Highly flexible and semi-transparent Ag–Cu alloy electrodes for high performance flexible thin film heaters

Abstract

We investigated the properties of thermally evaporated Ag–Cu films for application as flexible and semi-transparent electrodes for semi-transparent flexible thin film heaters (TFHs) and heat shielding films (HSFs). The effects of Ag–Cu thickness on the electrical, optical, morphological, and mechanical properties of the Ag–Cu films were investigated in detail. Based on figure of merit values calculated from the sheet resistance and optical transmittance, we optimized the thickness of the Ag–Cu alloy film. Optimized film showed no resistance changes and no cracks, even with inner and outer bending radii smaller than 5 mm, indicating sufficiently high flexibility for application in TFHs and HSFs. In addition, we measured the work function of the Ag–Cu films using Kelvin probe force microscopy to correlate the work function and surface morphology. The effect of the thickness of the Ag–Cu alloy electrodes on the saturation voltage and temperature of flexible TFHs was also investigated. In addition, we investigated the feasibility of using semi-transparent Ag–Cu alloy film in HSFs. Effective heat generation and heat shield performance of Ag–Cu alloy films suggest that the multi-functional Ag–Cu films described here can potentially be applied to create energy-efficient automobile windows and smart windows for building energy management systems.