A novel nanocomposite based on NiO_x-incorporated P3HT as hole transport material for Sb₂S₃ solar cells with enhanced device performance

To achieve superior photovoltaic performance on Sb₂S₃ solid state solar cells (ssSCs), the concomitant development of efficient hole transport materials (HTMs) is required. Herein, a novel solution processed HTM obtained by mixing NiO_x nanoparticles (NiO_x-NP) and poly(3-hexylthiophene) (P3HT) is reported. These P3HT:NiO_x-NP nanocomposite HTMs were obtained with different controlled concentrations of NiO_x-NP using a common solvent. Incorporation of NiO_x-NP significantly impacts on the structural and hole-transport layer properties of the nanocomposite films, which in turn contributes to improve the photovoltaic performance of the corresponding devices. Thus, Sb₂S₃ ssSCs based on HTM with an optimum concentration of NiO_x-NP in P3HT, i.e. P3HT:2% NiO_x-NP, yield a 50% improvement in the power conversion efficiency relative to control devices fabricated with pristine P3HT. The improved hole separation and injection at the Sb₂S₃/HTM interface, determined by steady-state photoluminescence quenching and electrochemical impedance spectroscopy studies, correlate well with the higher hole mobility of the nanocomposite and the current density and fill factor enhancements.