All‐Inorganic Perovskite Nanocrystals for High‐Efficiency Light Emitting Diodes: Dual‐Phase CsPbBr₃‐CsPb₂Br₅ Composites

Abstract

A dual‐phase all‐inorganic composite CsPbBr 3 ‐CsPb 2 Br 5 is developed and applied as the emitting layer in LEDs, which exhibited a maximum luminance of 3853 cd m –2 , with current density (CE) of ≈8.98 cd A –1 and external quantum efficiency (EQE) of ≈2.21%, respectively. The parasite of secondary phase CsPb 2 Br 5 nanoparticles on the cubic CsPbBr 3 nanocrystals could enhance the current efficiency by reducing diffusion length of excitons on one side, and decrease the trap density in the band gap on the other side. In addition, the introduction of CsPb 2 Br 5 nanoparticles could increase the ionic conductivity by reducing the barrier against the electronic and ionic transport, and improve emission lifetime by decreasing nonradiative energy transfer to the trap states via controlling the trap density. The dual‐phase all‐inorganic CsPbBr 3 ‐CsPb 2 Br 5 composite nanocrystals present a new route of perovskite material for advanced light emission applications.