Suresh
    Savitribai Phule Pune Univ, Dept Phys, Pune 411007, Maharashtra, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Vaidhyanathan, Ramanathan
    Indian Inst Sci Educ & Res, Ctr Energy Sci, Dept Chem, Doctor Homi Bhabha Rd, Pune 411008, Maharashtra, India.
    Ogale, Satishchandra
    Indian Inst Sci Educ & Res, Ctr Energy Sci, Dept Phys, Doctor Homi Bhabha Rd, Pune 411008, Maharashtra, India.
    Molecular and Self-Trapped Excitonic Contributions to the Broadband Luminescence in Diamine-Based Low-Dimensional Hybrid Perovskite Systems2018In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, no 20, article id 1800751Article in journal (Refereed)
    Abstract [en]

    The present solid state lighting (SSL) technology is based on using a combination of phosphors to give the desired white light emitting devices. The property of broadband emission from a single phosphor is not only difficult to achieve but also poses a challenge in device fabrication. Hybrid organic-inorganic perovskites especially in low dimensions (2D/1D) are being widely explored for their optoelectronic properties. Few of these materials exhibit broadband emission upon ultraviolet excitation, providing a scope for synthetic engineering in achieving commercially viable single-phosphor materials. In this work, three interesting diammonium-based low-dimensional hybrid perovskites for broadband photoluminescence (PL) are examined. The doubly protonated ethylenediamine-configured monoclinic (P2(1)/n) 1D ribbon assembly (H3NCH2CH2NH3)(8)(Pb4Br18)Br-6 (1) and the orthorhombic (Pbcm) 2D-twisted octahedral (H3NCH2CH2NH3)(Pb2Cl6) (2) show white luminescence, while the doubly protonated piperazine-configured orthorhombic (Pnnm) 0D dual-octahedral (C4N2H12)(4)(Pb2Br11)(Br)(H2O)(4) (3) exhibits bluish-white luminescence. Based on the PL of the organic diammonium salt, the time-resolved PL, Raman signatures, and density functional theory (DFT) calculations, it is shown that the broadband luminescence has dual origin: one around 400 nm from diammonium-related molecular fluorescence and another around 516 nm from self-trapped excitons. The structure-specific relative contributions and interplay between the two define the overall character of the broadband luminescence.

12 1 - 50 of 80
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