Chiral Organic Cations and Distorted Inorganic Polyhedra Composing Metal Halide Nonlinear Optical Materials

Abstract Organic–inorganic metal halides (OIMHs) exhibit a rich structural diversity and excellent semiconductor properties, making them attractive candidates in the field of nonlinear optics (NLO). Second harmonic generation, as an important NLO property, imposes strict symmetry constraints, requiring noncentrosymmetric structures. Currently, a key task in the NLO field is to design noncentrosymmetric structures for OIMHs and explore the relationship between structure and NLO performance. This will help further optimize the application of OIMHs in NLO materials. The design of noncentrosymmetric structures for OIMHs can be facilitated by the use of chiral organic cations or distorted inorganic polyhedra, both of which induce structural features that favor noncentrosymmetry. The NLO properties of OIMHs are summarized the relationship between structure and performance is analyzed, and the research directions in the field of NLO for these materials are further elaborated.