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Aitola, Kerttu
Publications (10 of 15) Show all publications
Jeon, I., Ueno, H., Seo, S., Aitola, K., Nishikubo, R., Saeki, A., . . . Matsuo, Y. (2018). Lithium-Ion Endohedral Fullerene (Li+@C-60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti-Oxidation. Angewandte Chemie International Edition, 57(17), 4607-4611
Open this publication in new window or tab >>Lithium-Ion Endohedral Fullerene (Li+@C-60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti-Oxidation
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2018 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 17, p. 4607-4611Article in journal (Refereed) Published
Abstract [en]

Herein, we report use of [Li+@C-60]TFSI- as a dopant for spiro-MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10-fold that of conventional devices using Li+TFSI-. Such high stability is attributed to the hydrophobic nature of [Li+@C-60]TFSI- repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li+@C-60]TFSI- could oxidize spiro-MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000h while illuminated under ambient conditions.

Keywords
air stability, doping, fullerenes, lithium, perovskite solar cells
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-353199 (URN)10.1002/anie.201800816 (DOI)000430165700027 ()29534325 (PubMedID)
Note

De 2 första författarna delar förstaförfattarskapet.

Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-06-13Bibliographically approved
Sveinbjörnsson, K., Kyi Thein, N. K., Saki, Z., Svanström, S., Yang, W., Cappel, U. B., . . . Johansson, E. (2018). Preparation of mixed-ion and inorganic perovskite films using water and isopropanol as solvents for solar cell applications. Sustainable Energy & Fuels, 2(3), 606-615
Open this publication in new window or tab >>Preparation of mixed-ion and inorganic perovskite films using water and isopropanol as solvents for solar cell applications
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2018 (English)In: Sustainable Energy & Fuels, E-ISSN 2398-4902, Vol. 2, no 3, p. 606-615Article in journal (Refereed) Published
Abstract [en]

Presently, the most efficient lead halide perovskite solar cells are manufactured by using high-boiling point organic solvents to dissolve the perovskite precursor materials prior to the perovskite formation. Previously, efforts have been made to exchange the said solvents for water with some success. Herein, we build on that work to develop a procedure for synthesising perovskite absorbers using only water and isopropanol as solvents. Our technique can be utilised for fabricating many different perovskite compositions, organic and inorganic. The technique is based on the high solubility of metal nitrates, such as lead(ii) nitrate and caesium(i) nitrate, in water and, respectively, their poor solubilities in isopropanol. The inclusion of CsNO3 to Pb(NO3)2 films does not result in a phase separation of the perovskite material as one would expect when using lead(ii) halide precursor films. Using the perovskite composition Cs0.1FA0.9Pb(I0.83Br0.17)3 we were able to reach an average solar cell power conversion efficiency of 13.0%. Furthermore, the technique can be applied to many different perovskite compositions making it appealing for large-scale manufacturing of perovskite solar cells.

Place, publisher, year, edition, pages
The Royal Society of Chemistry, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-340427 (URN)10.1039/C7SE00538E (DOI)000426712600011 ()
Funder
Göran Gustafsson Foundation for Research in Natural Sciences and MedicineSwedish Energy AgencyÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research Council FormasSwedish Foundation for Strategic Research Swedish Research Council
Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-05-23Bibliographically approved
Saki, Z., Aitola, K., Sveinbjörnsson, K., Yang, W., Svanström, S., Cappel, U. B., . . . Boschloo, G. (2018). The synergistic effect of dimethyl sulfoxide vapor treatment and C-60 electron transporting layer towards enhancing current collection in mixed-ion inverted perovskite solar cells. Journal of Power Sources, 405, 70-79
Open this publication in new window or tab >>The synergistic effect of dimethyl sulfoxide vapor treatment and C-60 electron transporting layer towards enhancing current collection in mixed-ion inverted perovskite solar cells
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2018 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 405, p. 70-79Article in journal (Refereed) Published
Abstract [en]

