Abstract
The triphenylamine dimer, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine (TPD) as neat film, and as guest in polystyrene (PS), 4.4'-N,N'-dicarbazole-biphenyl (CBP), and polycarbonate (PC) films is investigated by luminescence spectroscopy. The luminescence quantum distributions, E-L(lambda), are determined over a wide temperature range from 10 K to 291 K by photo-excitation in the singlet ...
Abstract
The triphenylamine dimer, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine (TPD) as neat film, and as guest in polystyrene (PS), 4.4'-N,N'-dicarbazole-biphenyl (CBP), and polycarbonate (PC) films is investigated by luminescence spectroscopy. The luminescence quantum distributions, E-L(lambda), are determined over a wide temperature range from 10 K to 291 K by photo-excitation in the singlet absorption region of TPD. The singlet-excited phosphorescence quantum distributions are extracted by fluorescence contribution subtraction. The absolute intrinsic luminescence quantum yields, fluorescence quantum yields. and singlet-excited phosphorescence quantum yields are calculated from the quantum distributions. Even at room temperature phosphorescence emission is obtained. The triplet-singlet radiative lifetimes are determined from extracted SO-T, absorption and emission spectra, and the phosphorescence lifetimes are estimated from the phosphorescence quantum yields and the radiative phosphorescence lifetimes. In TPD neat films fluorescence reduction by self-quenching is observed. CBP host to TPD guest excitation transfer is observed in the case of excitation into the CBP absorption region. (c) 2008 Elsevier B.V. All rights reserved.
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