Enhanced Absorption of Solar Cells by Graphene-Based Nano-Antenna Array

A novel graphene based nano-antenna array is designed to increase the absorption of sunlight in silicon wafers of solar cells. The unit cell of array is composed of two coupled particles. Particles are graphene nano-bar and nano square ring placed at the middle of a silicon substrate with the thickness of 30nm. The former performs as electric and the latter as magnetic resonating particles at visible light frequency range. First, the two resonating particles are considered solely. It is shown that their absorption is about 40% at wavelength near 643 and 626nm respectively. Next they are considered together and the coupling is investigated. It is observed that plasmonic hybridization represents how graphene particles behave next to each other at visible region. An absorption of almost 80% of incident light is achieved by resonating particles. It is also shown that metallic nano-particles do not affect the electromagnetic characteristic.