Transition metal(ii) ion doping of CsPb2Br5/CsPbBr3 perovskite nanocrystals enables high luminescence efficiency and stability

Abstract

All-inorganic cesium lead halide perovskite nanocrystals (NCs) have emerged as promising optoelectronic nanomaterials due to their color-tunable and high photoluminescence quantum yield (PLQY). However, poor stability of perovskite NCs under environmental conditions represents an important factor limiting their applications. Here, a facile and low-temperature method is developed to synthesize CsPb₂Br₅/CsPbBr₃ perovskite NCs doped with different transition metal(II) ions (Ni²⁺, Cu²⁺, and Zn²⁺). Such a metal-site doping strategy enables the effective elimination of Br vacancies (V_Br) and the suppression of non-radiative recombination. As a result, these transition metal(II)-doped CsPb₂Br₅/CsPbBr₃ perovskite NCs exhibit a greatly enhanced PLQY compared to undoped ones. More encouragingly, the films based on the Ni²⁺-doped NCs show remarkable water stability (60 days), and Cu²⁺-doped NCs present outstanding thermal stability (up to 150 °C), indicating that transition metal doping plays essential roles in modulating the reliability of perovskite NCs. Moreover, high luminescence across the entire visible spectrum is realized by anion exchange of these transition metal(II)-doped CsPb₂Br₅/CsPbBr₃ NCs.