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Effect of Photooxidation on the Transient Photoconductivity and Photoluminescence of Alq3

Published online by Cambridge University Press:  10 February 2011

I. Sokolik
Affiliation:
Dept. of Electrical Engr., City College of CUNY, 140th St. at Convent Ave.New York, NY10031
A. D. Walser
Affiliation:
Dept. of Phys., Rm. J419, City College of CUNY, 138th St. at Convent Ave., New York, NY10031
R. Priestley
Affiliation:
New York State Center for the Advanced Technology for Ultrafast Materials and Applications at the City University of New York
R. Dorsinville
Affiliation:
Center for Analysis of Surface and Interfaces (CASI)
C. W. Tang
Affiliation:
Eastman Kodak Company, Rochester, NY 14650.
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Abstract

Photogeneration of charge carriers and radiative excited states in pristine and photooxidized tris-(8-hydroxyquinoline) aluminum (Alq3) were studied by simultaneously measuring the photoconductive response and the kinetics of photoluminescence with subnanosecond resolution. 25 ps laser pulses at 355 nm were used for the excitation of vacuum-evaporated films of Alq3 2–4 μm thick. At equal excitation intensities the time dependence of the photoconductive response was very similar to that of the photoluminescence, independent of whether the sample was pristine or partially oxidized. Photooxidation of Alq3 substantially decreases the magnitude and lifetime of the photoconductivity and the photoluminescence. The decrease is shown to be a result of quenching of singlet molecular excitations by product(s) of photooxidation of Alq3. Photogeneration of charge carriers is controlled by the mutual annihilation of singlet excitons.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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References

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