We have used neutron reflectivity and nuclear reaction analysis to look at the interfacial width between two different types of conjugated polymer.
The interfacial widths are far greater than observed previously at amorphous polymer interfaces. To understand these broad interfaces we have compared our results to the predictions of self consistent field theory (SCFT), for both Gaussian and semiflexible chains. We have also demonstrated the ability to control the interfacial width in thin (~ 100 nm) bilayers, independent of the properties of the bulk of the films. This opens up the potential for fabricating LEDs that have identical charge transport properties from the electrodes to the interface, and differ only in the width of the polymer-polymer interface. We believe that this could provide a model system for studying the effect of mixing at polymer-polymer heterojunctions on device performance.
Reflectivity data and bilayer fits for annealed thick F8BT(339nm)/dF8(221nm) bilayers on silicon. (b) shows the low quality qz data shifted vertically for clarity
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AM Higgins (Swansea University), SJ Martin, M Geoghegan, SY Heriot (University of Sheffield), RL Thompson (University of Durham), R Cubitt (ILL, France), RM Dalgliesh (ISIS), I Grizzi (Cambridge Display Technology), RAL Jones (University of Sheffield)
Research date: December 2007
AM Higgins et. al. Macromolecules 39 (2006) 6699
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