An experimental and theoretical study of exciplex-forming compounds containing trifluorobiphenyl and 3,6-di-tert-butylcarbazole units and their performances in OLEDs

Keruckiene, R., Guzauskas, M., Lapienyte, L., Simokaitiene, J., Volyniuk, D., Cameron, J. , Skabara, P. J. , Sini, G. and Grazulevicius, J. V. (2020) An experimental and theoretical study of exciplex-forming compounds containing trifluorobiphenyl and 3,6-di-tert-butylcarbazole units and their performances in OLEDs. Journal of Materials Chemistry C, 8, pp. 14186-14195. (doi: 10.1039/D0TC02777D)

Abstract

Derivatives of trifluorobiphenyl and 3,6-di-tert-butylcarbazole were synthesised as potential components of emitting layers of OLEDs. Molecular design of the compounds was performed taking into consideration the hydrogen bonding ability of the fluorine atom and electron-donating ability of the carbazole moiety. Their toluene solutions exhibited very high triplet-energy values of 3.03 eV and 3.06 eV. Ionisation energies of the compounds in the solid-state were found to be in the range from 5.98 to 6.17 eV. Density functional theory (DFT) calculations using the ωB97XD functional, with the ω parameter tuned in the presence of the solvent, uncovered singlet–triplet energy splitting in good agreement with the experimental results. The materials were tested in the emissive layers of OLEDs, showing the ability to form exciplexes with complementary electron-accepting 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine. Using the synthesised compounds as exciplex-forming materials, highly efficient exciplex emission-based OLEDs were developed. In the best case, a high maximum current efficiency of 24.8 cd A−1, and power and external quantum efficiencies of 12.2 lm W−1 and 7.8%, respectively, were achieved.

• Item Type: Articles
• Additional Information: R. K. and L. L. acknowledge the Research, Development and Innovation Fund of Kaunas University of Technology (project grant no. PP-91C/19) for the financial support. The authors acknowledge the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement no. 823720. J. C. and P. J. S. also thank the EPSRC for funding (EP/N035496/2).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cameron, Dr Joseph and Skabara, Professor Peter
• Authors: Keruckiene, R., Guzauskas, M., Lapienyte, L., Simokaitiene, J., Volyniuk, D., Cameron, J., Skabara, P. J., Sini, G., and Grazulevicius, J. V.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Journal of Materials Chemistry C
• Publisher: Royal Society of Chemistry
• ISSN: 2050-7526
• ISSN (Online): 2050-7526
• Copyright Holders: Copyright © 2020 The Royal Society of Chemistry
• First Published: First published in Journal of Materials Chemistry C 8:14186-14195
• Publisher Policy: Reproduced under a Creative Commons Licence
• Data DOI: 10.5525/gla.researchdata.1061

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
303848		Molecular assembly of spintronic circuits with DNA	Peter Skabara	Engineering and Physical Sciences Research Council (EPSRC)	EP/N035496/2	Chemistry