The use of water and organic solvent-based polyaniline (PANI) films as hole injecting layer in organic photovoltaic cells is Studied. We have shown that the conductivity and the thickness of the polyaniline films greatly influence the performance of the devices. We proved that a PANI-based hole injecting layer with conductivity of 10(-2) S/cm is sufficient to achieve a good performance. Moreover, the dopant, the solvent and the addition of polyacrylamide (PAM) into the PANI play important roles. The best power conversion efficiency (eta = 2.5%) was reached with both water and organic solvent-based PANI under an illumination of AM 1.5G (100 mW/cm(2)). (C) 2009 Elsevier B.V. All rights reserved.