Self-powered broadband UV–NIR photodetector based on NbOCl2/WSe2 van der Waals heterostructure

Abstract

Achieving self-powered operation together with broadband photodetection in a single device remains a key challenge for next-generation optoelectronic systems, primarily due to limited spectral response and high power consumption of conventional photodetectors (PDs). Although two-dimensional van der Waals (vdW) heterostructures provide a highly viable framework for performance enhancement, efficient self-powered broadband detection is still hindered by insufficient built-in electric fields and incomplete carrier separation. Here, we report an NbOCl2/WSe2 vdW heterojunction PD that enables efficient self-powered broadband photodetection. By leveraging the intrinsic polarization of NbOCl2 and favorable type-II band alignment at the heterointerface, a robust internal electric field is induced, thereby accelerating the separation and transport of photogenerated carriers. Under 477 nm illumination, the PD delivers an open-circuit voltage of 100 mV and a short-circuit current of 0.264 nA, achieving a responsivity of 39.17 mA/W in the self-powered mode. The PD exhibits broadband spectral sensitivity spanning from 255 to 1010 nm, an on/off current ratio of approximately 102, and fast response times of 7.14/7.37 ms. Moreover, a signal identification system is demonstrated to demonstrate the broadband imaging capability, including wavelength-dependent image reconstruction and ASCII-coded optical signal transmission. These results highlight the strong potential of NbOCl2/WSe2 vdW heterostructures for self-powered broadband optoelectronic applications.