Enhanced Gas Sensing Performance of Organic Field-Effect Transistors by Modulating the Dimensions of Triethylsilylethynyl-Anthradithiophene Microcrystal Arrays

Abstract

This paper systematically compares the gas sensing properties of organic field-effect transistors (OFETs) based on patterned 5,11-bis(triethylsilylethynyl)anthradithiophene (TES-ADT) films, by adopting TES-ADT crystal arrays of various shapes and dimensions. The patterning and crystallization of spin-cast TES-ADT layers are achieved by the use of a solvent-containing engraved polydimethylsiloxane (PDMS) mold. Decreasing width of the TES-ADT pattern enhances gas sensing performance, as well as field-effect mobility of OFETs. The decreased grain boundary density at narrower line width contributes to the increase of field-effect mobility. On the other hand, the increased sensing performance is mainly due to the increased area of crystal edges, which provides a diffusion pathway for gas molecules to arrive at the semiconductor-dielectric interface. This study provides new perspectives on the diffusion pathway of gas molecules in OFET-based gas sensor, and will be useful for the design of active channel to boost the gas sensing properties of OFETs.