Enhancement of photoluminescence quantum yield in lead-free inorganic copper based halide perovskites via zinc doping

Abstract

CsPbBr₃ exhibits strong green emission, but its toxicity limits its widespread application. Lead-free perovskites exhibit excellent optoelectronic properties while eliminating the toxicity of lead; at the same time, doping substitution is an effective means to further optimize the optoelectronic performance of perovskites. In this work, zinc(II) is chosen to achieve heterovalent substitution in the copper(I) based perovskite Cs₃Cu₂Cl₅ and obtain strong green luminescence. The photoluminescence quantum yield (PLQY) reached 70.19% at an optimal doping concentration, which is twice the PLQY of undoped Cs₃Cu₂Cl₅ and much higher than that of most doped lead-free perovskites. Furthermore, a white light emitting diode (WLED) was fabricated with doped Cs₃Cu₂Cl₅:0.20 Zn²⁺ as a green phosphor, commercial blue phosphor Sr(PO₄)Cl:Eu⁺, and commercial red phosphor CaAlSiN₃:Eu²⁺. The color rendering index (CRI) is 95.8, while the correlated color temperature (CCT) is 4573 K, which is much better than that of the WLED fabricated with CsPbBr₃. This research provides important guidance on the fabrication of green light emission Zn-doped Cs₃Cu₂Cl₅ instead of toxic CsPbBr₃ and has potential in WLED lighting.