Institut für Physik und Astronomie
Refine
Year of publication
Document Type
- Article (14)
- Doctoral Thesis (1)
Is part of the Bibliography
- yes (15)
Keywords
- conjugated polymers (2)
- Konjugierte Polymere (1)
- Mehrstoffsystem (1)
- OLED (1)
- TCAD (1)
- UV-vis spectroscopy (1)
- charge transport (1)
- conducting polymer (1)
- degradation (1)
- high performance polymers (1)
Institute
Understanding the origin of inefficient photocurrent generation in organic solar cells with low energy offset remains key to realizing high-performance donor-acceptor systems. Here, we probe the origin of field-dependent free-charge generation and photoluminescence in wnon-fullereneacceptor (NFA)-based organic solar cells using the polymer PM6 and the NFA Y5-a non-halogenated sibling to Y6, with a smaller energetic offset to PM6. By performing time-delayed collection field (TDCF) measurements on a variety of samples with different electron transport layers and active layer thickness, we show that the fill factor and photocurrent are limited by field-dependent free charge generation in the bulk of the blend. We also introduce a new method of TDCF called m-TDCF to prove the absence of artifacts from non-geminate recombination of photogenerated and dark charge carriers near the electrodes. We then correlate free charge generation with steady-state photoluminescence intensity and find perfect anticorrelation between these two properties. Through this, we conclude that photocurrent generation in this low-offset system is entirely controlled by the field-dependent dissociation of local excitons into charge-transfer states. (c) 2023 Author(s).