Organic Field-Effect Transistors Comprising Semiconductor Layers Laminated on Thermoplastic Gate Dielectric Layers

Organic field-effect transistors (FETs) may be cost-effective alternatives to amorphous-silicon transistors in certain applications. Vacuum-deposited polycrystalline organic semiconductor films exhibit equivalent mobilities to amorphous silicon, and typically outperform polymeric semiconductors. While polymers can be deposited by inkjet printing or thermal transfer, efficient additive deposition of vacuum-deposited and insoluble organics has not yet been described. Here we demonstrate a model for thermal printing of such films, featuring a thermoplastic "receiver" polymer layer that captures semiconductor films from "donor" substrates, and acts as gate insulator. The compound 5,5'- bis(4-isopropylphenyl)-2,2'-bithiophene (diPr-PTTP) is shown to have favorable solid state properties for this process. Its x-ray structure is determined, and its performance and those of pentacene and copper phthalocyanine are evaluated. Mobilities >0.01 cm2/Vs and on/off ratios approaching 10,000 are obtained from transferred films. After transfer diPr-PTTP retained a mobility after transfer of one-third the value of the same material vapor-deposited directly onto the receiver layer.