Efficient Zn-Alloyed Low-Toxicity Quasi-Two-Dimensional Pure-Red Perovskite Light-Emitting Diodes

Metal halide perovskites have attracted extensive attention in next-generation solid-state lighting and displays due to their fascinating optoelectronic properties. However, the toxicity of lead (Pb) impedes their practical application. Herein, we report an efficient Zn-alloyed quasi-two-dimensional (quasi-2D) pure-red perovskite light-emitting device (PeLED) by introducing zinc ions (Zn²⁺) into the perovskite lattice and partially substituting Pb²⁺. The substitution of Zn²⁺ is confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, grazing-incidence wide-angle X-ray scattering, and transmission electron microscopy measurements. In addition, the vacancy defect density of Pb and the halogen is reduced by the introduction of Zn²⁺ in the PEA₂(Cs_0.3MA_0.7)₂(Zn_xPb_1–x)₃I₁₀ perovskite system, which leads to a more ordered crystal orientation, compact morphology, and increased photoluminescence quantum efficiency. Benefiting from the improved photoelectric properties, a maximum EQE of 9.5% and a luminescence of 453 cd m^–2 are achieved for the Zn-alloyed PeLEDs, with a maximum emission peak of 658 nm and stable electroluminescence spectra under various applied biases.