SKM 2023 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Focus: Organic Solar Cells Based on Non-fullerene Acceptors: Loss Mechanism and Options for Above 20 % Efficiencies II
CPP 11.7: Vortrag
Montag, 27. März 2023, 17:00–17:15, GÖR 226
Triplet Excitons and associated Efficiency-Limiting Pathways in NFA-based Organic Solar Cell Blends — Jeannine Grüne1,2, Giacomo Londi3, Alexander J. Gillett2, Yoann Olivier3, Vladimir Dyakonov1, and •Andreas Sperlich1 — 1Experimental Physics 6, Julius Maximilian University of Würzburg, Germany — 2Cavendish Laboratory, University of Cambridge, UK — 3Laboratory for Computational Modeling of Functional Materials, Université de Namur, Belgium
Organic solar cells (OSC) have made great progress in recent years, but are now reaching a performance plateau. Triplet states are known to adversely affect efficiency by opening a channel for non-radiative recombination pathways. Here, we use the complementary spin-sensitive methods of photoluminescence detected magnetic resonance (PLDMR) and transient electron paramagnetic resonance (trEPR) corroborated by transient absorption and quantum-chemical calculations to unravel exciton pathways in OSC blends employing the (non-) halogenated polymer donors PBDB-T, PM6 and PM7 together with NFAs Y6 and Y7. We reveal that all blends form triplet excitons on the NFA populated via non-geminate hole back transfer and, in blends with halogenated donors, also by spin-orbit coupling driven intersystem crossing. Identifying these triplet formation pathways in all tested solar cell absorber films highlights the untapped potential for improved charge generation to further increase efficiencies.