Flexible ZnSnO ₃/Ag/ZnSnO ₃ multilayer electrodes grown by roll-to-roll sputtering on flexible polyethersulfone substrates

The authors report on the characteristics of flexible ZnSnO ₃ (ZTO)/Ag/ZTO multilayer electrodes sputtered on a flexible polyethersulfone substrate using roll-to-roll sputtering at room temperature. The sheet resistance and optical transmittance of the flexible ZTO/Ag/ZTO multilayer were mainly affected by the thickness and morphology of the Ag layer inserted between the ZTO layers. Dependence of photoluminescence peak intensity on the Ag thickness indicates that the high transmittance of the flexible ZTO/Ag/ZTO electrode can be explained by surface plasmon resonance as well as antireflection effects. At the optimized Ag thickness (10 nm), the flexible ZTO/Ag/ZTO exhibited a resistivity of 4.15 × 10 ^-5 ω-cm, an optical transmittance of 86.03%, and a figure of merit value of 42.83 × 10 ^-3 ω ^-1 comparable to those of conventional crystalline ITO electrodes. In addition, the optimized ZTO/Ag/ZTO sample showed constant resistance change (δR/R) during repeated bending cycles, indicating the robustness of the ZTO/Ag/ZTO electrode as a flexible electrode for cost efficient-flexible displays and photovoltaics.