Contribution of TADF and exciplex emission for efficient “warm-white” OLEDs

Gintare Grybauskaite-Kaminskiene; Khrystyna Ivaniuk; Gintautas Bagdziunas; Pavlo Turyk; Pavlo Stakhira; Gleb Baryshnikov; Dmytro Volyniuk; Vladyslav Cherpak; Boris Minaev; Zenon Hotra; Hans Ågren; Juozas Vidas Grazulevicius

doi:10.1039/C7TC05392D

Contribution of TADF and exciplex emission for efficient “warm-white” OLEDs†

Gintare Grybauskaite-Kaminskiene,^a Khrystyna Ivaniuk,^b Gintautas Bagdziunas,

^a Pavlo Turyk,^b Pavlo Stakhira,^b Gleb Baryshnikov,

^cd Dmytro Volyniuk,

^a Vladyslav Cherpak,^e Boris Minaev,^cd Zenon Hotra,^bf Hans Ågren

^cg and Juozas Vidas Grazulevicius

*^a

Author affiliations

* Corresponding authors

^a Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, Kaunas, Lithuania
E-mail: juozas.grazulevicius@ktu.lt

^b Lviv Polytechnic National University, S. Bandera 12, 79013 Lviv, Ukraine

^c Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 10691 Stockholm, Sweden

^d Bohdan Khmelnytsky National University, Shevchenko 81, 18031 Cherkassy, Ukraine

^e School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

^f Rzeszów University of Technology, W. Pola 2, Rzeszów 35-959, Poland

^g Institute of Nanotechnology, Spectroscopy and Quantum Chemistry, Siberian Federal University, Svobodny pr. 79, Russia

Abstract

The bicarbazole derivative 4,4′-(9H,9′H-[3,3′-bicarbazole]-9,9′-diyl)bis(3-(trifluoromethyl)benzonitrile), denoted as pCNBCzoCF₃, was synthesized and tested for white OLED applications. pCNBCzoCF₃ demonstrated an extremely small value of the singlet–triplet energy gap that caused intensive thermally activated delayed fluorescence (TADF). In addition, this compound is able to form exciplex-type excited states at the interface with star-shaped 4,4′,4′′-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA). Combining the TADF emission of pCNBCzoCF₃ with the exciplex emission from the pCNBCzoCF₃/m-MTDATA interface, we fabricated a number of highly efficient “warm-white” OLEDs, the electroluminescence of which was close to candle emission. The best device demonstrated a very high brightness of 40 900 Cd m⁻² (at 15 V), current efficiency of 53.8 Cd A⁻¹ and power efficiency of 19.3 lm W⁻¹, while the external quantum efficiency reached 18.8%. The fabricated devices demonstrated high emission characteristics even for the standard test at 1000 Cd m⁻² (current efficiency of 46.2 Cd A⁻¹, power efficiency of 10.6 lm W⁻¹, EQE of 17.0%).

This article is part of the themed collection: Materials and Nano Research in Atlanta

Journal of Materials Chemistry C

Contribution of TADF and exciplex emission for efficient “warm-white” OLEDs†

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Contribution of TADF and exciplex emission for efficient “warm-white” OLEDs

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