Inorganic Chain Mediated Excitonic Properties in One-Dimensional Lead Halide Hybrid Perovskites

Semiconductors that emit intrinsic white light are considered
next-generation
lighting sources. Herein, the broadband emission of one-dimensional
(1D) lead halide perovskites, TMAPbBr3–xIx (x = 0, 1,
1.5, 2, 3; TMA+ = tetramethylammonium), is systematically
investigated. Lattice distortion causes the conversion of dark excitons
to bright self-trapped excitons. Owing to its strongly localized exciton
recombination and high absorption probability, TMAPbBr3 is the most viable in this family. A delocalized hole increases
the nonradiative recombination rate of excitons in TMAPbBr3–xIx alloys. In 1D TMAPbBr3–xIx perovskites,
the vibration mode of the Pb–X bond stretching of the PbX6 octahedra contributes more to the effect on exciton–phonon
coupling than the mode of the X–Pb–X angle bending.
Pb–X bond stretching and spontaneous polarization can tune
exciton binding energy. This systematic study of excitonic behavior
in 1D compounds relates the nature of ground states to the unknown
excited states and provides the rational design of materials with
stable and efficient broadband emission.

发射本征白光的半导体被视作下一代照明光源。本文系统研究了一维（1D）卤化铅钙钛矿TMAPbBr₃–ₓIₓ（x = 0、1、1.5、2、3；TMA+ = 四甲基铵阳离子）的宽带发射特性。晶格畸变可促使暗激子转化为亮自陷激子。得益于强局域化的激子复合效应与较高的吸收概率，TMAPbBr₃是该系列材料中最具应用前景的体系。离域化空穴会提升TMAPbBr₃–ₓIₓ合金中激子的非辐射复合速率。在一维TMAPbBr₃–ₓIₓ钙钛矿中，PbX₆八面体的Pb–X键伸缩振动模式对激子-声子耦合的贡献度，高于X–Pb–X键角弯曲振动模式。Pb–X键伸缩与自发极化可调控激子结合能。本项针对一维化合物激子行为的系统研究，将基态本质与尚不明确的激发态建立关联，为开发兼具稳定与高效宽带发射性能的材料提供了理性设计路径。