Femtosecond transient-absorption dynamics are presented for an oligomer and a number of polymers from the poly(arylene vinylene) family for excitation densities in the range from 1018-1021 cm-3. We report careful studies of the wavelength and pump-intensity dependence of the photoinduced absorption in a model five-ring oligomer. 2-methoxy-5-(2′-ethylhexyloxy)-distyryl benzene. We show that a single photoexcited species, the intrachain exciton, is responsible for all observable spectral features at low excitation densities. At higher excitation densities, nonlinear relaxation processes are observed in both polymers and the oligomer, consistent with exciton-exciton annihilation as a nonlinear-decay mechanism.
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jul 15 1997|
ASJC Scopus subject areas
- Condensed Matter Physics