Bis(diphenylamino)-9,9′-spirobifluorene functionalized Ir(iii) complex: A conceptual design en route to a three-in-one system possessing emitting core and electron and hole transport peripherals

Hsiao Fan Chen, Ken Tsung Wong*, Yi Hung Liu, Yu Wang, Yi Ming Cheng, Min Wen Chung, Pi Tai Chou, Hai-Ching Su

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Conceptual design of a three-in-one (luminescence chromophore with electron and hole transports) system was demonstrated by a functionalized Ir(iii) complex 3, in which 4,5-diazafluorene and bis(diphenylamino) serve as electron and hole transporting sites, respectively. The poor emission quantum yield of 3 was systematically examined via a series of photophysical studies in combination with theoretical approaches. The far lifting of the π-electron from -NPh 2 renders virtually no 3 MLCT contribution to the lowest transition in the triplet manifold as compared with that of the parent model 2 without amino substituents. With an empirical approach, we conclude that an energy gap law may account for the major deactivation process. A light-emitting electrochemical cell (LEC) device based on 3 shows peak EQE, peak current efficiency and peak power efficiency at 2.4 V of 0.020%, 0.013 cd A -1 and 0.017 lm/W, respectively. The low device efficiencies are in accordance with the low PL quantum yield, stemming from the ligand-centered radiationless deactivation. The conceptual design presented here should provide valuable information for future progress en route to an ideal three-in-one system suited for OLEDs.

Original languageEnglish
Pages (from-to)768-774
Number of pages7
JournalJournal of Materials Chemistry
Volume21
Issue number3
DOIs
StatePublished - 21 Jan 2011

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