Self-Assembled δ-CsPbI3 Nanowires for Stable White Light Emission

An all-inorganic cesium lead halide perovskite shows great potential for high-performance optoelectronic devices due to its superior thermal stability compared to the organic–inorganic hybrid counterpart. Among the CsPbI3 family, orthorhombic phase (δ-) CsPbI3, in contrast to its cubic phase (α-) counterpart, has been believed to be a non-functional material because of its poor optoelectronic property. Herein, stable and white-light-emitting δ-CsPbI3 nanowires (NWs) were obtained from α-CsPbI3 quantum dots through self-assembled and phase transition processes after precisely controlled thermal annealing treatment. The optimized δ-CsPbI3 NWs exhibit a broad emission spectrum (∼410 to ∼800 nm) and an impressive photoluminescence quantum yield of 8%. Moreover, as a proof-of-concept application, the white-light-emitting diode (WLED) lamp bead with excellent operational stability are obtained by packing an InGaN-based violet chip (395 nm) and δ-CsPbI3 NWs. Our results give a perspective on δ-phase CsPbI3 for its applications as WLEDs.