Mechanism Study of Chiral Optical Activity in Hydrogen-Bond Induced Lead-Free Perovskites with Lattice Distortion

This proposal aims to elucidate the mechanism of chiral optical activity in hydrogen-bond induced, lead-free perovskites exhibiting lattice distortion. Chiral perovskites demonstrate distinct optical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL), highlighting their potential for advanced optoelectronic applications. We propose a "cascade cation insertion" strategy to synthesize six perovskite variants (P/M-DMA₄InCl₇, P/M-DMA₂CsInSbₓCl₆, and P/M-DMAPbCl₃), in which the introduction of dimethylammonium (DMA) induces strong N–H⋅⋅⋅Cl hydrogen bonds, resulting in helical distortions within In/Pb–Cl octahedral frameworks and thereby generating structural chirality. Although Cs incorporation reduces overall crystallographic chirality, localized chiral luminescence remains due to persistent N–H⋅⋅⋅Cl hydrogen bonding. We propose employing inelastic neutron scattering (INS) to directly probe and clarify these interactions, aiming to establish a novel mechanism by which non-chiral organic cations regulate chiral structure, thus guiding the development of highly efficient chiral optical materials.