Enhancing Chiroptical Selectivity and Device Stability of Chiral Perovskite Photodetectors Via Interfacial AlF₃...

Chiral halide perovskites are promising materials for circularly polarized light (CPL) optoelectronics owing to their strong light absorption, long carrier diffusion lengths, and intrinsic chiroptical activity. However, most reported CPL perovskite devices still suffer from limited chiroptical selectivity and poor operational stability, hindering practical applications. Here, we report a facile interfacial passivation strategy using an atomic layer deposition (ALD)-grown AlF₃ film for high-performance and stable CPL photodetectors (PDs). The dense AlF₃ underlayer modifies the local interfacial environment of the perovskite, promotes grain growth, and reduces defect sites in the chiral perovskite films. Consequently, the AlF₃-based films exhibit enhanced apparent chiroptical properties, with circular dichroism (CD) and circularly polarized photoluminescence (CPL-PL) g-factors increasing by approximately 3.8-fold and 2-fold, respectively, compared with pristine films. CPL PDs fabricated on the AlF₃ underlayer achieve a photoresponsivity of 54 mA W^-1, a specific detectivity of 1.68 × 10¹¹ Jones, and a photocurrent g-factor of 0.48, representing an 84% enhancement over pristine devices. Interfacial AlF₃ passivation also significantly improves device durability, providing a T₇₀ operational lifetime more than 9.3 times longer under ambient conditions. This work demonstrates an effective interface-engineering strategy for simultaneously enhancing chiroptical selectivity, device performance, and operational stability in CPL perovskite optoelectronics.