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  • 9251.
    Zhang, Jinbao
    et al.
    Uppsala University.
    Hua, Yong
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Ctr Mol Devices, Organ Chem, SE-10044 Stockholm, Sweden.
    Xu, Bo
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Ctr Mol Devices, Organ Chem, SE-10044 Stockholm, Sweden.
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Liu, Peng
    KTH Royal Inst Technol, Dept Chem, Ctr Mol Devices, Appl Phys Chem, Teknikringen 30, SE-10044 Stockholm, Sweden.
    Johansson, Malin B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomolecular Sci, FSB,ISIC,LSPM, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland.
    Kloo, Lars
    KTH Royal Inst Technol, Dept Chem, Ctr Mol Devices, Appl Phys Chem, Teknikringen 30, SE-10044 Stockholm, Sweden.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sun, Licheng
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Ctr Mol Devices, Organ Chem, SE-10044 Stockholm, Sweden.
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomolecular Sci, FSB,ISIC,LSPM, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland.
    The Role of 3D Molecular Structural Control in New Hole Transport Materials Outperforming Spiro-OMeTAD in Perovskite Solar Cells2016Ingår i: Advanced Energy Materials, Vol. 6, nr 19, artikel-id 1601062Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents new hole-transport materials (HTMs) to replace the central spiro linkage inspiro-OMeTAD by a CC bond in H11 and CC double bond in H12. This structural change results in a facile synthetic process and a significant change in the molecular geometry. EmployingH11 as HTM in combination with mixed ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.85Br0.15)3, gives a solar cell power conversion efficiency of 19.8%.

  • 9252.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Monash Univ, Dept Mat Engn, Clayton, Vic 3800, Australia.
    Hultqvist, Adam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Tian
    Monash Univ, Dept Mat Engn, Clayton, Vic 3800, Australia.
    Jiang, Liangcong
    Monash Univ, Dept Mat Engn, Clayton, Vic 3800, Australia.
    Ruan, Changqing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Cheng, Yibing
    Monash Univ, Dept Mat Engn, Clayton, Vic 3800, Australia.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Johansson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Al2O3 Underlayer Prepared by Atomic Layer Deposition for Efficient Perovskite Solar Cells.2017Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 19, s. 3810-3817Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Perovskite solar cells, as an emergent technology for solar energy conversion, have attracted much attention in the solar cell community by demonstrating impressive enhancement in power conversion efficiencies. However, the high temperature and manually processed TiO2 underlayer prepared by spray pyrolysis significantly limit the large-scale application and device reproducibility of perovskite solar cells. In this study, lowtemperature atomic layer deposition (ALD) is used to prepare a compact Al2 O3 underlayer for perovskite solar cells. The thickness of the Al2 O3 layer can be controlled well by adjusting the deposition cycles during the ALD process. An optimal Al2 O3 layer effectively blocks electron recombination at the perovskite/fluorine-doped tin oxide interface and sufficiently transports electrons through tunneling. Perovskite solar cells fabricated with an Al2 O3 layer demonstrated a highest efficiency of 16.2 % for the sample with 50 ALD cycles (ca. 5 nm), which is a significant improvement over underlayer-free PSCs, which have a maximum efficiency of 11.0 %. Detailed characterization confirms that the thickness of the Al2 O3 underlayer significantly influences the charge transfer resistance and electron recombination processes in the devices. Furthermore, this work shows the feasibility of using a high band-gap semiconductor such as Al2 O3 as the underlayer in perovskite solar cells and opens up pathways to use ALD Al2 O3 underlayers for flexible solar cells.

  • 9253.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Häggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jouini, Mohamed
    Jarboui, Adel
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Solid-State Dye-Sensitized Solar Cells Based on Poly( 3,4ethylenedioxypyrrole) and Metal-Free Organic Dyes2014Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 15, nr 6, s. 1043-1047Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3,4-ethylenedioxypyrrole) (PEDOP), combined with metal-free organic sensitizers, is efficiently used for the first time as the hole-transporting material in solid-state dye-sensitized solar cells. Devices employing PEDOP as the hole conductor and D35 or D21 L6 as the sensitizer show a ten-times-higher energy-conversion efficiency (of 4.5% and 3.3%, respectively) compared to Ru-Z907-based devices. This is due to the efficient suppression of electron recombination.

  • 9254.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jarboui, Adel
    CNRS, Sorbonne Paris Cite, Inst Univ Paris Diderot Paris 7, ITODYS UMR 7086, F-75205 Paris 13, France..
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, FSB ISIC LSPM, CH-1015 Lausanne, Switzerland..
    Jouini, Mohamed
    CNRS, Sorbonne Paris Cite, Inst Univ Paris Diderot Paris 7, ITODYS UMR 7086, F-75205 Paris 13, France..
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, FSB ISIC LSPM, CH-1015 Lausanne, Switzerland.;King Abdulaziz Univ, Ctr Excellence Adv Mat Res, Jeddah 21589, Saudi Arabia..
    Photoelectrochemical Polymerization of EDOT for Solid State Dye Sensitized Solar Cells: Role of Dye and Solvent2015Ingår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, s. 220-227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aromatic-unit, commercially available, and cost-effective precursor 3, 4-ethylenedioxythiophene (EDOT), was employed instead of bis-EDOT to generate by in-situ photoelectrochemical polymerization (PEP) a conducting polymer-type hole conductor poly (3, 4-ethylenedioxythiophene) (PEDOT) for dye sensitized solar cell (DSC) devices. In order to conduct efficiently the PEP of EDOT, two electrolytic media, aqueous micellar and organic, and two Donor-pi-Acceptor sensitizers, were investigated. By using the electrolytic aqueous micellar medium, the PEP was efficient due to the low oxidation potential of the precursor in water. A DSC device based on PEDOT generated from aqueous PEP showed an energy conversion efficiency (eta) of 3.0% under 100 mWcm (2), higher by two orders of magnitude than that of a DSC device based on PEDOT from organic PEP (eta = 0.04%). The comparison of the properties of the as-obtained PEDOT polymers from aqueous and organic PEP by UV-VIS-NIR measurements shows the formation of PEDOT at a highly doped state from aqueous PEP. The thermodynamic and kinetic requirements for efficiency of PEP process in each medium are investigated and discussed on the basis of the light absorption abilities and electrochemical redox potentials measured for the two organic sensitizers.

