Utilizing Angle‐Dependent Photovoltage Effect in a CH₃NH₃PbCl₃/Si Heterojunction toward High‐Performance Polarized Light Detection in Ultraviolet Region

Abstract Organic–inorganic hybrid MAPbCl₃ perovskite (MA⁺ = CH₃NH₃⁺) in UV photodetection is drawing interest due to its superior semiconductor properties and UV‐matchable optical bandgap. However, MAPbCl₃‐based photodetector targeting high‐performance polarized light detection has remained unexplored due to the isotropic structure of MAPbCl₃. The photovoltaic effect in the heterojunction, which shows an angle dependence on light polarization, provides opportunities to break the restriction of intrinsic structure for realizing polarization‐sensitive photodetection. Herein, an effective strategy is reported to realize high‐performance polarization‐sensitive UV photodetection by constructing a heterojunction with two isotropic materials MAPbCl₃ and Silicon (Si). Emphatically, the photovoltage in MAPbCl₃/Si heterojunction changes with the angle of polarized light with the maximum (minimum) value of 0.15 V (0.05 V), originating from the built‐in electric field. More interestingly, driven by the photovoltage, the device thus exhibits a large polarization ratio (I_max/I_min) of 2.9 at 377 nm under the self‐driven mode. Besides, the present device also delivers high‐performance photodetection in UV region owing to the superior photoresponse of MAPbCl₃, including a high detectivity (D*) of 2.93 × 10¹¹ Jones, a superior responsibility of 8 mA W^–1, a substantial switching ratio of 900, and an ultrafast response speed of 40/98 µs at 0 V bias. This work opens a new avenue for high‐performance polarization‐sensitive photodetection by utilizing angle‐dependent photovoltage effect.