TY - GEN A1 - Das, Chittaranjan A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Schmeißer, Dieter T1 - Engineering of Sub-Nanometer SiOₓ Thickness in Si Photocathodes for Optimized Open Circuit Potential T2 - ChemSusChem N2 - Silicon is one of the most promising materials to be used for tandem-cell water-splitting devices. However, the electrochemical instability of bare Si makes it difficult to be used for stable devices. Besides that, the photovoltage loss in Si, caused by several factors (e.g., metal oxide protection layer and/or SiO₂/Si or catalyst/Si interface), limits its use in these devices. In this work, we present that an optimized open circuit potential (OCP) of Si can be obtained by controlling the SiOₓ thickness in sub-nanometer range. It can be done by means of a simple and cost-effective way using the combination of a wet chemical etching and the low temperature atomic layer deposition (ALD) of TiO₂. We have found that a certain thickness of the native SiOₓ is necessary to prevent further oxidation of the Si photocathode during the ALD growth of TiO₂. Moreover, covering the Si photocathode with an ALD TiO₂ layer enhances its stability. KW - atomic layer deposition KW - open circuit potential KW - Si photocathodes KW - silica KW - stability Y1 - 2016 U6 - https://doi.org/10.1002/cssc.201600777 SN - 1864-5631 SN - 1864-564X VL - 9 IS - 17 SP - 2332 EP - 2336 ER - TY - CHAP A1 - Kot, Małgorzata A1 - Wojciechowski, Konrad A1 - Snaith, Henry J. A1 - Schmeißer, Dieter T1 - Characterization of the perovskite solar cells containing atomic layer deposited Al2O3 buffer layer T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft e.V. N2 - Hybrid perovskites have potential to overcome performance limits of the current solar cell technologies and achieve low cost and high versatility. Nonetheless, they are prone to degradation in presence of moisture within a couple of hours or days. In this work, we use the atomic layer deposition (ALD) of Al2O3 on the CH3NH3PbI3 perovskite at room temperature in order to verify if this thin ALD layer may protect the perovskite film against moisture degradation and to check the impact of the Al2O3 on the solar to power conversion efficiency (PCE). Depth profiling X-ray photoelectron spectroscopy study shows that the ALD precursors are chemically active only at the perovskite surface and the film bulk is not affected. The perovskite film coated with Al2O3 layer has enhanced moisture stability. Solar cells with a fresh-made CH3NH3PbI3 perovskite film have shown PCE of 15.4%, while the one with 50 days aged perovskite only 6.1%. However, when the aged perovskite is covered with RT-ALD-Al2O3 the PCE value is clearly enhanced.[1] [1] M. Kot et al., Room temperature ALD impact on efficiency, stability and surface properties in perovskite solar cells, ChemSusChem,acctepted. KW - Perovskite solar cell KW - atomic layer deposition KW - Al2O3 KW - efficiency recovery Y1 - 2017 UR - http://www.dpg-verhandlungen.de/year/2017/conference/dresden/part/cpp/session/38/contribution/5 SN - 0420-0195 SP - S. 147 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Kus, Peter A1 - Tsud, Nataliya A1 - Matolínová, Iva A1 - Albrecht, Steve A1 - Matolin, Vladimir A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposition for perovskite solar cells T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3 N2 - After few years of efficiency driven research on perovskite solar cells, the focus now is shifting to understand the underlying processes governing the high efficiency and also to obtain long-term stable devices. Among various deposition methods, atomic layer deposition (ALD) may represent one of the best options, being possible to coat substrates in a very efficient way and at very low temperatures. In our previous work [1] we reported that the efficiency of the solar cell containing aged perovskite film can be enhanced twice while covering the perovskite with a thin ALD alumina film at room temperature. In this work, the chemical, electronic and morphological properties of the fresh perovskite film treated by ALD pulses of the trimethylaluminium and water at room temperature investigated using X-ray Photoelectron Spectroscopy and Field Emission Scanning Electron Microscopy will be discused and correlated with the solar cells performance and stability. [1] M. Kot et al., ChemSusChem 2016, 9, 3401. KW - Perovskite solar cells KW - atomic layer deposition KW - X-Ray photoelectron spectroscopy (XPS) KW - atomic force microscopy KW - field emission scanning electron microscopy KW - photo-conversion efficiency Y1 - 2018 SN - 0420-0195 SP - S. 174 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Kruszyńska, Joanna A1 - Ostapko, Jakub A1 - Ozkaya, Veysel A1 - Surucu, Belkis A1 - Szawcow, Oliwia A1 - Nikiforow, Kostiantyn A1 - Hołdyński, Marcin A1 - Tavakoli, Mohammad Mahdi A1 - Yadav, Pankaj A1 - Kot, Małgorzata A1 - Kołodziej, Grzegorz Piotr A1 - Wlazło, Mateusz A1 - Satapathi, Soumitra A1 - Akin, Seckin A1 - Prochowicz, Daniel T1 - Atomic Layer Engineering of Aluminum-Doped Zinc Oxide films for Efficient and Stable