Solution-processed nanocomposite dielectrics for low voltage operated OFETs

A novel, solution processed high-k nanocomposite/low-k polymer bilayer gate dielectric that enables the fabrication of organic field-effect transistors (OFETs) that operate effectively at 1 V in high yields is reported. Barium strontium titanate (BST) and barium zirconate (BZ) nanoparticles are dispersed in a poly (vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP) polymer matrix to form a high-k nanocomposite layer. This is capped with a thin layer (ca 30 nm) of cross-linked poly(vinyl phenol) (PVP) to improve the surface roughness and dielectric-semiconductor interface and reduces the leakage current by at least one order of magnitude. OFETs were fabricated using solution-processed semiconductors, poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione)thieno[3,2-b]thiophene) and a blend of 6,13-bis (triisopropylsilylethynyl) pentacene and poly (α-methylstyrene), in high yield (>90%) with negligible hysteresis and low leakage current density (10^-9 A cm^-2 at ±1).