Interfacial nucleation behavior of inkjet-printed 6,13 bis(tri-isopropylsilylethynyl) pentacene on dielectric surfaces

Abstract

The performance of organic thin film transistors (OTFTs) is heavily dependent on the interface property between the organic semiconductor and the dielectric substrate. Device fabrication with bottom-gate architecture by depositing the semiconductors with a solution method is highly recommended for cost-effectiveness. Surface modification of the dielectric layer is employed as an effective approach to control film growth. Here, we perform surface modification via a self-assembled monolayer of silanes, a spin-coated polymer layer or UV-ozone cleaning, to prepare surfaces with different surface polarities and morphologies. The semiconductor is inkjet-printed on the surface-treated substrates as single-line films with overlapping drop assignment. Surface morphologies of the dielectric before film deposition and film morphologies of the inkjet-printed semiconductor are characterized with polarized microscopy and AFM. Electrical properties of the films are studied through organic thin-film transistors with bottom-gate/bottom-contact structure. With reduced surface polarity and nanoscale aggregation of silane molecules on the substrates, semiconductor nucleates from the interior interface between the ink solution and the substrate, which contributes to film growth with higher crystal coverage and better film quality at the interface. Surface treatment with hydrophobic silanes is a promising approach to fabrication of high performance OTFTs with nonpolar conjugated molecules via solution methods.