@misc{KotHenkelMuelleretal., author = {Kot, Małgorzata and Henkel, Karsten and M{\"u}ller, Klaus and Kegelmann, Lukas and Albrecht, Steve and Tsud, Nataliya and K{\´u}s, Peter and Matolinov{\´a}, Iva and Schmeißer, Dieter}, title = {Al2O3-Atomic Layer Deposited Films on CH3NH3PbI3 : Intrinsic Defects and Passivation Mechanisms}, series = {Energy Technology , The Journal of Physical Chemistry C}, volume = {7}, journal = {Energy Technology , The Journal of Physical Chemistry C}, number = {11}, issn = {2194-4288}, doi = {10.1002/ente.201900975}, pages = {10}, abstract = {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.}, language = {en} } @misc{KotVorokhtaWangetal., author = {Kot, Małgorzata and Vorokhta, Mykhailo and Wang, Zhiping and Snaith, Henry J. and Schmeißer, Dieter and Flege, Jan Ingo}, title = {Thermal stability of CH3NH3PbIxCl3-x versus [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films by X-ray photoelectron spectroscopy}, series = {Applied Surface Science}, volume = {513}, journal = {Applied Surface Science}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2020.145596}, pages = {7}, abstract = {The thermal stability of CH3NH3PbIxCl3-x and [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films was studied in-situ by X-ray photoelectron spectroscopy. It was found that below 85 °C both of them are relatively stable. After annealing above 85 °C, we observe a clear perovskite surface decomposition, i.e., a release of organic cations and creation of "metallic lead". The mixed cation lead mixed halide perovskite, however, decomposes at a much lower rate. For both perovskite films, the metallic to the total lead ratio changes with the same rate for the same annealing temperatures. The release of A-site cations from the ABX3 crystal structure of perovskite and/or creation of "metallic lead" causes also a small shift of the valence band maximum towards the Fermi level. The release of [HC(NH2)2]± or Cs± is not as significant as the release of CH3NH3±; therefore, it may explain why [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 solar cells are thermally more stable. Therefore, as the stability of CH3NH3PbIxCl3-x is same as the stability of [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 below 85 °C, there must be more severe degradation pathways that are currently underappreciated on the solar cell level.}, language = {en} } @misc{LaroussiKotFlegeetal., author = {Laroussi, Arwa and Kot, Małgorzata and Flege, Jan Ingo and Raouafi, Noureddine and Mirsky, Vladimir M.}, title = {Self-assembled monolayers from symmetrical di-thiols: Preparation, characterization and application for the assembly of electrochemically active films}, series = {Applied Surface Science}, volume = {513}, journal = {Applied Surface Science}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2020.145827}, abstract = {1,3-dimercaptopropan-2-ol, a symmetrical di-thiol, has been synthesized and applied as a new type of anchor molecule to prepare a self-assembled monolayer (SAM) on the gold surface. The formed monolayers were studied by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, kinetic capacitance, and contact angle measurements. The SAM structure depends on the adsorption conditions. A short incubation time of the electrode at high concentration of this di-thiol leads to the predominating binding through one thiol group of the adsorbate to the gold surface, while a long incubation at low concentration leads to the predominating binding by both thiol groups. A comparative study of the desorption and replacement of SAMs indicates a strong stability increase when the SAM molecules bond gold surface by two bonds mainly. This monolayer was used to immobilize electrochemically active p-benzoquinone moiety. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10-10 mol·cm-2 which corresponds to the functionalization of 65 ± 5\% of SAM molecules. The obtained highly stable SAM with redox-active terminal group can be applied for different tasks of chemical sensing and biosensing. As an example, an application of this system for electrocatalytical oxidation of dihydronicotinamide adenosine dinucleotide (NADH) was tested.