Chiral Substitution on Spaced Cations Lead to Improved Properties and Reversible Phase Transition, Broadband Emission in Parent Compound (3APr)PbBr4

Hybrid organic‐inorganic perovskites (HOIP) due to their excellent optoelectronic properties and flexible structure have attracted enthusiastic interest. In particular, introducing chirality is a method to enhance compound performance. Herein, we report a multifunctional compound: (3APr)PbBr4 (1) (3APr=3‐Pyrrolidinamine) and corresponding enantiomer R and S‐(3APr)PbBr4 (R/S‐2). Compound 1 show reversible solid‐state phase transition, step‐like dielectric anomaly and broadband yellow emission under uv light excitation. Accompany with phase transition, structure dimension transition from 2D to 1D without space group change. Through introduce chirality, the R/S‐2 display mirror image 1D structural relationship, increased quantum yield from 3.43% (1) to 13.65% (R/S‐2) and exhibits corresponding CD signals. Then combine to first‐principles analysis, it was found that fluorescence is attributed to the formation of instantaneous defects during excitation, leading to the formation of self‐trapped excitons (STEs). This finding will further promote the development of multifunctional compound and the study of chiral substitution enhance compound properties.