The Effects of Morphology Formation on the Performance of Organic Photovoltaics
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Organic solar cells show the promise of being a flexible, lightweight, and low-cost alternative to silicon-based cells. However, to compete with traditional cells, they still lack long-term stability and power conversion efficiency. In this talk, we discuss a model for the formation of acceptor and donor regions during the production of organic solar cells, as well as the impact of this donor-acceptor morphology on the device performance. The morphology formation is based on a spinodal decomposition in a solvent, where the solvent is allowed to evaporate. This yields a coupling of the respective phase field equations via a degenerate mobility. In turn, the device’s electrical performance is highly dependent on the formed morphology. This becomes clear when taking the exciton-charge dynamics typical for organic materials into account. Created excitons require additional energy, provided by the energy offset between donor- and acceptor-materials to generate free charges. We provide some insight into the thermodynamic consistent modelling of the morphology formation and its effects on the device performance, as well as several numerical examples based on finite element simulations.
