title: Significantly Increasing the Ductility of High Performance Polymer Semiconductors through Polymer Blending.
abstract: Polymer semiconductors based on donor-acceptor monomers have recently resulted in significant gains in field effect mobility in organic thin film transistors (OTFTs). These polymers incorporate fused aromatic rings and have been designed to have stiff planar backbones, resulting in strong intermolecular interactions, which subsequently result in stiff and brittle films. The complex synthesis typically required for these materials may also result in increased production costs. Thus, the development of methods to improve mechanical plasticity while lowering material consumption during fabrication will significantly improve opportunities for adoption in flexible and stretchable electronics. To achieve these goals, we consider blending a brittle donor-acceptor polymer, poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (PCDTPT), with ductile poly(3-hexylthiophene). We found that the ductility of the blend films is significantly improved compared to that of neat PCDTPT films, and when the blend film is employed in an OTFT, the performance is largely maintained. The ability to maintain charge transport character is due to vertical segregation within the blend, while the improved ductility is due to intermixing of the polymers throughout the film thickness. Importantly, the application of large strains to the ductile films is shown to orient both polymers, which further increases charge carrier mobility. These results highlight a processing approach to achieve high performance polymer OTFTs that are electrically and mechanically optimized.
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Joshua I
authors.initials: JI
authors.lastname: Scott
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xue
authors.affiliation: Center for Polymers and Organic Solids, University of California-Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
authors.forename: R Joseph
authors.initials: RJ
authors.lastname: Kline
authors.affiliation: Organic and Carbon Electronics Laboratory, Department of Physics, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Hoffman
authors.affiliation: Organic and Carbon Electronics Laboratory, Department of Physics, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Dougherty
authors.affiliation: Analytical Instrumentation Facility, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Chuanzhen
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Center for Polymers and Organic Solids, University of California-Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Bazan
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: O'Connor
keywords: blend films; ductility; polymer semiconductors; thin film transistors; vertical segregation