Anomalous temperature dependence of solvent-enhanced dye diffusion in polymer films

T. Graves-Abe, F. Pschenitzka, J. C. Sturm

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

One promising method to pattern full color polymer Organic Light-Emitting Diode (OLED) displays is to print dye from a pre-patterned organic film onto a spin-cast polymer and then diffuse the dye into the film at room temperature in a solvent vapor environment. This method utilizes the well-known tendency for a polymer film to absorb solvent vapor, which depresses the glass transition temperature of the polymer and dramatically increases diffusion of the dye. In this work, we have studied the temperature dependence of this process. The dye coumarin 6 (C6) was transferred onto films consisting of 2-(4-biphenylyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) mixed with the polymer poly(9-vinylcarbazole) (PVK). Samples were then placed on a heated stage in a chamber and exposed to acetone vapor to diffuse the C6 into the polymer film. The profile of the diffused dye was determined by depth-dependent photoluminescence measurements and Secondary Ion Mass Spectroscopy. We observed that the amount of diffused dye decreased at higher temperatures, in contrast to conventional thermally-driven diffusion. The results are understood by noting that the decrease in the polymer glass-transition temperature and the corresponding rapid increase in dye diffusivity depend on the quantity of solvent absorbed by the polymer, which decreases as the temperature of the polymer is raised.

Original languageEnglish (US)
Pages (from-to)43-48
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume725
DOIs
StatePublished - 2002
EventOrganic and Polymeric materials and Devices - Optical, Electrical and Optoelectronic Properties - San Francisco, CA, United States
Duration: Apr 1 2002Apr 5 2002

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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