Perovskite Solar Cells T2 - Advanced Materials Interfaces N2 - Atomic layer deposition (ALD) has been considered as an efficient method to deposit high quality and uniform thin films of various electron transport materials for perovskite solar cells (PSCs). Here, the effect of deposition sequence in the ALD process of aluminum-doped zinc oxide (AZO) films on the performance and stability of PSCs is investigated. Particularly, the surface of AZO film is terminated by diethylzinc (DEZ)/H2O (AZO-1) or trimethylaluminum (TMA)/H2O pulse (AZO-2), and investigated with surface-sensitive X-ray photoelectron spectroscopy technique. It is observed that AZO-2 significantly enhances the thermal stability of the upcoming methylammonium lead iodide (MAPbI3) layer and facilitates charge transport at the interface as evidenced by photoluminescence spectroscopes and favorable interfacial band alignment. Finally, planar-type PSC with AZO-2 layer exhibits a champion power conversion efficiency of 18.09% with negligible hysteresis and retains 82% of the initial efficiency after aging for 100 h under ambient conditions (relative humidity 40 ± 5%). These results highlight the importance of atomic layer engineering for developing efficient and stable PSCs. KW - atomic layer deposition KW - electron transporting layers KW - perovskites KW - solar cells KW - stability of perovskite solar cells Y1 - 2022 U6 - https://doi.org/10.1002/admi.202200575 SN - 2196-7350 VL - 9 IS - 17 ER - TY - GEN A1 - Kot, Małgorzata A1 - Das, Chittaranjan A1 - Kegelmann, Lukas A1 - Köbler, Hans A1 - Vorokhta, Mykhailo A1 - Escudero, Carlos A1 - Albrecht, Steve A1 - Abate, Antonio A1 - Flege, Jan Ingo T1 - Application of atomic layer deposition and x-ray photoelectron spectroscopy in perovskite solar cells T2 - Verhandlungen der DPG N2 - In this work we have utilized near-ambient pressure and ultra-high vacuum X-ray photoelectron spectroscopy as well as atomic layer deposition to investigate perovskite solar cells (PSCs). We have demonstrated that ultrathin room temperature atomic layer-deposited aluminium oxide on the perovskite surface very effectively suppresses iodine migration[1] and improves the long term stability and efficiency of PSCs [2,3]. Furthermore, exposure to light proves more detrimental to the perovskite film than exposure to water vapor.[2] Absorbed photons create Frenkel defects in the perovskite crystal and their number strongly depends on the used illumination. The higher the photon flux, the higher the concentration of Frenkel defects, and thus the stronger the degradation of power conversion efficiency and the stronger the hysteresis in the J-V characteristics. [1] C. Das, M. Kot et al., Cell Reports Physical Science 2020, 1, 100112. [2] M. Kot et al., ChemSusChem 2020, 13, 5722. [3] M. Kot et al., ChemSusChem 2018, 11, 3640. KW - atomic layer deposition KW - x-ray photoelectron spectroscopy KW - perovskite solar cells KW - aluminium oxide KW - iodine migration KW - long term stability KW - Frenkel defects Y1 - 2022 UR - https://www.dpg-verhandlungen.de/year/2022/conference/regensburg/part/hl/session/5/contribution/4 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - GEN A1 - Gawlińska-Nęcek, Katarzyna A1 - Kot, Małgorzata A1 - Starowicz, Zbigniew A1 - Janusz-Skuza, Marta A1 - Panek, Piotr A1 - Marth, Ludwig A1 - Plate, Paul A1 - Flege, Jan Ingo T1 - Reaction dynamics between formamidinium lead iodide and Copper Oxide T2 - ACS Applied Materials & Interfaces N2 - Copper oxide (CuOx) has been announced as a very promising hole-transporting layer for perovskite solar cells. However, in our previous work, we have shown that once a formamidinium lead triiodide (FAPI) perovskite is spin-coated on a spray-coated cuprous oxide (Cu2O) substrate, the Cu2O diffuses into and reacts with the FAPI film. In order to verify if the degradation products are related to the oxidation state of CuOx and/or its preparation method, in this work, we first prepared CuOx films by thermal oxidation at temperatures ranging from 120 to 300 °C. While increasing the process temperature, a transformation from copper I (Cu2O) to copper II (CuO) oxidation states was observed. For both oxidation states of copper, FAPI perovskite degradation was found; however, some alterations in the reaction products were noticed. In contrast to our expectations, the introduction of an ultrathin plasma-enhanced atomic layer deposited Al2O3 layer in between both films only partially blocked the CuOx migration into the FAPI film. It can be concluded that regardless of the chemical composition and/or preparation method of CuOx, the overlayered FAPI film gets decomposed. In order to use CuOx as a hole-transporting layer in solar cells, new strategies must be developed to limit these unwanted chemical reactions. KW - copper oxide hole-transporting layer KW - formamidinium lead iodide instability KW - perovskite solar cells KW - atomic layer deposition KW - aluminum oxide Y1 - 2024 U6 - https://doi.org/10.1021/acsami.4c12990 SN - 1944-8244 VL - 16 IS - 42 SP - 57878 EP - 57887 PB - American Chemical Society (ACS) ER -