Achieving Ultrahigh Photoluminescence Quantum Yield in Highly Stable CsCuI Perovskite Single Crystals Through Melt Growth.

Low-dimensional halide perovskites CsCuI have garnered increasing attention for their exceptional luminescent properties, attributed to their stability, high photoluminescence quantum yield (PLQY), and scintillation efficiency. Here, we report the growth of transparent CsCuI crystals via the Bridgman method, emphasizing precise control of melt stoichiometry for optimal performance. Through melt composition optimization, significant improvements in crystal clarity and structural integrity were achieved, enhancing transmittance from 30% to over 80% and achieving nearly 100% PLQY.