Copper-Doped CsPbI₃ Nanocrystals: Improved Stability and Ultrafast Photophysical Dynamics

CsPbI3 nanocrystals (NCs) are highly promising for optoelectronic applications due to their excellent photoluminescence quantum yield (PLQY), adjustable emission wavelength, and high color purity. However, their poor stability poses significant challenges for practical applications and further development. In this study, we synthesized CsPbI3 NCs doped with copper ions (Cu2+) using a hot-injection method, with Cl– ions effectively passivating surface defects. We then examined the effects of varying Cu2+ doping levels (0%, 5%, 10%, and 15%) on their properties. X-ray diffraction (XRD) analysis showed that Cu2+ doping caused the main diffraction peak to shift to higher angles, indicating the successful substitution of Pb2+ by Cu2+ in the crystal structure. Specifically, doping with 10% Cu2+ increased the photoluminescence quantum efficiency from 53.88% to 94.24% and extended the exciton lifetime from 36.60 to 50.26 ns. From 17.72 to 50.11 ps, the bleach recovery rate for Cu2+-doped samples is approximately 25%, while that for undoped samples is 28%. Additionally, the environmental stability of the NCs was greatly improved. This study highlights the potential of using transition metal ion doping to enhance the optoelectronic properties and stability of the photoluminescence quantum efficiency.