The open-circuit voltage dependence on light intensity and temperature is calculated for organic photovoltaics, taking into account the generalized Einstein relation for disordered semiconductors. The results show that open-circuit voltage losses in bulk-heterojunction organic solar cells are affected from the diffusion enhancement inherent to disordered semiconductors. The model is validated by the fitting to recently published experimental data. (C) 2011 Elsevier B.V. All rights reserved.