Arrays of crystalline and regularly spaced pentacene nanocolumns, with a typical diameter of ca. 150 nm, were fabricated by glancing angle deposition on indium tin oxide substrates. The nanocolumn arrays were used to form large interface area organic heterojunction photovoltaic cells (OPVCs) by spin coating [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor material to fill the voids between nanocolumn. The light to electrical energy conversion efficiency of nanocolumn-based OPVCs was three times higher compared to planar heterojunction OPVCs of the same materials due to a significantly enlarged donor/acceptor interface area where exciton dissociation can occur. Further OPVC performance improvement was achieved through employing a thin pentacene electron-blocking layer before nanocolumn formation, which prevented electron current leakage to the anode. © 2011 Elsevier B.V. All rights reserved.