Inverted perovskite solar cells (PSCs) have been introduced as better candidate for roll-to-roll printing and scaleup than their conventional configuration counterparts, while their fabrication is technically more demanding. The common light absorbing layer in inverted PSCs is the single cation methylammonium lead iodide (MAPbI(3)) perovskite, whereas mixed-ion perovskites are chemically more stable. In mixed-ion perovskites, where FA (formamidinium) is the main replacement for MA, the electron affinity is larger than in MAPbI3 perovskites, leading to possible barriers against photoelectron collection by the electron transporting layer (ETL). In this paper we report on a mixed-ion (FAPbI(3))(0.83)(MAPbBr(3))(0.17) inverted PSC with improved photocurrent through using a dimethyl sulfoxide vapor treatment of perovskite layer and replacing the conventional [6,6]-phenyl-C-71 butyric acid methyl ester (PC70BM) with C-60/bathocuproine (BCP) as more effective ETL. The treatment of perovskite layer results in reduction of impurity phases of 8-FAPbI(3) and Pbl(2). Photoluminescence and open circuit voltage decay data demonstrate better charge carrier collection by the C-60/BCP compared to the PC70BM ETL, and an electron barrier for the back flow of electrons from ETL to perovskite. Our improvements in perovskite crystalization and electron transfer layer simultaneously lead to increasing the current density from 10 to 21 mA cm(-2).

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Mixed-ion perovskite, Dimethyl sulfoxide (DMSO) vapor treatment, Crystalline quality, Electron transporting layer (ETL)
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-372328 (URN)10.1016/j.jpowsour.2018.09.100 (DOI)000451102500009 ()
Funder
Swedish Foundation for Strategic Research , AMA15-0130
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-01-08Bibliographically approved
Hultqvist, A., Aitola, K., Sveinbjörnsson, K., Saki, Z., Larsson, F., Törndahl, T., . . . Edoff, M. (2017). Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance. ACS Applied Materials and Interfaces, 9(35), 29707-29716
Open this publication in new window or tab >>Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 35, p. 29707-29716Article in journal (Refereed) Published
Abstract [en]

The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH2)(2), CH3NH3)Pb(I,Br)(3) (FAPbI(3):MAPbBr(3)) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum, and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)(2) either by itself or in combination with H2O during the ZnO atomic layer deposition (ALD) process is found to enhance the decomposition of the bulk of the perovskite film into PbI2 without even forming ZnO. In contrast, the Sn precursor Sn(N(CH3)(2))(4) does not seem to degrade the bulk of the perovskite film, and conformal SnOx films can successfully be grown on top of it using atomic layer deposition. Using this SnOx film as the electron selective layer in inverted perovskite solar cells results in a lower power conversion efficiency of 3.4% than the 8.4% for the reference devices using phenyl-C-70-butyric acid methyl ester. However, the devices with SnOx show strong hysteresis and can be pushed to an efficiency of 7.8% after biasing treatments. Still, these cells lacks both open circuit voltage and fill factor compared to the references, especially when thicker SnOx films are used. Upon further investigation, a possible cause of these losses could be that the perovskite/SnOx interface is not ideal and more specifically found to be rich in Sn, O, and halides, which is probably a result of the nucleation during the SnOx growth and which might introduce barriers or alter the band alignment for the transport of charge carriers.

Keywords
perovskite solar cell, atomic layer deposition, interfaces, electron selective layers, precursor chemistry
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-335852 (URN)10.1021/acsami.7b07627 (DOI)000410597500034 ()28792724 (PubMedID)
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2018-02-12Bibliographically approved
Liu, P., Xu, B., Hua, Y., Cheng, M., Aitola, K., Sveinbjörnsson, K., . . . Kloo, L. (2017). Design, synthesis and application of a pi-conjugated, non-spiro molecular alternative as hole-transport material for highly efficient dye-sensitized solar cells and perovskite solar cells. Journal of Power Sources, 344, 11-14
Open this publication in new window or tab >>Design, synthesis and application of a pi-conjugated, non-spiro molecular alternative as hole-transport material for highly efficient dye-sensitized solar cells and perovskite solar cells
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2017 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 344, p. 11-14Article in journal (Refereed) Published
Abstract [en]

Two low-cost, easily synthesized pi-conjugated molecules have been applied as hole-transport materials (HTMs) for solid state dye-sensitized solar cells (ssDSSCs) and perovskite solar cells (PSCs). For X1-based devices, high power conversion efficiencies (PCEs) of 5.8% and 14.4% in ssDSSCs and PSCs has been demonstrated. For X14-based devices, PCEs were improved to 6.1% and 16.4% in ssDSCs and PSCs, respectively.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keywords
Hole-transport materials, Dye-sensitized solar cells, Perovskite solar cells
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-320214 (URN)10.1016/j.jpowsour.2017.01.092 (DOI)000395956300002 ()
Funder
Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg Foundation
Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2017-11-29Bibliographically approved
Zhang, X., Aitola, K., Hägglund, C., Kaskela, A., Johansson, M. B., Sveinbjörnsson, K., . . . Johansson, E. M. J. (2017). Dry-Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells. ChemSusChem, 10(2), 434-441
Open this publication in new window or tab >>Dry-Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 2, p. 434-441Article in journal (Refereed) Published
Abstract [en]

