Combating open circuit voltage loss in Sb2Se3 solar cell with an application of SnS as a back surface field layer

Recently, Sb2Se3 based solar cells have shown severe open-circuit voltage (V-OC) loss that results in low device efficiency. In the present work, a model of Sb2Se3 solar cell with tin sulfide (SnS) as a back surface field layer (BSF) layer was designed and investigated via a solar cell capacitance simulator (SCAPS)-1D simulation software. The influence of the ultrathin BSF layer was investigated as a function of Sb2Se3 absorber thickness, and the corresponding device performance was analyzed. Apart from this, the effect of high BSF layer thickness, doping concentration, interface defect density, and resistance were also examined. Applying the BSF layer decreased the valence band offset value, which eases the hole transport at the back interface. At the same time, the high electric field region generated at the back interface creates a barrier for the minority carriers. Synergistically, in the presence of the BSF layer, the carrier recombination current densities were found to be almost negligible. As a result, the introduction of the 10 nm thin BSF layer significantly improved the device's V-OC and power conversion efficiency (PCE) from 0.416 to 0.603 V and 9.61 to 17.75%, respectively for the absorber layer thickness of 700 nm. The present simulation study performed with the full earth-abundant element-based low-cost materials may assist the photovoltaic community in combating the V-OC loss and further improving the PCE of Sb2Se3 based solar cells.