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Frontiers in Luminescent Organic Semiconductor Materials and Devices, 2023

DOI: 10.1117/12.2644998

Nature Research, Nature Communications, 1(11), 2020

DOI: 10.1038/s41467-020-15034-0

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High energy acceptor states strongly enhance exciton transfer between metal organic phosphorescent dyes

Journal article published in 2020 by Xander de Vries, Reinder Coehoorn ORCID, Peter A. Bobbert ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

AbstractExciton management in organic light-emitting diodes (OLEDs) is vital for improving efficiency, reducing device aging, and creating new device architectures. In particular in white OLEDs, exothermic Förster-type exciton transfer, e.g. from blue to red emitters, plays a crucial role. It is known that a small exothermicity partially overcomes the spectral Stokes shift, enhancing the fraction of resonant donor-acceptor pair states and thus the Förster transfer rate. We demonstrate here a second enhancement mechanism, setting in when the exothermicity exceeds the Stokes shift: transfer to multiple higher-lying electronically excited states of the acceptor molecules. Using a recently developed computational method we evaluate the Förster transfer rate for 84 different donor–acceptor pairs of phosphorescent emitters. As a result of the enhancement the Förster radius tends to increase with increasing exothermicity, from around 1 nm to almost 4 nm. The enhancement becomes particularly strong when the excited states have a large spin-singlet character.