Inorganic Chain\nMediated Excitonic Properties in One-Dimensional\nLead Halide Hybrid Perovskites

Abstract

Semiconductors that emit intrinsic white light are considered\nnext-generation\nlighting sources. Herein, the broadband emission of one-dimensional\n(1D) lead halide perovskites, TMAPbBr_3–<i>x</i>I_<i>x</i> (<i>x</i> = 0, 1,\n1.5, 2, 3; TMA⁺ = tetramethylammonium), is systematically\ninvestigated. Lattice distortion causes the conversion of dark excitons\nto bright self-trapped excitons. Owing to its strongly localized exciton\nrecombination and high absorption probability, TMAPbBr₃ is the most viable in this family. A delocalized hole increases\nthe nonradiative recombination rate of excitons in TMAPbBr_3–<i>x</i>I_<i>x</i> alloys. In 1D TMAPbBr_3–<i>x</i>I_<i>x</i> perovskites,\nthe vibration mode of the Pb–X bond stretching of the PbX₆ octahedra contributes more to the effect on exciton–phonon\ncoupling than the mode of the X–Pb–X angle bending.\nPb–X bond stretching and spontaneous polarization can tune\nexciton binding energy. This systematic study of excitonic behavior\nin 1D compounds relates the nature of ground states to the unknown\nexcited states and provides the rational design of materials with\nstable and efficient broadband emission.