Photocurrent generation in plain [6,6]-phenyl C61 butyric acid methyl ester (PCBM) is realized by inserting poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with a wide band gap between indium tin oxide (ITO) anode and PCBM. The insertion blocks electron injection from PCBM to ITO while keeping hole transfer from PCBM to ITO via PEDOT:PSS, which results in a photocurrent from the plain PCBM layer, achieving a light-to-electricity quantum efficiency of up to 2.6%. Contrarily, no photocurrent is detected in a device without such a PEDOT:PSS layer. Exciton dissociation and simultaneous free carrier separation at PEDOT:PSS-PCBM interface is responsible for the generated photocurrent. (C) 2010 Published by Elsevier B.V.