Surface-type multifunctional sensor based on 5,10,15,20-tetrakis(4'-isopropylphenyl) porphyrin

In this study, an organic semiconductor 5,10,15,20-tetrakis(4'-isopropylphenyl) porphyrin (TIPP) was synthesized and investigated as an active material in surface-type multifunctional sensor. As electrodes, 100 nm thick Ag films were deposited on 25 mm x 25 mm glass substrate with 40 mu m gap between them. Thin film of TIPP of area 15 mm x 15 mm was thermally sublimed to cover the gap between the silver electrodes. Thickness of TIPP film was 100 nm. A change in electrical resistance and capacitance of the fabricated device was observed with the increase in relative humidity (RH), temperature, and illumination. Hysteresis, response, and recovery times were investigated over a wide range of RH (0-94%). Activation energy of the TIPP was estimated. An equivalent circuit of the Ag/TIPP/Ag humidity, temperature, and illumination sensor was developed. Humidity, temperature, illumination dependent capacitive, and resistive properties of this sensor make it promising for use in a humidity, temperature, and lux multi-meters.