  • 9255.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Simiyu, Justus
    Univ Nairobi, Dept Phys, POB 30197-00100, Nairobi, Kenya.
    Johansson, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Cheung, Ocean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Häggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    SB ISIC LSPM, Ecole Polytech Fed Lausanne, Lab Photomol Sci, Chemin Alamb,Stn 6,CH G1 523, CH-1015 Lausanne, Switzerland.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. SB ISIC LSPM, Ecole Polytech Fed Lausanne, Lab Photomol Sci, Chemin Alamb,Stn 6,CH G1 523, CH-1015 Lausanne, Switzerland.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    The effect of mesoporous TiO2 pore size on the performance of solid-state dye sensitized solar cells based on photoelectrochemically polymerized Poly(3,4-ethylenedioxythiophene) hole conductor2016Ingår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 210, s. 23-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photoelectrochemical polymerization of poly(3,4-ethylenedioxythiphene) (PEDOT) has recently been introduced and widely investigated for fabrication of the hole transporting material (HTM) in highly efficient solid state dye sensitized solar cells (sDSCs). In this work, the effects of the surface area and pore size of TiO2 film were for the first time investigated in the sDSCs employing the in-situ polymerizated PEDOT HTM. Three different varieties of mesoporous TiO2 particles with controllable surface area and pore size were synthesized through the basic route in order to study the corresponding sDSC photovoltaic performances. It was found that the pore size plays an important role in the kinetics of the photoelectrochemical polymerization (PEP) process and the formation of the PEDOT capping layer. Larger pore sizes provided a more favourable pathway for the precursor diffusion through the mesoporous pores during the PEP process, which contributed towards a more efficient PEP. However, the interfacial contact area between the formed polymer and the dyes on the surface of TiO2 particle would be lower in the case of larger pore sizes, which consequently caused a less efficient dye regeneration process. Electronic diffusion on the other hand was improved for larger particle sizes. Employing an organic dye LEG4 and the self-made TiO2 with an optimal pore size of 25 nm and particle size of 24 nm, the sDSCs showed a promising power conversion efficiency (PCE) of 5.2%, higher than 4.5% for the commercial TiO2 Dyesol DSL-30. By measuring the dye regeneration yield and the kinetics through photoinduced absorption, it was observed that the homemade TiO2 based device had more efficient dye regeneration compared to the Dyesol based device, which could result from the better interfacial contact between the PEDOT and the dye. This work provides important information on the effect of meso-pore size on sDSCs and points to the necessity of further photoanode optimization toward the enhancement of the PCE of polymeric hole conductor-based DSCs.

  • 9256.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, Chemin Alambics, CH-1015 Lausanne, Switzerland.
    Hao, Yan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Holcombe, Thomas W
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Swiss Fed Inst Technol,Stn 6, CH-1015 Lausanne, Switzerland.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Grätzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Swiss Fed Inst Technol,Stn 6, CH-1015 Lausanne, Switzerland.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, Chemin Alambics, CH-1015 Lausanne, Switzerland.
    Efficient Blue-Colored Solid-State Dye-Sensitized Solar Cells: Enhanced Charge Collection by Using an in Situ Photoelectrochemically Generated Conducting Polymer Hole Conductor.2016Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 17, nr 10, s. 1441-1445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A high power conversion efficiency (PCE) of 5.5 % was achieved by efficiently incorporating a diketopyrrolopyrrole-based dye with a conducting polymer poly(3,4-ethylenediothiophene) (PEDOT) hole-transporting material (HTM) that was formed in situ, compared with a PCE of 2.9 % for small molecular spiro-OMeTAD-based solid-state dye solar cells (sDSCs). The high PCE for PEDOT-based sDSCs is mainly attributed to the significantly enhanced charge-collection efficiency, as a result of the three-order-of-magnitude higher hole conductivity (0.53 S cm(-1) ) compared with that of the widely used low molecular weight HTM spiro-OMeTAD (3.5×10(-4)  S cm(-1) ).

  • 9257.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, EPFL FSB ISIC LSPM, Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland..
    Jouini, Mohamed
    Inst Univ Paris Diderot Paris 7, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Johansson, Malin B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Xiaoliang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Nazeeruddin, Mohammad Khaja
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Grp Mol Engn Funct Mat, CH-1015 Lausanne, Switzerland..
    Boschloo, Gerrit
    Uppsala Univ, Angstrom Lab, Dept Chem, Phys Chem,Ctr Mol Devices, SE-75120 Uppsala, Sweden..
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, EPFL FSB ISIC LSPM, Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland.;King Abdulaziz Univ, Ctr Excellence Adv Mat Res, Jeddah 21589, Saudi Arabia..
    Efficient solid-state dye sensitized solar cells: The influence of dye molecular structures for the in-situ photoelectrochemically polymerized PEDOT as hole transporting material2016Ingår i: NANO ENERGY, ISSN 2211-2855, Vol. 19, s. 455-470Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid-state dye sensitized solar cells (sDSCs) with organic small molecule hole transporting materials (HTMs) have limited efficiencies due to the incomplete pore filling of the HTMs in the thick mesoporous electrodes and the low hole conductivity of HTMs. Hereby, highly efficient sDSCs with power conversion efficiency of 7.11% and record photocurrent of 13.4 mA cm-2 are reported, prepared by effectively incorporating in-situ photoelectrochemically polymerized PEDOT as HTM in combination with a multifunctional organic, metal-free dye. In order to fundamentally understand how the dye molecules affect the photoelectrochemical polymerization (PEP), the properties of the generated PEDOT and the photovoltaic performance, sDSCs based on a series of dyes are systematically investigated. Detailed comparative studies reveal that the difference between the dye redox potential and monomer onset oxidation potential plays a crucial role in the PEP kinetics and the doping density of PEDOT HTM. The structure of the dyes, functioning as an electron blocking layer, affects the charge recombination at the TiO2/dye/PEDOT interface. The analysis shows that a donor-n-acceptor dye with well-tuned energy levels and bulky structure results in an in-situ electrochemically doped PEDOT HTM with a high hole conductivity (2.0 S cm(-1)) in sDSCs, leading to efficient dye regeneration and photocharge collection. It is hoped that this work will further encourage research on the future design of new dye molecules for an efficient PEP in order to further enhance the photovoltaic performance of solid-state dye sensitized solar cells.

