Low temperature cross-linked, high performance polymer gate dielectrics for solution-processed organic field-effect transistors

Poly(methyl methacrylate) (PMMA) and polystyrene (PS) functionalized with both propargyl and azido groups have been synthesized by free radical copolymerization. The thin-films of the bi-functionalized PMMA or PS can be effectively cross-linked by TAAC reaction at a relatively low temperature (100 °C). This bi-functional approach significantly improved the efficiencies of the cross-linking reactions in the solid state and substantially enhanced solvent resistance of the cross-linked dielectric layers. The cross-linked thin-films displayed smooth surfaces and the cross-linked PMMA thin films showed low leakage current densities. The solution processed organic field-effect transistors of bottom-gate bottom-contact structures based on cross-linked PMMA gate dielectric layers exhibited high device performance with a field-effect mobility of 0.59 cm² V⁻¹ s⁻¹, and an on/off current ratio of 10⁵.