Effect of self assembled monolayers on charge carrier photogeneration in sexithiophene based diodes

Photogeneration process in organic materials may occur via multiple mechanisms depending on experimental conditions. In this work we investigate how self-assembled monolayers of two types of benzoic acid molecules (ABA and NBA) affect photocarrier generation in a sexithiophene based photovoltaic cell. Photogeneration of free carriers in organic photovoltaic cells results from dissociation of Frenkel excitons. This dissociation is either thermally assisted process and/or results from the interaction with structural defects in the bulk or with the surface states. A theoretical model is used for quantitative description of the open circuit voltage as a function of generation rates at the electrodes. The orientation and the magnitude of dipole moment of SAM molecules are the crucial factors that affect the organic photovoltaic parameters.