Polyethylene interfacial dielectric layer for organic semiconductor single crystal based field-effect transistors

Organic semiconductor single crystals (OSSCs) have shown their promising potential in high-performance organic field-effect transistors (OFETs). The interfacial dielectric layers are critical in these OFETs as they not only govern the key semiconductor/dielectric interface quality but also determine the growth of OSSCs by their wetting properties. However, reported interfacial dielectric layers either need rigorous preparation processes, rely on certain surface chemistry reactions, or exhibit poor solvent resistance, which limits their applications in low-cost, large-area, monolithic fabrication of OSSC-based OFETs. In this work, polyethylene (PE) thin films and lamellar single crystals are utilized as the interfacial dielectric layers, providing solvent resistive but wettable surfaces that facilitate the crystallization of 6,13-bis(tri-isopropylsilylethynyl)pentacene (TIPS-PEN) and 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene (TIPS-TAP). As evidenced by the presence of ambipolar behavior in TIPS-PEN single crystals and the high electron mobility (2.3 ± 0.34 cm² V^-1 s^-1) in TIPS-TAP single crystals, a general improvement on electron transport with PE interfacial dielectric layers is revealed, which likely associates with the chemically inertness of the saturated C-H bonds. With the advantages in both processing and device operation, the PE interfacial dielectric layer potentially offers a monolithic way for the enhancement of electron transport in solution-processed OSSC-based OFETs.