Yazar "Prochowicz, Daniel" seçeneğine göre listele

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    Acetate-based ionic liquid engineering for efficient and stable CsPbI2Br perovskite solar cells with an unprecedented fill factor over 83%
    (Elsevier, 2024) Sadegh, Faranak; Ebic, Murat; Prochowicz, Daniel; Ans, Muhammad; Kruszynska, Joanna; Satapathi, Soumitra; Moghadam, Majid
    The current investigation addresses the persistent challenge of poor ambient stability exhibited by inorganic lead halide perovskites, primarily stemming from intrinsic phase transitions and the presence of defect states. This area of research has been considerably unexplored thus far. On the other hand, the notable effects of ionic liquids (ILs) in improving both stability and efficiency of perovskite photovoltaics have been substantial. In line with these developments, this study endeavors to synergize these two critical domains by introducing an acetate (Ac)based IL into the inorganic perovskite precursor solution to tailor the crystal growth and charge carrier dynamics in CsPbI2Br films, resulting in prolonged stability and enhanced photovoltaic performance. The integration of 1-butyl-3-methylimidazolium acetate (BMIMAc) can indeed accelerate the crystallization of the inorganic perovskite film by interacting the Ac anion with uncoordinated Pb2+ cation in CsPbI2Br. This interaction prompts the formation of smaller grains, which in turn inhibits the creation of non-photoactive phases. Moreover, the presence of BMIMAc as a passivation agent introduces significant defect-healing capabilities, eliminated charge recombination, and increased hydrophobicity. This work endeavors to pave the way for high-efficiency, enduring, and more robust inorganic PSCs through the integration of innovative materials and advanced understanding of fundamental principles, resulting uniform and dense perovskite film. Accordingly, 1.1 mol% BMIMAc-passivated device enables an impressive efficiency of 15.6% with an unprecedented fill factor (FF) exceeding 83%. Remarkably, even after undergoing extended light-soaking for 600 h, the BMIMAc-passivated device retains approximately 85% of its initial efficiency.
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    Deconvoluting the Impedance Response of Halide Perovskite Single Crystals: The Distribution of Relaxation Time Method
    (Amer Chemical Soc, 2023) Pandey, Siddhi Vinayak; Parikh, Nishi; Mahapatra, Apurba; Kalam, Abul; Akin, Seckin; Satapathi, Soumitra; Prochowicz, Daniel
    Electrochemical impedance spectroscopy (EIS) has beenemergingas a promising tool to study the core mechanisms occurring withinmetal halide perovskites (MHPs). Generally, MHPs show one or two semicirclesin the Nyquist spectra in the probed frequency range. However, inthe presence of external stimuli, often a Warburg diffusion or aninductive loop is observed at low frequencies. In such cases, a comparisonof low-frequency parameters in both cases cannot be drawn becauseof the lack of a unique electrical circuit (EC). To overcome the issueof lack of EC, transformation of the frequency-domain technique tothe time domain is carried out. In this work, we investigated threedifferent cases of MAPbI(3), MAPbBr(3), and surface-passivatedMAPbBr(3) single crystals (SCs), which showed one suppressedsemicircle, two semicircles, and a Warburg-like diffusion, respectively,in the Nyquist response of EIS. Next, we transformed these spectrainto the time domain using the distribution of relaxation times (DRT)technique, a machine-learning-assisted tool. The obtained resultssuggest that in the case of Nyquist spectra with one semicircle (thecase of MAPbI(3) SCs), the observed time constants usingEC and DRT are close enough. However, in the case of MAPbBr(3) SC, three different time constants are obtained, associated withhigh, medium, and low frequencies, although the Nyquist response showedtwo semicircles. At last, in the presence of surface-passivated SCs,the Warburg-like feature changes significantly for different passivationtimes. Interestingly, the DRT spectra showed almost similar time constants,through which reliable information on the low-frequency RC can beextracted. Thus, DRT can pave the way for the easy and reliable interpretationof EIS spectra, which is not possible using EC.
