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

Abstract

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 NiO_x as the hole transport layer (HTL). The inclusion of NiO_x 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 NiO_x 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 NiO_x film and device has undergone extensive investigation. The final NiO_x 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 NiO_x as a hole-transport layer and offer fresh perspectives on choosing hole-transport layers for Sb₂(S,Se)₃ thin-film cells.