Schwenzer Jonas A, Hellmann Tim, Nejand Bahram Abdollahi, Hu Hang, Abzieher Tobias, Schackmar Fabian, Hossain Ihteaz M, Fassl Paul, Mayer Thomas, Jaegermann Wolfram, Lemmer Uli, Paetzold Ulrich W
Light Technology Institute, Karlsruhe Institute of Technology, Engesserstr. 13, 76131 Karlsruhe, Germany.
Technical University of Darmstadt, Surface Science Laboratory, Department of Materials and Earth Sciences, Otto-Berndt-Strasse 3, 64287 Darmstadt, Germany.
ACS Appl Mater Interfaces. 2021 Apr 7;13(13):15292-15304. doi: 10.1021/acsami.1c01547. Epub 2021 Mar 25.
One of the great challenges of hybrid organic-inorganic perovskite photovoltaics is the material's stability at elevated temperatures. Over the past years, significant progress has been achieved in the field by compositional engineering of perovskite semiconductors, e.g., using multiple-cation perovskites. However, given the large variety of device architectures and nonstandardized measurement protocols, a conclusive comparison of the intrinsic thermal stability of different perovskite compositions is missing. In this work, we systematically investigate the role of cation composition on the thermal stability of perovskite thin films. The cations in focus of this study are methylammonium (MA), formamidinium (FA), cesium, and the most common mixtures thereof. We compare the thermal degradation of these perovskite thin films in terms of decomposition, optical losses, and optoelectronic changes when stressed at 85 °C for a prolonged time. Finally, we demonstrate the effect of thermal stress on perovskite thin films with respect to their performance in solar cells. We show that all investigated perovskite thin films show signs of degradation under thermal stress, though the decomposition is more pronounced in methylammonium-based perovskite thin films, whereas the stoichiometry in methylammonium-free formamidinium lead iodide (FAPbI) and formamidinium cesium lead iodide (FACsPbI) thin films is much more stable. We identify compositions of formamidinium and cesium to result in the most stable perovskite compositions with respect to thermal stress, demonstrating remarkable stability with no decline in power conversion efficiency when stressed at 85 °C for 1000 h. Thereby, our study contributes to the ongoing quest of identifying the most stable perovskite compositions for commercial application.
有机-无机杂化钙钛矿光伏面临的重大挑战之一是该材料在高温下的稳定性。在过去几年中，通过对钙钛矿半导体进行成分工程，例如使用多阳离子钙钛矿，该领域已取得显著进展。然而，鉴于器件结构种类繁多且测量协议不规范，目前缺少对不同钙钛矿成分固有热稳定性的决定性比较。在这项工作中，我们系统地研究了阳离子组成对钙钛矿薄膜热稳定性的作用。本研究关注的阳离子是甲铵（MA）、甲脒（FA）、铯及其最常见的混合物。我们比较了这些钙钛矿薄膜在85°C长时间应力作用下的热降解情况，包括分解、光学损失和光电变化。最后，我们展示了热应力对钙钛矿薄膜在太阳能电池中性能的影响。我们发现，所有研究的钙钛矿薄膜在热应力下均表现出降解迹象，不过基于甲铵的钙钛矿薄膜分解更为明显，而不含甲铵的甲脒碘化铅（FAPbI）和甲脒铯碘化铅（FACsPbI）薄膜的化学计量更为稳定。我们确定甲脒和铯的组成会产生热应力方面最稳定的钙钛矿成分，在85°C下应力1000小时时，功率转换效率无下降，稳定性显著。因此，我们的研究有助于持续探索用于商业应用的最稳定钙钛矿成分。
