Cu2ZnSnS4 films were examined in Eu3+/Eu2+ electrolyte to evaluate various analytical expressions for photocurrent response as a function of applied potential. A Gartner model, which considers charge transfer (across the double layer) was evaluated. This model shows an adequate fit in the negative photocurrent region. The fit of the Gartner model over a broader range of photocurrent is improved by modifying it to include the contributions due to space charge current and dark current as proposed and demonstrated in this study. Various other models and relevant fitting parameters are also evaluated and discussed in this article. (C) 2012 Elsevier B.V. All rights reserved.