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HL: Fachverband Halbleiterphysik

HL 61: Posters III (Organic-inorganic perovskite semiconductors; Organic photovoltaics and electronics; Photovoltaics; Energy science; New materials and concepts)

HL 61.25: Poster

Wednesday, March 18, 2015, 15:00–20:00, Poster F

Investigation of Recombination Processes in Organic Solar Cells — •Sascha Ullbrich, Donato Spoltore, Janine Fischer, Christian Körner, Koen Vandewal, and Karl Leo — Institut für Angewandte Photophysik, Dresden, Deutschland

Recombination of charge carriers is one of the most important loss mechanisms in a solar cell. In competition to generation, it defines the open-circuit voltage by setting the equilibrium charge carrier density. Thus, it is necessary to study and understand recombination mechanisms in order to tap the full potential of organic photovoltaics. In this work, non-geminate recombination mechanisms and recombination dynamics of organic solar cells based on small molecules with different active layer thicknesses are studied. Charge extraction measurements and intensity dependent current-voltage characteristics are used to determine charge carrier densities, recombination rates and the dominant recombination mechanism under steady state conditions. We observe a change from bimolecular to trap-assisted recombination towards lower carrier densities and a decreasing recombination order with increasing active layer thicknesses.