Highly-efficient all-inorganic lead-free 1D CsCu2I3 single crystal for white-light emitting diodes and UV photodetection

Lead-based halide perovskites have received great research interest in producing exceptional optoelectronic devices owing to their superior photophysical properties. However, inclusion of toxic Pb in these perovskites brings great risk to public health and hinders their use. Here we report the use of copper(I) to fully substitute Pb to produce Pb-free one-dimensional (1D) CsCu2I3 single crystals (SCs). High-quality, air stable, and yellow-emitting 1D CsCu2I3 SC with length as long as 13 mm is synthesized via inverse temperature crystallization method. A record photoluminescence quantum yield (PLQY) first exceeding 50% (50.4%) is obtained with oleic acid as additive during growth. White light-emitting diodes produced by using the 1D CsCu2I3 SC as yellow phosphors are strikingly capable of working continuously for more than 580 h with a half-lifetime of ~150 h in air. Photodetectors fabricated by the 1D CsCu2I3 SC show distinct UV response with fast response time as low as 50.4 ms (at 340 nm). Our findings pave a way by using the copper(I)-based 1D CsCu2I3 SCs for future high-efficiency solid-state lighting and fast UV photodetection applications.