Single-walled carbon nanotubes (SWCNTs) show great potential as an alternative material for front electrodes in photovoltaic applications, especially for flexible devices. In this work, a press-transferred transparent SWCNT film was utilized as front electrode for colloidal quantum dot solar cells (CQDSCs). The solar cells were fabricated on both glass and flexible substrates, and maximum power conversion efficiencies of 5.5 and 5.6 %, respectively, were achieved, which corresponds to 90 and 92% of an indium-doped tin oxide (ITO)-based device (6.1 %). The SWCNTs are therefore a very good alternative to the ITO-based electrodes especially for flexible solar cells. The optical electric field distribution and optical losses within the devices were simulated theoretically and the results agree with the experimental results. With the optical simulations that were performed it may also be possible to enhance the photovoltaic performance of SWCNT-based solar cells even further by optimizing the device configuration or by using additional optical active layers, thus reducing light reflection of the device and increasing light absorption in the quantum dot layer.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
carbon nanotubes, colloidal quantum dots, electrodes, optical loss, solar cells
National Category
Chemical Sciences Nano Technology
Identifiers
urn:nbn:se:uu:diva-319657 (URN)10.1002/cssc.201601254 (DOI)000394571900014 ()27873480 (PubMedID)
Funder
Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologySwedish Energy AgencySwedish Research Council FormasÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research CouncilEU, European Research Council, 604472
Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-11-29Bibliographically approved
Aitola, K., Domanski, K., Correa-Baena, J.-P., Sveinbjörnsson, K., Saliba, M., Abate, A., . . . Boschloo, G. (2017). High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact. Advanced Materials, 29(17), Article ID 1606398.
Open this publication in new window or tab >>High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact
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2017 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 17, article id 1606398Article in journal (Refereed) Published
Abstract [en]

Mixed ion perovskite solar cells (PSC) are manufactured with a metal-free hole contact based on press-transferred single-walled carbon nanotube (SWCNT) film infiltrated with 2,2,7,-7-tetrakis(N, N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD). By means of maximum power point tracking, their stabilities are compared with those of standard PSCs employing spin-coated Spiro-OMeTAD and a thermally evaporated Au back contact, under full 1 sun illumination, at 60 degrees C, and in a N-2 atmosphere. During the 140 h experiment, the solar cells with the Au electrode experience a dramatic, irreversible efficiency loss, rendering them effectively nonoperational, whereas the SWCNT-contacted devices show only a small linear efficiency loss with an extrapolated lifetime of 580 h.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-322670 (URN)10.1002/adma.201606398 (DOI)000400344800016 ()
Available from: 2017-05-30 Created: 2017-05-30 Last updated: 2017-05-30Bibliographically approved
Cappel, U. B., Svanström, S., Lanzilotto, V., Johansson, F. O. L., Aitola, K., Philippe, B., . . . Rensmo, H. (2017). Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells. ACS Applied Materials and Interfaces, 9(40), 34970-34978
Open this publication in new window or tab >>Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 34970-34978Article in journal (Refereed) Published
Abstract [en]

