Performance enhancement of thin-film c-Si solar cell with group III-V material grating structures

Efficient light trapping structures in a solar cell improves the overall performance of the devices and substantially reduce its overall cost. Even though thin-film photovoltaic (PV) offers significant cost reduction by reducing the overall thickness compared to traditional bulky thick film Photovoltaics, the overall performance is not optimal due to lower absorption properties. Thus to improve the overall efficiency the absorption of the PV cell has to be improved. In this paper, to improve the optical absorption of the PV cells, we present a new diffraction grating structure known as assembly grating by implementing the commercially available group III-V materials. Through optimization of the spacing of grating separations, hence the lattice constants and the ratio of each grating heights, we found 39.70% ultimate efficiency under terrestrial ASTM-1.5, 1 sun condition with Indium Phosphide (InP) as the grating material over the range of 400-2000 nm. Proposed structures show around 14.61% higher efficiency than same lattice constant c-Si thin-film photovoltaics.