Enhancement in the efficiency of Sb₂(S,Se)₃ thin-film solar cells with spin-coating NiO_x as the hole transport layer

The photovoltaic conversion efficiency of Sb-2(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 Sb-2(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 Sb-2(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 Sb-2(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 Sb-2(S,Se)(3) thin-film cells.