Chen Yinan, Motti Silvia G, Oliver Robert D J, Wright Adam D, Snaith Henry J, Johnston Michael B, Herz Laura M, Filip Marina R
Department of Physics, University of Oxford, Clarendon Laboratory, OX1 3PU Oxford, U.K.
Institute for Advanced Study, Technical University of Munich, Lichtenbergstrasse 2a, D-85748 Garching, Germany.
J Phys Chem Lett. 2022 May 12;13(18):4184-4192. doi: 10.1021/acs.jpclett.2c00938. Epub 2022 May 5.
Halogen mixing in lead-halide perovskites is an effective route for tuning the band gap in light emission and multijunction solar cell applications. Here we report the effect of halogen mixing on the optoelectronic properties of lead-halide perovskites from theory and experiment. We applied the virtual crystal approximation within density functional theory, the approximation, and the Bethe-Salpeter equation to calculate structural, vibrational, and optoelectronic properties for a series of mixed halide perovskites. We separately perform spectroscopic measurements of these properties and analyze the impact of halogen mixing on quasiparticle band gaps, effective masses, absorption coefficients, charge-carrier mobilities, and exciton binding energies. Our joint theoretical-experimental study demonstrates that iodide-bromide mixed-halide perovskites can be modeled as homovalent alloys, and local structural distortions do not play a significant role for the properties of these mixed species. Our study outlines a general theoretical-experimental framework for future investigations of novel chemically mixed systems.
卤化物混合于铅卤化物钙钛矿中是一种在发光和多结太阳能电池应用中调节带隙的有效途径。在此，我们从理论和实验两方面报告卤化物混合对铅卤化物钙钛矿光电性质的影响。我们在密度泛函理论、该近似以及贝叶斯 - 萨尔皮特方程中应用虚拟晶体近似，以计算一系列混合卤化物钙钛矿的结构、振动和光电性质。我们分别对这些性质进行光谱测量，并分析卤化物混合对准粒子带隙、有效质量、吸收系数、电荷载流子迁移率和激子结合能的影响。我们的联合理论 - 实验研究表明，碘化 - 溴化混合卤化物钙钛矿可被建模为同价合金，并且局部结构畸变对这些混合物种的性质不起显著作用。我们的研究为未来新型化学混合体系的研究概述了一个通用的理论 - 实验框架。
