Effects of Humidity and Temperature on Orange Dye-Based Organic Field Effect Transistors Fabricated at Different Gravity

Abstract

This study reports the fabrication of organic field effect transistors (OFETs) using 3-[ethyl[4-[(4-nitrophenyl)azo]phenyl]amino]propanenitrile, usually known as Orange-Dye 25 (OD) and its composite with sugar. The study investigated the heat- and humidity-dependent electrical characteristics of the fabricated devices. Fabrication was carried out from the aqueous solution of the materials using different gravity conditions, i.e., at positive (normal) gravity (+1g) and at negative gravity (−1g). A thin layer (10–15 μm) of OD or OD:sugar was deposited by drop-casting on pre-fabricated drain and source silver (Ag) electrodes having 30 μm separation and 2 mm length followed by aluminum (Al) thermal evaporation to achieve a Schottky barrier. Devices fabricated using OD at −1g were more sensitive in capacitance–temperature and impedance–humidity relationships than those fabricated at +1g. Moreover, OFETs fabricated at −1g using OD:sugar offered capacitance–temperature sensitivity much higher than the devices fabricated at +1g. It has been observed that, in the drop-casting method, the properties of OFETs are dependent upon gravity as well as the solution composition employed for channel definition.