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Triplet energies and excimer formation in meta- and para-linked carbazolebiphenyl matrix materials

Title data

Bagnich, Sergey A. ; Rudnick, Alexander ; Schrögel, Pamela ; Strohriegl, Peter ; Köhler, Anna:
Triplet energies and excimer formation in meta- and para-linked carbazolebiphenyl matrix materials.
In: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. Vol. 373 (2015) Issue 2044 .
ISSN 1471-2962
DOI: https://doi.org/10.1098/rsta.2014.0446

Abstract in another language

We present a spectroscopic investigation on the effect of changing the position where carbazole is attached to biphenyl in carbazolebiphenyl (CBP) on the triplet state energies and the propensity to excimer formation. For this, two CBP derivatives have been prepared with the carbazole moieties attached at the (para) 4- and 4′-positions (pCBP) and at the (meta) 3- and 3′-positions (mCBP) of the biphenyls. These compounds are compared to analogous mCDBP and pCDBP, i.e. two highly twisted carbazoledimethylbiphenyls, which have a high triplet energy at about 3.0 eV and tend to form triplet excimers in a neat film. This torsion in the structure is associated with localization of the excited state onto the carbazole moieties. We find that in mCBP and pCBP, excimer formation is prevented by localization of the triplet excited state onto the central moiety. As conjugation can continue from the central biphenyls into the nitrogen of the carbazole in the para-connected pCBP, emission involves mainly the benzidine. By contrast, the meta-linkage in mCBP limits conjugation to the central biphenyl. The associated shorter conjugation length is the reason for the higher triplet energy of 2.8 eV in mCBP compared with the 2.65 eV in pCBP.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie - Univ.-Prof. Dr. Anna Köhler
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 21 May 2015 06:17
Last Modified: 26 Apr 2016 08:23
URI: https://eref.uni-bayreuth.de/id/eprint/13944