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

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.