Ultraviolet to Near-Infrared Polarization-Sensitive Photodetectors Based on (Phenethylammonium)₂PbI₄/PdSe₂ Nanosheet Heterojunctions

Two-dimensional (2D) Ruddlesden–Popper perovskites have demonstrated significant potential in high-performance optoelectronic devices due to their exceptional optoelectronic properties and remarkable stability. However, research on photodetection in 2D perovskite/PdSe 2 nanosheet heterojunction structures remains limited. In this work, a stable photodetector with high responsivity based on a heterostructure of 2D perovskite (PEA) 2 PbI 4 and PdSe 2 nanosheets is demonstrated. The device performance reveals that photodetectors fabricated with 191 nm-thick (PEA) 2 PbI 4 and 2.5 nm-thick PdSe 2 nanosheets provide broadband detection from ultraviolet to near-infrared regions and offer tunable photoresponse profiles. Specifically, under 532 nm illumination and a 1 V bias, the device achieves a responsivity of 1.81 A/W and a specific detectivity of 5.53 × 10 11 Jones. The device also demonstrates ultrafast transient response speeds at the microsecond scale, outperforming a single PdSe 2 nanosheet by approximately 2 orders of magnitude. Furthermore, it maintains excellent stability with less than 5% photocurrent degradation after continuous cycling over thousands of illumination cycles. Notably, owing to the in-plane lattice asymmetry of PdSe 2, the device exhibits high sensitivity to linearly polarized visible light, achieving linear dichroism ratios ( I max / I min ) of 1.05 and 1.12 at 405 and 532 nm, respectively. The capability of linear polarization imaging at visible wavelengths was achieved through the self-constructed imaging platform. This work holds significant implications for advancing research in 2D material heterojunctions, nanomaterial-based optoelectronics, and high-performance photodetectors.