Self-powered broadband WS2/CuO heterojunction photodetector with a TiO2 buffer layer

Here, we fabricated a WS 2 /CuO heterostructure photodiode on an FTO substrate using a sputtering method with a TiO 2 buffer layer to investigate the broadband photoresponse from UV to red wavelengths. The device exhibits rectifying and photovoltaic characteristics, enabling self-powered operation over a broad spectral range from UV to red wavelengths (368–622 nm). Under UV illumination, the device achieves a photoresponse ratio of 101, a responsivity of 0.25 mA/W, and a specific detectivity of 3.9 × 10 7 Jones which decrease as the incident photon energy decreases in the visible wavelength range. The photoresponse gradually decreases with increasing wavelength, while the self-powered device exhibits rise and decay times of 50 and 100 ms, respectively. The results demonstrate that the TiO 2 buffer-assisted WS 2 /CuO heterojunction provides an effective strategy for broadband self-powered photodetection and offers potential for low-power optoelectronic applications.