Dynamic Symmetry Conversion in Mixed-Halide Hybrid Perovskite upon Illumination,ACS Energy Letters

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Dynamic Symmetry Conversion in Mixed-Halide Hybrid Perovskite upon Illumination
ACS Energy Letters ( IF 19.3 ) Pub Date : 2021-10-12 , DOI: 10.1021/acsenergylett.1c01798
Satoshi Tominaka ₁ , Izuru Karimata ₂ , Takahide Matsuoka ₃ , Moeri Sakamoto ₂ , Takahito Nakajima _{2,

3} , Koji Ohara ₄ , Takashi Tachikawa _{2,

5}

Affiliation

Organic–inorganic hybrid halide perovskites (ABX₃, where A = CH₃NH₃⁺ (methylammonium ion, MA); B = Pb²⁺; and X = Br^–, I^–, or Cl^–) have excellent optoelectronic properties and are highly efficient photovoltaic materials, but their chemical instability impedes their development for use in next-generation solar cells, wherein they serve as the light-harvesting material. Here, we propose a mechanism of photoluminescence red-shift, a performance-loss phenomenon known as light-induced halide segregation, in mixed-halide perovskites upon illumination using in situ single-particle spectroscopy and synchrotron-based X-ray techniques. Our experimental analyses suggest a defect-assisted photoinduced transition from ordinary nonpolar phases to polar phases at the local scale within seconds is coupled with organic cation reorientation, which in turn narrows the bandgap; first-principles calculations quantitatively supported this result. Our findings provide deeper insights into the nature of local polar domains in hybrid perovskite materials and help improve device stability and efficiency.

中文翻译：

混合卤化物杂化钙钛矿在光照下的动态对称转换

有机-无机杂化卤化物钙钛矿（ABX ₃，其中 A = CH ₃ NH ₃⁺（甲基铵离子，MA）；B = Pb ²⁺；X = Br ^–、I ^–或 Cl ^–) 具有优异的光电特性，是高效的光伏材料，但它们的化学不稳定性阻碍了它们在下一代太阳能电池中的应用，其中它们用作光收集材料。在这里，我们提出了一种光致发光红移的机制，一种称为光诱导卤化物偏析的性能损失现象，在混合卤化物钙钛矿中使用原位单粒子光谱和基于同步加速器的 X 射线技术照射。我们的实验分析表明，缺陷辅助的光诱导在几秒钟内在局部尺度上从普通非极性相到极性相的转变与有机阳离子重新定向相结合，从而使带隙变窄；第一性原理计算定量地支持了这一结果。

更新日期：2021-11-12

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