Amplification of polarization ratio is observed in monolayer Dion-Jacobson hybrid perovskites

Dion-Jacobson (DJ) hybrid perovskites are considered to be of profound research interest as promising semiconductors in the photovoltaic field. However, it is still a great challenge to construct polar DJ perovskites, and research on the influence of the configuration of diammonium cations on the photophysical properties is also lacking. Herein, starting from the NNPD (N,N-dimethylpropane-1,3-diaminium) cation, the molecule (NNPD)PbBr(4)2 with P2(1)/c space group is obtained. Further molecular modification from NNPD to NMPD (N-methylpropane-1,3-diaminium), a polar semiconductor (NMPD)PbBr(4)1, which crystallizes in the Pn space group is successfully synthesized. Due to the synergic effects of the reorientation of NMPD cations and the deviation of the inorganic layer from the symmetry plane, the positive and negative charge centers in the structure separated. Especially, benefiting from the bulk photovoltaic effect (BPVE) in 1, large polarization ratios at 377 nm (similar to 5.26) and 405 nm (similar to 5.46) under zero bias have been achieved, which are much larger than the values obtained by relying on the intrinsic structure anisotropy of 1 (377 nm, similar to 2.10, 405 nm, and similar to 2.13). This study expands the application of polar DJ hybrid perovskites (HPs) in the field of self-driven polarization detection.