Artificial Metamaterials for High Efficiency Silicon Solar Cells

Abstract

The reduction of the significant optical losses due to the reflection and the increase of the penetration of the solar photons into the silicon initiated the development of new photoelectrical techniques for silicon solar cells. Insertion of metamaterials in solar cells seems to be one of the interesting approaches owing to the promising properties of these news materials. Metamaterials are a class of man-made subwavelength structured composite materials. Metamaterials with their unusual electromagnetic properties allow unprecedented guiding of the incident light. In this paper, we undertake a numerical study of the optical response of a multilayer planar waveguide structure based on metamaterials for silicon solar cells. The structure comprises three layers embedded in air. The metamaterial layer is sandwiched between a glass layer and a silicon layer. We first analyze the electromagnetic parameters of the metamaterial layer. We then determine the optical parameters of this structure, namely the reflection, the transmission and the absorption. This study is based on the use of the transfer matrix method which is a very useful algorithm for reflection and transmission calculations of multilayer structures. According to the law of conservation of energy, the absorption coefficient is inferred from the transmission and reflection coefficients. Numerical simulations by using MAPLE software show a weak reflection of light at the air/glass front interface for optimal thicknesses of the structure’s layers. These results are compared with those of a conventional cell structure without metamaterial. Additionally, the effect of the incidence angles for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations is discussed.