  • 9258.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Xu, Bo
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Organ Chem, Ctr Mol Devices, SE-10044 Stockholm, Sweden..
    Johansson, Malin B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hadadian, Mahboubeh
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Lab Photomol Sci, Inst Chem Sci & Engn, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland.;Ferdowsi Univ Mashhad, Dept Chem, Mashhad 91779, Iran..
    Baena, Juan Pablo Correa
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Lab Photomol Sci, Inst Chem Sci & Engn, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland..
    Liu, Peng
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, Teknikringen 30, SE-10044 Stockholm, Sweden..
    Hua, Yong
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Organ Chem, Ctr Mol Devices, SE-10044 Stockholm, Sweden..
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Lab Photomol Sci, Inst Chem Sci & Engn, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland..
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sun, Licheng
    KTH Royal Inst Technol, Dept Chem Chem Sci & Engn, Organ Chem, Ctr Mol Devices, SE-10044 Stockholm, Sweden..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Lab Photomol Sci, Inst Chem Sci & Engn, Chemin Alambics Stn 6, CH-1015 Lausanne, Switzerland..
    Constructive Effects of Alkyl Chains: A Strategy to Design Simple and Non-Spiro Hole Transporting Materials for High-Efficiency Mixed-Ion Perovskite Solar Cells2016Ingår i: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 6, nr 13, artikel-id 1502536Artikel i tidskrift (Refereegranskat)
  • 9259.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Xu, Bo
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem Chem Sci & Engn, Organ Chem, SE-10044 Stockholm, Sweden.
    Johansson, Malin B
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, EPFL FSB ISIC LSPM, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sun, Licheng
    KTH Royal Inst Technol, Ctr Mol Devices, Dept Chem Chem Sci & Engn, Organ Chem, SE-10044 Stockholm, Sweden.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, EPFL FSB ISIC LSPM, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Strategy to Boost the Efficiency of Mixed-Ion Perovskite Solar Cells: Changing Geometry of the Hole Transporting Material.2016Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, nr 7, s. 6816-6825Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hole transporting material (HTM) is an essential component in perovskite solar cells (PSCs) for efficient extraction and collection of the photoinduced charges. Triphenylamine- and carbazole-based derivatives have extensively been explored as alternative and economical HTMs for PSCs. However, the improvement of their power conversion efficiency (PCE), as well as further investigation of the relationship between the chemical structure of the HTMs and the photovoltaic performance, is imperatively needed. In this respect, a simple carbazole-based HTM X25 was designed on the basis of a reference HTM, triphenylamine-based X2, by simply linking two neighboring phenyl groups in a triphenylamine unit through a carbon-carbon single bond. It was found that a lowered highest occupied molecular orbital (HOMO) energy level was obtained for X25 compared to that of X2. Besides, the carbazole moiety in X25 improved the molecular planarity as well as conductivity property in comparison with the triphenylamine unit in X2. Utilizing the HTM X25 in a solar cell with mixed-ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.85Br0.15)3, a highest reported PCE of 17.4% at 1 sun (18.9% under 0.46 sun) for carbazole-based HTM in PSCs was achieved, in comparison of a PCE of 14.7% for triphenylamine-based HTM X2. From the steady-state photoluminescence and transient photocurrent/photovoltage measurements, we conclude that (1) the lowered HOMO level for X25 compared to X2 favored a higher open-circuit voltage (Voc) in PSCs; (2) a more uniform formation of X25 capping layer than X2 on the surface of perovskite resulted in more efficient hole transport and charge extraction in the devices. In addition, the long-term stability of PSCs with X25 is significantly enhanced compared to X2 due to its good uniformity of HTM layer and thus complete coverage on the perovskite. The results provide important information to further develop simple and efficient small molecular HTMs applied in solar cells.

  • 9260.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Xu, Bo
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, Organ Chem,Ctr Mol Devices, SE-10044 Stockholm, Sweden..
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Mingorance, Alba
    CSIC, Catalan Inst Nanosci & Nanotechnol ICN2, Campus UAB, Barcelona 08193, Spain.;Barcelona Inst Sci & Technol, Campus UAB, Barcelona 08193, Spain..
    Ruan, Changqing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Hua, Yong
    KTH Royal Inst Technol, Dept Chem, Ctr Mol Devices, Appl Phys Chem, Teknikringen 30, SE-10044 Stockholm, Sweden..
    Wang, Linqin
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, Organ Chem,Ctr Mol Devices, SE-10044 Stockholm, Sweden..
    Vlachopoulos, Nick
    EPFL FSB ISIC LSPM, Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Lira-Cantu, Monica
    CSIC, Catalan Inst Nanosci & Nanotechnol ICN2, Campus UAB, Barcelona 08193, Spain.;Barcelona Inst Sci & Technol, Campus UAB, Barcelona 08193, Spain..
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. EPFL FSB ISIC LSPM, Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, Organ Chem,Ctr Mol Devices, SE-10044 Stockholm, Sweden.;Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Johansson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Incorporation of Counter Ions in Organic Molecules: New Strategy in Developing Dopant-Free Hole Transport Materials for Efficient Mixed-Ion Perovskite Solar Cells2017Ingår i: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 7, nr 14, artikel-id 1602736Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hole transport matertial (HTM) as charge selective layer in perovskite solar cells (PSCs) plays an important role in achieving high power conversion efficiency (PCE). It is known that the dopants and additives are necessary in the HTM in order to improve the hole conductivity of the HTM as well as to obtain high efficiency in PSCs, but the additives can potentially induce device instability and poor device reproducibility. In this work a new strategy to design dopant-free HTMs has been presented by modifying the HTM to include charged moieties which are accompanied with counter ions. The device based on this ionic HTM X44 dos not need any additional doping and the device shows an impressive PCE of 16.2%. Detailed characterization suggests that the incorporated counter ions in X44 can significantly affect the hole conductivity and the homogeneity of the formed HTM thin film. The superior photovoltaic performance for X44 is attributed to both efficient hole transport and effective interfacial hole transfer in the solar cell device. This work provides important insights as regards the future design of new and efficient dopant free HTMs for photovotaics or other optoelectronic applications.

  • 9261.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Xu, Bo
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ruan, Changqing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Wang, Linqin
    Liu, Peng
    Zhang, Wei
    Vlachopoulos, Nick
    Kloo, Lars
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sun, Licheng
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, FSB ISIC LSPM,Stn 6, Chemin Alamb, CH-1015 Lausanne, Switzerland.
    Johansson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    The Importance of Pendant Groups on Triphenylamine-Based Hole Transport Materials for Obtaining Perovskite Solar Cells with over 20% Efficiency2018Ingår i: Advanced Energy Materials, ISSN 1614-6832, Vol. 18, nr 2, artikel-id 1701209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tremendous progress has recently been achieved in the field of perovskite solar cells (PSCs) as evidenced by impressive power conversion efficiencies (PCEs); but the high PCEs of >20% in PSCs has so far been mostly achieved by using the hole transport material (HTM) spiro-OMeTAD; however, the relatively low conductivity and high cost of spiro-OMeTAD significantly limit its potential use in large-scale applications. In this work, two new organic molecules with spiro[fluorene-9,9-xanthene] (SFX)-based pendant groups, X26 and X36, have been developed as HTMs. Both X26 and X36 present facile syntheses with high yields. It is found that the introduced SFX pendant groups in triphenylamine-based molecules show significant influence on the conductivity, energy levels, and thin-film surface morphology. The use of X26 as HTM in PSCs yields a remarkable PCE of 20.2%. In addition, the X26-based devices show impressive stability maintaining a high PCE of 18.8% after 5 months of aging in controlled (20%) humidity in the dark. We believe that X26 with high device PCEs of >20% and simple synthesis show a great promise for future application in PSCs, and that it represents a useful design platform for designing new charge transport materials for optoelectronic applications.

