Mechanochemical Synthesis of Lead-Free Halide Layered Double Perovskites: A Green and Scalable Approach

The search for nontoxic and stable alternatives to halide perovskites has driven significant research into lead-free double perovskite compositions. Among these, layered variants offer unique properties, but their synthesis often relies on solvent or heat-intensive methods. Herein, we demonstrate a scalable and solvent-free mechanochemical approach for the synthesis of ⟨111⟩-oriented layered double perovskites (LDPs). Three distinct solid solutions, Cs₄Cu_1-xMn_xSb₂Cl₁₂, Cs₄Cd_1-xMn_xSb₂Cl₁₂ and Cs₄Cd_1-xMn_xBi₂Cl₁₂ (x = 0-1), were successfully obtained in batch sizes of up to 5.0 g. All compounds can be obtained in less than 30 min and retain their expected optical properties, highlighting mechanochemistry as a green and scalable route to lead-free layered perovskites.