Ta2NiS5/GaSe van der Waals heterojunctions for self-driven photodetection

Two-dimensional (2D) van der Waals (vdW) heterojunctions provide an effective platform for realizing high-performance optoelectronic devices due to their tunable band alignments and unique layered structure. In this work, well-crystallized Ta2NiS5 single crystals were successfully synthesized using the chemical vapor transport method. Based on the complementary electronic structures, Ta2NiS5/GaSe vdW heterojunction photodetectors with type-II band alignment were designed and fabricated. The optoelectronic performance of the devices was systematically investigated, revealing a self-driven photodetection behavior without external bias. The photodetector exhibits a responsivity of 53.6 mA/W, a specific detectivity of 6.4 × 1010 Jones, and time-resolved response with rise/decay times of 60/50 ms, respectively. The efficient self-driven photoresponse is attributed to the built-in electric field, which facilitates effective separation and transport of photogenerated carriers. These results demonstrate the potential of Ta2NiS5-based vdW heterostructures for photodetection and provide valuable insights for the development of next-generation 2D optoelectronic devices.