On the Improvement of Blue Emission for All sp(2)-Hybridized Bistriphenylenyls: Incorporating Phenylenyl Moieties To Enhance Film Amorphism
Journal
JOURNAL OF PHYSICAL CHEMISTRY C
Journal Volume
113
Journal Issue
17
Pages
7405-7410
Date Issued
2009-04
Date
2009-04
Author(s)
Abstract
The film amorphism of 2,2′-bistriphenylenyl (BTP), a blue-light emitter with all sp2-hybridized polyaromatic, is enhanced by incorporating phenyl groups between the two triphenylene (TP) planes. This series of compounds are BTP, 1,4-di(triphenylen-2-yl)benzene (T1), and 4,4′-di(triphenylen-2-yl)biphenyl (T2), where the latter preserve the characteristics of all sp2 hydrocarbons and improve the optimized electroluminescence (EL) performance. Specifically, the most efficient T2-based device can reach a maximum external quantum efficiency of 5.2% and a very high luminescence of 47776 cd/m2 in the deep-blue region with Commission Internationale d’Énclairage (CIE) coordinates of (0.15, 0.12). The efficiency approaches the upper theoretical limit of 5−5.5%, estimated for a singlet emitter with a refractive index of 1.7−1.5. For comparison, the optimized BTP-based devices confer the corresponding values of 4.2%, 21 204 cd/m2, and (0.14, 0.11). Such an improvement is ascribed to the effect of introducing the phenylene moiety on the film amorphism, examined by single-crystal X-ray analysis, atomic force microscopy, photoluminescent spectroscopy, and HOMO/LUMO energy levels for the materials involved in EL devices.
Type
journal article
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On the improvement of blue emission for all sp2-hybridized bistriphenylenyls Incorporating phenylenyl moieties to enhance film amorphism.pdf
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