Spin and spectral signatures of polaron pairs in {pi}-conjugated polymers
- Department of Physics, University of Utah, Salt Lake City, Utah 84112 (United States)
We have studied polaron pair photoexcitations in a variety of {pi}-conjugated polymer films by photoinduced absorption (PA) and optically detected magnetic resonance (ODMR). Both luminescent and nonluminescent polymers have been studied. An exchange interaction between polarons broadens their magnetic resonance spectrum, permitting the unambiguous identification of the polaron pair species by ODMR. Both isotropic and anisotropic exchange interactions have been observed. An isotropic exchange interaction broadens the spin-(1)/(2) resonance associated with polarons, whereas an anisotropic exchange interaction gives rise to both full-field and half-field powder patterns. We have successfully modeled the observed spin-(1)/(2) ODMR spectra and estimate the strength of the isotropic exchange interaction I. An anisotropic exchange interaction has been observed in C{sub 60}-doped 2,5-dioctyloxy poly(p-phenylene vinylene) and cis-rich polyacetylene. Both polarons and polaron pairs are characterized by two absorption bands. However, the high-energy PA band of polaron pairs is blueshifted with respect to that of isolated polarons and the low-energy PA band of polaron pairs is relatively weak. We have also observed neutral soliton pair excitations in polymers with degenerate ground states. {copyright} {ital 1997} {ital The American Physical Society}
- DOE Contract Number:
- FG03-93ER45490
- OSTI ID:
- 664453
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 8; Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
EPR study of polarons in a conducting polymer with nondegenerate ground states: Alkali metal complexes of poly (p-phenylene) and phenylene oligomers
Polarons in ladder-type polymer films: Recombination channels and electron-phonon coupling