Investigation of electronic transport mechanisms in Sb2Se3 thin-film solar cells

Electronic transport mechanisms in Sb2Se3 thin-film solar cells were investigated using temperature-dependent current-voltage (J-V) measurements. Sb2Se3 thin films were deposited via the vapor transporting deposition method using a double-temperature-zone tubular furnace system, and comparative studies were performed for Sb2Se3 films formed on substrates located at three different positions away from the furnace center. The device efficiency varied from 3.83 to 6.24%. First, structural properties obtained by X-ray diffraction, Raman and scanning electron microscopy measurements verified the optimal Sb2Se3 film quality for the cell with the highest efficiency. Then, temperature-dependent saturation current and open-circuit voltage (V-oc) measurements revealed that the dominant carrier recombination occurred in the CdS/Sb2Se3 interface region, which possibly influenced the V-oc for all cells: the highest V-oc for the optimal Sb2Se3 cell was at least partly due to it having the lowest CdS/Sb2Se3 interface recombination rate. Finally, the reverse bias current relationship revealed that non-ohmic shunt current (space-charge-limited current, SCLC) plays an important role in affecting the performance of solar cells, as lower-efficiency cells had higher non-ohmic shunt current.