title: Nanoscale ordered structure distribution in thin solid film of conjugated polymers: its significance in charge transport across the film and in performance of electroluminescent device.
abstract: We use ultrahigh-vacuum conducting atomic force microscopy to probe the local current distributions in spin-cast thin films from the solutions of poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and poly(9,9-di-n-octyl-2,7-fluorene) (PFO). We found that spatially homogeneous distribution of the ordered structures (well-packed chains and/or aggregates) in MEH-PPV can be controlled by the selection of solvent or mixed solvent, by which effects of spatial charge transport distribution in MEH-PPV thin films on the performance of polymer light-emitting diodes (PLEDs) are unambiguously clarified. For PFO thin film, after the treatment by immersing in the mixed nonsolvent composed of a solvent and nonsolvent, the ordered structures (beta-phase) are generated; its excess content can result in highly conducting regions. However, the device efficiency can be promoted significantly by optimizing the content of beta-phase.
authors.affiliation: Chemical Engineering Department, National Tsing Hua University, Hsinchu, 30013 Taiwan, ROC.
authors.forename: Ming-Chih
authors.initials: MC
authors.lastname: Chen
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Hung
authors.forename: An-Chung
authors.initials: AC
authors.lastname: Su
authors.forename: Su-Hua
authors.initials: SH
authors.lastname: Chen
authors.forename: Show-An
authors.initials: SA
authors.lastname: Chen