title: Reversible optical control of conjugated polymer solubility with sub-micrometer resolution.
abstract: Organic electronics promise to provide flexible, large-area circuitry such as photovoltaics, displays, and light emitting diodes that can be fabricated inexpensively from solutions. A major obstacle to this vision is that most conjugated organic materials are miscible, making solution-based fabrication of multilayer or micro- to nanoscale patterned films problematic. Here we demonstrate that the solubility of prototypical conductive polymer poly(3-hexylthiophene) (P3HT) can be reversibly "switched off" using high electron affinity molecular dopants, then later recovered with light or a suitable dedoping solution. Using this technique, we are able to stack mutually soluble materials and laterally pattern polymer films by evaporation or with light, achieving sub-micrometer, optically limited feature sizes. After forming these structures, the films can be dedoped without disrupting the patterned features; dedoped films have identical optical characteristics, charge carrier mobilities, and NMR spectra as as-cast P3HT films. This method greatly simplifies solution-based device fabrication, is easily adaptable to current manufacturing workflows, and is potentially generalizable to other classes of materials.
authors.affiliation: Department of Chemical Engineering and Materials Science and ‡Department of Chemistry, University of California , Davis, California, United States.
authors.forename: Ian E
authors.initials: IE
authors.lastname: Jacobs
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Burg
authors.forename: David J
authors.initials: DJ
authors.lastname: Bilsky
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Rotondo
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Augustine
authors.forename: Pieter
authors.initials: P
authors.lastname: Stroeve
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Moulé
keywords: conductive polymers; doping; patterning; photolithography; solubility