Highly efficient orange and green solid-state light-emitting electrochemical cells based on cationic Ir(III) complexes with superior steric hindrance
Resource
Advanced Functional Materials,17(6),1019-1027.
Journal
Advanced Functional Materials
Journal Volume
17
Journal Issue
6
Pages
1019-1027
Date Issued
2007-04
Date
2007-04
Author(s)
Abstract
Highly efficient orange and green emission from single-layered solid-state light-emitting electrochemical cells based on cationic transition-metal complexes [Ir(ppy)2sb]PF6 and [Ir(dFppy) 2sb]PF6 (where ppy is 2-phenylpyridine, dFppy is 2-(2,4-difluorophenyl)pyridine, and sb is 4,5-diaza-9,9′-spirobifluorene) is reported. Photoluminescence measurements show highly retained quantum yields for [Ir(ppy)2sb]PF6 and [Ir(dFppy)2 sb]PF 6 in neat films (compared with quantum yields of these complexes dispersed in m-bis(N-carbazolyl)benzene films). The spiroconfigured sb ligands effectively enhance the steric hindrance of the complexes and reduce the self-quenching effect. The devices that use single-layered neat films of [Ir(ppy)2sb]PF6 and [Ir(dFppy)2sb]PF 6 achieve high peak external quantum efficiencies and power efficiencies of 7.1 % and 22.6 1m W-1) at 2.5 V, and 7.1 % and 26.2 1m W-1 at 2.8 V, respectively. These efficiencies are among the highest reported for solid-state light-emitting electrochemical cells, and indicate that cationic transition-metal complexes containing ligands with good steric hindrance are excellent candidates for highly efficient solid-state electrochemical cells. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.
Other Subjects
Complexation; Light emission; Measurement theory; Photoluminescence; Quantum theory; Transition metals; Green emission; Photoluminescence measurements; Steric hindrance; Electrochemical cells
Type
journal article
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Highly efficient orange and green solid-state light-emitting electrochemical cells based on cationic Ir-III complexes with enhanced steric hindrance.pdf
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