Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Organic Electronics and Photovoltaics I: Light-Emitting Devices

HL 13.7: Talk

Monday, March 20, 2017, 12:30–12:45, ZEU 260

Impact of charge carrier injection on single-chain photophysics of conjugated polymers — •Felix J. Hofmann, Jan Vogelsang, and John M. Lupton — Universität Regensburg

Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process, or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distribution of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The results are of interest to developing a microscopic understanding of the intrinsic charge-exciton quenching interaction in devices.