Iridium(I) pyridyl azolate complexes with saturated red metal-to-ligand charge transfer phosphorescence; Fundamental and potential applications in organic light-emitting diodes
Resource
Chemistry-A European Journal 13 (9): 2686-2694
Journal
Chemistry - A European Journal
Journal Volume
13
Journal Issue
9
Pages
2689-2694
Date Issued
2007
Author(s)
Fang, Chung-Hong
Chen, Yao-Lun
Yang, Cheng-Han
Chi, Yun
Yeh, Yu-Shan
Li, Elisa Y.
Cheng, Yi-Ming
Hsu, Chia-Jung
Chen, Chin-Ti
Abstract
Preparation of a new series of neutral metal complexes [(cod)Ir(fppz)] (1), [(cod)Ir(bppz)] (2), [(cod)Ir(fptz)] (3) and [(cod)Ir(bptz)] (4), bearing one cod ligand and a pyridyl azolate chelate are reported. A single-crystal X-ray diffraction study of 3 reveals the expected distorted square-planar geometry. The lowest absorption band consists of IrI atom increased triplet dpi-->pi* transitions (3MLCT), the assignment of which is firmly supported by the theoretical approaches. Complexes 1-4 exhibit weak phosphorescence in degassed solution at room temperature, whereas much more intense, solid-state phosphorescence appears in the range 622-649 nm. The pure MLCT emission was used as a prototypical model to address its remarkable spectral differences from the IrIII isoquinoline pyrrolide complex (5), which has mainly 3pipi phosphorescence. Complex 3 was used as a dopant to fabricate red-emitting phosphorescent organic light-emitting diodes (OLEDs). For the 7 % doped device, a maximum brightness of 3010 cd m-2 was achieved at an applied voltage of 15 V and with CIE coordinates of (0.56, 0.33), demonstrating for the first time the potential of neutral IrI complexes in OLED applications.
Type
journal article
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