}, language = {en} } @misc{DasKotHellmannetal., author = {Das, Chittaranjan and Kot, Małgorzata and Hellmann, Tim and Wittich, Carolin and Mankel, Eric and Zimmermann, Iwan and Schmeißer, Dieter and Nazeeruddin, Mohammad Khaja and Jaegermann, Wolfram}, title = {Atomic Layer-Deposited Aluminum Oxide Hinders Iodide Migration and Stabilizes Perovskite Solar Cells}, series = {Cell Reports Physical Science}, volume = {1}, journal = {Cell Reports Physical Science}, number = {7}, issn = {2666-3864}, doi = {10.1016/j.xcrp.2020.100112}, pages = {18}, abstract = {Iodide migration causes degradation of the perovskite solar cells. Here,we observe the direct migration of iodide into the hole-transport layer in a device. We demonstrate that ultrathin room temperature atomic layer-deposited Al2O3 on the perovskite surface very effectively hinders the migration. The perovskite-Al2O3 interface enables charge transfer across the Al2O3 layer in the solar cells, without causing any drastic changes in the properties of the perovskite absorber. Furthermore, it helps to preserve the initial properties of the perovskite film during exposure to light and air under real operating conditions, and thus, improves the stability of the solar cells. The ultrathin Al2O3 layer deposited at room temperature significantly increases the lifetime of the perovskite solar cells, and we hope this may be a step toward the mass production of stable devices.}, language = {en} } @misc{KotKegelmannKoebleretal., author = {Kot, Małgorzata and Kegelmann, Lukas and K{\"o}bler, Hans and Vorokhta, Mykhailo and Escudero, Carlos and K{\´u}š, Peter and Šm{\´i}d, Břetislav and Tallarida, Massimo and Albrecht, Steve and Abate, Antonio and Matol{\´i}nov{\´a}, Iva and Schmeißer, Dieter and Flege, Jan Ingo}, title = {In situ Near-Ambient Pressure X-ray Photoelectron Spectroscopy Reveals the Influence of Photon Flux and Water on the Stability of Halide Perovskite}, series = {ChemSusChem}, volume = {13}, journal = {ChemSusChem}, number = {21}, issn = {1864-5631}, doi = {10.1002/cssc.202001527}, pages = {5722 -- 5730}, abstract = {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.}, language = {en} } @misc{MahmoodinezhadMoralesNaumannetal., author = {Mahmoodinezhad, Ali and Morales, Carlos and Naumann, Franziska and Plate, Paul and Meyer, Robert and Janowitz, Christoph and Henkel, Karsten and Kot, Małgorzata and Flege, Jan Ingo}, title = {Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma}, series = {Verhandlungen der DPG - SurfaceScience21}, volume = {2021}, journal = {Verhandlungen der DPG - SurfaceScience21}, publisher = {Deutsche Physikalische Gesellschaft e.V.}, address = {Bad Honnef}, abstract = {Indium oxide thin films were deposited on Si (100) by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium (TMIn) and oxygen plasma (O2) in a low-temperature range of 80 to 200 °C. The In2O3 layers were characterized by in-situ spectroscopic ellipsometry (SE), ex-situ X-ray photoelectron spectroscopy (XPS) and electrical measurements. The SE data show a growth rate of 0.56 {\AA}/cycle within the ALD window (100 to 150 °C) with a thickness inhomogeneity of ≤1.2\%. In addition, the highest refractive index is 2.07 (at 632.8 nm) for the layer grown at 150 °C, and the films exhibit indirect and direct band gaps of 2.8±0.1 eV and 3.3±0.2 eV, respectively. XPS characterization indicates no carbon incorporation and a temperature-dependent off-stoichiometry of the layers. The chemical analysis of the In 3d and O 1s core levels confirms the formation of In-O bonds and suggests the additional presence of hydroxyl groups and defects. With increasing temperature, the contribution of OH groups and defects decreases whereas that of In-O bonds increases. Notably, higher growth temperatures result in an indium rich phase within the layers.}, language = {en} } @misc{LaroussiKotFlegeetal., author = {Laroussi, Arwa and Kot, Małgorzata and Flege, Jan Ingo and Raouafi, Noureddine and Mirsky, Vladimir M.