A Self-Powered Circularly Polarized Light Photodetector with High Responsivity Based on the Chiral Quasi-2D Perovskite Film.

Low-dimensional hybrid organic-inorganic perovskites (HOIPs) containing chiral organic ligands have recently emerged as promising candidates for circularly polarized light (CPL) detection, which can distinguish left- and right-handed CPL directly. However, the increase in responsivity and realization of self-powered CPL photodetector remain a challenge. Meanwhile, there is a trade-off between the photocurrent responsivity and the ability to differentially absorb CPL in detectors based on these low-dimensional perovskites. Herein, we report the CPL photodetector based on chiral quasi-2D perovskite films (S/R-MBA)₂MAPb₂I₇ and propose a crystallization regulation method using dimethyl sulfoxide (DMSO) and methylammonium thiocyanate (MASCN). We found that the photoelectric response capability and circular dichroism (CD) intensities of chiral quasi-2D perovskite can be enhanced simultaneously by the improved crystallinity and surface morphology of chiral films. Meanwhile, the formation of the tetragonal perovskite structure leads to symmetry-breaking distortion of the inorganic frameworks, further enhancing the chirality of the perovskite films. In addition, the distribution of n-phase can be tuned by DMSO and MASCN to form graded band alignment, effectively promoting the charge transfer in perovskite. As a result, a self-powered CPL photodetector with a high responsivity of 0.82 A/W and an anisotropy factor of 0.09 at 0 V bias is obtained. To the best of our knowledge, it is the first attempt to enhance the CD characteristics of chiral quasi-2D perovskite films. We believe our work further advances the research of low-dimensional chiral perovskite films in the field of CPL detection.