  • 9262.
    Zhang, Jinbao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Yang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Shen, Yang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Park, Byung-Wook
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hao, Yan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Kloo, Lars
    Gabrielsson, Erik
    Sun, Licheng
    Jarboui, Adel
    Perruchot, Christian
    Jouini, Mohamed
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Poly(3,4-ethylenedioxythiophene) Hole-Transporting Material Generated by Photoelectrochemical Polymerization in Aqueous and Organic Medium for All-Solid-State Dye-Sensitized Solar Cells2014Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, nr 30, s. 16591-16601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We applied organic donor-pi-acceptor (D-pi-A) sensitizers for photoelectrochemical polymerization (PEP) because of their appropriate energy levels and high light absorption. The polymerized conducting polymer PEDOT was used as hole conductor in all-solid-state dye-sensitized solar cells (ssDSCs). By combination of the D-pi-A sensitizers and the generated PEDOT from PEP of bis-EDOT in acetonitrile, the resulting device showed an average power conversion efficiency of 5.6%. Furthermore, the PEP in aqueous micellar electrolytic medium was also employed because of the ability to decrease oxidation potential of the precursor, thereby making the polymerization process easier. The latter method is a cost-effective and environmentally friendly approach. Using as hole conductor the so-obtained PEDOT from PEP of bis-EDOT in aqueous electrolyte, the devices exhibited impressive power conversion efficiency of 5.2%. To compare the properties of the generated polymer from bis-EDOT in these two PEP methods, electron lifetime, photoinduced absorption (PIA) spectra, and UV-vis-NIR spectra were measured. The results showed that PEDOT from organic PEP exhibits a delocalized conformation with high conductivity and a smooth and compact morphology; a rough morphology with high porosity and polymer structure of relatively shorter chains was assumed to be obtained from aqueous PEP. Therefore, better dye regeneration but faster charge recombination was observed in the device based on PEDOT from aqueous PEP of bis-EDOT. Subsequently, to extend the aqueous PEP approach in consideration of the ability to decrease the oxidation potential of the precursor, the easily available precursor EDOT was for the first time used for PEP in aqueous medium in a variant of the aforementioned procedure, and the device based on the so-obtained PEDOT shows a more than 70-fold increase in efficiency, 3.0%, over that based on the polymer generated from EDOT by PEP in organic media. It was demonstrated that aqueous micellar PEP with EDOT as monomer is an efficient strategy for generation of conducting polymer hole-transporting materials.

  • 9263.
    Zhang, Jing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Biochemical Study and Technical Applications of Fungal Pectinase2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Pectinases are a group of enzymes produced by bacteria, fungi, higher plants and animals. Pectinases can modify and degrade pectins, a class of heterogeneous and multifunctional polysaccharides present in middle lamellae and primary cell walls of plants. Pectins have been showed to play diverse roles in cell physiology, growth, adhesion and separation. Pectinases are used technically in the processing of fiber production and fruit juice or wine making. We have studied the mechanisms and applications of pectinases, especially in retting, a microbiological process where bast fibers in flax and other bast fiber cultivars are released from each other and from the woody core.

    A strong correlation was found between the ability to perform retting and the degradation of sparsely esterified pectin, a substrate of polygalacturonase. This led to the conclusion that polygalacturonase plays a key role in the enzymatic retting of flax. We purified and characterized an extracellular polygalacturonase produced by Rhizopus oryzae, a very potent retting organism. The purified enzyme which appeared to be the single active component in retting, has non-methylated polygalacturonan as its preferred substrate. Peptide sequences indicate that the enzyme, like another polygalacturonase (EC. 3.2.1.15), belongs to glycosyl hydrolase family 28. It contains, however, an N-terminal sequence absent from other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium, Ralstonia solanacearum.

    Our finding that removal of calcium ions from the plant material by pre-incubation in dilute acid in enzymatic retting could reduce enzyme consumption by several orders of magnitude, improves the economical feasibility of the enzymatic retting process. Comparisons with different acids showed that the action was mainly pH dependent.

    Pectinases were employed as analytical tools in a study of stored wood discoloration and, together with cellulases, in a mechanical process for making pulp from flax and hemp in paper production.

    Delarbeten
    1. Polygalacturonase is the key component in enzymatic retting of flax
    Öppna denna publikation i ny flik eller fönster >>Polygalacturonase is the key component in enzymatic retting of flax
    2000 (Engelska)Ingår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 81, nr 1, s. 85-89Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting.

    Nyckelord
    flax, retting, polygalacturonase
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-93934 (URN)10.1016/S0168-1656(00)00286-8 (DOI)000088655800009 ()10936663 (PubMedID)
    Tillgänglig från: 2006-01-12 Skapad: 2006-01-12 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    2. The active component in the flax-retting system of the zygomycete Rhizopus oryzae sb is a family 28 polygalacturonase
    Öppna denna publikation i ny flik eller fönster >>The active component in the flax-retting system of the zygomycete Rhizopus oryzae sb is a family 28 polygalacturonase
    Visa övriga...
    2005 (Engelska)Ingår i: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 32, nr 10, s. 431-438Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The zygomycete Rhizopus oryzae sb is a very efficient organism for retting of flax, the initial microbiological step in the process of making linen. An extracellular polygalacturonase, when isolated could perform retting, and therefore probably is the key component in the retting system of R. oryzae. This was purified and characterized. The purified enzyme has a molecular mass of 37,436 Da from mass spectrometric determination, an isoelectric point of 8.4, and has non-methylated polygalacturonic acid as its preferred substrate. Peptide sequences indicate that the enzyme belongs to family 28, in similarity with other polygalacturonases (EC. 3.2.1.15). It contains, however an N-terminal sequence absent in other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium Ralstonia solanacearum. The biochemical background for the superior retting efficiency of R. oryzae sb is discussed.

