Interfacial spreading for rapid formation of uniform gate dielectric layers on flat and curved substrates for organic devices†

Abstract

Spin coating represents a mainstream method for depositing polymer gate dielectric layers in organic electronic devices. However, it encounters various challenges, including significant material waste, thickness variations from the center to edge of the substrate due to gradual changes in the centrifugal force, and substrate limitations. To address these drawbacks, this paper proposes an interfacial-spreading method based on the Marangoni effect, aimed at achieving highly uniform gate dielectrics on both flat and curved substrates. Using only ∼11 μL of the precursor solution, crosslinked poly(4-vinylphenol) (CL-PVP) films were successfully fabricated. The prepared films exhibited a thickness coefficient of variation of 0.04, four times lower than that of spin-coated films (0.17). Additionally, the CL-PVP gate dielectric could be mechanically patterned. The interfacial-spreading method minimized thickness variations and reduced material consumption by approximately tenfold in relation to spin coating. Organic-semiconductor-based transistors fabricated using the interfacial-spread CL-PVP gate dielectrics demonstrated performance comparable with those prepared using spin-coated films. Furthermore, a complementary-type inverter was fabricated to validate the functionality of the prepared films in electronic circuits. The CL-PVP gate dielectric could be successfully deposited on curved substrates (radius of curvature of up to 7.5 mm), displaying a thickness nearly identical to that on flat substrates and comparable with that on spin-coated films. Overall, the interfacial-spreading method represents a promising low-waste, and substrate-flexible alternative to spin coating for polymer gate dielectric formation, with potential adaptability to various polymer solutions.