}, title = {Self-Assembled Monolayers from Symmetrical Di-Thiols: Preparation, Characterization and Application for the Assembly of Electrochemically Active Films}, series = {Engineering Proceedings}, volume = {6}, journal = {Engineering Proceedings}, number = {1}, issn = {2673-4591}, doi = {10.3390/I3S2021Dresden-10112}, abstract = {1,3-dimercaptopropan-2-ol, a symmetrical di-thiol, has been synthesized and applied as a new type of anchor molecule to prepare a self-assembled monolayer (SAM) on a gold surface. The formed monolayers were studied by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, kinetic capacitance, and contact angle measurements. The SAM structure depends on the adsorption conditions. A short incubation time of the electrode at high concentration of this di-thiol leads to the predominating binding through one thiol group of the adsorbate to the gold surface, while a long incubation at low concentration leads to the predominating binding by both thiol groups. A comparative study of the desorption and replacement of SAMs indicates a strong stability increase when the SAM molecules bond gold surfaces by two bonds mainly. This monolayer was used to immobilize electrochemically active p-benzoquinone moiety. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10-10 mol cm-2, which corresponds to the functionalization of 65 ± 5\% of SAM molecules. The obtained highly stable SAM with redox-active terminal group can be applied for different tasks of chemical sensing and biosensing. As an example, an application of this system for electrocatalytical oxidation of dihydronicotinamide adenosine dinucleotide (NADH) was tested.}, language = {en} } @misc{MahmoodinezhadMoralesNaumannetal., author = {Mahmoodinezhad, Ali and Morales, Carlos and Naumann, Franziska and Plate, Paul and Meyer, Robert and Janowitz, Christoph and Henkel, Karsten and Kot, Małgorzata and Z{\"o}llner, Marvin Hartwig and Wenger, Christian and Flege, Jan Ingo}, title = {Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma}, series = {Journal of Vacuum Science and Technology A}, volume = {39}, journal = {Journal of Vacuum Science and Technology A}, number = {6}, issn = {0734-2101}, doi = {10.1116/6.0001375}, abstract = {Indium oxide (InxOy) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium and oxygen plasma in a low-temperature range of 80-200 °C. The optical properties, chemical composition, crystallographic structure, and electrical characteristics of these layers were investigated by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), as well as current-voltage and capacitance-voltage measurements. The SE results yielded a nearly constant growth rate of 0.56 {\AA} per cycle and a thickness inhomogeneity of ≤1.2\% across 4-in. substrates in the temperature range of 100-150 °C. The refractive index (at 632.8 nm) was found to be 2.07 for the films deposited at 150 °C. The PEALD-InxOy layers exhibit a direct (3.3 ± 0.2 eV) and an indirect (2.8 ± 0.1 eV) bandgap with an uptrend for both with increasing substrate temperature. Based on XPS characterization, all InxOy samples are free of carbon impurities and show a temperature-dependent off-stoichiometry indicating oxygen vacancies. XRD diffraction patterns demonstrate an onset of crystallization at 150 °C. Consistent with the optical, XPS, and XRD data, the films deposited at ≥150 °C possess higher electrical conductivity. Our findings prove that a low-temperature PEALD process of InxOy is feasible and promising for a high-quality thin-film deposition without chemical impurities on thermally fragile substrates.}, language = {en} } @misc{DasZiaMortanetal., author = {Das, Chittaranjan and Zia, Waqas and Mortan, Claudiu and Hussain, Navid and Saliba, Michael and Flege, Jan Ingo and Kot, Małgorzata}, title = {Top-Down Approach to Study Chemical and Electronic Properties of Perovskite Solar Cells: Sputtered Depth Profiling Versus Tapered Cross-Sectional Photoelectron Spectroscopies}, series = {Solar RRL}, volume = {5}, journal = {Solar RRL}, number = {10}, issn = {2367-198X}, doi = {10.1002/solr.202100298}, abstract = {A study of the chemical and electronic properties of various layers across perovskite solar cell (PSC) stacks is challenging. Depth-profiling photoemission spectroscopy can be used to study the surface, interface, and bulk properties of different layers in PSCs, which influence the overall performance of these devices. Herein, sputter depth profiling (SDP) and tapered cross-sectional (TCS) photoelectron spectroscopies (PESs) are used to study highly efficient mixed halide PSCs. It is found that the most used SDP-PES technique degrades the organic and deforms the inorganic materials during sputtering of the PSCs while the TCS-PES method is less destructive and can determine the chemical and electronic properties of all layers precisely. The SDP-PES dissociates the chemical bonding in the spiro-MeOTAD and perovskite layer and reduces the TiO2, which causes the chemical analysis to be unreliable. The TCS-PES revealed a band bending only at the spiro-MeOTAD/perovskite interface of about 0.7 eV. Both the TCS and SDP-PES show that the perovskite layer is inhomogeneous and has a higher amount of bromine at the perovskite/TiO2 interface.