Preparation of vertical structure SnS2/SnSe2/H–TiO2 ternary heterojunction and its high performance ultraviolet/visible photodetector

Abstract

Developing highly efficient heterojunction photodetector, especially ternary heterojunctions of vertical structure, is a promising strategy to enhance the migration of photo-generated electron for exploit potentialities of optoelectronic devices. In this study, we successfully deposited two-dimensional layered SnSe2 NSs and SnS2 NSs vertically on TiO2 NTs arrays using chemical vapor deposition (CVD), constructing a novel ternary SnS2/SnSe2/H–TiO2 heterojunction. The morphology, structure, and composition of the samples were analyzed, and highly sensitive ultraviolet/visible light photodetectors were fabricated. Photocurrent measurements demonstrated that the prepared SnS2/SnSe2/H–TiO2 ternary heterojunction exhibited superior light detection capability at different wavelengths (370 nm, 450 nm, 520 nm) compared to the pristine H–TiO2 and its binary heterojunctions (SnS2/H–TiO2, SnSe2/H–TiO2). Under a bias voltage of 1 V and 370 nm illumination, it achieved a high photocurrent of 7.45 mA cm−2, a switch ratio of 7.924, as well as high responsivity (9.39 A/W), high EQE (3.15 × 103 %), and large detectivity (9.53 × 1010 Jones). The excellent performance of the SnS2/SnSe2/H–TiO2 ternary heterojunction reveals its enormous potential in the development of wide-band, high-performance photodetectors.