Investigations on work functions of gasochromic color dyes as gate materials for FET based gas sensors

We present investigations on gasochromic color dyes as gas sensitive gate materials for field-effect transistor (FET) based gas sensors. Therefore the work function of two color dyes N',N',N,N-tetramethyl-p-phenylenediamine (TMPD) and bromphenolblue (BPB) were characterized using a Kelvin probe. TMPD is selective to NO2 and shows changes in the output of the Kelvin probe of 50 mV during exposure to 0.5 ppm NO2. BPB is an indicator for ammonia. Even 3 ppm NH3 cause a change of 10 mV. In addition, the gasochromic materials are highly selective to only one gas. The results show, that these dyes are suitable as sensitive gate materials and offer the possibility to build a low-power FET, detecting NO2 and NH3 in air at room temperature.