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, Cs4Cu1-xMnxSb2Cl12, Cs4Cd1-xMnxSb2Cl12 and Cs4Cd1-xMnxBi2Cl12 (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.