SKM 2023 – scientific programme
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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 11.5: Talk
Monday, March 27, 2023, 16:30–16:45, GÖR 226
Relating free charge carrier generation and field induced photoluminescence quenching in a non-fullerene-based organic blend with a low energy offset — •Manasi Pranav1, Thomas Hultzsch1, Bowen Sun1, Rong Wang2, Safa Shoaee1, Larry Lüer2, Christoph Brabec2, and Dieter Neher1 — 1Institute of Physics and Astronomy, University of Potsdam, 14476 Germany — 2Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander-Universität Erlangen-Nürnberg Martensstrasse 7, 91058 Erlangen, Germany
Many studies currently target the process of free charge carrier generation and recombination in relation to the energy level offset in organic blends based on non-fullerene acceptors (NFA). Here, we add to this discussion with a focus on the NFA Y5, characterized by a smaller highest occupied molecular orbital offset in PM6:Y5 compared to PM6:Y6, despite molecular similarity between Y5 and Y6. We find that the PM6:Y5 blend exhibits a pronounced field-dependence of free charge generation, as measured with the time-delayed collection field (TDCF) technique. We verify this with a new arbitrary-waveform TDCF technique that provides finer control over the time-delay parameters. In addition to this, we also observe a surprisingly pronounced effect of the electric field on both the steady state photoluminescence (PL) intensity and the transient PL lifetime. These results indicate that the field dependence of photo-current, free charge carrier generation and PL quenching in this low-offset system are governed by the same mechanism: likely field-induced exciton dissociation.