Layered two-dimensional organo-metal halide perovskites are currently in the limelight, largely because their versatile chemical composition offers the promise of tunable photophysical properties. We report here on (time-dependent) density functional theory [(TD)DFT] calculations of alkyl-ammonium lead iodide perovskites, where significant changes in the electronic structure and optical properties are predicted when using long versus short alkyl chain spacers. The mismatch between the structural organization in the inorganic and organic layers is epitomized for dodecyl chains that adopt a supramolecular packing similar to that of polyethylene, at the cost of distorting the inorganic frame and, in turn, opening the electronic band gap. These results rationalize recent experimental data and demonstrate that the optoelectronic properties of layered halide perovskite semiconductors can be modified through the use of electronically inert organic saturated chains.

中文翻译：

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用烷基链间隔物调节二维杂化钙钛矿半导体的光电性能

层状二维有机金属卤化物钙钛矿目前备受关注，这主要是因为它们的通用化学组成提供了可调节的光物理性质的希望。我们在此报告烷基铵碘化铅钙钛矿的（随时间变化的）密度泛函理论[（TD）DFT]计算，其中使用长和短烷基链间隔基时，预测了电子结构和光学性质的显着变化。对于采用类似于聚乙烯的超分子堆积的十二烷基链来说，无机层和有机层中的结构组织之间的不匹配被概括化了，其代价是使无机框架变形，进而打开了电子带隙。