Experimental Study on Flexible ZnO Based Nanogenerator Using Schottky Contact for Energy Harvesting Applications

This paper presents the synthesis and implementation of a metal-insulator-semiconductor-type energy harvester. The proposed harvester generates power from ambient vibration. The flexible nanogenerator (NG) is developed from well- aligned ZnO nanorods (NRs) on kapton substrate with ITO sputtered bottom contact using the low-temperature hydrothermal method. PMMA insulation region is coated over NRs with silver (Ag) as top electrode to reduce the external screening effect thereby improving the output signal strength. The crystalline and morphological properties of the NRs are studied using X-ray diffraction, field emission scanning electron microscopy analysis, Fourier transform infrared spectroscopy, and photoluminescence.The current–voltage characteristics of the ZnO NRs exhibited a clear rectifying behavior, attributed to the formation of a Schottky contact between ZnO and Ag contact with an insulation of PMMA layer. An experimental study to evaluate the device performance is carried out using tip excitation method. The synthesized NG generates open-circuit voltage of 400 mV, circuit current across optimum load of 10 kΩ is 30  μ A, and giving a maximum power density of 9  μ Wcm –2 at a force of 0.5 N at 12 Hz. Furthermore, the impedance analysis is performed for estimating the relationship between screening effects and RC time constant ( T RC ).