Efficient and stable all-inorganic Sb₂(S, Se)₃ solar cells via manipulating energy levels in MnS hole transporting layers

The use of organic hole transport layer (HTL) Spiro-OMeTAD in various solar cells imposes serious stability and cost problems, and thus calls for inorganic substitute materials. In this work, a novel inorganic MnS film prepared by thermal evaporation has been demonstrated to serve as a decent HTL in high-performance Sb₂(S, Se)₃ solar cells, providing a cost-effective all-inorganic solution. A low-temperature air-annealing process for the evaporated MnS layer was found to result in a significant positive effect on the power conversion efficiency (PCE) of Sb₂(S, Se)₃ solar cells, due to its better-matched energy band alignment after partial oxidation. Impressively, the device with the optimized MnS HTL has achieved an excellent PCE of about 9.24%, which is the highest efficiency among all-inorganic Sb₂(S, Se)₃ solar cells. Our result has revealed that MnS is a feasible substitute for organic HTL in Sb-based solar cells to achieve high PCE, low cost, and high stability.