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    The effect of B-site doping in all-inorganic CsPbIxBr3-x absorbers on the performance and stability of perovskite photovoltaics
    (Royal Soc Chemistry, 2023) Akman, Erdi; Ozturk, Teoman; Xiang, Wanchun; Sadegh, Faranak; Prochowicz, Daniel; Tavakoli, Mohammad Mahdi; Yadav, Pankaj
    Despite the impressive efficiency of perovskite solar cells (PSCs), their operational stability is still hindered by the thermodynamic instability of the hybrid organic-inorganic absorber layer with ABX(3) structure (A: organic/inorganic cation, B: metal cation, X: halogen anion and mixtures thereof). Due to the hygroscopic and volatile nature of the organic cations, i.e., methylammonium (MA(+)), they show very poor stability not only against thermal stress but also moisture. Therefore, a photoactive material free from organic components could offer great opportunities to prolong the operational stability of devices. In this context, all inorganic CsPbIxBr3-x perovskites are meticulously developed in terms of their structural/thermal stability and have triggered increasing research interest due to great prospects in the commercialization of perovskite technology. However, besides relatively low performance, the poor phase stability of inorganic perovskites associated with lattice strain and vacancies still requires a thorough understanding and permanent solutions for tackling these problems. In this comprehensive review, the recently reported B-site doping strategy in inorganic CsPbIxBr3-x perovskite thin films, which has been elucidated to passivate the defects, tune the grain orientation, and enhance the lifetime of charge-carriers, is presented based on different B-site elements belonging to group IIIA, IVA and VA, alkaline-earth, transition, and lanthanide metals. Solutions for confronting these current problems are elaborated and an outlook on further strategies is given.
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    Facile NaF Treatment Achieves 20% Efficient ETL-Free Perovskite Solar Cells
    (Amer Chemical Soc, 2022) Sadegh, Faranak; Akman, Erdi; Prochowicz, Daniel; Tavakoli, Mohammad Mahdi; Yadav, Pankaj; Akin, Seckin
    Electron transporting layer (ETL)-free perovskite solar cells (PSCs) exhibit promising progress in photovoltaic devices due to the elimination of the complex and energy-/timeconsuming preparation route of ETLs. However, the performance of ETL-free devices still lags behind conventional devices because of mismatched energy levels and undesired interfacial charge recombination. In this study, we introduce sodium fluoride (NaF) as an interface layer in ETL-free PSCs to align the energy level between the perovskite and the FTO electrode. KPFM measurements clearly show that the NaF layer covers the surface of rough underlying FTO very well. This interface modification reduces the work function of FTO by forming an interfacial dipole layer, leading to band bending at the FTO/perovskite interface, which facilitates an effective electron carrier collection. Besides, the part of Na+ ions is found to be able to migrate into the absorber layer, facilitating enlarged grains and spontaneous passivation of the perovskite layer. As a result, the efficiency of the NaF-treated cell reaches 20%, comparable to those of state-of-the-art ETL-based cells. Moreover, this strategy effectively enhances the operational stability of devices by preserving 94% of the initial efficiency after storage for 500 h under continuous light soaking at 55 degrees C. Overall, these improvements in photovoltaic properties are clear indicators of enhanced interface passivation by NaF-based interface engineering.
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    Probing the Low-Frequency Response of Impedance Spectroscopy of Halide Perovskite Single Crystals Using Machine Learning
    (Amer Chemical Soc, 2023) Parikh, Nishi; Akin, Seckin; Kalam, Abul; Prochowicz, Daniel; Yadav, Pankaj
    Electrochemical impedance spectroscopy (EIS) has emergedas a versatiletechnique for characterization and analysis of metal halide perovskitesolar cells (PSCs). The crucial information about ion migration andcarrier accumulation in PSCs can be extracted from the low-frequencyregime of the EIS spectrum. However, lengthy measurement time at lowfrequencies along with material degradation due to prolonged exposureto light and bias motivates the use of machine learning (ML) in predictingthe low-frequency response. Here, we have developed an ML model topredict the low-frequency response of the halide perovskite singlecrystals. We first synthesized high-quality MAPbBr(3) singlecrystals and subsequently recorded the EIS spectra at different appliedbias and illumination intensities to prepare the dataset comprising8741 datapoints. The developed supervised ML model can predict thereal and imaginary parts of the low-frequency EIS response with an R (2) score of 0.981 and a root mean squared error(RMSE) of 0.0196 for the testing set. From the ground truth experimentaldata, it can be observed that negative capacitance prevails at a higherapplied bias. Our developed model can closely predict the real andimaginary parts at a low frequency (50 Hz-300 mHz). Thus, ourmethod makes recording of EIS more accessible and opens a new wayin using the ML techniques for EIS.