Influence of regioisomerism in bis(terpyridine) based exciplexes with delayed fluorescence

A. Lennart Schleper, Sabina Hillebrandt, Christoph Bannwarth, Andreas Mischok, Seonil Kwon, Florian Buchner, Francisco Tenopala-Carmona, R. Jürgen Behm, Felix D. Goll, Philipp J. Welscher, Michael Usselmann, Ulrich Ziener*, Malte C. Gather*, Alexander J. C. Kuehne*

*Corresponding author for this work

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Exciplexes of individual electron donor and acceptor molecules are a promising approach to utilizing otherwise non-emissive triplet states in optoelectronic applications. In this work, we synthesize a series of bis(terpyridine) pyrimidine (BTP) isomers and employ them as electron acceptors in complexes with tris(4-carbazoyl-9-ylphenyl)amine (TCTA). We show that these TCTA : BTP complexes produce thermally activated delayed fluorescence (TADF) by exciplex emission, and we investigate the influence of the nitrogen position in the pyridine on the optical and electronic properties of the exciplex. The molecular arrangement of the complex is studied using scanning tunneling microscopy (STM) as well as classical force field and density functional theory (DFT) simulations. Finally, we fabricate organic light-emitting diodes (OLEDs) with maximum external quantum efficiencies ranging between 0.5% and 2% – depending on the BTP isomer.
Original languageEnglish
Pages (from-to)7699-7706
Number of pages8
JournalJournal of Materials Chemistry C
Issue number19
Early online date25 Apr 2022
Publication statusPublished - 21 May 2022


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