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Issue 21, 2013
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Multifunctional carbazolocarbazoles as hole transporting and emitting host materials in red phosphorescent OLEDs

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Abstract

A new series of carbazolo[4,3-c]carbazoles (1–3) have been examined as hole-transporting and emitting host materials in the fabrication of red phosphorescent OLEDs (PhOLEDs). The presence of different N-substituents including hydrogen, octyl and 4-butylphenyl attached to the carbazolo[4,3-c]carbazole skeleton was aimed to condition the charge transporting properties. Due to their resemblance in the electronic structure, these carbazolocarbazoles have been compared to a commonly used hole-transporting material such as N,N′-bis(naphthalen-1-yl)-N,N′-bisphenylbenzidine (NPB). Interestingly, the introduced structural differences endow compounds 1–3 with a wide range of hole-mobilities, which provide room for adjusting the carrier balance of OLEDs. Different approaches, including bi-layer and tri-layer architectures, have been employed for the successful fabrication of Ir(piq)2(acac) doped OLEDs using NPB and these novel carbazolocarbazoles as hole transport and host materials. The simplified bi-layer device demonstrated high performance with maximum efficiencies of 8.7%, 5.6 cd A−1 and 3.4 lm W−1 when using the N-alkylated derivative 2. Furthermore, the red PhOLEDs with tri-layer architecture using 3 as the HTL showed peak efficiencies of 12.2%, 8.7 cd A−1, and 9.3 lm W−1. In addition, both compounds 2 and 3 used in OLEDs exhibited superior performance to those of devices using NPB, demonstrating their high potential for employment in phosphorescent OLEDs.

Graphical abstract: Multifunctional carbazolocarbazoles as hole transporting and emitting host materials in red phosphorescent OLEDs

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Publication details

The article was received on 30 Jan 2013, accepted on 27 Mar 2013 and first published on 27 Mar 2013


Article type: Paper
DOI: 10.1039/C3TC30193A
Citation: J. Mater. Chem. C, 2013,1, 3421-3429

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    Multifunctional carbazolocarbazoles as hole transporting and emitting host materials in red phosphorescent OLEDs

    D. Curiel, M. Más-Montoya, C. Chang, P. Chen, C. Tai and A. Tárraga, J. Mater. Chem. C, 2013, 1, 3421
    DOI: 10.1039/C3TC30193A

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