Small Molecule/Polymer Blend Organic Transistors with Hole Mobility Exceeding 13 cm(2) V-1 s(-1)

The development of third-generation hole-transporting organic blend semiconductors and their application in high mobility OTFTs was reported. The small-molecule 2,7-dioctyl[1]-benzothieno[3,2-b][1]benzothiophene (C₈ -BTBT) was chosen due to its high solubility in various organic solvents and also because of its ability to form large inter molecular overlaps arising from well-ordered molecular arrays, which under certain circumstances can lead to exceptionally high hole mobilities. Indacenodithiophene-benzothiadiazole was selected as the complementary polymer binder primarily due to its good solubility, high hole mobility and comparable highest occupied molecular orbital (HOMO) energy level to that of C₈ ?BTBT. The use of solvent mixtures for dissolving the C₈-BTBT and Indacenodithiophene-benzothiadiazole was also investigated and has been shown to have a remarkable influence on the resulting layer morphology and overall transistor performance. Although it is currently difficult to identify - with a high degree of certainty - the dominant mechanism(s) responsible for the observed dramatic enhancement of the hole mobility, the results obtained indicate the coexistence of more than one process, with the most dominant process being the deactivation of hole traps.