Ultraviolet to Near-Infrared Polarization-SensitivePhotodetectors 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/PdSe₂ nanosheet heterojunction structures remains limited. In this work, a stable photodetector with high responsivity based on a heterostructure of 2D perovskite (PEA)₂PbI₄ and PdSe₂ nanosheets is demonstrated. The device performance reveals that photodetectors fabricated with 191 nm-thick (PEA)₂PbI₄ and 2.5 nm-thick PdSe₂ 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 × 10¹¹ Jones. The device also demonstrates ultrafast transient response speeds at the microsecond scale, outperforming a single PdSe₂ 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 PdSe₂, the device exhibits high sensitivity to linearly polarized visible light, achieving linear dichroism ratios (<i>I</i>_max/<i>I</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.