3D Chiral Metal Halide Semiconductors.

Chiral metal halides are promising materials for nonlinear optics and spin-selective devices. Typically, chirality is introduced via large chiral organic cations, leading to low-dimensional structures and limitations in charge transport. Here, we design a family of chiral metal halides based on the relatively small ditopic R/S-3-aminoquinuclidine (3-AQ) cation, forming an (R/S-3AQ)-Pb2Br6 structure closely related to the 3D corner-sharing octahedral network of perovskites. The resulting material exhibits a direct bandgap, isotropic band structure, and fully 3D photoexcitation. Circular dichroism confirms a chiral anisotropy factor consistent with theoretical predictions. Moreover, the material displays a Rashba effect in the conduction band, which is attributed to spin-orbit coupling and the lack of inversion symmetry. Offering rich chemical tunability and efficient 3D charge transport, this new class of chiral semiconductors provides a promising platform for advancing nonlinear optoelectronic and spintronic devices.