Direct Detection of Near-Infrared Circularly Polarized Light via Precisely Designed Chiral Perovskite Heterostructures.

Chiral metal halide perovskites (CMHPs) have recently shown great potential for direct circularly polarized light (CPL) detection. However, owing to the limited cutoff wavelength edge of these CMHPs, most of the detectors presented thus far are characterized only in the ultraviolet and visible range; CMHPs that target at the near-infrared (NIR) region are still greatly desired. Here, we design a novel CMHP heterostructure, synthesized via solution-processed epitaxial growth of crystalline 3D MAPbI on a 2D chiral (-BPEA)PbI (-BPEA = ()-1-(4-bromophenyl)ethylammonium) crystal, and provide the first demonstration of self-powered direct NIR-CPL detection. Compared with individual chiral (-BPEA)PbI, the heterostructure not only retains the spin selectivity but also allows much broader absorbance, especially beyond 780 nm, where the (-BPEA)PbI cannot absorb. Furthermore, the built-in electric potential in the heterojunction forces spontaneous separation/transport of photogenerated carriers, enabling the fabrication of devices operating without external energy supply. By making use of the abovementioned advantages, the self-powered CPL detectors of the (-BPEA)PbI/MAPbI heterostructures hence show competitive circular polarization sensitivity at 785 nm with a high anisotropy factor of up to 0.25. In addition, a large on/off switching ratio of ∼10 and an impressive detectivity of ∼10 Jones are also achieved. As a pioneer study, our results may broaden the material scope for future chiroptical devices based on CMHPs.