Type-III SnSe2/MoTe2 van der Waals heterojunction for room-temperature self-powered broadband photodetection

With the increasing demand for broadband photodetection technology spanning the infrared-to-visible spectrum in fields such as environmental monitoring, bio-imaging, and communication systems, the development of high-performance photodetectors that combine broadband response, high sensitivity, and self-powered operation at room temperature has become a critical research focus in optoelectronics. In this work, we present a broadband self-powered photodetector based on a MoTe₂/SnSe₂ heterostructure. The conduction and valence bands of these two materials form a broken-gap type-III heterojunction, resulting in a substantial band offset at the interface. This band alignment effectively suppresses thermally generated electron-hole pairs, drastically reducing dark current and enabling an ultra-high on/off ratio of up to 10⁵. The device exhibits a broadband photo-response from visible light (520 nm) to infrared (1550 nm), achieving a remarkable responsivity of 1.47 A/W and a specific detectivity of 1.48 × 10¹² Jones at 520 nm, while maintaining an impressive detectivity of 1.8 × 10¹¹ Jones at 1550 nm. Additionally, it demonstrates fast response dynamics with rise and decay times of 101 μs and 113 μs, respectively. Experimental demonstrations of its infrared communication and imaging capabilities further underscore its immense potential for practical applications. This work provides an effective strategy for designing ultra-low dark current, self-powered broadband photodetectors, paving the way for advanced optoelectronic technologies.