Two-dimensional Sb2Te3/MoSe2 van der Waals heterojunction for high-sensitivity photodetectors†

Photodetectors based on two-dimensional (2D) materials are revolutionizing optoelectronics by enabling high sensitivity, ultrafast response, and broadband detection. However, standalone 2D materials often suffer from high dark current, slow response times, and limited light absorption. Here, we demonstrate a high-performance photodetector based on a Sb₂Te₃/MoSe₂ van der Waals (vdW) heterojunction, leveraging the topologically protected surface states of Sb₂Te₃ and the strong light absorption of MoSe₂. The built-in electric field at the heterojunction interface enhances charge separation, suppresses recombination, and significantly reduces dark current. As a result, the device exhibits a high detectivity of 5.14 × 10¹² Jones, an exceptional photoresponsivity of 178 A W⁻¹, and fast response times of 110 μs (rise) and 230 μs (fall) under 532 nm illumination at 1 V bias. Additionally, the heterojunction enables broadband photodetection spanning 532 to 1550 nm, making it suitable for optical communication and sensing applications. This work provides new insights into the integration of topological insulators with transition metal dichalcogenides (TMDs) to achieve next-generation optoelectronic devices with superior performance.