Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Poster I
HL 13.20: Poster
Montag, 18. März 2024, 15:00–18:00, Poster E
Quantum-chemical calculations of structure, electronic properties, and spectra of neat PBDB-T:ITIC heterojunctions — Montassar Chaabani1, Samir Romdhane1, and •Wichard J. D. Beenken2 — 1Advanced Materials and Quantum Phenomena Laboratory, Physics Department, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia — 2Technische Universität Ilmenau, Institut für Physik, Ilmenau, Germany
In order to overcome the short-comings of polymer:fullerene heterojunctions in organic solar cells, an exchange of the fullerene by other organic molecules, e.g. ITIC has been proposed. In this context, we simulate the structural, electronic and optical properties of PBDB-T:ITIC interfaces quantum-chemically. We constructed oligomers in various conformations in order to represent a segment of the copolymer PBDB-T as well as three conformers of ITIC. These were combined to dimers in either parallel and T-shaped arrangement, and optimized in DFT calculations utilizing the B3LYP-GD3 functional, which considers the Van der Walls interaction semi-empirically. By comparing the MO-energies of the optimized PBDB-T oligomers, ITIC conformers, and dimers, we classified the resulting heterojunctions. Furthermore, we calculated the excited states of the dimers by TD-DFT in order to determine the exciton binding energies and to distinguish charge transfer from excitonic states. Eventually, we provide some indications, to the influence of the PBDB-T:ITIC interface design on the photovoltaic performance.
Keywords: non-fullerene; conjugated polymers; charge transfer; DFT; photovoltaic