    Nyckelord
    enzymatic retting, polygalacturonase, Rhizopus oryzae, pectin biodegradation, Ralstonia solanacearum
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-93935 (URN)10.1007/s10295-005-0014-y (DOI)16133102 (PubMedID)
    Tillgänglig från: 2006-01-12 Skapad: 2006-01-12 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    3. Effects of acidic media pre-incubation on flax enzyme retting efficiency
    Öppna denna publikation i ny flik eller fönster >>Effects of acidic media pre-incubation on flax enzyme retting efficiency
    Visa övriga...
    2003 (Engelska)Ingår i: Textile Research Journal 73(3): 263-267, Vol. 73, nr 3, s. 263-267Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-93936 (URN)
    Tillgänglig från: 2006-01-12 Skapad: 2006-01-12 Senast uppdaterad: 2011-02-15
    4. Enzymatic-mechanical pulping of bast fibers from flax and hemp
    Öppna denna publikation i ny flik eller fönster >>Enzymatic-mechanical pulping of bast fibers from flax and hemp
    Visa övriga...
    Ingår i: Cellulose Chemistry Technology 39 (1-2): 95-103Artikel i tidskrift (Refereegranskat) Published
    Identifikatorer
    urn:nbn:se:uu:diva-93937 (URN)
    Tillgänglig från: 2006-01-12 Skapad: 2006-01-12Bibliografiskt granskad
    5. Distribution and characterization of discolouring substances in Norway spruce (Picea abies L.Karst) pulp wood stored under water-sprinkling
    Öppna denna publikation i ny flik eller fönster >>Distribution and characterization of discolouring substances in Norway spruce (Picea abies L.Karst) pulp wood stored under water-sprinkling
    Visa övriga...
    2006 (Engelska)Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 60, nr 1, s. 93-98Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Discolouration of wood raw material during wet storage has a notable negative effect on the quality of the final product. In this study, fluorescence microscopy was used to investigate the spatial distribution of discolouring substances in water-sprinkled Norway spruce pulpwood. Water-sprinkled wood was characterised by the presence of discolouring substances on the pit membranes of wood cells. In vitro model studies on the interaction between a model bark substance (tannic acid) and torus constituents support the hypothesis that pectic structures facilitate the allocation of bark substances on pit membranes. Applied pectinase or tannase could not remove the discolouring substances from pit membranes. Manganese peroxidase had a minor but documented effect. The effect of manganese peroxidase, as well as HCl/vanillin labelling, indicated that the discolouring substance may be condensed tannins.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-93938 (URN)10.1515/HF.2006.016 (DOI)
    Tillgänglig från: 2006-01-12 Skapad: 2006-01-12 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
  • 9264.
    Zhang, Jing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Henriksson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Johansson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Polygalacturonase is the key component in enzymatic retting of flax2000Ingår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 81, nr 1, s. 85-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting.

  • 9265.
    Zhang, Jing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Henriksson, Hongbin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Szabo, Istvan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Henriksson, Gunnar
    Johansson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    The active component in the flax-retting system of the zygomycete Rhizopus oryzae sb is a family 28 polygalacturonase2005Ingår i: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 32, nr 10, s. 431-438Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The zygomycete Rhizopus oryzae sb is a very efficient organism for retting of flax, the initial microbiological step in the process of making linen. An extracellular polygalacturonase, when isolated could perform retting, and therefore probably is the key component in the retting system of R. oryzae. This was purified and characterized. The purified enzyme has a molecular mass of 37,436 Da from mass spectrometric determination, an isoelectric point of 8.4, and has non-methylated polygalacturonic acid as its preferred substrate. Peptide sequences indicate that the enzyme belongs to family 28, in similarity with other polygalacturonases (EC. 3.2.1.15). It contains, however an N-terminal sequence absent in other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium Ralstonia solanacearum. The biochemical background for the superior retting efficiency of R. oryzae sb is discussed.

  • 9266.
    Zhang, Jing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för naturvetenskaplig biokemi.
    Pettersson, Bert
    Akin, Danny
    Foulk, Jonn
    Johansson, Gunnar
    Henriksson, Gunnar
    Effects of acidic media pre-incubation on flax enzyme retting efficiency2003Ingår i: Textile Research Journal 73(3): 263-267, Vol. 73, nr 3, s. 263-267Artikel i tidskrift (Refereegranskat)
  • 9267.
    Zhang, Keliang
    et al.
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Zhang, Xudong
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    He, Wen
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Xu, Wangning
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Xu, Guogang
    Shandong Univ Sci & Technol, Coll Mat Sci & Engn, Qingdao 266590, Shandong, Peoples R China.
    Yi, Xinli
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Yang, Xuena
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Zhu, Jie-Fang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Rational design and kinetics study of flexible sodium-ion full batteries based on binder-free composite film electrodes2019Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 16, s. 9890-9902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A high-performance flexible sodium-ion full battery (FSIFB) is developed by using binder-free composite film (BFCF) electrodes without using conductive carbon and current collectors. Hard carbon fibers decorated with different electrochemical active materials are used as the supporting framework and 3D conductive network of FSIFBs for the first time. Different pre-sodiated anodes and the electrolyte additives are designed for well-matched FSIFBs. Using a porous Na3V2(PO4)(3) coated hard carbon fiber film with a mass loading of 2.34 mg cm(-2) as the cathode and a pre-sodiated graphene/SiC/hard carbon fiber film with a mass loading of 1.50 mg cm(-2) as the anode, an optimized FSIFB is designed. It delivers high output voltage (3.34 V), high energy density (234.1 W h kg(-1) at a high-current rate of 0.5 A g(-1)), ultralong cyclability (over 2905 cycles at 0.5 A g(-1) and 1000 cycles at 5 A g(-1)), and high coulombic efficiency (approaching 100%), which surpasses those of all FSIFBs reported so far. Furthermore, this FSIFB still maintains good electrochemical attributes even at serious bending states in water. The models of the solid electrolyte interphase behavior on the surface of electrodes in the FSIFB are studied by using EIS, and a reaction mechanism and an equivalent electrical circuit are proposed. We also provide the videos of the preparation process for a pouch-type FSIFB to demonstrate its simple operability and potential applications.

  • 9268.
    Zhang, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Exploring Electron Transfer Dynamics of Novel Dye Sensitized Photocathodes: Towards Solar Cells and Solar Fuels2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The design of dyes for NiO-based dye-sensitized solar cells (DSSCs) has drawn attention owing to their potential applications in photocatalysis and because they are indispensable for the development of tandem dye-sensitized solar cells. The understanding of the electron transfer mechanisms and dynamics is beneficial to guide further dye design and further improve the performance of photocathode in solar cells and solar fuel devices.

