Nanoscale Silver-Based Al-Doped ZnO Multilayer Transparent-Conductive Oxide Films

Abstract

Requirements of transparent-conductive oxide (TCO) films for solar cells and other optoelectronic applications are mainly focused on the electrical resistivity as low as 10(-5) cm, optical transmittance above similar to 85% in the visible region, a long-term stability in damp heat-treatment for 1000 h, a mechanical stability on flexible polymer substrates, and the large-area deposition technique for commercialization. In this study, the typical properties of the 45 nm thick Al-doped ZnO (AZO)/Ag/45 nm thick AZO multilayer films embedded by silver layers with various thicknesses were addressed to satisfy the requirements of TCO films for flexible electronic device applications. The AZO/9 nm thick Ag/AZO multilayer films as deposited on poly(ether sulfone) (PES) polymer substrates at 30 degrees C by radio-frequency magnetron sputtering, which the deposition on large-area substrates is possible, exhibited the electrical resistivity of approximately 5x10(-5) cm, optical transmittance of 88% at 550 nm wavelength, no appreciable change in electrical resistance and optical transmittance after damp heat-treatment for 1000 h, and a strong mechanical stability between multilayer films and PES substrates after a severe bending test. The results presented in the multilayer films can provide a platform for TCO films deposited on polymer substrates to enable the flexible electronic device applications.