In this work, a multilayer structure, PEDOT:PSS/insulator/PEDOT:PSS (CC), was designed and used as the anode in a polymer solar cell (PSC) to enhance the efficiency at low annealing temperature. The efficiency for PSC with CIC multilayers could increase around 22% as Compared to the reference cell. The internal electrical field enhancement due to the effective work function increase by CIC multilayer was assumed and responded to efficiency enhancement. The work function of the multilayer anode structure was explored by an electrostatic force microscopy (EFM) analysis. The EFM result shows that the surface potential of PEDPT:PSS in CIC structure is around 0.6 V higher than PEDOT:PSS in reference structure, indicating a higher work function for PEDOT:PSS in multilayer structure. By the input photon-to-current conversion efficiency (IPCE) study, the major enhancement in photocurrent occurred at solar spectrum range of 400-650 nm. Further applied to plastic substrate, the PSC exhibits 9.2% enhancement in efficiency. (C) 2010 Elsevier B.V. All rights reserved.