Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (07): 1593-1598.doi: 10.3866/PKU.WHXB201204181

• THERMODYNAMICS, KINETICS, AND STRUCTURAL CHEMISTRY • Previous Articles     Next Articles

Synthesis and Photoelectrical Properties of Room-Temperature Phosphorescent (ppy)2Ir(pybi) Complex

YUE Yan1, XU Hui-Xia2, HAO Yu-Ying1,2, XIE Xiao-Dong1, QU Li-Tao1, WANG Hua2, XU Bing-She2   

  1. 1. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan, 030024, P. R. China;
    2. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan, 030024, P. R.China
  • Received:2011-12-22 Revised:2012-03-31 Published:2012-06-07
  • Contact: XU Hui-Xia, HAO Yu-Ying E-mail:hyy_123991@sina.com; xuhuixia0824@163.com
  • Supported by:

    The project was supported by the National Natural Scinace Foudation of China (21071108, 60976018, 21101111, 51002102), Program for Changjiang Scholar and Innovative Research Team in University of Ministry of Education of China (IRT 0972), and Natural Science Foundation of Shanxi Province, China (200811008, 2010021023-2).

Abstract:

A blue-green emitter of iridium(III) complex (ppy)2Ir(pybi), has been synthesized (ppy= 2-phenyridine and pybi=2-(2-pyridyl)benzimdazole) and its structure was characterized by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR), mass spectroscopy (MS), and elemental analysis. Its photophysical properties and energy-level structure were studied by UV-Vis absorption, excitation and emission spectroscopy, and cyclic voltammetry combining timedependent density functional theory (TD-DFT). The electrophosphorescent performance of (ppy)2Ir(pybi) was characterized by using 4,4'-bis(9-carbazolyl)-1,1'-biphenyl (CBP) as host. The results indicated that the UV-Vis absorption bands were located at 250, 295, 346, and 442 nm, which were in good agreement with the TD-DFT simulation results. The blue-green phosphorescent emission was observed with peaks at 495, 518 nm in CH2Cl2 solution at room temperature. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energy levels and optical gap were -6.11, -3.43, and 2.68 eV, respectively. Theoretical calculation revealed that the HOMO for (ppy)2Ir(pybi) was mainly distributed on the ppy ligand and the iridium ion, whereas the LUMO was centered mainly on the pybi ligand. The device based on the system of (ppy)2Ir(pybi) doped into CBP has an electroluminescence (EL) spectrum with a peak wavelength of 508 nm, a maximum luminance of 8451 cd·m-2, and a maximum current efficiency of 17.6 cd·A-1. These investigations will provide an important experimental basis for the application of (ppy)2Ir(pybi) in the organic electroluminescent field.

Key words: Phosphorescent emitting material, 2-Phenylpyridine, 2-(2-Pyridyl)benzimdazole, Photoelectrical property, Molecular orbital

MSC2000: 

  • O641