Doping of conjugated polythiophenes with alkyl silanes

Chi Yueh Kao, Bumsu Lee, Leszek S. Wielunski, Martin Heeney, Iain McCulloch, Eric Garfunkel, Leonard C. Feldman, Vitaly Podzorov

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A strong modification of the electronic properties of solution-processable conjugated polythiophenes by self-assembled silane molecules is reported. Upon bulk doping with hydrolized fluoroalkyl trichlorosilane, the electrical conductivity of ultrathin polythiophene films increases by up to six orders of magnitude, reaching record values for polythiophenes: (1.1±0.1) ×103S cm-1 for poly(2,5-bis(3-tetradecylthiophen -2-yl)thieno[3,2-b]thiophene) (PBTTT) and 50±20 S cm-1 for poly(3-hexyl)thiophene (P3HT). Interband optical absorption of the polymers in the doped state is drastically reduced, making these highly conductive films transparent in the visible range. The dopants within the porous polymer matrix are partially crosslinked via a silane self-polymerization mechanism that makes the samples very stable in vacuum and nonpolar environments. The mechanism of SAM-induced conductivity is believed to be based on protonic doping by the free silanol groups available within the partially crosslinkedSAMnetwork incorporated in the polythiophene structure. The SAM-doped polythiophenes exhibit an intrinsic sensing effect: a drastic and reversible change in conductivity in response to ambient polar molecules, which is believed to be due to the interaction of the silanol groups with polar analytes. The reported electronic effects point to a new attractive route for doping conjugated polymers with potential applications in transparent conductors and molecular sensors.

Original languageEnglish (US)
Pages (from-to)1906-1911
Number of pages6
JournalAdvanced Functional Materials
Issue number12
StatePublished - Jun 23 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • General Chemistry
  • Biomaterials
  • General Materials Science
  • Condensed Matter Physics
  • Electrochemistry


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