Morphology and charge transport in poly(2-methoxy-5-(2 '-ethylhexyloxy)-1,4-phenylenevinylene) films

U Jeng, C H Hsu, H S Sheu, H.Y. Lee, A R Inigo, H C Chiu, W S Fann, S H Chen, A C Su, T L Lin, K.Y. Peng, S A Chen

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Abstract

Structural characteristics of optical quality poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) films drop-cast from toluene solutions have been examined by use of wide-angle (WAXS) and small-angle X-ray scattering (SAXS) as well as field-emission scanning electron microscopy. For the as-cast film SAXS and WAXS patterns clearly suggest existence of nanodomains of mesomorphic order. Under grazing incidence, both SAXS and WAXS patterns of the as-cast film exhibit impressive uniaxial symmetry with strong scattering along the film normal; however, the corresponding normal-incidence patterns are circularly isotropic, implying in-plane random orientation. A structural model consisting of preferentially uniaxial-oriented nanodomains and disordered matrix is therefore proposed for the as-cast film. Annealing at 210 degrees C results in disorientation of nanodomains: this decrease in structural asymmetry upon heat treatment correlates well with concomitant changes in charge transport behavior determined from time-of-flight measurements, manifesting dramatically decreased charge mobility as well as transition from nondispersive to dispersive modes.

Original languageEnglish
Pages (from-to)6566-6574
Number of pages9
JournalMacromolecules
Volume38
Issue number15
Early online date30 Jun 2005
DOIs
Publication statusPublished - 26 Jul 2005

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Keywords

  • structural characterisitcs
  • morphology
  • X-ray scattering
  • charge transport

Cite this

Jeng, U., Hsu, C. H., Sheu, H. S., Lee, H. Y., Inigo, A. R., Chiu, H. C., ... Chen, S. A. (2005). Morphology and charge transport in poly(2-methoxy-5-(2 '-ethylhexyloxy)-1,4-phenylenevinylene) films. Macromolecules, 38(15), 6566-6574. https://doi.org/10.1021/ma050367u