Sensor technology has been use in advanced application, resulting in low power, miniaturized, high-speed, and cost-effective system. Organic electronics is becoming a prominent topic in the fields of displays, sensor arrays, and photovoltaics, among other things. OFETs provided high-quality components for active matrix displays, radio frequency identification tags, and a variety of other small-scale integrated systems. This will allow for the low-cost and low-temperature fabrication of mechanically flexible electronics on flexible substrates. Conducting polymers (CPs) are organic compounds with π -orbital system that allows electrons to travel from one end of the polymer to the other. Because of its mechanical flexibility, ease of synthesis and high electrical conductivity, conducting polymer (CP) is used. At room temperature, CPs can help sensors to improve their speed, sensitivity, and sort response time. Polyaniline (PANI), Polypyrrole (PPy), Poly (phenyl vinlene) (PPV), Poly (3, 4-ethylene-dioxythiophene), and PEDOT are only a few of the organic conducting polymers available. PANI, a p-type organic semiconductor material with good electrical conductivity and stability, is one of these organic compounds. Because of its ease of synthesis, room temperature operation, and relative stability, polyaniline (PANI) has been use for a variety of applications including logic circuit components, electromagnetic shielding, chemical sensing, and anticorrosion. This device can be used in low-power applications (Ref 1-4). Humidity sensors can be used to measure relative humidity (RH) in a variety of weather. PANI has been used in humidity sensor devices based on the electrical conductivity with water vapor. Polymers are the most common type of material used to fabricate the humidity sensors. Humidity is an important environmental characteristic that can be used for a variety of applications including instrumentation, automated systems, agriculture, and climatology. Plantation protection and soil moisture monitoring are two applications of humidity sensors in agriculture. To get high performance of humidity, sensing materials must have high surface to volume ratio to interact with the water molecules repeatedly for longer life cycle and faster response (Ref 5-6).
In this paper, we propose a bottom gate OFET device composed of PANI as a conducting channel and SiO2 act as an insulator on n-type silicon substrate, which will be used as a humidity sensor based on organic field-effect transistor (OFET). This device is compatible with low power applications. In this work, we only concentrate on fabrication of conducting polymer OFET with top contact to evaluate the humidity and verify I-V characteristics. The current saturation (ISat) of p-type OFETs was 0.8 μA, while the threshold voltage VTh was 2.2V. The FESEM (Field Emission Scanning Electron Microscopy) have been presented. The Proposed sensor shows that organic gate dielectrics are a low-cost alternative to inorganic gate dielectrics with good electrical performance.