Premium
Theoretical study on phosphorescence efficiency and color tuning from orange to blue‐green of Ir(III) complexes based on substituted 2‐phenylimidazo[1,2‐a]pyridine ligand
Author(s) -
Li XiaoNa,
Wu ZhiJian,
Li XiYan,
Zhang HongJie,
Liu XiaoJuan
Publication year - 2010
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21682
Subject(s) - phosphorescence , homo/lumo , chemistry , quantum efficiency , pyridine , excited state , density functional theory , ligand (biochemistry) , electroluminescence , iridium , photochemistry , photoluminescence , crystallography , computational chemistry , molecule , fluorescence , materials science , atomic physics , medicinal chemistry , physics , catalysis , biochemistry , optoelectronics , organic chemistry , receptor , quantum mechanics , layer (electronics)
The geometrical structures, phosphorescence quantum yields, and electroluminescence (EL) efficiency of six iridium(III) complexes containing 2‐phenylimidazo[1,2‐a]pyridine ligand are investigated by density functional theory (DFT), which show a wide color tuning of photoluminescence from orange (λ em = 550 nm) to blue‐green (λ em = 490 nm). The calculated results shed some light on the reasons of the remarkably manipulated excited‐state and EL properties through substitution effect. The Mulliken charge calculation reveals that attached CF 3 groups on phenyl and imidazo[1,2‐a]pyridine (impy) moieties ( 4 ) can make both of them as electron‐deficient region, which will lead to the contraction of the whole coordination sphere and strengthen the metal–ligand interaction. While attaching two CF 3 groups on phenyl ring can make it more electron‐deficient, which will induce electron transferring from acac and impy fragment to phenyl ring, and also result in the contracted structure. The largest metal‐to‐ligand charge transfer ( 3 MLCT) character and the smaller S 1 – T 1 energy gap (Δ E S 1− T 1 ) value increase the emission quantum yields of 4 and 6 than other complexes. For EL efficiency, because of the similar highest occupied molecular orbital (HOMO) levels of 4 and 6 to that of holes injection material poly(N‐vinylcarbazole) (PVK) and the larger dipole moments, majority hole will be accumulated on the HOMO of 4 and 6 . Combination with the lower lowest unoccupied molecular orbital energy levels compared with PVK, the recombination zones of 4 and 6 can be well confined within emitting material layer (EML) and lead to the higher EL efficiency. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011.