In this work, we introduced halogen-substituted chiral molecules as A-site cations to synthesize a series of novel organic–inorganic hybrid two-dimensional (2D) chiral perovskite materials (R-X-p-mBZA)₂PbBr₄ (X = H, F, Cl, Br; p: para-position; mBZA = α-methylbenzylamine) for the first time. This halogen-substituted cation strategy collectively solved problems of narrow emission, weak chirality and low photoluminescence quantum yield (PLQY) for the emerged chiral perovskites. Photoluminescence (PL) spectra are significantly broadened due to the additional emission from self-trapped excitons (STEs) besides free excitons (FEs) states modulated by introducing significant disorder to the Pb–Br–Pb angle. The chirality of A-site chiral molecules is transferred and amplified to entire perovskite materials by fixing the chiral molecules at A-site via the interaction of halogen atoms. Furthermore, their PLQYs are improved with the reduction of energy gap and inhibition of the non-radiative transition from STEs to ground state. The halogen-substituted A-site cation strategy can be performed to develop organic–inorganic hybrid chiral perovskites with various optoelectronic applications.

中文翻译：

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手性钙钛矿材料（RXp-mBZA）2PbBr4（X = H，F，Cl，Br）的范德华力和卤素原子相互作用调节其光致发光光谱增宽，手性传递和放大。

在这项工作中，我们引入了卤素取代的手性分子作为A位阳离子，以合成一系列新颖的有机-无机杂化二维（2D）手性钙钛矿材料（RX- p -mBZA）₂ PbBr ₄（X = H， F，Cl，Br; p：对-位置; mBZA =α-甲基苄胺）。这种卤素取代的阳离子策略共同解决了出现的手性钙钛矿的窄发射，弱手性和低光致发光量子产率（PLQY）的问题。由于通过自陷激子（STEs）产生的额外发射以及通过对Pb-Br-Pb角引入显着无序调制的自由激子（FEs）状态，光致发光（PL）光谱得到了显着拓宽。通过将手性分子固定在A-位上，通过将A-位手性分子的手性转移并扩增为整个钙钛矿材料卤素原子的相互作用。此外，通过减小能隙并抑制从STE到基态的非辐射跃迁，改善了PLQY。可以执行卤素取代的A-位阳离子策略来开发具有多种光电应用的有机-无机杂化手性钙钛矿。