Highly Luminescent One-Dimensional Organic-Inorganic Hybrid Double-Perovskite-Inspired Materials for Single-Component Warm White-Light-Emitting Diodes.

Double perovskites (DPs) are one of the most promising candidates for developing white light-emitting diodes (WLEDs) owing to their intrinsic broadband emission from self-trapped excitons (STEs). Translation of three-dimensional (3D) DPs to one-dimensional (1D) analogues, which could break the octahedral tolerance factor limit, is so far remaining unexplored. Herein, by employing a fluorinated organic cation, we report a series of highly luminescent 1D DP-inspired materials, (DFPD) 2 M I InBr 6 (DFPD=4,4-difluoropiperidinium, M I =K + and Rb + ). Highly efficient warm-white photoluminescence quantum yield of 92 % is achieved by doping 0.3 % Sb 3+ in (DFPD) 2 KInBr 6 . Furthermore, single-component warm-WLEDs fabricated with (DFPD) 2 KInBr 6 :Sb yield a luminance of 300 cd/m 2 , which is one of the best-performing lead-free metal-halides WLEDs reported so far. Our study expands the scope of In-based metal-halides from 3D to 1D, which exhibit superior optical performances and broad application prospects.