Interface engineering with double-network dielectric structure for flexible organic thin film transistors

Taking inspiration from the characteristics and the limitations of flexible organic thin-film transistor (OTFT) devices, a novel surface modification method was proposed to modify the gate insulator to tune the mechanical compatibility and adhesion energy between gate insulator and semiconductor layer for high performance flexible OTFT devices. The surface modification method aimed to form a polymer network structure within the cross-linked polymer film by photo-polymerization of the liquid monomers which were infused into the crosslinked polymer film. The formation of double-network structure significantly improved the electrical performance of the flexible devices. The charge mobility increased from 0.17 cm(2)V(-1)s(-1) to 1.52 cm(2)V(-1)s(-1) and on/off current ratio increased by one or two orders of magnitude. During the bending tests, the devices modified with double-network dielectric structure exhibited excellent mechanical stability even after hundreds of successive bending cycles along with different bending radius. For instance, the mobility of the devices modified with methyl methacrylate only reduced by 2% after 500 successive bending cycles with a bending radius of 10 mm. It is ascribed to the improvement of mechanical compatibility and decrease of adhesion energy between gate insulator and semiconductor with the double network dielectric structure. More importantly, this work is a unique example to demonstrate the importance of mechanical compatibility and adhesion energy between gate insulator and semiconductor on the mechanical stability of flexible OTFT. Furthermore, these results clearly demonstrated that this method is a promising tool to tune the semiconductor/dielectric interface, especially the mechanical compatibility and adhesion energy between semiconductor layer and dielectric layer, which has great potential for high performance flexible OTFTs with excellent mechanical stability.