X-ray scattering study of thin films of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)

TitleX-ray scattering study of thin films of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)
Publication TypeJournal Article
Year of Publication2007
AuthorsM.L. Chabinyc, M.F. Toney, R.J. Kline, I. McCulloch, and M.J. Heeney
JournalJOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume129
Pagination3226-3237
Date PublishedMAR 21
ISSN0002-7863
AbstractPoly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT, is a semiconducting polymer that forms thin film transistors (TFTs) with high field effect mobility on silicon dioxide dielectrics that are treated with alkyltrichlorosilanes (similar to 0.2 to 0.5 cm(2)/V s) but forms TFTs with poor mobility on bare silicon dioxide (< 0.005 cm(2)/V s). The microstructure of spin-coated thin films of PBTTT on these surfaces was studied using synchrotron X-ray diffraction and atomic force microscopy. PBTTT crystallizes with lamellae of pi-stacked polymer chains on both surfaces. The crystalline domains are well-oriented relative to the substrate in the as-spun state and become highly oriented and more ordered with thermal annealing in the liquid crystalline mesophase. Although the X-ray scattering from PBTTT is nearly identical on both surfaces, atomic force microscopy showed that the domain size of the crystalline regions depends on the substrate surface. These results suggest that electrical transport in PBTTT films is strongly affected by the domain size of the crystalline regions and the disordered regions between them.
DOI10.1021/ja0670714