Recent advances of theoretical investigation on lead-free metal halide perovskites

Metal halide perovskites (MHPs) have aroused as promising candidates in diverse applications, however, the widespread use of Pb-based MHPs is troubled by issues of toxicity and instability. This has spurred significant research efforts to develop Pb-free alternatives with comparable or superior properties. Theoretical investigations play a critical role in this pursuit, offering unparalleled insights into material behaviors at microscopic spatial scales and ultrafast timescales. This review presents a thorough discussion of the theoretical advancements in Pb-free MHPs, encompassing their crystal structures, electronic properties, optical properties, the lattice dynamics, thermodynamic and chemical stability, mechanical properties, ion migration and thermoelectric properties, and the advantages of theoretical means and their vital role in understanding and optimizing the properties of Pb-free MHPs are systematically highlighted. Furthermore, this review identifies the current challenges and outlines potential directions for advancing the field, offering inspiration for innovation. This work aims to accelerate the replacement of Pb-based MHPs by Pb-free alternatives, fostering the development of sustainable, high-performance Pb-free MHPs for future applications.