Effect of humidity on electrical conductivity of zinc stearate nanofilms

Abstract

In this work, stearic acid (StAc) and zinc stearate (ZnSt2) nanofilms were deposited on glass and silver substrates using Langmuir-Blodgett (LB) film technique and their structural and electrical properties were investigated. X-ray diffraction and IR techniques revealed that more crystalline and better films were obtained from ZnSt2 compare to StAc. Electrical conductivity of ZnSt2 LB films with 13 layers having 28 nm thickness were measured in the range of humidity of 20-60% and it is seen that the conductivity was very sensitive to relative humidity (RH) above 40% at 25 °C and showed no hysteresis during adsorption and desorption of water vapor. Water vapor adsorption isotherm of ZnSt2 powders was determined and conductivity increase with humidity was attributed to water vapor adsorption. Constant electrical conductivity of the ZnSt2 films at low relative humidities and at low voltage values is an advantageous property which allows using them as organic nanofilms with insulating properties.