Charge transportation mechanisms in TiO2/SnS/Ag solar cells

The charge transportation in nanostructured SnS thin film solar cells was studied with an emphasis on the band alignments and charge space limited current (SCLC) behavior. SnS nanostructures were synthesized using the coprecipitation method and deposited as a form of thin films using ethyl cellulose. The effect of deposition parameters including annealing temperature and film thickness were investigated on the role of mentioned properties. Primary characterizations show the formation of polycrystalline orthorhombic SnS nanostructures with rod-like morphology. Optical studies showed an increase in annealing temperature and thickness resulted in an increase and decrease in the optical energy band gap of absorber layers, respectively. Electrical measurements revealed the dominating effect of TiO2/SnS interface compared to the SnS/Ag interface when annealing temperature was increased. Also, increasing the annealing temperature and absorber film thickness enhanced and reduced the ideality factor (n) and mobility (mu) of devices related to the crystalline features, respectively.