Erbing Axel, Philippe Bertrand, Park Byung-Wook, Cappel Ute B, Rensmo Håkan, Odelius Michael
Department of Physics, Stockholm University, AlbaNova University Center SE-106 91 Stockholm Sweden
Department of Physics and Astronomy, Uppsala University Box 516 SE-751 20 Uppsala Sweden
Chem Sci. 2022 Jul 19;13(32):9285-9294. doi: 10.1039/d2sc03440a. eCollection 2022 Aug 17.
The valence band of lead halide hybrid perovskites with a mixed I/Br composition is investigated using electronic structure calculations and complementarily probed with hard X-ray photoelectron spectroscopy. In the latter, we used high photon energies giving element sensitivity to the heavy lead and halide ions and we observe distinct trends in the valence band as a function of the I : Br ratio. Through electronic structure calculations, we show that the spectral trends with overall composition can be understood in terms of variations in the local environment of neighboring halide ions. From the computational model supported by the experimental evidence, a picture of the microheterogeneity in the valence band maximum emerges. The microheterogeneity in the valence band suggests that additional charge transport mechanisms might be active in lead mixed halide hybrid perovskites, which could be described in terms of percolation pathways.
通过电子结构计算研究了具有混合I/Br组成的卤化铅混合钙钛矿的价带，并辅以硬X射线光电子能谱进行探测。在后者中，我们使用了高光子能量，以实现对重铅离子和卤离子的元素敏感性，并且观察到价带随I : Br比例的变化呈现出明显的趋势。通过电子结构计算，我们表明，整体组成的光谱趋势可以根据相邻卤离子局部环境的变化来理解。从实验证据支持的计算模型中，出现了价带最大值处微观不均匀性的图景。价带中的微观不均匀性表明，在混合卤化铅混合钙钛矿中可能存在其他电荷传输机制，这可以用渗流路径来描述。
