Spectroscopic investigation of the electro-optic nonlinearity in poly(2,5-thienylene vinylene)

We report the results of a spectroscopic investigation of the quadratic electro-optic nonlinearity in poly(2,5-thienylene vinylene). Electroabsorption spectra closely resemble the second energy derivative of the unperturbed π-π* absorption and show oscillations associated with the strong vibronic features present therein. The dispersion of both the real and imaginary parts of χ(3) (−ω;0,0,ω) has been determined and we find that Re{χ(3)} has a peak value of 7.5×10−9 esu at 1.83 eV and Im{χ(3)} has a peak value of 6.2×10−9 esu at 1.78 eV. This nonlinearity is responsible for a photorefractive effect under resonant photoexcitation.