High performance self-powered PbSe/WSe2 p-n heterojunction photodetector for image sensing

PbSe materials, with their narrow bandgap, excellent optical absorption and outstanding optical response, are ideal for infrared photodetectors, exhibiting unique advantages in optical communication, infrared imaging and thermal detection. Nevertheless, PbSe typically has a non-layered crystal structure and inherent isotropy, making the synthesis of low-dimensional nanomaterials challenging. Besides, PbSe photoconductive detectors suffer from high dark current due to intrinsic defects and thermally excited carriers, which is detrimental to device performance. Here, we utilized physical vapor deposition (PVD) method to grow high-quality PbSe nanosheets and combined them with two-dimensional (2D) transition metal dichalcogenides (TMDs) material WSe₂ to fabricate a self-powered PbSe/WSe₂ p-n heterostructure photodetector. Under illumination with a 650 nm laser at a power density of 128.97 mW/cm² and 0 V bias, the PbSe/WSe₂ heterojunction device exhibited significant photovoltaic characteristics and generated a short-circuit current of 161.7 nA. Furthermore, under 0.02 mW/cm² of 650 nm laser illumination at 0 V bias, the device achieved an excellent responsivity (R) of 15.6 A/W and a specific detectivity (D*) of 1.08×10¹¹ Jones. And the response speed of the heterojunction device at 0 V (511 μs/74 μs) was three orders of magnitude faster than that of PbSe nanosheets (93 ms/104 ms). The device also demonstrated broadband detection capabilities from 405 nm to 1550 nm and excellent imaging performance in the near-infrared region at 0 V bias. In summary, the outstanding photoelectric detection performance and imaging capabilities of the PbSe/WSe₂ heterojunction nanosheet detector indicate its significant potential for applications in miniaturized, low-noise, broadband, high-speed and high-performance photodetectors.