Solvothermal‐Assisted Synthesis of Cs 3 Cu 2 I 5 Crystals With Near‐Unity PLQY: Excellent Stabili
Yu Fu, Qidi Guo, Renjie Ru, Wen Wang, Shulin Duan, Haiqing Sun, Rui Liu, Huiling Zhu, Jianxu Ding, Xiaoyuan Zhan, Weiwei ZhangABSTRACT
Metal halide perovskites have attracted considerable research interest due to their outstanding optoelectronic properties. In this work, a cost‐effective and sustainable solvothermal‐assisted approach was developed for the synthesis of non‐toxic, stable, and highly efficient lead‐free copper(I)‐based iodine perovskite (Cs 3 Cu 2 I 5 ) crystalline powders. The as‐synthesized Cs 3 Cu 2 I 5 crystals exhibit intense blue light emission (≈ 445 nm) with a near‐unity photoluminescence quantum yield (PLQY), along with a long fluorescence lifetime and remarkable stability. The solvothermal treatment facilitates the formation of near‐perfect nanoscale crystal embryos, which serve as high‐quality nucleation sites and thereby promote more efficient secondary crystallization during the subsequent anti‐solvent process, ultimately resulting in a substantial enhancement in PLQY. The controllable and reversible phase transformation between Cs 3 Cu 2 I 5 and CsCu 2 I 3 further broadens their potential in anti‐counterfeiting applications. Moreover, a standard white light‐emitting diode with color coordinates (0.33, 0.33) was successfully fabricated by blending Cs 3 Cu 2 I 5 blue‐emitting powders with CsCu 2 I 3 yellow‐emitting powders at a specific ratio. These results demonstrate that Cs 3 Cu 2 I 5 crystal powders synthesized via the solvothermal‐assisted approach hold considerable promise for solid‐state lighting and anti‐counterfeiting applications.