Spin coated single-walled carbon nanotubes (SWNTs) are incorporated in organic bulk heterojunction photovoltaic devices as the hole transport layer (HTL). The SWNTs films were repetitively spin coated with dichloroethane to various thicknesses, and were evaluated as the HTL in poly(3-hexylthiophene) (P3HT) and 1-(3-methoxy-carbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) photovoltaic devices. Insertion of a 12.2 nm thick SWNTs layer leads to power conversion efficiencies as high as 3.04%, compared to 1.16% and 2.84% for the devices without and with the traditional PEDOT:PSS as the HTL, respectively. (C) 2011 Elsevier B.V. All rights reserved.