Abstract
With the aim of enhancing the field-effect mobility and air stability of self-aligned regioregular poly(3-hexylthiophene), P3HT, by promoting two-dimensional molecular ordering, we transformed the chemical structure of the P3HT chain from a benzoid to a quinoid structure by doping the P3HT solution with HAuCl4 prior to film formation. We found that, for the appropriate HAuCl4 concentration, the P3HT nanocrystals adopt a highly ordered molecular structure with a field-effect mobility of 0.03 cm 2 V-1 s-1, which is an improvement by a factor of more than 100. This increase in field-effect mobility is due to a significant enhancement of molecular ordering and the perpendicular orientation of the nanocrystals with respect to the insulator substrate. This resulted from the change in the P3HT chain conformation from a benzoid to a quinoid structure due to oxidation by HAuCl4. The quinoid structure favors a linear or expanded-coil conformation, so the thiophene inter-ring bonds have increased double-bond character, which improves the molecular ordering. Furthermore, the electrical properties of a doped P3HT device had highly improved stability to air without encapsulation. These results suggest that the effect of unintentional doping by oxygen on HAuCl4-doped P3HT film is insignificant because the p-type doping effect of HAuCl4 is the major contributor.
Original language | English |
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Pages (from-to) | 1705-1710 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry C |
Volume | 112 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2008 Feb 7 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Energy(all)
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films