Lead‐Free Chiral Hybrid Metal Halides for Circularly Polarized Light‐Emitting Diodes

Chiral hybrid metal halides are rapidly emerging as a promising class of semiconductors for next‐generation circularly polarized (CP) optoelectronics. As low‐toxicity analogues to asymmetric lead‐based perovskites, these materials combine strong spin–orbit coupling with intrinsic or induced structural asymmetry, enabling robust chiroptical activity. Capable of generating circularly polarized photoluminescence and electroluminescence (EL), they offer exciting opportunities for applications in circularly polarized light‐emitting diodes (CP‐LED), CP‐sensitive photodetectors, and spin‐selective photovoltaics. In this review, we summarize recent progress in the design, synthesis, and device applications of lead‐free chiral metal halides, including Sn‐, Sb‐, Mn‐, Cu‐, Ln‐ and In/Sb‐based perovskites and related halide frameworks, by highlighting how crystallographic chirality, dimensionality, and chemical composition govern their electronic structure and CPL behavior. We discuss the structure–property relationship that underpins CP‐EL efficiency and dissymmetry factors, and reveal how optoelectronic devices accommodate these materials for spin‐polarized light emission and detection. Finally, we outline existing problems, key challenges and future directions toward scalable, high‐performance, and environmentally friendly CPL optoelectronic devices based on lead‐free chiral metal‐halide semiconductors.