The performance of inverted polymer solar cells (PSCs) was enhanced by introducing TiOx and poly(9,9-dioctylfluorenyl-2,7-diyl) (PFD) as a hybrid buffer layer. Surface morphology and work function measurement demonstrated that PFD interlayer eliminated the defects and traps from TiOx surface and acted as an efficient charge transport matrix, resulting in enhanced electron mobility and reduced interface resistance. Therefore, the employment of TiOx/PFD composite layer improved to extract electron from active layer to ITO electrode and dramatically increased device efficiency from 5.717% to 7.272%, accounting for a 27.2% increase. The achieved high device efficiency, low-cost materials, and solution processes of TiOx/PFD layer provide a promising candidate for realizing high performance photovoltaic devices. (C) 2016 Elsevier Ltd. All rights reserved.