Intensity-dependent equivalent circuit parameters of organic solar cells based on pentacene and C-60

Abstract

We present studies of the current-voltage characteristics of organic solar cells based on heterojunctions of pentacene and C-60 as a function of illumination intensity. The photovoltaic response at a given illumination level is parameterized and modeled using the equivalent circuit model developed for inorganic pn-junction solar cells. Reduction in shunt resistance and increase in diode reverse saturation current density are observed upon increase of the light intensity. We demonstrate that this effect can be modeled by a refined equivalent circuit model that contains an additional shunt resistance and an additional diode the properties of which are functions of the light intensity. The effects of these additional components on the overall photovoltaic performance are discussed. (c) 2005 American Institute of Physics.