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

► Dipolar self assembled monolayers consisting of benzoic acid molecules are grafted on top of ITO electrodes. ► Coated ITO samples of the type ITO/SAM/sexithiophene/Al are compared to bare ITO ones in order to reveal the influence of the SAM layer. ► Dramatic effect is observed on I-V characteristics under illumination depending on the dipole orientation of the SAM layer. ► A theoretical model is developed to relate the open circuit voltage to photogeneration rates at both electrodes. ► Experimental results are consistent with the model that predicts a shift of open circuit voltage depending both on molecular dipole magnitude and its orientation.