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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Molecular Electronics and Excited State Properties I

CPP 3.7: Vortrag

Montag, 16. März 2020, 11:00–11:15, ZEU 260

Electronic and optical properties of BCF-doped oligothiophenes from ab initio many-body theory — •Richard Schier, Ana Valencia, and Caterina Cocchi — Humboldt-Universität zu Berlin und IRIS Adlershof

Doping in organic semiconductors is an attractive research area for molecular electronics although the fundamental mechanisms ruling it are not yet fully understood. Recently, Lewis-acids such as tris(pentafluorophenyl)borane (BCF)^[1] have been regarded with particular interest as a new class of dopants for organic semiconductors^[2]. To gain insight into the microscopic properties of these materials, we investigate the electronic structure and optical properties of donor/acceptor interfaces formed by a single quarterthiophene (4T) molecule doped by a BCF species. For comparison, we consider also other adducts with 4T doped by hexafluorobenzene (C₆F₆) and the trihalide BF₃. We carry out our study from first principles, in the framework of hybrid density-functional theory and many-body perturbation theory. For all systems, we find that the frontier orbitals are poorly hybridized and rather segregated on the donor or the acceptor depending on the specific level alignment of the system. As a consequence, the optical spectra of the systems appear almost as a superposition of those of the respective constituents. A careful analysis reveals interaction signatures in the form of dark excitations and peak shifts^[3].

[1] Körte et al., Angew. Chem. 56, 8578 (2017) [2] Yurash et al., Nat. Mater. 18, 1327 (2019) [3] Schier et al., to be submitted (2020)