}, language = {en} } @misc{JanowitzMahmoodinezhadKotetal., author = {Janowitz, Christoph and Mahmoodinezhad, Ali and Kot, Małgorzata and Morales, Carlos and Naumann, Franziska and Plate, Paul and Z{\"o}llner, Marvin Hartwig and B{\"a}rwolf, Florian and Stolarek, David and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation}, series = {Dalton Transactions}, volume = {51}, journal = {Dalton Transactions}, issn = {1477-9234}, doi = {10.1039/D1DT04008A}, pages = {9291 -- 9301}, abstract = {An Al2O3/ZnO heterojunction was grown on a Si single crystal substrate by subsequent thermal and plasma-assisted atomic layer deposition (ALD) in situ. The band offsets of the heterointerface were then studied by consecutive removal of the layers by argon sputtering, followed by in situ X-ray photoelectron spectroscopy. The valence band maximum and conduction band minimum of Al2O3 are found to be 1.1 eV below and 2.3 eV above those of ZnO, resulting in a type-I staggered heterojunction. An apparent reduction of ZnO to elemental Zn in the interface region was detected in the Zn 2p core level and Zn L3MM Auger spectra. This suggests an interface formation different from previous models. The reduction of ZnO to Zn in the interface region accompanied by the creation of oxygen vacancies in ZnO results in an upward band bending at the interface. Therefore, this study suggests that interfacial properties such as the band bending as well as the valence and conduction band offsets should be in situ controllable to a certain extent by careful selection of the process parameters.}, language = {en} } @misc{KruszyńskaOstapkoOzkayaetal., author = {Kruszyńska, Joanna and Ostapko, Jakub and Ozkaya, Veysel and Surucu, Belkis and Szawcow, Oliwia and Nikiforow, Kostiantyn and Hołdyński, Marcin and Tavakoli, Mohammad Mahdi and Yadav, Pankaj and Kot, Małgorzata and Kołodziej, Grzegorz Piotr and Wlazło, Mateusz and Satapathi, Soumitra and Akin, Seckin and Prochowicz, Daniel}, title = {Atomic Layer Engineering of Aluminum-Doped Zinc Oxide films for Efficient and Stable Perovskite Solar Cells}, series = {Advanced Materials Interfaces}, volume = {9}, journal = {Advanced Materials Interfaces}, number = {17}, issn = {2196-7350}, doi = {10.1002/admi.202200575}, pages = {8}, abstract = {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.}, language = {en} } @misc{DasKediaZuoetal., author = {Das, Chittaranjan and Kedia, Mayank and Zuo, Weiwei and Mortan, Claudiu and Kot, Małgorzata and Flege, Jan Ingo and Saliba, Michael}, title = {Band Bending at Hole Transporting Layer-Perovskite Interfaces in n-i-p and in p-i-n Architecture}, series = {Solar RRL}, volume = {6}, journal = {Solar RRL}, number = {9}, issn = {2367-198X}, doi = {10.1002/solr.202200348}, abstract = {Interfaces between hybrid perovskite absorber and its adjacent charge-transporting layers are of high importance for solar cells performance. Understanding their chemical and electronic properties is a key step in designing efficient and stable perovskite solar cells. In this work, the tapered cross-section photoemission spectroscopy (TCS-PES) method is used to study the methylammonium lead iodide (CH3NH3PbI3) (MAPI)-based solar cells in two configurations, that is, in an inverted p-i-n and in a classical n-i-p architecture. It is revealed in the results that the MAPI film deposited once on the n-type TiO2 and once on the p-type NiOx substrates is neither an intrinsic semiconductor nor adapts to the dopant nature of the substrate underneath, but it is heavily n-type doped on both substrates. In addition to that, the TCS-PES results identify that the band bending between the MAPI film and the hole transporting layer (HTL) layer depends on the perovskite solar cells architecture. In particular, a band bending on the HTL side in the n-i-p and at the MAPI in the p-i-n architecture is found. The flat band of NiOx at the NiOx/MAPI interface can be explained by the Fermi level pinning of the NiOx at the interface.