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The photovoltaic conversion efficiency of Sb2(S,Se)3 thin-film cells is significantly limited by carrier recombination at the back-contact interface. Therefore, an increasing number of studies have focused on back-contact interface optimisation. This study enhances the photovoltaic conversion efficiency of Sb2(S,Se)3 thin-film solar cells by utilizing NiOx as the hole transport layer (HTL). The inclusion of NiOx helps address the mismatch between the energy-level alignment of Sb2(S,Se)3 and the metal electrode, resulting in increased carrier collection efficiency and reduced carrier recombination at the back-contact interface, thus enhancing the performance of solar cells as a result. Under the same conditions, the NiOx film has a more suitable energy-level alignment with the Sb2(S,Se)3 film than the device fabricated with spiro-OMeTAD as the HTL, as it can extract and transport holes more efficiently and block electron transport. In addition, the influence of solution concentration and the annealing temperature on the NiOx film and device has undergone extensive investigation. The final NiOx device achieved a photovoltaic conversion efficiency of 7.40% and maintained an initial efficiency of 92% after 700 h, showing higher stability than the spiro-OMeTAD device. These findings show the enormous potential of NiOx as a hole-transport layer and offer fresh perspectives on choosing hole-transport layers for Sb2(S,Se)3 thin-film cells. [ABSTRACT FROM AUTHOR]

Antimony selenide (Sb 2 Se 3 ) has attracted considerable attention for its simple composition, nontoxic nature, and abundance. However, the efficiency of Sb 2 Se 3 solar cells is limited by the low carrier concentration and high recombination rate at the interface between Sb 2 Se 3 and the Au layer. For this paper, the KOH solution used as the etchant was used to increase the efficiency of Sb 2 Se 3 solar cells. The KOH solution not only reacts with (etching the surface) but also diffuses inside the Sb 2 Se 3 film. This study unexpectedly demonstrates that KOH also increases the doping density and improves the back contact (the thin Sb 2 O 3 layer exists with the etching of the KOH solution) of Sb 2 Se 3 solar cells. Lastly, the best power conversion efficiency of 7.16% is demonstrated with a high open-circuit voltage of 0.407 V; we believe our work can serve as a guide for further development of high-efficiency Sb 2 Se 3 solar cells.