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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Molecular Electronics and Excited State Properties I

CPP 3.8: Vortrag

Montag, 16. März 2020, 11:30–11:45, ZEU 260

Ab initio modelling of local interfaces in doped organic semiconductors — Ana Maria Valencia, •Guerrini Michele, and Caterina Cocchi — Humboldt-Universität zu Berlin

Despite the intensive efforts in the last decade, a clear and comprehensive understanding of the microscopic properties of doped organic semiconductors is still missing. Due to the complexity of these systems, which notoriously exhibit high level of disorder, also the results from quantum-mechanical ab initio methods are somehow constrained by the choice of the model structures. For a reliable prediction of electronic and optical properties, it is essential to rationalize the role of local interfaces between interacting donor and acceptor species. We address this problem from hybrid density-functional theory and many-body perturbation theory, investigating the structural, electronic, and optical properties of oligothiophenes doped by F4TCNQ. We consider different structures from isolated dimers and trimers, to periodic stacks and crystalline arrangements. Our results show that, depending on the amount and the nature of the local donor/acceptor interfaces, the choice of the simulated structure critically impacts the resulting electronic structure and degree of charge transfer. On the other hand, the optical spectra appear less sensitive to these characteristics, although a detailed inspection of the electron and hole densities discloses different excitation character depending on the relative donor/acceptor concentration [1] as well as on the donor length [2].

[1] Valencia, Guerrini, Cocchi, submitted (2019).

[2] Valencia & Cocchi, JPCC 123, 9617 (2019).