Nickel acetate (Ni(Ac)2) was successfully introduced to the low band-gap system for the first time and incorporated as the anode interlayer in conventional polymer solar cells (PSCs). For PBDT-TS1/PC71BM system, the device based on as-prepared Ni(Ac)(2) performs a lower power conversion efficiency (PCE) of 6.26% in comparison to that of PEDOT:PSS-based device (6.56%). After appropriate pre-bias treatment, the device efficiency rapidly increases to 7.27%, which is 11% and 16% higher than that of PEDOT:PSS- and as-prepared Ni(Ac)(2)-based device, respectively, due to the suppressed charge recombination and enhanced hole transport at anode interface. More importantly, device with pre-bias treated Ni(Ac)(2) as anode interlayer exhibits significantly improved lifetime in N-2 atmosphere. The Ni(Ac)(2)-based PSCs could maintain almost 85% of its original PCE after 200 h, while PEDOT:PSS-based PSCs only retains 60% of its original efficiency. This work demonstrates that the low-cost Ni(Ac)(2) is an ideal anode interlayer material, which could simultaneously improve the device efficiency and stability, to replace the widely used and high-cost PEDOT:PSS. (C) 2017 Elsevier Ltd. All rights reserved.