Author :
Qiu, Chengfeng ; Chen, Haiying ; Wong, Man ; Kwok, Hoi S.
Author_Institution :
Dept. of Electr. & Electron. Eng., Hong Kong Univ. of Sci. & Technol., Kowloon, China
Abstract :
Organic light-emitting diodes made of tris-8-(hydroxyquinoline) aluminum as the electron-transport layers, N, N´-diphenyl-N, N´ bis (3-methylphenyl)-1, 1´-biphenyl-4,4´-diamine (TPD) as the hole-transport layers, and 2-1, 1-dimethylethyl-62-2, 3, 6, 7-tetrahydro-1, 1, 7, 7-tetramethyl-1H, 5H-benzo(ij) quinolizin-9-yl ethenyl-4H-pyran-4-ylidene propanedinitrile (DCJTB) as the guest dopant have been studied. It is determined that (a) emission from guest DCJTB in a host transport material results primarily from separate trapping of holes and electrons, rather than the more commonly proposed Forster transfer mechanism, (b) DCJTB is a more efficient hole than electron trap, and (c) the lifetime of a doped device is longer when TPD is used as the host material
Keywords :
electroluminescence; electron traps; hole traps; light emitting diodes; EL spectra; dopant emission mechanism; doped OLEDs; doped device lifetime; electroluminescence; electron trapping; electron-transport layers; guest dopant; hole trapping; hole-transport layers; host materials effects; organic LEDs; organic light-emitting diodes; Aluminum; Charge carrier processes; Doping; Electron emission; Electron traps; Excitons; Light emitting diodes; Organic light emitting diodes; Organic materials; Solid state circuits;
