Self-Powered, Broadband, and Polarization-Sensitive Photodetector Based on the ReSe ₂ /Ta ₂ NiSe ₅ van der Waals Heterojunction

Photodetectors that simultaneously integrate high responsivity, fast response, self-powered operation, and polarization sensitivity are highly needed for advanced imaging and optical information processing, yet remain challenging to realize in a simple device architecture. Here, the in-plane anisotropic ReSe 2 and narrow-bandgap Ta 2 NiSe 5 are utilized to construct a ReSe 2 /Ta 2 NiSe 5 van der Waals heterojunction photodetector with self-powered broadband operation from 375 to 850 nm. Under 532 nm illumination in the self-powered mode, the device exhibits a responsivity of 0.381 A W –1 and a specific detectivity of 5.71 × 10 9 Jones. The device also presents a fast temporal response with rise and fall times of 44 and 70 μs, respectively, as well as a −3 dB bandwidth of approximately 5 kHz, demonstrating excellent weak light and high-speed detection capability. Moreover, under zero bias, the device exhibits photocurrent polarization ratios of 1.56 and 1.83 for the vertically stacked and laterally stacked configurations, respectively, indicating a clear polarization-sensitive photoresponse. Benefiting from these features, the device further enables real-time polarization-resolved imaging of specific patterns and reliable optoelectronic signal recognition. This work establishes a simple and effective strategy for the development of miniaturized, low-power, broadband photodetectors with intrinsic polarization sensitivity based on 2D van der Waals heterostructures.