Interpreting the dispersion of χ(3)(-3ω; ω, ω, ω) of polythiophenes
Journal
Synthetic Metals
Journal Volume
49
Journal Issue
1-3
Pages
59-69
Date Issued
1992
Author(s)
Abstract
The dispersion of χ(3)(-3ω; ω, ω, ω) for poly(3-hexylthiophene) (P3HT) and five other polythiophenes which possess a mixed aromatic-quinoid backbone structure has been characterized using third-harmonic generation (THG). The data were interpreted using perturbation theory and the essential states mechanism. The nonlinearity of the P3HT is well described by the two-level model, while the mixed backbone systems need three levels to reproduce properly the measured dispersion. It is demonstrated that the three-level model leads to an interference minimum in the dispersion of the nonlinearity. The χ(3)(-ω; ω, - ω, ω) is predicted from the parameters derived by fitting the THG data, and the resulting figure of merit is discussed. © 1992.
Type
journal article