Transient photocurrent response of Bi2S3/rGO nanocomposites synthesized by UV-assisted sonication method

In this paper, bismuth sulfide/reduced graphene oxide (Bi2S3/rGO) nanocomposites were synthesized by UV-assisted sonication. X-ray diffraction (XRD) studies of samples showed Bi2S3 polycrystalline phase with orthorhombic crystal lattice, which their crystallinity is related to UV-sonication irradiation time. Field emission scanning electron microscopy (FESEM) images of Bi2S3 samples indicate that particles aggregate and increase their average size by increasing the irradiation time. Transmission electron microscopy (TEM) images of Bi2S3/rGO composites showed that particles are not agglomerated in the presence of rGO sheets, and uniformly distributed on these sheets, and their average size has decreased due to the incorporation of these sheets. The x-ray photoelectron spectroscopy (XPS) analysis showed that the samples have the high purity grade of the Bi2S3 phase. UV-vis spectra of all samples, have broad absorption in visible and near infrared regions. Photoluminescence (PL) studies of Bi(2)S(3 )samples, showed three emission peaks in the violet, green, and infrared regions of the electromagnetic spectrum. Finally, the effect of calcination temperature and rGO concentration were investigated on electrical performance and optical response of samples made from nanocomposites. The results showed that they all had n-type conductivity and their photocurrent is strongly dependent on calcination temperature and rGO concentration and the highest response was in the UV range.