}, language = {en} } @misc{KotDasKegelmannetal., author = {Kot, Małgorzata and Das, Chittaranjan and Kegelmann, Lukas and K{\"o}bler, Hans and Vorokhta, Mykhailo and Escudero, Carlos and Albrecht, Steve and Abate, Antonio and Flege, Jan Ingo}, title = {Application of atomic layer deposition and x-ray photoelectron spectroscopy in perovskite solar cells}, series = {Verhandlungen der DPG}, journal = {Verhandlungen der DPG}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {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.}, language = {en} } @misc{ZiaMalekshahiByranvandRudolphetal., author = {Zia, Waqas and Malekshahi Byranvand, Mahdi and Rudolph, Toby and Rai, Monika and Kot, Małgorzata and Das, Chittaranjan and Kedia, Mayank and Zohdi, Mohammadreza and Zuo, Weiwei and Yeddu, Vishal and Saidaminov, Makhsud I. and Flege, Jan Ingo and Kirchartz, Thomas and Saliba, Michael}, title = {MAPbCl3 Light Absorber for Highest Voltage Perovskite Solar Cells}, series = {ACS Energy Letters}, volume = {9}, journal = {ACS Energy Letters}, issn = {2380-8195}, doi = {10.1021/acsenergylett.3c02777}, pages = {1017 -- 1024}, abstract = {Perovskite solar cells (PSCs) excel in achieving high open-circuit voltages (VOC) for narrow bandgaps (∼1.6 eV) but face challenges with wide-bandgap perovskites, like methylammonium lead trichloride (MAPbCl3) with a 3.03 eV bandgap. These materials are transparent in visible absorbing ultraviolet (UV) light. However, achieving uniform film crystallization remains a hurdle. Here, we enhance MAPbCl3 crystallization by manipulating annealing atmospheres (nitrogen, air, and MACl vapor). Excess MACl vapor improves surface coverage, which is crucial for film stability. We demonstrate that the microstructure of the perovskite film, including surface morphology, grain boundaries, and interfaces, can affect the photovoltaic properties. The subsequently obtained VOC of 1.78 V is the highest recorded for single-junction PSCs to the best of our knowledge. Surprisingly, the conventional hole-transport layer spiro-OMeTAD, optimized for narrow bandgaps, sustains such high voltages. Photoluminescence measurements reveal a trap-assisted recombination peak at 1.65 eV, indicating deep traps as significant to voltage loss in MAPbCl3.}, language = {en} } @misc{GawlińskaNęcekKotStarowiczetal., author = {Gawlińska-Nęcek, Katarzyna and Kot, Małgorzata and Starowicz, Zbigniew and Jarzębska, Anna and Panek, Piotr and Flege, Jan Ingo}, title = {Instability of Formamidinium Lead Iodide (FAPI) Deposited on a Copper Oxide Hole Transporting Layer (HTL)}, series = {ACS Applied Materials \& Interfaces}, volume = {16}, journal = {ACS Applied Materials \& Interfaces}, number = {21}, publisher = {American Chemical Society (ACS)}, issn = {1944-8244}, doi = {10.1021/acsami.4c03440}, pages = {27936 -- 27943}, abstract = {Copper oxide appears to be a promising candidate for a hole transport layer (HTL) in emerging perovskite solar cells. Reasons for this are its good optical and electrical properties, cost-effectiveness, and high stability. However, is this really the case? In this study, we demonstrate that copper oxide, synthesized by a spray-coating method, is unstable in contact with formamidinium lead triiodide (FAPI) perovskite, leading to its decomposition. Using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) spectrophotometry, we find that the entire copper oxide diffuses into and reacts with the FAPI film completely. The reaction products are an inactive yellow δ-FAPI phase, copper iodide (CuI), and an additional new phase of copper formate hydroxide (CH2CuO3) that has not been reported previously in the literature.