Regensburg 2025 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
HL: Fachverband Halbleiterphysik
HL 39: Poster III
HL 39.19: Poster
Wednesday, March 19, 2025, 15:00–18:00, P3
Quantum-chemical calculations of structure, electronic properties, and spectra of a model for PBDB-T:ITIC heterojunctions — Montassar Chaabani1, Samir Romdhane2, and •Wichard J. D. Beenken2 — 1Advanced Materials and Quantum Phenomena Laboratory, Physics Department, Faculty of Sciences of Tunis, University of Tunis El Manar, Tuins, Tunesia — 2Technische Universität Ilmenau, Institut für Physik, Ilmenau, Germany
We modeled PBDB-T:ITIC heterojunctions by applying DFT on dimers built of various conformers of a PBDB-T segment and the ITIC molecule. These variations represented the non-uniformity of the interface between the donor and the acceptor in the organic solar cell. Based on this model, we calculated electronic and optical properties most relevant for charge separation at the interface using DFT and TD-DFT, respectively. For almost half of our modeled dimers, we found that the band offsets between them and the pristine donor and acceptor materials resulted in charge carrier trapping leading to inefficient charge separation as well as non-geminate recombination. When we calculated the exciton binding energy by TD-DFT using either the B3LYP or the HSE06 functional, we obtained very different qualitative and quantitative results. We, therefore, compared our results with experimental data from ultraviolet photoelectron spectroscopy, CV, ER-EIS, PL, absorption spectroscopy, EQE and EL. Finally we discuss the impact of our findings on characteristic photovoltaic parameters, particularly the open circuit voltage and the short-circuit current.
Keywords: non-fullerene; conjugated polymers; charge transfer; DFT; TD-DFT