Thin Films in Triboelectric Nanogenerators for Blue Energy Harvesting: Fabrication, Characterization, and Modeling

Renewable energy attracts many researchers as the non-renewable one has negative environmental impacts and limited availability. One of the main types of renewable energy is the blue energy where electricity is generated by water waves using triboelectric nanogenerators (TENGs). Thin films play an important role in the performance and therefore the efficiency of TENGs as they represent the electrodes between which electrons move producing electricity. In order to increase the generated electricity from TENGs, the properties of these electrodes should be modified. Therefore, in this paper, nano- and micro-size thin films are fabricated and characterized by measuring the geometrical parameters and electrical properties. Thin films are fabricated using aluminum with thicknesses 0.5 μm and 1.5 μm on acrylic substrate and 0.5 μm copper film on different types of dielectric materials including PVC and polystyrene. Atomic force microscopy is used to measure the geometrical parameters of the fabricated films including thickness and surface roughness. Also, Gwyddion software is used for the grain size evaluation. On the other hand, Keithley is used for measuring the electrical properties including electrical conductivity and sheet resistance. It is found that the electrical conductivity of aluminum films is inversely proportional to the thickness. The corresponding measured values of the electrical conductivity of the fabricated thinner and thicker aluminum films equal 1.7 x 107 (Ω.m)-1 and 1.4×107 (Ω.m)-1, respectively. Whereas, the electrical conductivity of the fabricated copper film equals 8.8×107 (Ω.m)-1. In addition, the temperature effects on the electrical conductivity are studied. Finally, simulation of a TENG using COMSOL software is accomplished in order to evaluate the electrical outputs of potential, charge, and energy.