}, language = {en} } @misc{KotHenkelSchmeisser, author = {Kot, Małgorzata and Henkel, Karsten and Schmeißer, Dieter}, title = {Internal chemical potential in mixed covalent-ionic photosensitive systems}, series = {Journal of Vacuum Science \& Technology A}, volume = {43 (2025)}, journal = {Journal of Vacuum Science \& Technology A}, number = {1}, publisher = {American Vacuum Society}, issn = {0734-2101}, doi = {10.1116/6.0004179}, pages = {1 -- 9}, abstract = {The internal chemical potential Γ of mixed covalent-ionic systems represents the potential differences between the covalent and the ionic intrinsic defect states located within the ionic gap. It is the key parameter to control the carrier densities, the stability regimes, and the photosensitive properties of materials. In this work, we describe first the quantitative analysis of the carrier densities in dependence on the internal potential Nπ(Γ) based on the common features of the electronic structure of mixed covalent-ionic materials. Subsequently, this method is applied on two mixed covalent-ionic materials, i.e., formamidinium lead triiodide and gallium oxide, as representatives of the respective families of perovskites (halides) and transparent conducting oxide thin films. Based on this analysis, the carrier densities as well as the photosensitivity mechanisms and the related specific properties of these materials in dependence on their internal chemical potential are discussed.}, language = {en} } @misc{KodalleMalekshahiByranvandGoudreauetal., author = {Kodalle, Tim and Malekshahi Byranvand, Mahdi and Goudreau, Meredith and Das, Chittaranjan and Roy, Rajarshi and Kot, Małgorzata and Briesenick, Simon and Zohdi, Mohammadreza and Rai, Monika and Tamura, Nobumichi and Flege, Jan Ingo and Hempel, Wolfram and Sutter-Fella, Carolin M. and Saliba, Michael}, title = {An integrated deposition and passivation strategy for controlled crystallization of 2D/3D Halide Perovskite films}, series = {Advanced Materials}, volume = {36}, journal = {Advanced Materials}, number = {24}, publisher = {Wiley}, address = {Weinheim}, issn = {0935-9648}, doi = {10.1002/adma.202309154}, pages = {12}, abstract = {This work introduces a simplified deposition procedure for multidimensional (2D/3D) perovskite thin films, integrating a phenethylammonium chloride (PEACl)-treatment into the antisolvent step when forming the 3D perovskite. This simultaneous deposition and passivation strategy reduces the number of synthesis steps while simultaneously stabilizing the halide perovskite film and improving the photovoltaic performance of resulting solar cell devices to 20.8\%. Using a combination of multimodal in situ and additional ex situ characterizations, it is demonstrated that the introduction of PEACl during the perovskite film formation slows down the crystal growth process, which leads to a larger average grain size and narrower grain size distribution, thus reducing carrier recombination at grain boundaries and improving the device's performance and stability. The data suggests that during annealing of the wet film, the PEACl diffuses to the surface of the film, forming hydrophobic (quasi-)2D structures that protect the bulk of the perovskite film from humidity-induced degradation.}, language = {en} } @misc{KapuścikWojcieszakPokoraetal., author = {Kapuścik, Paulina and Wojcieszak, Damian and Pokora, Patrycja and Mańkowska, Ewa and Domaradzki, Jarosław and Mazur, Michał and Mazur, Piotr and Kosto, Yuliia and Morales, Carlos and Kot, Małgorzata and Flege, Jan Ingo}, title = {Low temperature hydrogen sensor with high sensitivity based on CeOx thin film}, series = {Sensors and Actuators B: Chemical}, volume = {417}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier BV}, issn = {0925-4005}, doi = {10.1016/j.snb.2024.136148}, pages = {12}, abstract = {In this work, a 500 nm-thick cerium oxide thin film was prepared by electron beam evaporation. It was found that the deposition of 7 nm thick Pd catalyst was required for obtaining a sensor response to hydrogen. The Pd/CeOx sensing structure has a high response of 5000 towards 25 ppm H2 at a working temperature of 200 °C and exhibits a sensor response of 1.3 at temperatures near ambient. Furthermore, the sensing structure exhibited excellent response/recovery kinetics. The results confirm that the CeOx-based materials are a promising material for the fabrication of room-temperature hydrogen sensors.}, language = {en} } @misc{KotDasAlonsoetal., author = {Kot, Małgorzata and Das, Chittaranjan and Alonso, Clara Patricia Aranda and Prochowicz, Daniel}, title = {Perovskites: from materials science to devices}, series = {Journal of Materials Chemistry C}, volume = {12}, journal = {Journal of Materials Chemistry C}, number = {28}, publisher = {Royal Society of Chemistry (RSC)}, address = {Cambridge}, issn = {2050-7526}, doi = {10.1039/d4tc90109f}, pages = {10244 -- 10245}, abstract = {An introduction to the Journal of Materials Chemistry C themed collection on perovskite materials.