Construction of g-C3N4/SnSe2/H-TiO2 Ternary Heterojunction for High-Performance Photodetectors

Two-dimensional layered materials have been widely used in the field of photodetectors because of their unique photoelectric properties. Among them, the multi-heterojunction based on two-dimensional materials with high carrier separation efficiency is expected to be designed as a high-performance photodetector (PD). This work focuses on the fabrication of g-C3N4/SnSe2/H-TiO2 ternary heterojunctions for photodetectors, obtained by depositing SnSe2 and g-C3N4 nanosheets onto TiO2 nanotube arrays using chemical vapor deposition and impregnation methods, respectively. The formation of the g-C3N4/SnSe2/H-TiO2 ternary heterojunction enhances and broadens absorption in the ultraviolet-visible range. Photoelectrochemical measurements have confirmed that the fabricated g-C3N4/SnSe2/H-TiO2 ternary heterojunction photodetector exhibits remarkable light detection capabilities at 370, 450, and 520 nm, meaning broadband photodetection behavior. Notably, under light illumination of 370 nm wavelength, it demonstrates a high responsivity of 2.742 A/W, an impressive detectivity of 5.84×10¹⁰ Jones, an external quantum efficiency of 9.21×10² %, and excellent stability. This high performance can be attributed to the effective separation and transfer of photogenerated carriers within the ternary heterojunction, significantly enhancing the photoresponse. The construction of the novel broadband-responsive ternary g-C3N4/SnSe2/TiO2 heterojunction holds promise for driving the future development of wideband, high-performance, and highly integrated photodetectors.