Fluorinated ethylene propylene thin film for water droplet energy harvesting

We investigate water droplet energy harvesting using transparent hydrophobic polymers. The hydrophobic polymer acts as protection while at the same time harvest energy from the impacting water droplets. The electrodes are mounted at the edges of a transparent window. Such a scheme has the advantage that it allows easy integration with existing technologies and avoids the extra costs and reduced transmittance upon incorporation of partially transparent oxide electrodes covering the entire polymer. Since the electrodes are mounted at the edges of the hydrophobic polymer, the transmittance through the transparent portion is very high, here shown to be >94% for visible light when using thin films of fluorinated ethylene propylene (FEP). It is demonstrated that the system can be mounted on a commercial solar cell for harvesting electrical power from the impact of water droplets, generating an average power of up to 10 mW per square meter of electrode area.