| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
|
|---|
| Research Abstract |
Recent discovery of electroluminescence in a polymer, poly (phenylene vinylene) , PPV has brought much attention to polarons, a nonlinear excitation in one-dimensional conjugated polymers, as a candidate of charge carriers responsible for electroluminescence through charge recombination. We have shown that ESR and ENDOR spectroscopies are useful in observing the microscopic shapes of paramagnetic excitations in conjugated polymers. The purpose of the present project is to conduct ESR and ENDOR observations of polarons generated by light illumination, doping etc. in PPV and its derivatives and to develop a theoretical model to analyze the data to obtain the polaron shapes as well as the electronic states of polymers.
In this year, we have been successful in determining the detailed shape of polarons in PPV and the magnitudes of Coulomb interactions affecting the shape by analyzing the ENDOR and newly obtained TRIPLE (electon-nuclear-nuclear triple resonance) data of trapped polarons in the dark state of the polymer, provided from Dr. T.Ohnishi of Sumitomo Chemical Co. The obtained results with the maximum spin densities reside on vinylene sites successfully explained the reduction of ODESR linewidth in a derivative, cyano-PPV where the protons of vinylene sites are substituted by cyano groups, reported by British and American groups. The results have been published in JPSJ.In addition to these, light-induced ESR (LESR) of photogenerated polarons has been successfully detected in cyano-substituted PPV derivatives provided from Prof. R.H.Friend of Cavendish Laboratory. The analysis of the observed LESR line shapes as well as the excitation spectra of LESR intensities are currently under progress to study the effect of molecular structures on the polaron shapes and the electronic states of one-dimensional polymers.
|
