Highly efficient orange and green solid-state light-emitting electrochemical cells based on cationic IrIII complexes with enhanced steric hindrance

Hai-Ching Su*, Fu Chuan Fang, Tsyr Yuan Hwu, Hsing Hung Hsieh, Hsiao Fan Chen, Gene Hsiang Lee, Shie Ming Peng, Ken Tsung Wong, Chung Chih Wu

*Corresponding author for this work

Research output: Contribution to journalArticle

168 Scopus citations

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.

Original languageEnglish
Pages (from-to)1019-1027
Number of pages9
JournalAdvanced Functional Materials
Volume17
Issue number6
DOIs
StatePublished - 16 Apr 2007

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