    Time-resolved spectroscopy techniques, especially femtosecond and nanosecond transient absorption spectroscopy, supply sufficient resolution to get insights into the charge transfer processes in p-type dye sensitized solar cell and solar fuel devices. In paper I-V, several kinds of novel organic “push-pull” and inorganic charge transfer dyes for sensitization of p-type NiO, were systematically investigated by time-resolved spectroscopy, and photo-induced charge transfer dynamics of the organic/inorganic dyes were summarized. The excited state and reduced state intermediates were investigated in solution phase as references to confirm the charge injection and recombination on the NiO surface. The charge recombination kinetics is remarkably heterogeneous in some cases occurring on time scales spanning at least six orders of magnitude even for the same dye.

    In this thesis, we also proposed a novel concept of solid state p-type dye sensitized solar cells (p-ssDSSCs) for the first time (paper VI), using an organic dye P1 as sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as electron conductor. Femtosecond and nanosecond transient absorption spectroscopy gave evidence for sub-ps hole injection from excited P1 to NiO, followed by electron transfer from P1●- to PCBM. The p-ssDSSCs device showed an impressive 620 mV open circuit photovoltage.

    Chapter 6 (paper VII) covers the study of electron transfer mechanisms in a covalently linked dye-catalyst (PB-2) sensitized NiO photocathode, towards hydrogen producing solar fuel devices. Hole injection from excited dye (PB-2*) into NiO VB takes place on dual time scales, and the reduced PB-2 (PB-2●-) formed then donates an electron to the catalyst unit.  The subsequent regeneration efficiency of PB-2 by the catalyst unit (the efficiency of catalyst reduction) is determined to ca. 70%.

    Delarbeten
    1. Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells
    Öppna denna publikation i ny flik eller fönster >>Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells
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    2016 (Engelska)Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, s. 18515-18527Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In a photophysical study, two diketopyrrolopyrrole (DPP)-based sensitizers functionalized with4-thiophenecarboxylic acid as an anchoring group and a bromo (DPPBr) or dicyanovinyl (DPPCN2)group, and a dyad consisting of a DPP unit linked to a naphthalenediimide group (DPP–NDI), wereinvestigated both in solution and grafted on mesoporous NiO films. Femtosecond transient absorptionmeasurements indicate that ultrafast hole injection occurred predominantly on a timescale of B200 fs,whereas the subsequent charge recombination occurred on a surprisingly wide range of timescales,from tens of ps to tens of ms; this kinetic heterogeneity is much greater than is typically observed fordye-sensitized TiO2 or ZnO. Also, in contrast to what is typically observed for dye-sensitized TiO2, therewas no significant dependence on the excitation power of the recombination kinetics, which can beexplained by the hole density being comparatively higher near the valence band of NiO beforeexcitation. The additional acceptor group in DPP–NDI provided a rapid electron shift and stabilizedcharge separation up to the ms timescale. This enabled efficient (B95%) regeneration of NDI bya CoIII(dtb)3 electrolyte (dtb = 4,40-di-tert-butyl-2,20-bipyridine), according to transient absorptionmeasurements. The regeneration of DPPBr and DPPCN2 by CoIII(dtb)3 was instead inefficient, as mostrecombination for these dyes occurred on the sub-ns timescale. The transient spectroscopy data thuscorroborated the trend of the published photovoltaic properties of dye-sensitized solar cells (DSSCs)based on these dyes on mesoporous NiO, and show the potential of a design strategy with a secondaryacceptor bound to the dye. The study identifies rapid initial recombination between the dye and NiO asthe main obstacle to obtaining high efficiencies in NiO-based DSSCs; these recombination componentsmay be overlooked when studies are conducted using only methods with ns resolution or slower.

    Nyckelord
    Ultrafast, pDSSCs, Charge recombination
    Nationell ämneskategori
    Fysikalisk kemi
    Forskningsämne
    Kemi med inriktning mot fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-300147 (URN)10.1039/c6cp01762b (DOI)000379486200081 ()27338174 (PubMedID)
    Forskningsfinansiär
    EnergimyndighetenKnut och Alice Wallenbergs Stiftelse
    Tillgänglig från: 2016-08-03 Skapad: 2016-08-03 Senast uppdaterad: 2017-11-28Bibliografiskt granskad
    2. Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells
    Öppna denna publikation i ny flik eller fönster >>Second Generation of DiketopyrrolopyrroleDyes for NiO based Dye-Sensitized Solar Cells
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    2016 (Engelska)Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 15, s. 7923-7940Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study, four new diketopyrrolopyrrole (DPP) sensitizers, with a dicarboxylated triphenylamine anchoring group for attachment to NiO, were prepared and their electronic absorption, emission and electrochemical properties were recorded. The nature of the electronic excited-states was also modeled with TD-DFT quantum chemistry calculations. The photovoltaic performances of these new dyes were characterized in NiO-based dye-sensitized solar cells (DSCs) with the classical iodide/triiodide and cobaltII/III-polypyridine electrolytes, in which they proved to be quite active. Laser spectroscopy on dye/NiO/electrolyte films gave evidence for ultrafast hole injection into NiO (0.2-10 ps time scales). For the dyes with an appended naphtalenediimide (NDI) acceptor unit, ultrafast electron transfer to the NDI dramatically prolonged the lifetime of the charge separated state NiO(+)/dye-, from the ps time scale to an average lifetime ≈ 0.25 ms, which is among the slowest charge recombinations ever reported for dye/NiO systems. This allowed for efficient regeneration by CoIIIpolypyridine electrolytes, which translated into much improved PV-performance compared to the DPP dyes without appended NDI. Overall, these results underscore the suitability of DPP as sensitizers for NiO-based photoelectrochemical devices for photovoltaic and photocatalysis.

    Nationell ämneskategori
    Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-280841 (URN)10.1021/acs.jpcc.5b12489 (DOI)000374811100004 ()
    Forskningsfinansiär
    EU, Europeiska forskningsrådet, Marches -278845Knut och Alice Wallenbergs StiftelseEnergimyndighetenVetenskapsrådet
    Tillgänglig från: 2016-03-15 Skapad: 2016-03-15 Senast uppdaterad: 2017-11-30Bibliografiskt granskad
    3. A study of oligothiophene–acceptor dyes in p-type dye-sensitized solar cells
    Öppna denna publikation i ny flik eller fönster >>A study of oligothiophene–acceptor dyes in p-type dye-sensitized solar cells
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    2016 (Engelska)Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 22, s. 18165-18177Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Two new dyes, E1 and E2, equipped with triphenylamine as the electron donor, oligothiophene as the linkerand different electron acceptor groups, have been designed and synthesized as photosensitizers for p-typedye-sensitized solar cells (p-DSCs). A systematic study of the effect of molecular structures on the observedphotophysical properties, the electron/hole recombination process, the overall performance and theinterfacial charge separation was carried out. Transient absorption spectroscopy (TAS) shows that the E1dye with a napthoilene-1,2-benzimidazole (NBI) unit as the acceptor has a longer lifetime in the reducedstate than the E2 dye with a malononitrile subunit on the NiO surface.

