SKM 2021 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 11: Organic Electronics and Photovoltaics, Electrical and Optical Properties (joint session CPP/KFM)

KFM 11.8: Vortrag

Donnerstag, 30. September 2021, 15:45–16:00, H3

Ultrafast Energy Conversion in Organic Photovoltaic Materials: First-principles modelling of the prototypical P3HT-PCBM blend heterojunction — •Elisa Palacino-González and Thomas la Cour Jansen — University of Groningen, Faculty of Science and Engineering, Nijenborgh 4, 9747 AG Groningen

One of the reasons behind the low energy conversion efficiency of organic photovoltaic cells has been ascribed to electronic-vibrational dynamics affecting the ultrafast charge separation material upon light absorption. The absence of a comprehensive theoretical description of this process has restrained further advancements in this direction. Here the first step towards this is presented by introducing a first-principles modelling of the key prototype P3HT-PCBM heterojunction system with a realistic description of the blend environment. MD simulations with the GROMOS 53A6 force field are performed to determine structural and dynamical properties of the blend. Representative strongly coupled subsystems of donor-acceptor pairs with a few P3HT-PCBM moieties are selected from the MD structures, with the bright donor state localised on the P3HT molecule and the charge transfer state with a hole on P3HT and the electron on PCBM. Using an electronic basis, the Hamiltonian includes localised excitons and charge transfer states. Excitation energies fluctuating along the MD trajectory are determined using TDDFT and an electrostatic mapping scheme, which are used to define the spectral densities of the system-bath coupling. The resultant molecular Hamiltonian will be used in the quantum dynamical and spectral simulations in the following step.