Regensburg 2019 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 50: Organic Electronics and Photovoltaics III - Organic Photovoltaics
CPP 50.7: Talk
Thursday, April 4, 2019, 11:00–11:15, H18
Energy Distribution of Charge-Transfer Excitons at Organic Donor-Acceptor Interfaces: Simulations for Room Temperature — •Sebastian Schellhammer1,2, Gianaurelio Cuniberti1,2, and Frank Ortmann2 — 1Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062 Dresden, Germany — 2Center for Advancing Electronics Dresden, Technische Universität Dresden, 01062 Dresden, Germany
Charge transfer (CT) excitons at donor-acceptor interfaces determine the performance of organic solar cells. The subgap absorption by such excitons is also used to design sensitive near-infrared photodetectors based on the broad CT exciton bands. However, the prediction of the energetics of the CT exciton band has ever been a great challenge. We present an approach for an efficient computation of the CT energies at room temperature based on time-dependent density functional theory including the band tail broadening induced by thermal fluctuations in a semi-classical way. This method is demonstrated for different donor molecules with C60 as electron accepting material. A comparison to experimental CT band characteristics shows excellent agreement for both the linewidth broadening as well as the CT energies. The approach thus combines accuracy with modest computational cost.