Humidity, light and temperature dependent characteristics of Au/N-BuHHPDI/Au surface type multifunctional sensor

This paper reports the sensing properties of organic semiconducting material N-butyl-N′-(6-hydroxyhexyl) perylene-3,4,9,10-tetracarboxylic acid diimide (N-BuHHPDI). A multifunctional surface type Au/N-BuHHPDI/Au sensor has been fabricated by depositing 140 nm thin layer of N-BuHHPDI on pre-patterned gold (Au) electrodes, using vacuum thermal deposition. The effect of humidity, light and temperature on the electrical capacitance and resistance of the device has been investigated. The sensor responded exponentially toward the variation in humidity, light and temperature. An equivalent circuit of the multifunctional sensor has also been developed. By using the Tauc's law, optical band gaps (2 eV, 2.18 eV and 3.78 eV) of N-BuHHPDI have been obtained from its UV-vis spectrum. Atomic force microscopy (AFM) has been employed to study the morphology of N-BuHHPDI thin film. The environmental-conditions-dependent properties make the device useful for its applications in measurement of humidity, temperature and light.