    Nationell ämneskategori
    Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-280839 (URN)10.1039/c5ra26310g (DOI)000370717900043 ()
    Forskningsfinansiär
    VetenskapsrådetEnergimyndighetenKnut och Alice Wallenbergs StiftelseÅForsk (Ångpanneföreningens Forskningsstiftelse), 14-452Stiftelsen Olle Engkvist Byggmästare
    Tillgänglig från: 2016-03-15 Skapad: 2016-03-15 Senast uppdaterad: 2017-11-30
    4. Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes
    Öppna denna publikation i ny flik eller fönster >>Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes
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    2014 (Engelska)Ingår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, nr 13, s. 2254-2258Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Three new cyclometalated iridium complexes were prepared and investigated on nanocrystalline NiO cathodes. Nanosecond transient absorption spectroscopy experiments show they present a surprisingly slow geminate charge recombination upon excitation on NiO, representing thus the first examples of simple sensitizers with such feature. These complexes were used in dye-sensitized solar cells using nanocrystalline NiO film as semiconductor. The long-lived charge separated state of these Ir complexes make them compatible with other redox mediators than I-3(-)/I-, such as a cobalt electrolyte and enable to reach significantly high open circuit voltage.

    Nationell ämneskategori
    Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-230103 (URN)10.1021/jz5009714 (DOI)000338693200015 ()
    Tillgänglig från: 2014-09-01 Skapad: 2014-08-19 Senast uppdaterad: 2017-12-05
    5. Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells
    Öppna denna publikation i ny flik eller fönster >>Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells
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    2016 (Engelska)Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 81, s. 77184-77194Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Porphyrin dyes were synthesized for use in p-type (NiO) dye sensitized solar cells based on different designprinciples. One porphyrin was designed with a significant charge transfer character in the excited statebecause of push–pull effects of the substituents. Another porphyrin had instead an appended NDIacceptor group (NDI ¼ naphthalene diimide). The dyes were characterized by spectroscopic,electrochemical and DFT methods. Solar cells based on sensitized, meso-porous NiO showed ratherpoor performance compared to other organic dyes, but with a clear improvement for the dye with theNDI acceptor. Ultrafast transient absorption spectroscopy and nanosecond laser photolysis showed thathole injection into NiO was followed by unusually rapid charge recombination, predominantly ona 50–100 ps time scale, which is likely the main reason for the poor photovoltaic performance. Againthe porphyrin with the NDI group showed a more long-lived charge separation that should lead to betterdye regeneration in a solar cell, which can explain its better photovoltaic performance.

    Nyckelord
    porphyrins, electron transfer dynamics, NiO
    Nationell ämneskategori
    Fysikalisk kemi
    Forskningsämne
    Kemi med inriktning mot kemisk fysik
    Identifikatorer
    urn:nbn:se:uu:diva-301387 (URN)10.1039/c6ra15195g (DOI)000382482200011 ()
    Forskningsfinansiär
    EU, Europeiska forskningsrådet, Marches-278845Energimyndigheten
    Tillgänglig från: 2016-08-22 Skapad: 2016-08-22 Senast uppdaterad: 2017-11-28Bibliografiskt granskad
    6. Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism
    Öppna denna publikation i ny flik eller fönster >>Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism
    2016 (Engelska)Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 7, s. 5080-5085Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Solid state p-type dye-sensitized solar cells (p-ssDSCs) have been proposed and fabricated for the first time, using the organic dye P1 as the sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as the electron conductor. The p-ssDSC has shown an impressive open circuit photovoltage of 620 mV. Femtosecond and nanosecond transient absorption spectroscopy has given evidence for sub-ps hole injection from the excited P1 to NiO, followed by electron transfer from P1˙ to PCBM.

    Nationell ämneskategori
    Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-280843 (URN)10.1039/C5CP05247E (DOI)000370421500001 ()
    Forskningsfinansiär
    Knut och Alice Wallenbergs StiftelseEnergimyndigheten
    Tillgänglig från: 2016-03-15 Skapad: 2016-03-15 Senast uppdaterad: 2017-11-30Bibliografiskt granskad
    7. Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices
    Öppna denna publikation i ny flik eller fönster >>Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices
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    2017 (Engelska)Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 11, s. 2480-2495Artikel i tidskrift (Refereegranskat) [Forskning på konstnärlig grund] Published
    Abstract [en]

    A covalently-linked organic dye-cobaloxime catalyst system is developed by facile click reaction for mechanistic studies and application in a dye sensitized solar fuel device based on mesoporous NiO. This system has been systematically investigated by photophysical measurements, density functional theory, time resolved fluorescence, transient absorption spectroscopy as well as photoelectron spectroscopy. The results show that irradiation of the dye-catalyst on NiO leads to ultrafast hole injection into NiO from the excited dye, followed by a fast electron transfer to reduce the catalyst unit. Moreover, they suggest that the dye undergoes structural changes in the excited state and that excitation energy transfer occurs between neighboring molecules. The photoelectrochemical experiments also show the hydrogen production by this system-based NiO photocathode. The axial chloride ligands of the catalyst are released during photocatalysis to create the active sites for proton reduction. A working mechanism of the dye-catalyst on photocathode is eventually proposed on the basis of this study.

    Nyckelord
    DSSFDs, electron transfer, Cobaloxime catalyst
    Nationell ämneskategori
    Fysikalisk kemi
    Forskningsämne
    Kemi med inriktning mot kemisk fysik
    Identifikatorer
    urn:nbn:se:uu:diva-301412 (URN)10.1002/cssc.201700285 (DOI)000403005900021 ()
    Tillgänglig från: 2016-08-23 Skapad: 2016-08-23 Senast uppdaterad: 2017-12-28Bibliografiskt granskad
  • 9269.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Solid state p-type dye-sensitized solar cells: concept, experiment and mechanism2016Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 7, s. 5080-5085Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid state p-type dye-sensitized solar cells (p-ssDSCs) have been proposed and fabricated for the first time, using the organic dye P1 as the sensitizer on mesoporous NiO and phenyl-C61-butyric acid methyl ester (PCBM) as the electron conductor. The p-ssDSC has shown an impressive open circuit photovoltage of 620 mV. Femtosecond and nanosecond transient absorption spectroscopy has given evidence for sub-ps hole injection from the excited P1 to NiO, followed by electron transfer from P1˙ to PCBM.

