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Issue 8, 2020
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Benzimidazole–triazine based exciplex films as emitters and hosts to construct highly efficient OLEDs with a small efficiency roll-off

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Abstract

Although efficient exciplex-based organic light-emitting diodes (OLEDs) with simple device structures have shown great progress recently, highly efficient electron acceptor materials are still rare. Here, a series of newly developed electron acceptors for exciplex-OLEDs composed of benzimidazole and triazine hybrids are discussed. All three compounds display a triplet energy of 2.67–2.69 eV, ensuring a high photoluminescence quantum yield of 78.0–89.7% when mixed with an electron donor (TAPC: 4,4′-cyclohexylidenebis[N,N-bis(p-tolyl)aniline]). Exciplex-based OLEDs with these electron acceptors and TAPC blend films as the emitting layers exhibit low driving voltages of 2.6–3.0 V at 100 cd m−2 and 3.1–4.2 V at 1000 cd m−2. High efficiencies of 53.2–80.1 lm W−1 and 39.7–60.1 cd A−1 are obtained, and the highest external quantum efficiencies (EQE) are 12.5–18.4%. Green electro-phosphorescent emitters are also fabricated with exciplex-based cohosts by doping with tris(2-phenylpyridine)iridium (Ir(ppy)3), one of which shows the highest EQE of 29.6%, and the EQE can be maintained at 27.4% at 5000 cd m−2. Therefore, the benzimidazole–triazine electron acceptors show promise as exciplex emitters and cohosts for OLEDs.

Graphical abstract: Benzimidazole–triazine based exciplex films as emitters and hosts to construct highly efficient OLEDs with a small efficiency roll-off

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Supplementary files

Article information


Submitted
13 Nov 2019
Accepted
10 Jan 2020
First published
13 Jan 2020

J. Mater. Chem. C, 2020,8, 2700-2708
Article type
Paper

Benzimidazole–triazine based exciplex films as emitters and hosts to construct highly efficient OLEDs with a small efficiency roll-off

B. Liang, J. Wang, Y. Cui, J. Wei and Y. Wang, J. Mater. Chem. C, 2020, 8, 2700
DOI: 10.1039/C9TC06212B

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