In this study, polymer: fullerene bulk-heterojunction hybrid solar cells with the structure indium tin oxide (ITO)/nickel oxide (NiO)/poly (3-hexylthiophene) (P3HT):[6, 6]-phenyl C61-butyric(PCBM):titania (TiO2):platinum (Pt) nanoparticles (NPs)/Ca/Alwere fabricated. The effects of a p-type NiO thin layer deposited by thermal evaporation between the active layer P3HT: PCBM: TiO2:Pt and ITO on cell performance were examined. The results show that the NiO interfacial layer between the ITO and active layer can increase the efficiency and stability of the prepared hybrid solar cells. The optimum cell performance by ITO/NiO(5 nm)/P3HT:PCBM:TiO2 (15 wt.%): Pt (0.03 wt.%)/Ca/Al (best cell structure) is an open-circuit voltage (Voc) = 0.61 V, short circuit current density (Jsc) = 6.22 mA/cm(2), fill factor (FF) = 54.8%, and eta = 2.1%. (C) 2013 Elsevier B.V. All rights reserved.