Metal halide perovskites have emerged as materials of high interest for solar energy-to-electricity conversion, and in particular, the use of mixed-ion structures has led to high power conversion efficiencies and improved stability. For this reason, it is important to develop means to obtain atomic level understanding of the photoinduced behavior of these materials including processes such as photoinduced phase separation and ion migration. In this paper, we implement a new methodology combining visible laser illumination of a mixed-ion perovskite ((FAP-bI(3))(0.85)(MAPbBr(3))(0.15)) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
Keywords
photoelectron spectroscopy, laser illumination, lead halide perovskite, ion migration, phase separation, stability
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-340141 (URN)10.1021/acsami.7b10643 (DOI)000413131500043 ()28925263 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 321319Swedish Research Council, 2014-6019Swedish Research Council, 2014-6463StandUpSwedish Foundation for Strategic Research , RMA15-0130
Available from: 2018-01-26 Created: 2018-01-26 Last updated: 2018-01-26Bibliographically approved
Cheng, M., Aitola, K., Chen, C., Zhang, F., Liu, P., Sveinbjörnsson, K., . . . Sun, L. (2016). Acceptor Donor Acceptor type ionic molecule materials for efficient perovskite solar cells and organic solar cells. Nano Energy, 30, 387-397
Open this publication in new window or tab >>Acceptor Donor Acceptor type ionic molecule materials for efficient perovskite solar cells and organic solar cells
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2016 (English)In: Nano Energy, ISSN 2211-2855, Vol. 30, p. 387-397Article in journal (Refereed) Published
Abstract [en]

Perovskite solar cells (PSCs) have attracted significant interest and hole transporting materials (HTMs) play important roles in achieving high efficiency. Here, we report additive free ionic type HTMs that are based on 2-ethylhexyloxy substituted benzodithiophene (BDT) core unit. With the ionization of end-capping pyridine units, the hole mobility and conductivity of molecular materials are greatly improved. Applied in PSCs, ionic molecular material M7-TFSI exhibits the highest efficiency of 17.4% in the absence of additives [lithium bis(trifluor-omethanesulfonyl)imide and 4-tert-butylpyridine]. The high efficiency is attributed to a deep highest occupied molecular orbital (HOMO) energy level, high hole mobility and high conductivity of M7-TFSI. Moreover, due to the higher hydrophobicity of M7-TFSI, the corresponding PSCs showed better stability than that of Spiro-OMeTAD based ones. In addition, the strong absorption and suitable energy levels of materials (M6, M7-13r and M7-TFSI) also qualify them as donor materials in organic solar cells (OSCs) and the devices containing M7-TFSI as donor material displayed an efficiency of 6.9%.

Keywords
Perovskite solar cell, Organic solar cell, Hole transport material, Donor material
National Category
Physical Chemistry Nano Technology
Identifiers
urn:nbn:se:uu:diva-314051 (URN)10.1016/j.nanoen.2016.10.041 (DOI)000390636100047 ()
Funder
Swedish Energy AgencyKnut and Alice Wallenberg Foundation
Available from: 2017-02-06 Created: 2017-01-26 Last updated: 2017-02-06Bibliographically approved
Sveinbjörnsson, K., Aitola, K., Zhang, J., Johansson, M. B., Zhang, X., Correa-Baena, J.-P., . . . Johansson, E. M. J. (2016). Ambient air-processed mixed-ion perovskites for high-efficiency solar cells. Journal of Materials Chemistry A, 4(42), 16536-16545
Open this publication in new window or tab >>Ambient air-processed mixed-ion perovskites for high-efficiency solar cells
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2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 42, p. 16536-16545Article in journal (Refereed) Published
Abstract [en]

Mixed-ion (FAPbI(3))(1-x)(MAPbBr(3))(x) perovskite solar cells have achieved power conversion efficiencies surpassing 20%. However, in order to obtain these high efficiencies the preparation is performed in a controlled inert atmosphere. Here, we report a procedure for manufacturing highly efficient solar cells with a mixed-ion perovskite in ambient atmosphere. By including a heating step at moderate temperatures of the mesoporous titanium dioxide substrates, and spin-coating the perovskite solution on the warm substrates in ambient air, a red intermediate phase is obtained. Annealing the red phase at 100 degrees C results in a uniform and crystalline perovskite film, whose thickness is dependent on the substrate temperature prior to spin-coating. The temperature was optimized between 20 and 100 degrees C and it was observed that 50 degrees C substrate temperature yielded the best solar cell performances. The average efficiency of the best device was 17.6%, accounting for current-voltage (I-V) measurement hysteresis, with 18.8% performance in the backward scan direction and 16.4% in the forward scan direction. Our results show that it is possible to manufacture high-efficiency mixed-ion perovskite solar cells under ambient conditions, which is relevant for large-scale and low-cost device manufacturing processing.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-310043 (URN)10.1039/c6ta06912f (DOI)000387166900031 ()
Funder
Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologySwedish Energy AgencyÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research Council FormasSwedish Research Council
Available from: 2016-12-09 Created: 2016-12-09 Last updated: 2018-01-31Bibliographically approved
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