Fabrication of nanostructured yttria stabilized zirconia multilayered films and their optical humidity sensing capabilities based on transmission

The present paper reports the study of modulation in intensity of light transmitted through the thin films of nanostructured yttria stabilized zirconia (YSZ) with the exposure of moisture at room temperature. For this purpose the precursor of YSZ was prepared and used for the deposition of multilayered thin films on borosilicate substrates. The film was then investigated using SEM, XRD and UV-vis absorption techniques. The refractive index of the sensing material was found as 1.448829. SEM showed the macroporous nature of the film and XRD revealed the minimum crystallite size as 5 nm which was further confirmed using TEM and Zeta nanosizer. Energy band-gaps of one-, two-, three- and four- layered films were estimated as 3.927, 3.919, 3.873 and 3.830 eV respectively by UV-vis spectrophotometer. These films were employed as transmission based opto-electronic humidity sensor. Maximum sensitivity was found as similar to 1.937, 1.642, 1.393 and 1.143 mu W/%RH for one, two, three and four- layered films, respectively. Response and recovery times of the sensor were found as 28 s and 30 s respectively. Experiments were repeated time to time and found that the sensor was similar to 94% stable after long run. Thus the investigated opto-electronic sensor has excellent potential to replace an electrical humidity sensor. (C) 2016 Elsevier B.V. All rights reserved.