Multiple Hydrogen Bond-Induced Structural Distortion for Broadband White-Light Emission in Two-Dimensional Perovskites

Abstract

Low-dimensional hybrid lead-halide perovskites with broadband white-light emission upon near-UV excitation have attracted immense scientific interest due to their potential application for the next generation of solid-state lighting as well as scintillators for radiation detection. Recently, broadband emission material is mostly reported in structural distorted perovskites. However, it is still unclear how to generate structural distortion in low-dimensional perovskites. Herein, we find strong structural distortion could be realized by introducing multiple hydrogen bonds for stronger supramolecular interactions between the organic cations and metal-halide inorganic frameworks, which is favorable to exciton self-trapping for broadband white-light emission in hybrid perovskites. The multifunctionalized metformin-configured two-dimensional (2D)-layered perovskites, MFPbClxBr4-x (x = 0–4), presents a broadband white-light emission, which is mainly attributed to electron–phonon coupling induced self-trapped excitons (STEs) in the highly distorted structure. Meanwhile, the emission of the novel MFPbClxBr4-x can be simply tuned from “cold” to “warm” white light by tailoring the anionic component of mixing-halide perovskites. It is of high value to explore the possibility of biguanide derivatives as a new type of template of cations for structural diversity of perovskite material systems as well as to understand structure−property relationships in structural design for realizing desired properties for photovoltaic applications.