Organometal halides are promising materials for photovoltaic applications, offering tunable electronic levels, excellent charge transport, and simplicity of thin-film device fabrication. Two-dimensional (2D) perovskites have emerged as promising candidates over three-dimensional (3D) ones due to their interesting optical and electrical properties. However, maximizing the power conversion efficiency is a critical issue to improve the performance of these solar cells. In this work, we studied the photophysics of a two-dimensional (2D) perovskite (CH₃NH₃)₂Pb(SCN)₂I₂ thin film using steady-state and time-resolved absorption and emission spectroscopy and compared it with the three-dimensional (3D) counterpart CH₃NH₃PbI₃. We observed a higher bandgap and faster charge recombination in (CH₃NH₃)₂Pb(SCN)₂I₂ compared to CH₃NH₃PbI₃. This work provides an improved understanding of fundamental photophysical processes in perovskite structures and provides the guideline for the design, synthesis, and fabrication of solar cells.

中文翻译：

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尺寸对杂化钙钛矿光电性能的影响

有机金属卤化物是用于光伏应用的有前途的材料，具有可调节的电子能级，出色的电荷传输能力以及薄膜器件制造的简便性。二维（2D）钙钛矿因其有趣的光学和电学性质而成为优于三维（3D）钙钛矿的有前途的候选物。然而，最大化功率转换效率是改善这些太阳能电池的性能的关键问题。在这项工作中，我们使用稳态和时间分辨吸收和发射光谱研究了二维（2D）钙钛矿（CH ₃ NH ₃）₂ Pb（SCN）₂ I ₂薄膜的光物理特性，并将其与三维（3D）对应CH₃ NH ₃ PbI ₃。我们观察到与CH ₃ NH ₃ PbI ₃相比，（CH ₃ NH ₃）₂ Pb（SCN）₂ I ₂具有更高的带隙和更快的电荷重组。这项工作可以更好地理解钙钛矿结构中的基本光物理过程，并为太阳能电池的设计，合成和制造提供指导。