Chiral Methylbenzylammonium Bismuth Iodide with Zero-Dimensional Perovskite Derivative Structure

Abstract

Chiral hybrid metal halide perovskites provide hopes of combining chirality induced by the organic sublattice with optoelectronic properties arising from the inorganic sublattice. The field is still in its infancy, with material space mainly focused on two-dimensional hybrid lead halide perovskites. Here we report a zero-dimensional Pb-free perovskite derivative structure with chemical composition [(R-/S-MBA)₄Bi₂I₁₀], where MBA stands for methylbenzylammonium. Single-crystal X-ray diffraction data show that the enantiomerically pure R-MBA and S-MBA induce chirality in the Bi–I inorganic sublattice. Consequently, chiroptical properties like circular dichroism (CD) is observed for the excitonic transitions of (R-/S-MBA) ₄Bi₂I_10. Temperature-dependent (7–300 K) photoluminescence shows excitonic and shallow-defect emissions, indicating fewer deep-defect trap states. Further ultrafast exciton many-body interactions studied by transient absorption spectroscopy reveal Stark effect, band gap renormalization, and shallow-defect states absorption near the band-edge. The material design, structure, and optical properties reported here will be useful to develop next-generation Pb-free perovskites for chiral optoelectronics.