Pressure‐assisted cooling to grow ultra‐stable Cs3Cu2l5 and CsCu2l3 single crystals for solid‐state lighting and visible light communication

Abstract Owing to the excellent optical properties, white light‐emitting diodes (WLEDs) based on metal halide perovskites have attracted great attention as promising light source for solid‐state lighting and wireless visible light communication (VLC). However, the instability and toxicity of classic hybrid lead halides hinder their practical applications. Here, a pressure‐assisted cooling method is developed to grow lead‐free Cs3Cu2I5 and CsCu2I3 single crystals, which exhibit more excellent stability, larger size and uniform orientations in comparison with pressure‐free cooling method. Then, both single crystals are used as the emitters of WLEDs without encapsulation, exhibiting a high Color Rendering Index of 91, a decent Commission Internationale de l'Eclairage coordinate of (0.33, 0.33), a proper Correlated Color Temperature of 5436 K, as well as an excellent 1350‐h operating stability at atmosphere. Furthermore, the prepared WLEDs are utilized in wireless VLC, which possesses a −3 dB bandwidth of 10.1 MHz.