Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer

Suhao Wang; Adam Kiersnowski; Wojciech Pisula; Klaus Müllen

doi:10.1021/ja211630w

Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer

J Am Chem Soc. 2012 Mar 7;134(9):4015-8. doi: 10.1021/ja211630w. Epub 2012 Feb 27.

Authors

Suhao Wang¹, Adam Kiersnowski, Wojciech Pisula, Klaus Müllen

Affiliation

¹ Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.

PMID: 22353165
DOI: 10.1021/ja211630w

Abstract

Probing the role of the first monolayer in the evolution of the film polymer microstructure is essential for the fundamental understanding of the charge carrier transport in polymeric field-effect transistors (FETs). The monolayer and its subsequent microstructure of a conjugated polymer [poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT] film were fabricated via solution deposition by tuning the dip-coating speed and were then studied as accumulation and transporting layers in FETs. Investigation of the microstructure of the layers prepared at different coating velocities revealed that the monolayer serves as an important base for further development of the film. Significant improvement of the charge carrier transport occurs only at a critical multilayer network density that establishes the required percolation pathways for the charge carriers. Finally, at a low dip-coating speed, the polymer chains are uniaxially oriented, yielding pronounced structural anisotropy and high charge carrier mobilities of 1.3 cm(2) V(-1) s(-1) in the alignment direction.