Studies on Synthesis and Characterization of a Chemically Deposited Nanostructured Thin Film of Ternary Compound Silver Bismuth Sulfide (AgBi2S3) onto n-Type Wide Band Gap Semiconducting Titanium Dioxide (TiO2)

Silver bismuth sulfide (AgBi2S3) belongs to the I–V–VI group of semiconducting materials and is a non-toxic, earth capacious compound. It has an energy gap of 1.2 eV, which is very close to the exemplary energy gap of 1.39 eV for solar cell absorbers. It also has a high absorption coefficient of 105 cm−1 at 600 nm. This work reports the chemical deposition of a nanostructured thin film of ternary compound silver bismuth sulfide (AgBi2S3) on a mesoporous layer of titanium dioxide (TiO2) deposited by a spin coating method. The synthesized layer of TiO2/AgBi2S3 was characterized by techniques such as XRD, UV–visible spectroscopy, surface morphology, energy dispersive x-ray composition analysis, and cross-section. Nanoparticles of the ternary metal chalcogenide AgBi2S3 with a diameter of about 150–200 nm were synthesized chemically, and this layer, with a thickness of about 15 µm, was deposited on the FTO glass substrate. The absorbance of TiO2/AgBi2S3 thin film increased over the entire visible and IR regions of the spectrum. TiO2’s optical energy gap was reduced from 3.07 eV to 1.7 eV after sensitization with AgBi2S3 nanoparticles. The results of characterization confirm the deposition of a very thin layer of TiO2/AgBi2S3, which will be further explored for photovoltaic applications.