Morphologically and electrochemically stable bipolar host for efficient green electrophosphorescence
- 22 January 2010
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
- Vol. 12 (10), 2438-2442
- https://doi.org/10.1039/b922110g
Abstract
A new host tBu-o-CzOXD is facilely synthesized through a simple aromatic nucleophilic substitution reaction between 3,6-di-tert-butyl-9H-carbazole and 2,5-bis(2-fluorophenyl)-1,3,4-oxadiazole. Its thermal, electrochemical, electronic absorption and photoluminescent properties are fully investigated. A high glass transition temperature (Tg) of 149 °C is observed for tBu-o-CzOXD due to the introduction of bulky tert-butyl moiety, significantly higher than 97 °C of o-CzOXD without tert-butyl substituent. Moreover, encapsulation of tert-butyl on the 3- and 6-positions of carbazole greatly enhances the electrochemical stability as compared to o-CzOXD. Green phosphorescent OLEDs hosted by tBu-o-CzOXD show a maximum luminance of 48293 cd m−2 at 17.1 V, a maximum current efficiency of 38.4 cd A−1 and a maximum power efficiency of 34.7 lm W−1 . Furthermore, the devices exhibit a slow current efficiency roll-off. The device merits, together with the excellent morphological and electrochemical stability, make the new compound an ideal host material for phosphorescent emitters.Keywords
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