A PVP‐Modified CdS‐Based Photodetector: Self‐Powered and Broadband Detection via Double Heterojunction Synergy

PVP doping can effectively improve the quality of the film to enhance the photoelectric conversion performance of the device. Based on this, a heterojunction was constructed by integrating PVP‐modified CdS, PbI 2 and p‐Si, thereby extending the spectral response range of the device. PbI 2 /n‐CdS/p‐Si heterojunction photodetector was prepared by sol–gel spin coating method. The heterojunction detector was characterized by scanning electron microscopy, absorption spectroscopy, and X‐ray photoelectron spectroscopy. Compared with n‐CdS/p‐Si devices, the PbI 2 /n‐CdS/p‐Si heterojunction photodetector extends its limited detection range to 365–1200 nm, and the device has self‐powered performance, and the switching ratio is increased from 743 to 4436. At 5 V, the device has a peak responsivity of 576 mA/W at 425 nm, a response time of less than 20 ms, and a high detection rate of 5.92 × 10 12 Jones. This work demonstrates an effective strategy to enhance the photoelectric conversion properties of CdS thin films by PVP doping and constructs a self‐powered PbI 2 /n‐CdS/p‐Si heterojunction photodetector with wide spectral detection.