  • 9270.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Favereau, Ludovic
    Université de Nantes, France.
    Farre, Yoann
    Université de Nantes, France.
    Maufroy, Antoine
    Université de Nantes, France.
    Pellegrin, Yann
    Université de Nantes, France.
    Blart, Errol
    Université de Nantes, France.
    Hissler, Muriel
    Inst Sci Chim Rennes, France.
    Jacquemin, Denis
    Université de Nantes; Institut Universitaire de France.
    Odobel, Fabrice
    Université de Nantes, France.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Molecular-structure control of electron transferdynamics of push–pull porphyrins as sensitizers forNiO based dye sensitized solar cells2016Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 81, s. 77184-77194Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Porphyrin dyes were synthesized for use in p-type (NiO) dye sensitized solar cells based on different designprinciples. One porphyrin was designed with a significant charge transfer character in the excited statebecause of push–pull effects of the substituents. Another porphyrin had instead an appended NDIacceptor group (NDI ¼ naphthalene diimide). The dyes were characterized by spectroscopic,electrochemical and DFT methods. Solar cells based on sensitized, meso-porous NiO showed ratherpoor performance compared to other organic dyes, but with a clear improvement for the dye with theNDI acceptor. Ultrafast transient absorption spectroscopy and nanosecond laser photolysis showed thathole injection into NiO was followed by unusually rapid charge recombination, predominantly ona 50–100 ps time scale, which is likely the main reason for the poor photovoltaic performance. Againthe porphyrin with the NDI group showed a more long-lived charge separation that should lead to betterdye regeneration in a solar cell, which can explain its better photovoltaic performance.

  • 9271.
    Zhang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Favereau, Ludovic
    Farre, Yoann
    Mijangos, Edgar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pellegrin, Yann
    Blart, Errol
    Odobel, Fabrice
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells2016Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, s. 18515-18527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a photophysical study, two diketopyrrolopyrrole (DPP)-based sensitizers functionalized with4-thiophenecarboxylic acid as an anchoring group and a bromo (DPPBr) or dicyanovinyl (DPPCN2)group, and a dyad consisting of a DPP unit linked to a naphthalenediimide group (DPP–NDI), wereinvestigated both in solution and grafted on mesoporous NiO films. Femtosecond transient absorptionmeasurements indicate that ultrafast hole injection occurred predominantly on a timescale of B200 fs,whereas the subsequent charge recombination occurred on a surprisingly wide range of timescales,from tens of ps to tens of ms; this kinetic heterogeneity is much greater than is typically observed fordye-sensitized TiO2 or ZnO. Also, in contrast to what is typically observed for dye-sensitized TiO2, therewas no significant dependence on the excitation power of the recombination kinetics, which can beexplained by the hole density being comparatively higher near the valence band of NiO beforeexcitation. The additional acceptor group in DPP–NDI provided a rapid electron shift and stabilizedcharge separation up to the ms timescale. This enabled efficient (B95%) regeneration of NDI bya CoIII(dtb)3 electrolyte (dtb = 4,40-di-tert-butyl-2,20-bipyridine), according to transient absorptionmeasurements. The regeneration of DPPBr and DPPCN2 by CoIII(dtb)3 was instead inefficient, as mostrecombination for these dyes occurred on the sub-ns timescale. The transient spectroscopy data thuscorroborated the trend of the published photovoltaic properties of dye-sensitized solar cells (DSSCs)based on these dyes on mesoporous NiO, and show the potential of a design strategy with a secondaryacceptor bound to the dye. The study identifies rapid initial recombination between the dye and NiO asthe main obstacle to obtaining high efficiencies in NiO-based DSSCs; these recombination componentsmay be overlooked when studies are conducted using only methods with ns resolution or slower.

  • 9272.
    Zhang, Ming-Tian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Proton-Coupled Electron Transfer from Tryptophan: A Concerted Mechanism with Water as Proton Acceptor2011Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, nr 23, s. 8806-8809Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanism of proton-coupled electron transfer (PCET) from tyrosine in enzymes and synthetic model complexes is under intense discussion, in particular the pH dependence of the PCET rate with water as proton acceptor. Here we report on the intramolecular oxidation kinetics of tryptophan derivatives linked to [Ru(bpy)(3)](2+) units with water as proton acceptor, using laser flash-quench methods. It is shown that tryptophan oxidation can proceed not only via a stepwise electron proton transfer (ETPT) mechanism that naturally shows a pH-independent rate, but also via another mechanism with a pH-dependent rate and higher kinetic isotope effect that is assigned to concerted electron-proton transfer (CEP). This is in contrast to current theoretical models, which predict that CEP from tryptophan with water as proton acceptor can never compete with ETPT because of the energetically unfavorable PT part (pK(a)(Trp(center dot)H(+)) = 4.7 >> pK(a)(H3O+) approximate to -1.5). The moderate pH dependence we observe for CEP cannot be explained by first-order reactions with OH- or the buffers and is similar to what has been demonstrated for intramolecular PCET in [Ru(bpy)(3)](3+) -tyrosine complexes (Sjodin, M.; et al. J. Am. Chem. Soc. 2000, 122, 3932. Irebo, T.; et al. J. Am. Chem. Soc. 2007, 129, 15462). Our results suggest that CEP with water as the proton acceptor proves a general feature of amino acid oxidation, and provide further experimental support for understanding of the PCET process in detail.

  • 9273.
    Zhang, Ming-Tian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Irebo, Tania
    Johansson, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Hammarstrom, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Proton-Coupled Electron Transfer from Tyrosine: A Strong Rate Dependence on Intramolecular Proton Transfer Distance2011Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, nr 34, s. 13224-13227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Proton-coupled electron transfer (PCET) was examined in a series of biomimetic, covalently linked Ru(II)(bpy)(3)-tyrosine complexes where the phenolic proton was H-bonded to an internal base (a benzimidazyl or pyridyl group). Photooxidation in laser flash/quench experiments generated the Ru(III) species, which triggered long-range electron transfer from the tyrosine group concerted with short-range proton transfer to the base. The results give an experimental demonstration of the strong dependence of the rate constant and kinetic isotope effect for this intramolecular PCET reaction on the effective proton transfer distance, as reflected by the experimentally determined proton donor-acceptor distance.

  • 9274.
    Zhang, Ming-Tian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Nilsson, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Bimolecular proton-coupled electron transfer from tryptophan with water as the proton acceptor2012Ingår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, nr 7, s. 7732-7736Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Proton-coupled