Improving the performance of Sb₂Se₃ thin film solar cells over 4% by controlled addition of oxygen during film deposition

Sb 2 Se 3 has attracted great research interest very recently as a promising absorber material for thin film photovoltaics due to its suitable bandgap, high absorption coefficient, and non‐toxic, low cost, and earth abundant nature. In this work, a significant efficiency improvement to 4.8% of superstrate cadmium sulfide (CdS)/Sb 2 Se 3 solar cells is obtained by the controlled addition of oxygen during thermal evaporation of Sb 2 Se 3 films. Systematic materials and device physics characterization reveal that oxygen addition during Sb 2 Se 3 film evaporation significantly improves the CdS/Sb 2 Se 3 heterojunction quality through effective passivation of interfacial defect states, resulting in a substantial enhancement in device circuit voltage and short circuit current density. The 4.8% device is the highest efficiency thus far reported for Sb 2 Se 3 thin film solar cells.