The work-function of indium tin oxide (ITO) electrodes was tuned with an interfacial dipole layer (WPF-oxy-F) to reverse the polarity in polymer solar cells (PSCs) with an inverted structure. The photoactive layer was based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Silver (Ag) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were used as the top anode. The optimized conditions for the fabricated I-PSCs included an open-circuit voltage (V-oc) of 0.68 V, a fill factor (FF) of 64%, and a power conversion efficiency (PCE) of 3.86% through post-annealing at 170 degrees C. The high performance of I-PSC is due partly to the improved interfacial contact at active/PEDOT:PSS and mainly to the increase of the work-function of annealed PEDOT:PSS/Ag at 170 degrees C for 30 min. Here, we investigated the effect of post-annealing on I-PSC devices by carrying out various annealing sequences. (C) 2013 Elsevier B.V. All rights reserved.