TY - GEN A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Das, Chittaranjan A1 - Kus, Peter A1 - Tsud, Nataliya A1 - Matolínová, Iva A1 - Albrecht, Steve A1 - Matolin, Vladimir A1 - Schmeißer, Dieter T1 - Room temperature atomic layer deposited Al₂O₃ improves perovskite solar cells efficiency over time T2 - ChemSusChem N2 - Electrical characterisation of perovskite solar cells consisting of room-temperature atomic-layer-deposited aluminium oxide (RT-ALD-Al₂O₃) film on top of a methyl ammonium lead triiodide (CH₃NH₃PbI₃) absorber showed excellent stability of the power conversion efficiency (PCE) over along time. Under the same environmental conditions (for 355 d), the average PCE of solar cells without the ALD layer decreased from 13.6 to 9.6 %, whereas that of solar cells containing 9 ALD cycles of depositing RT-ALD-Al₂O₃on top of CH₃NH₃PbI₃ increased from 9.4 to 10.8 %. Spectromicroscopic investigations of the ALD/perovskite interface revealed that the maximum PCE with the ALD layer is obtained when the so-called perovskite cleaning process induced by ALD precursors is complete. The PCE enhancement over time is probably related to a self-healing process induced by the RT-ALD-Al₂O₃ film. This work may provide a new direction for further improving the long-term stability and performance of perovskite solar cells. KW - Perovskite Solar Cells (PSCs) KW - Atomic layer deposition (ALD) KW - long time stabilty KW - X-Ray photoelectron spectroscopy (XPS) KW - Field-emission scanning electron microscopy (FESEM) Y1 - 2018 U6 - https://doi.org/10.1002/cssc.201801434 SN - 1864-5631 SN - 1864-564X VL - 11 IS - 20 SP - 3640 EP - 3648 ER - TY - GEN A1 - Kot, Małgorzata A1 - Henkel, Karsten A1 - Müller, Klaus A1 - Kegelmann, Lukas A1 - Albrecht, Steve A1 - Tsud, Nataliya A1 - Kús, Peter A1 - Matolinová, Iva A1 - Schmeißer, Dieter T1 - Al2O3-Atomic Layer Deposited Films on CH3NH3PbI3 : Intrinsic Defects and Passivation Mechanisms T2 - Energy Technology , The Journal of Physical Chemistry C N2 - The initial interaction of atomic layer deposited films of Al2O3 at room temperature on CH3NH3PbI3 (MAPI) films is studied. Synchrotron radiation–based photoelectron spectroscopy is applied to analyze the initial changes in the Al-derived features by comparing samples with different Al2O3 film thicknesses. It is found that polarons and excitons, both intrinsic defects of Al2O3, play a key role in the interface formation. The polaronic states uptake a charge from the MAPI substrate. This charge is transferred to and stabilized in the excitonic state of Al2O3 which is assigned to predominately tetrahedral coordinated Al sites. This charge transfer is initiated by vacancies present in the MAPI substrate and stabilizes a covalent bonding at the Al2O3–MAPI interface but also causes a roughening of the interface which may lead to the formation of grain boundaries. On top of the rough interface, 2D Al2O3 clusters with an increasing number of octahedrally coordinated Al—O bonds grow, and with increasing Al2O3 coverage, they introduce self-healing of the structural defects. KW - charge donation and transfer cycles KW - covalent interfaces KW - defect monitoring KW - model of Al2O3–CH3NH3PbI3 interactions KW - resonant photoelectron spectroscopy Y1 - 2019 U6 - https://doi.org/10.1002/ente.201900975 SN - 2194-4288 SN - 2194-4296 VL - 7 IS - 11 ER - TY - GEN A1 - Kot, Małgorzata A1 - Kegelmann, Lukas A1 - Köbler, Hans A1 - Vorokhta, Mykhailo A1 - Escudero, Carlos A1 - Kúš, Peter A1 - Šmíd, Břetislav A1 - Tallarida, Massimo A1 - Albrecht, Steve A1 - Abate, Antonio A1 - Matolínová, Iva A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - In situ Near-Ambient Pressure X-ray Photoelectron Spectroscopy Reveals the Influence of Photon Flux and Water on the Stability of Halide Perovskite T2 - ChemSusChem N2 - For several years, scientists have been trying to understand the mechanisms that reduce the long‐term stability of perovskite solar cells. In this work, we examined the effect of water and photon flux on the stability of CH3NH3PbI3 perovskite films and solar cells using in situ near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS), field emission scanning electron microscopy (FESEM), and current density–voltage (J–V) characterization. The used amount of water vapor (up to 1 mbar) had a negligible impact on the perovskite film. The higher the photon flux, the more prominent were the changes in the NAP‐XPS and FESEM data; also, a faster decline in power conversion efficiency (PCE) and a more substantial hysteresis in the J‐V characteristics were observed. Based on our results, it can be concluded that the PCE decrease originates from the creation of Frenkel pair defects in the perovskite film under illumination. The stronger the illumination, the higher the number of Frenkel defects, leading to a faster PCE decline and more substantial hysteresis in the J‐V sweeps. KW - field emission scanning electron microscopy (FESEM) KW - Frenkel defects KW - near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) KW - perovskite KW - photon-induced degradation Y1 - 2020 U6 - https://doi.org/10.1002/cssc.202001527 SN - 1864-5631 SN - 1864-564X VL - 13 IS - 21 SP - 5722 EP - 5730 ER - TY - GEN A1 - Kosto, Yuliia A1 - Kapuscik, Paulina A1 - Tschammer, Rudi A1 - Guttmann, Dominic A1 - Mankowska, Ewa A1 - Matvija, Peter A1 - Morales, Carlos A1 - Mazur, Michał A1 - Henkel, Karsten A1 - Matolinova, Iva A1 - Domaradzki, Jarosław A1 - Flege, Jan Ingo T1 - Bare and Pd-doped ceria thin films prepared by ALD and EBE for hydrogen detection T2 - Verhandlungen der DPG N2 - The need to store and use hydrogen safely as part of green economy based on renewable energy evokes a necessity to reliably detect it at ambient conditions. The majority of currently used sensors are working at elevated temperatures (200-500 °C). In this work, we demonstrate that ceria films deposited on a commercial electrode by atomic layer deposition (ALD) and electron beam evaporation (EBE) electrically respond to hydrogen (from 20 to 500 ppm) at much lower temperatures (50-200 °C). The results reveal that <1.5 nm thin Pd adlayer increases the electrical response by several orders of magnitude for both ceria films. The NAP-XPS study under changing oxidative/reductive atmospheres sheds light on the mechanism of Pd-CeOx thermal activation and the role of the deposition technique in the reactivity of the oxide. KW - Hydrogen sensor KW - Atomic layer deposition (ALD) KW - ceria KW - Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) Y1 - 2024 UR - https://www.dpg-verhandlungen.de/year/2024/conference/berlin/part/o/session/59/contribution/5 SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER -