Circularly polarized luminescence in chiral hybrid metal halides

Chiral hybrid metal halides (CHMHs) have emerged as a promising class of ionic crystalline materials for circularly polarized luminescence (CPL). In these materials, organic cations primarily act as chirality sources, whereas the inorganic frameworks serve as the luminescent centers. The interactions between chiral organic cations and inorganic frameworks enable intrinsic CPL emission. The soft and ionic nature of CHMHs further distinguishes them from conventional covalent luminophores, offering exceptional structural and chiroptical tunability. This tutorial review summarizes recent progress in CPL-active CHMHs, focusing on the fundamental routes for CPL generation, amplification and application. Representative synthetic strategies for CHMHs are introduced, followed by an analysis of luminescence mechanisms and their relevance to CPL generation. Key strategies to enhance CPL performance, including composition engineering and external-field regulation, are also reviewed. Beyond fundamental understanding, emerging applications enabled by the unique properties of CHMHs, including circularly polarized light-emitting diodes, CPL-resolved scintillators, and anti-counterfeiting technologies, are summarized. Finally, key challenges and future perspectives are outlined to guide the development of high-performance CHMH-based chiroptical materials and devices.