title: Cationic iridium complexes with intramolecular π-π interaction and enhanced steric hindrance for solid-state light-emitting electrochemical cells.
abstract: Cationic iridium complexes incorporated 4,5-diaza-9,9'-spirobifluorene as N(∧)N ancillary ligands, in which one (2) or two (3) phenyl groups were introduced onto 4,5-diazafluorene to afford intraligand π-π interactions. The X-ray crystal structures of complexes 2 and 3 show that the pendant phenyl ring forms strong intramolecular face-to-face π-stacking with the difluorophenyl ring of the cyclometalated ligand with distances of 3.38 Å for complex 2 and 3.40 and 3.46 Å for complex 3. This π-π stacking interaction minimizes the expansion of the metal-ligand bonds in the excited state, resulting in a longer device lifetime in the light-emitting electrochemical cell (LEC) devices.
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
authors.forename: Hsiao-Fan
authors.initials: HF
authors.lastname: Chen
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Hung
authors.forename: Shou-Wei
authors.initials: SW
authors.lastname: Chen
authors.forename: Ting-Chih
authors.initials: TC
authors.lastname: Wang
authors.forename: Shih-Wei
authors.initials: SW
authors.lastname: Lin
authors.forename: Shu-Hua
authors.initials: SH
authors.lastname: Chou
authors.forename: Chih-Teng
authors.initials: CT
authors.lastname: Liao
authors.forename: Hai-Ching
authors.initials: HC
authors.lastname: Su
authors.forename: Hsiao-An
authors.initials: HA
authors.lastname: Pan
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Liu
authors.forename: Ken-Tsung
authors.initials: KT
authors.lastname: Wong