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

Abstract

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 Pb²⁺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.