Predicting the J-V Curve in Organic Photovoltaics Using Impedance Spectroscopy

Abstract

Impedance spectroscopy is used as a method to predict the current-voltage curve in organic photovoltaic devices. This technique allows the quantification of the recombination rate, series resistance, carrier density, and lifetime very close to normal operating conditions. The current density is reconstructed from the generation and recombination rates. Excellent agreement with measured results is observed using this simple model. The order of recombination is found to be strongly bias dependent, displaying a shift in the dominant form of recombination from trap-mediated at low carrier densities to bimolecular at high carrier densities. Mobility is shown for a range of intensities and is found to vary significantly with fabrication conditions.