Electronic excitations and alternation of conjugated polymers

Soos, ZG and Ramasesha, S and Galvão, DS and Kepler, RG and Etemad, S (1993) Electronic excitations and alternation of conjugated polymers. In: SYMP ON SYNTHETIC ELECTROACTIVE MATERIALS FOR NONLINEAR OPTICS AND ELECTRONICS, AT THE 1992 SPRING CONF OF THE EUROPEAN MATERIAL RESEARCH SOC, JUN 02-05, 1992, STRASBOURG, FRANCE.

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Abstract

The electronic excitations and fluorescence of conjugated polymers are related to large or small alternation ? of the transfer integrals t(1 ± ?) along the backbone. The fluorescence of polysilanes (PSs) and poly (para-phenylenevinylene (PPV) is linked to large ?, which places the one-photon gap Eg below the lowest two-photon gap Ea and reduces distortions due to electron-phonon (e-p) coupling. In contrast to small ? not, vert, similar 0.1 in ?-conjugated polymers, such as polyacetylene (PA), para-conjugated phenyls lead to an extended ?-system with increased alternation, to states localized on each ring and to charge-transfer excitations between them. Surprisingly good agreement is found between semiempirical parametric method 3 (PM3) bond lengths and exact Pariser-Parr-Pople (PPP) ?-bond orders for trans-stilbene, where the PPV bipolarons are confined to two phenyls. Stilbene spectra are consistent with increased alternation and small e-p distortions.

Item Type:	Conference Paper
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	08 Feb 2011 04:51
Last Modified:	08 Feb 2011 04:51
URI:	http://eprints.iisc.ac.in/id/eprint/35450

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