Bulk Photovoltaic Effect in Chiral Layered Hybrid Perovskite Enables Highly Sensitive Near-Infrared Circular Polarization Photodetection

A bulk photovoltaic effect (BPVE), as a form of optoelectronic conversion phenomenon mostly appearing in polar materials, has shown tremendous potential in applications of solar harvesting and photodetectors. However, materials exhibiting near-infrared (NIR) BPVEs to meet the growing requirement of night vision and modern informational technology are scarce and urged to be developed. Recently discovered polar hybrid perovskites (PHPs) with various chemical and structural tunabilities provide opportunities to obtain materials with desired optoelectronic properties. Herein, by precisely regularizing the arrangement of PbI6 octahedra, chiral PHPs of [R/S-BEPA]2FAPb2I7 (RBFP and SBFP, space group P21, R/S-BEPA = (R/S)-1-(4-bromophenyl)­ethylammonium, FA = formidinum) with a state-of-the-art bandgap (Eg = 1.45 eV) were designed and synthesized successfully. Benefited from chiral polar structures and a narrow bandgap, bulk crystal devices of SBFP exhibit Vis–NIR BPVEs with an optimized open circuit voltage and short circuit current up to 0.91 V and 14 μA cm–2, respectively. Moreover, boosted by the chiral BPVE, a broad spectrum (from 405 to 785 nm) circularly polarized light (CPL) detection with high asymmetry factors up to 0.376 based on the bulk crystal devices of SBFP was realized. Notably, SBFP is the first single compound PHP capable of directly detecting NIR CPL signals without an external absorber or a specific laser source. This work provides an ideal platform for having a deeper understanding of the interplay between the BPVE and optical helicity in the NIR region in the future.