Magneto‐Chiroptical Hybrid Perovskites with Anomalous Photovoltaic Effect for High‐Performance Self‐Driven Photodetectors

Abstract Organic–inorganic hybrid perovskites show promising applications in photodetectors due to their high absorption coefficients and outstanding optoelectronic properties. However, most hybrid perovskites exhibit centrosymmetric structures, requiring external electric fields for photodetection. Herein, 2D chiral hybrid perovskite ( R / S )‐3BrMBA 2 PbBr 4 is synthesized, which exhibits broadband circularly polarized luminescence with a luminescence asymmetry factor of 1.5 × 10 −2 . Furthermore, the circular dichroism (CD) of ( R / S )‐3BrMBA 2 PbBr 4 undergoes significant enhancement and inversion under a magnetic field due to the Zeeman effect, achieving an 8‐fold increase in the CD asymmetry factor and Zeeman splitting energy of 0.3 meV. The non‐centrosymmetric structure endows ( R / S )‐3BrMBA 2 PbBr 4 single crystals with net polarization along the b ‐axis, along with efficient second‐harmonic generation (SHG) CD and a high asymmetry factor (g SHG‐CD = 0.87). The self‐driven photodetector fabricated from ( R )‐3BrMBA₂PbBr₄ demonstrates an anomalous photovoltaic effect under ultraviolet light illumination, generating a photovoltage of 4.8 V that far exceeds its bandgap (E g = 2.96 eV), while simultaneously demonstrating robust X‐ray detection and circularly polarized light discrimination at zero external bias. The work provides significant insights into the application of chiral hybrid perovskites in low‐energy, multifunctional optoelectronic systems and paves the way for the development of advanced photodetection technologies.