Sputtering Deposition of a Binder-Free V₂O₅/ZnO Thin Film for Transparent Supercapacitor Applications

Modern transparent technology requires high-energy-density and long-lasting transparent energy storage devices. In this study, we deposited a V 2 O 5 /ZnO film on flexible substrates by the magnetron sputtering technique and varied its radio power from 50 to 110 W. We found that the film thickness increased from 0.85 to 1.67 μm and decreased to 1.35 μm, and transparency decreased from 78 to 70% and increased to 76% from 50 to 80 and 110 W, respectively, resulting in highly energetic secondary electrons. The V 2 O 5 /ZnO films exhibited pseudocapacitive behavior. The optimized V 2 O 5 /ZnO-80 W film showed a high areal capacitance of 83.59 mF/cm 2 and a capacitance retention of 95.18% after 5000 cycles with a remarkable transparency of 70%. Further, the fabricated sandwich-like transparent symmetric supercapacitor (TSSC) delivered a high areal energy density of 0.46 μWh/cm 2 at a power density of 62 μW/cm 2 and capacitance retention of 75.41% after 6000 cycles. These results demonstrated that homogeneously deposited binder-free V 2 O 5 /ZnO thin films with high active mass loading and high film thickness are more suitable for high-performance transparent supercapacitor applications.