Expanding the Cage of 2D Bromide Perovskites by Large A-Site Cations

Two-dimensional (2D) halide perovskites have outstanding optoelectronic properties, and they feature a variety of organic cation spacers cage A-site cations that can be incorporated into their structures. It has recently been reported the Goldschmidt tolerance factor relaxed expanded in iodide 2D perovskites. Bromide perovskites, whose multilayer structures optical properties are much less studied, provide great platform for studying structure–property relationships with large cations. Herein, we report synthesis structure three new bromide perovskites?(BA)2(MHy)2Pb3Br10 (BA, butylammonium; MHy, methylhydrazinium), (BA)2(EA)2Pb3Br10 (EA is ethylammonium), (BA)2(DMA)Pb2Br7 (DMA dimethylammonium). We compared them other different but same spacer layer thickness. Single-crystal show Pb–Br bonds elongated to accommodate Additionally, octahedra (BA)2(MHy)2Pb3Br10 highly distorted, stacking patterns inner outer layers lead formation n = 3 phases. Density functional theory calculations larger (e.g., DMA, EA) smaller band dispersions effective masses than those Cs+ MA. also exhibits one largest Rashba splittings literature. Structures exhibit high gaps within number short photoluminescence (PL) lifetimes. Temperature- power-dependent PL measurements reveal broad shoulder peak originates from trap states.