Kavand, Marzieh and Baird, Douglas and van Schooten, Kipp and Malissa, Hans and Lupton, John M. and Boehme, Christoph (2016) Discrimination between spin-dependent charge transport and spin-dependent recombination in pi-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance. PHYSICAL REVIEW B, 94 (7): 075209. ISSN 2469-9950, 2469-9969
Full text not available from this repository.Abstract
Spin-dependent processes play a crucial role in organic electronic devices. Spin coherence can give rise to spin mixing due to a number of processes such as hyperfine coupling, and leads to a range of magnetic field effects. However, it is not straightforward to differentiate between pure single-carrier spin-dependent transport processes which control the current and therefore the electroluminescence, and spin-dependent electron-hole recombination which determines the electroluminescence yield and in turn modulates the current. We therefore investigate the correlation between the dynamics of spin-dependent electric current and spin-dependent electroluminescence in two derivatives of the conjugated polymer poly(phenylene-vinylene) using simultaneously measured pulsed electrically detected (pEDMR) and optically detected (pODMR) magnetic resonance spectroscopy. This experimental approach requires careful analysis of the transient response functions under optical and electrical detection. At room temperature and under bipolar charge-carrier injection conditions, a correlation of the pEDMR and the pODMR signals is observed, consistent with the hypothesis that the recombination currents involve spin-dependent electronic transitions. This observation is inconsistent with the hypothesis that these signals are caused by spin-dependent charge-carrier transport. These results therefore provide no evidence that supports earlier claims that spin-dependent transport plays a role for room-temperature magnetoresistance effects. At low temperatures, however, the correlation between pEDMR and pODMR is weakened, demonstrating that more than one spin-dependent process influences the optoelectronicmaterials' properties. This conclusion is consistent with prior studies of half-field resonances that were attributed to spin-dependent triplet exciton recombination, which becomes significant at low temperatures when the triplet lifetime increases.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | LIGHT-EMITTING-DIODES; THIN-FILM DEVICES; POLARON PAIRS; MAGNETORESISTANCE; SEMICONDUCTORS; SPINTRONICS; ANTHRACENE; BIPOLARON; EXCITONS; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 05 Apr 2019 08:52 |
| Last Modified: | 05 Apr 2019 08:52 |
| URI: | https://pred.uni-regensburg.de/id/eprint/3453 |
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