Polymer solar cells (PSCs) with different anode buffer layers were fabricated to investigate dipoleassisted hole extraction on the performance improvement of PSCs. The power conversion efficiency (PCE) of PSCs was increased from 4.77% to 6.18% with 29.6% improvement due to the increased short circuit current density (J) from 12.00 to 15.65 mA/cm2 induced by the oriented LiF dipole-assisted hole extraction. More hole could be swept-out from the active layers by oriented LiF dipole/PEDOT:PSS combined anode buffer layers. The dipole-assisted hole extraction could be further demonstrated from the J-V curves of hole-only devices with different anode buffer layers. (C)2014 Elsevier B.V. All rights reserved.