Flexible Organic Electrolyte-Gated Transistors Based on Thin Polymer Blend Films of Crystalline C8-BTBT and Amorphous PTAA

Thin films of polymer blends consisting of a crystalline small-molecular semiconductor, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), and an amorphous polymer semiconductor, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), are studied and applied to organic electrolyte-gated transistors (OEGTs). The compositions can be easily controlled by adjusting the mixing ratios of the solutions in chloroform. In the thin-film state, PTAA acts as a structural matrix and a charge-transport bridge for C8-BTBT grains. The C8-BTBT:PTAA blends have a compositional effect on the thin-film properties and performance of OEGTs. As a result, the C8-BTBT:PTAA blend films with weight ratios of 8:2 exhibit a hole mobility twice that of pristine C8-BTBT films. Moreover, OEGTs based on the C8-BTBT:PTAA blend exhibit better charge-transport properties on flexible plastic substrates under bending conditions, compared to flat devices.