Uniform nucleation and growth of Cs 3 Cu 2 I 5 nanocrystals with high luminous efficiency and structural stability and their application in white light-emitting diodes.

Copper-based ternary halide composites have attracted great attention due to their superior chemical stability and optical properties. Herein, we developed an ultrafast high-power ultrasonic synthesis strategy to realize the uniform nucleation and growth of highly luminescent and stable CsCuI nanocrystals (NCs). The as-synthesized CsCuI NCs show uniform hexagonal morphology with an average mean size of 24.4 nm and emit blue light with a high photoluminescence quantum yield (PLQY) of ∼85%. Moreover, the CsCuI NCs exhibit a remarkable stability during continuous eight times heating/cooling cycling tests (303-423 K). We also demonstrated an efficient and stable white light-emitting diode (WLED) with a high luminous efficiency (LE) of 41.5 lm W and a Commission Internationale de l'Eclairage (CIE) color coordinate of (0.33,0.33).