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Persistent Photoconductivity in Poly(P-Phenylenevinylene) - Spectral Response and Slow Relaxation

Cited 167 time in Web of Science Cited 166 time in Scopus
Authors
Lee, C. H.; Yu, G.; Heeger, A. J.
Issue Date
1993
Publisher
The American Physical Society
Citation
Phys. Rev.B 47, 15543-15553
Abstract
We report the spectral response and slow decay of the steady-state photoconductivity in poly(p-phenylenevinylene) (PPV) films. The spectral response of the photoconductivity is in good agreement with that calculated from the absorption data with the assumption of rapid recombination at the surface of the film; the results indicate direct photogeneration of free charge carriers via an interband transition. The photoconductivity is, therefore, consistent with a description of the electronic structure of PPV in terms of a semiconductor band model (rather than an exciton model). The very slow stretched-exponential relaxation of the photoinduced conductivity is reminiscent of the persistent photoconductivity observed in inorganic semiconductors. By assuming that the photocurrent is carried predominantly by mobile polarons near the surface, one can construct a model for the persistent photoconductivity in which the recombination of long-lived bipolarons is inhibited in the bulk where bipolarons have a lower free energy than polarons. The persistent photoconductivity, therefore, is caused by the slow dispersive diffusion of photogenerated bipolarons to the surface where they dissociate into polarons and where both polaron transport and recombination occur.
ISSN
1098-0121
Language
English
URI
http://hdl.handle.net/10371/13599
DOI
https://doi.org/10.1103/PhysRevB.47.15543
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Electrical and Computer Engineering (전기·정보공학부)Journal Papers (저널논문_전기·정보공학부)
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