Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (04): 949-956.doi: 10.3866/PKU.WHXB201201163

• PHOTOCHEMISTRY AND RADIATION CHEMISTRY • Previous Articles     Next Articles

Luminescence Characteristics of Blue Emission Phosphorescent Material Firpic

WANG Jian, ZHANG Fu-Jun, XU Zheng, WANG Yong-Sheng   

  1. Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, P. R. China
  • Received:2011-11-23 Revised:2012-01-05 Published:2012-03-21
  • Contact: ZHANG Fu-Jun
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (973) (2010CB327704), National Natural Science Foundation of China (10804006, 60576016), National Outstanding Young Scientists Foundation of China (60825407), Natural Science Foundation of Beijing, China (1102028), Program of Introducing Talents of Discipline to Universities, China (B08002), Fundamental Research Funds for the Central Universities, China (2011JBM123, 2010JBZ003), and Talent Plan of Red Berry of Beijing Jiaotong University, China.

Abstract: The luminescent properties of bis[(4,6-difluorophenyl)-pyridinato-N,C2']c(picolinate)iridium(III) (FIrpic) dependence on the doping concentrations and different annealing treatments were investigated. The color of emission from thin films and organic light emitting diodes (OELDs) could be adjusted from blue to yellow-green by controlling the FIrpic doping concentration. There was good spectral overlap from 440 to 480 nm between the FIrpic photoluminescence (PL) spectra and its absorption spectra. The 476 nm emission intensity decreased as the FIrpic doping concentration increased, and this effect could be attributed to FIrpic self-absorption. The PL and electroluminescence (EL) spectra were measured under different excitation power densities and in different doping concentrations, respectively. The intensity of emission peak at 530 nm was enhanced as the excitation power density or FIrpic doping concentration increased. This suggests that the emission peak at 530 nm originates from the excimer emission between FIrpic molecules. The morphologies of the thin film and changes in the EL spectra were analyzed before and after annealing treatment. This demonstrated that FIrpic molecular aggregation promoted by annealing treatment could increase the intensity of excimer emission between FIrpic molecules. The emission color of OLEDs could be adjusted from blue to yellow-green by changing the FIrpic doping concentration, optimizing the device structure, and using annealing treatment on the devices.

Key words: Organic light emitting diode, Phosphorescent material, Self-absorption, Excimer emission, Annealing


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