Highly conductive and adhesive ternary Cu–Cr–Zr alloy electrode for flexible optoelectronic applications

Abstract In this study, high-performance ternary Cu-0.13 wt% Cr-0.04 wt% Zr (Cu–Cr–Zr) alloy films on flexible polyimide (PI) substrate were investigated for the metallization of flexible thin-film transistor. The optimized Cu–Cr–Zr film was endowed excellent electrical resistivity (21.7 mΩ μm) and adhesion strength (5 B). The results showed that the sputtering rate increased with the increase of the sputtering power and pressure, and the adhesion strength tended to increase while the resistivity decreased with the rise of annealing temperature. X-ray diffraction (XRD) analysis showed that the copper grain size increased significantly as the rise of annealing temperature, which indicates the attenuation of the grain boundary scattering and accounts for the decrease of the resistivity. Compared with the glass substrate, lower resistance was achieved on PI substrate, which is related to the surface morphology. The smoothness and adhesion of the Cu–Cr–Zr film were improved more distinctly on the PI substrate can be attributed to more low interfacial energy sites of PI. Further mechanical bending test demonstrated that the robust Cu–Cr–Zr film has good stability and durability without significant deterioration after 50 k times bending.