Adjustment of the composition, structure, and properties of a lead-free layered double perovskite

In recent years, due to the toxicity and instability of halide lead-based perovskites, the search for alternatives that retain the superior optoelectronic performance of halide lead-based perovskite materials while being non-toxic and stable has gradually become an important research topic. Among them, the lead-free perovskites with the general formula A₄M^IIM^III₂X₁₂ are very promising in solving the problem of lead ion toxicity. Here, we have studied the Cs₄CuSb₂Cl₁₂ perovskite material, which is a three-layer (n = 3) perovskite structure oriented along <111>. In this paper, a series of Cs₄Cu_1-xCd_xSb₂Cl₁₂ (0 ≤ x ≤ 1) and Cs₄Cu_1-yMn_ySb₂Cl₁₂ (0 ≤ y ≤ 1) microcrystals were synthesized. By varying the value of x and y, we successfully tuned the bandgap and optical properties of Cs₄CuSb₂Cl₁₂. This allowed us to establish a clear correlation between the material's composition, structure, and properties, laying the foundation for further research and application of Cs₄CuSb₂Cl₁₂ materials.