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Midgap levels of photoexcited conductive polymers. I. A simple description of the midgap levels based on molecular orbital interaction
Author(s) -
Tanaka Kazuyoshi,
Yoshizawa Kazunari,
Yamabe Tokio
Publication year - 1991
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560400304
Subject(s) - polyacetylene , polypyrrole , homo/lumo , molecular orbital , ground state , phenylene , chemistry , band gap , conductive polymer , polymer , electrical conductor , polarization (electrochemistry) , chemical physics , materials science , computational chemistry , molecular physics , molecule , condensed matter physics , physics , atomic physics , polymerization , organic chemistry , composite material
We studied the midgap levels appearing in the photoexcited conductive polymers such as trans ‐ and cis ‐polyacetylenes, poly( p ‐phenylene), polypyrrole, and polyacene based on the molecular orbital analysis. The midgap levels are constructed from the transformation of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the ground state. As the result of the localization of the wave functions associated with these midgap levels, large polarization is induced between adjacent carbon atoms. Based on the examination of the energy gap between the two midgap levels, the polymers with a nondegenerate ground state such as cis ‐polyacetylene, poly( p ‐phenylene), and polypyrrole would show no sizable photoconductivities.