The quartz crystal microbalance (QCM) technique was applied to investigate humidity sensing
properties of a copper phthalocyanine (CuPc) thin film prepared by drop cast method. The humidity
adsorption and desorption kinetics of(CuPc) thin film was evaluated. The QCM and electrical
measurements results showed that humidity sensing properties of CuPc is very sensitive to humidity
changes and reversible adsorption/desorption performance which is an indicative of a good humidity
sensor even at room temperature. Reproducible experimental results indicated that CuPc thin films
have an abundant potential for humidity sensing applications at ambient temperature. According to
the first-principle density functional theory calculations, the promising humidity sensing properties
of CuPc can be attributed to the considerable charge transfer from the water molecule into Cu atom.