Fabricação de transistores eletroquímicos orgânicos

Abstract

This work aimed to manufa cture and characterize organic electrochemical transistors. Electrical contacts were constructed using the sputtering technique, for the formation of gold (Au) electrodes, and photolithography, for the tin doped indium oxide elect rodes. Organic polymer poly (3,4 ethylenedioxythio phene):poly (styrene sulfonate) formed the active layer and an Ag/ AgCl pellet was used as gate electrode . Electrical characterizations evaluated parameters such as the material of the el ectrodes, channel geometry (W/ L ratio equal to 240, 300, 400 and 600) and different concentrations of NaCl in deionized water. There were also tests with urea in dairy solutions diluted in deionized water (1: 100 by volume), in order to evaluate the use of the transistor as a sensor. Ob serving the response of the Au and ITO electrodes, it was defined that the first would be used, since the highest transconductance values were obtained with this material. Among the available geomet ries, it was found that the W/ L ratio of 600 provided a maximum transconductance of 9 26x10 3 S, being the highest among the analyzed devices, and a linear behavior in the range of 5x10 5 M to 5x10 2 M in NaCl solutions. The tests with urea dissolved in milk also showed a linear function, where the increase in t he concentration of urea generated a greater electrical current in the channel, indicating an increase in the degree of doping of the organic polymer. Finally, this work produced a reproducible manufacturing process and affirmed the potential of electroche mical organic transistors in the area of sensors, as tools for quantitative and qualitative analysis.