Enhance luminescence or change morphology: effect of the doping method on Cu2+-doped CsPbBr3 perovskite nanocrystals

Although various cations have been explored as a substitute for Pb2+ in CsPbX3 nanocrystals (NCs), there has been little research to study the influence of the doping methods on the doping results. Cu2+ is one such candidate as a transition metal with low toxicity, yet there are limited studies on Cu2+-doped CsPbX3 NCs, especially on the effect of the doping methods. Herein, Cu2+ was successfully doped into CsPbBr3 NCs with the replacement of Pb(2+)via a hot-injection method and postsynthetic cation-exchange reaction. Using the hot-injection method, the introduction of additional Cu2+ promoted the formation of CsPbBr3 nanoplates with a uniform thickness. The size of the CsPbBr3 nanoplates increased with the increase in the temperature. Differently, using the postsynthetic cation-exchange reaction, doping moderate Cu2+ ions into CsPbBr3 NCs evidently improved the PLQY, prolonged the PL lifetime, and decreased the non-radiative decay, resulting from an effective passivation of the surface defects on CsPbBr3 NCs. The different effect of Cu2+ was the outcome of how the CuBr2 interacted with the CsPbBr3 NCs in the different protocols. Our results should promote further research on the substitution of Pb2+ with other cations, providing effective protocols to prepare low-dimensional CsPbBr3 nanoplates with a uniform thickness and easily controlled lateral size, and can achieve an enhancement of the PLQY of CsPbBr3 NCs, which will benefit the further development of CsPbX3 in optoelectronic and other fields.