Improving the fundamental understanding of charge carrier extraction and recombination mechanisms in organic photovoltaics is key to the development of more efficient photovoltaic systems. Time resolved charge extraction (TRCE) measurements are ideally suited to the study of charge carrier extraction and recombination dynamics from the nanosecond to millisecond timescale. TRCE allows the measurement of charge carrier density, charge carrier lifetime, bimolecular recombination coefficient, and external quantum efficiency for a wide range of charge densities.
The application of an applied bias during TRCE measurements has been used to further improve the versatility of this technique. The applied bias helps to suppress recombination occurring during the extraction process, yielding a more accurate measure of charge density within the device. Through variation of applied bias, information of the degree of shallow trapped states and charge transport properties can also be ascertained. A variety of both efficient and inefficient organic photovoltaic systems have been studied using this technique, providing insight into charge carrier extraction and recombination dynamics present in these systems.