High-performance reverse electrowetting energy harvesting using atomic-layer-deposited dielectric film

Reverse electrowetting-on-dielectric (REWOD), which is a novel technology for energy harvesting, was demonstrated by depositing Al2O3 via atomic layer deposition (ALD). Specifically, thin layers of Al2O3 about 100 nm-thick were successfully formed by ALD to obtain dense films with high capacitances. REWOD with the ALD Al2O3 thin films exhibited high performances under low-voltage and low-excitation-frequency conditions. The maximum power density was 11 mW/cm2 with a DC bias of 24 V and an external excitation frequency of 2 Hz. Moreover, ALD and sputtered thin films were compared by investigating their capacitances and leakage current densities. Due to the differences between the film densities and growth methods, the ALD thin films exhibited higher capacitances and lower leakage current densities. It was also determined that the leakage current affects the REWOD energy harvesting performance. By analyzing these features, it was confirmed that ALD thin films are suitable for REWOD energy harvesting.