Poly(vinyl alcohol)-assisted synthesis of 3D Bi2S3 submicrometric structures for feasible chip photodetector applications†

Abstract

Bismuth sulfide (Bi₂S₃) is a chalcogenide semiconductor with a relatively narrow energy band gap that is promising for use in solar cells and photodetectors. This paper presents a highly efficient microwave synthesis of Bi₂S₃ submicrometric structures using poly(vinyl alcohol) (PVA) as a viscosity modification agent. The chemical composition, morphology, crystal structure, and optical properties of the prepared materials were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). The use of PVA in Bi₂S₃ synthesis resulted in a change in material morphology from microrods to nanosheets and a slight increase in the energy band gap from 1.34 eV to 1.43 eV. The Bi₂S₃ nanosheets were examined as photosensitive materials for the detection of visible light. High ON/OFF ratios of 66, 44, and 15 and large specific detectivities of 1.12 × 10¹¹, 7.68 × 10¹⁰, and 6.43 × 10¹⁰ Jones were achieved under blue (468 nm, 0.52 μW cm⁻²), green (517 nm, 0.95 μW cm⁻²), and red (628 nm, 0.13 μW cm⁻²) light illuminations, respectively. The photosensitive properties of Bi₂S₃ nanosheets were remarkable compared to that of many other photodetectors based on Bi₂S₃ micro- and nanostructures.