UV-assisted sonochemical synthesis and optoelectrical properties of Bi2S3/rGO nanocomposites

In the present study, a simple UV-assisted sonication method is used for the development of bismuth sulfide (Bi2S3) nanostructures on graphene sheets. X-ray diffraction (XRD) and Raman results indicated that graphene oxide (GO) layers are reduced. Field emission scanning electron microscopy (FESEM) images also indicated that Bi2S3 particles without rGO sheets are agglomerated. In comparison, when adding these sheets, the particles are uniformly spread (decorated) and their size is reduced significantly due to the incorporation of rGO sheets. UV-Vis studies reveal that the band gap in Bi2S3/rGO nanocomposites compared with Bi2S3 has a shift toward shorter wavelengths, suggesting some changes in the electronic band structure of Bi2S3 due to the existence of rGO sheets. Photoluminescence (PL) analysis indicated emission bands in infrared and visible regions resulting from the band edge emission and crystal defects in the samples, respectively. The electrical investigations showed reduced recombination of photogenerated carriers in the nanocomposites. Moreover, the results indicated that the concentration of rGO is an important factor in determining the optoelectrical behavior of these devices.