The relative fluorescence yield of vacuum-evaporated films of tris-(8-hydroxyquinolinato) aluminum (III) (Alq(3)) as a function of steady-state exciting light intensity has been measured. The yield decreases, due to singlet exciton-exciton interaction, with increasing intensities, to a half of the low-intensity yield at 5 x 10(21) ph/cm(2)/s. The second order singlet-singlet annihilation rate constant is found to be gamma(ss) = (1.1 +/- 0.5) x 10(-10) cm(3)/s. If the reaction is diffusion-limited, this rate implies an average singlet exciton diffusivity D-s = (6 +/- 2) x 10(-5) cm(2)/s, and permits to rule out singlet-singlet interaction as the reason for the observed large-current density roll-off in the electroluminescence efficiency of Alq(3)-based light emitting diodes. (C) 2004 Published by Elsevier B.V.
Mezyk, J., Kalinowski, J., Meinardi, F., Tubino, R. (2004). Singlet exciton interactions in solid films of Alq 3. CHEMICAL PHYSICS LETTERS, 395(4-6), 321-326 [10.1016/j.cplett.2004.08.014].
Singlet exciton interactions in solid films of Alq 3
MEINARDI, FRANCESCO;TUBINO, RICCARDO
2004
Abstract
The relative fluorescence yield of vacuum-evaporated films of tris-(8-hydroxyquinolinato) aluminum (III) (Alq(3)) as a function of steady-state exciting light intensity has been measured. The yield decreases, due to singlet exciton-exciton interaction, with increasing intensities, to a half of the low-intensity yield at 5 x 10(21) ph/cm(2)/s. The second order singlet-singlet annihilation rate constant is found to be gamma(ss) = (1.1 +/- 0.5) x 10(-10) cm(3)/s. If the reaction is diffusion-limited, this rate implies an average singlet exciton diffusivity D-s = (6 +/- 2) x 10(-5) cm(2)/s, and permits to rule out singlet-singlet interaction as the reason for the observed large-current density roll-off in the electroluminescence efficiency of Alq(3)-based light emitting diodes. (C) 2004 Published by Elsevier B.V.
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