Nonlinear Optical Properties of Semiconducting Polymers
Abstract
This program focused on the nonlinear optical properties of semiconducting conjugated polymers. Specific emphasis was on fast time (picosecond regime) measurements of the photoconductivity of semiconducting polymers and on nonlinear optics (NLO) measurements related to the mechanism and origin of the nonlinearity and on attempts to optimize the magnitude of the nonlinear response. In the transient photoconductivity area, these publications focused on the carrier generation, mobility and carrier recombination processes. The results are of particular importance; by implementing the Auston switch technique (to enable fast transient photoconductivity measurements with temporal resolution <100 ps), we were able to explore the photogeneration process early times. The results have caused a reevaluation of the previously accepted Onsager geminate recombination process. We succeeded in demonstrating that for conjugated polymers the nonlinear response is highly anisotropic with substantial nonlinearity only when the pump is polarized along the direction parallel to the polymer backbone. In attempting to sort out the NLO mechanism we carried out comparative studies on cis and trans-polyacetylene. The larger NLO response from the trans-isomer (larger by at least a factor of 20) shows the importance of the degerate ground state.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 26, 1990
- Accession Number
- ADA241001
Entities
People
- Alan J. Heeger
Organizations
- University of California, Santa Barbara