}, language = {en} } @misc{MoralesPlateMarthetal., author = {Morales, Carlos and Plate, Paul and Marth, Ludwig and Naumann, Franziska and Kot, Małgorzata and Janowitz, Christoph and Kus, Peter and Z{\"o}llner, Marvin Hartwig and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {Bottom-up design of a supercycle recipe for atomic layer deposition of tunable Indium Gallium Zinc Oxide thin films}, series = {ACS Applied Electronic Materials}, volume = {6}, journal = {ACS Applied Electronic Materials}, number = {8}, publisher = {American Chemical Society (ACS)}, issn = {2637-6113}, doi = {10.1021/acsaelm.4c00730}, pages = {5694 -- 5704}, abstract = {We present a successful bottom-up approach to design a generic plasma-enhanced atomic layer deposition (PEALD) supercycle recipe to grow high-quality indium gallium zinc oxide (IGZO) thin films with tunable composition at a relatively low temperature of 150 °C. In situ real-time ellipsometric characterization in combination with ex situ complementary techniques has been used to optimize the deposition process and quality of the films by identifying and solving growth challenges such as degree of oxidation, nucleation delays, or elemental composition. The developed supercycle approach enables facile control of the target composition by adapting the subcycle ratios within the supercycle process. Compared to other low-temperature deposition techniques resulting in amorphous films, our PEALD-IGZO process at 150 °C results in nearly amorphous, nanocrystalline films. The preparation of IGZO films at low temperature by a supercycle PEALD approach allows controlling the thickness, composition, and electrical properties while preventing thermally induced segregation.}, language = {en} } @misc{GawlińskaNęcekKotStarowiczetal., author = {Gawlińska-Nęcek, Katarzyna and Kot, Małgorzata and Starowicz, Zbigniew and Janusz-Skuza, Marta and Panek, Piotr and Marth, Ludwig and Plate, Paul and Flege, Jan Ingo}, title = {Reaction dynamics between formamidinium lead iodide and Copper Oxide}, series = {ACS Applied Materials \& Interfaces}, volume = {16}, journal = {ACS Applied Materials \& Interfaces}, number = {42}, publisher = {American Chemical Society (ACS)}, issn = {1944-8244}, doi = {10.1021/acsami.4c12990}, pages = {57878 -- 57887}, abstract = {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.}, language = {en} } @misc{ZuoMalekshahiByranvandKodalleetal., author = {Zuo, Weiwei and Malekshahi Byranvand, Mahdi and Kodalle, Tim and Zohdi, Mohammadreza and Lim, Jaekeun and Carlsen, Brian and Friedlmeier, Theresa Magorian and Kot, Małgorzata and Das, Chittaranjan and Flege, Jan Ingo and Zong, Wansheng and Abate, Antonio and Sutter-Fella, Carolin M. and Li, Meng and Saliba, Michael}, title = {Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization}, series = {Advanced Materials}, volume = {35}, journal = {Advanced Materials}, number = {39}, issn = {0935-9648}, doi = {10.1002/adma.202302889}, abstract = {The most efficient and stable perovskite solar cells (PSCs) are made from a complex mixture of precursors. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g., by vacuum, an airstream, or a so-called antisolvent. Unfortunately, most oversaturation triggers do not expel the lingering (and highly coordinating) dimethyl sulfoxide (DMSO), which is used as a precursor solvent, from the thin films; this detrimentally affects long-term stability. In this work, (the green) dimethyl sulfide (DMS) is introduced as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, MAPbI3 PSCs are processed, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6\% efficiency, among the highest reported efficiencies for this system. To confirm the universality of the strategy, DMS is tested for FAPbI3 as another composition, which shows higher efficiency of 23.5\% compared to 20.9\% for a device fabricated with chlorobenzene. This work provides a universal strategy to control perovskite crystallization using coordination chemistry, heralding the revival of perovskite compositions with pure DMSO.}, language = {en} }