Solution processed glass/fluorine-doped tin oxide/aluminum-doped zinc oxide double layer thin films for transparent heater and near-infrared reflecting applications

Double layer glass/fluorine-doped tin oxide (FTO)/aluminum-doped zinc oxide (AZO) multifunctional thin films were achieved via ultrasonic spray pyrolysis (USP) method without employing a post-deposition annealing. Transparent heater and near-infrared heat reflection behaviors were investigated. The samples were characterized in terms of their structural, morphological, optical, and electrical properties. The top AZO layer exhibited a polycrystalline structure without any preferred orientation. The double layer structure showed very high average transmittance (87%, 400–700 nm) in the visible and reflectance (55%, 2500 nm) in the near-infrared, regions. In addition, the sheet resistance and resistivity of the film were measured as 14.85 (Ω sq−1) and 1.78 × 10−3 (Ω cm), respectively. The saturation temperature, response time, surface temperature uniformity, areal power density, and thermal resistance values were found to be 111 °C, 174 s, 11.42%, 0.299 W/cm2, and 282.8 °C cm2 W−1 for a sample with an active area of 31.5 cm2 and input voltage of 9 V. In addition, dry-ice cooled samples (−25 °C) showed impressive deicing performance depending on the input power. In case of 12 V, all ice was defrosted, and water droplets were evaporated within 2 min and 10 s. During this process, a heating rate of ⁓43 °C/min was achieved.