Plasmonic effects of nanoholes in a silver back reflector for improved light trapping in thin film amorphous silicon solar cells

Abstract

The efficiency of thin film Si photovoltaic (PV) cells is lower than cells made of c-Si wafers, but thin film solar cells provide a PV technology with lower materials consumption and less energy used in production. Therefore, research is ongoing to enhance the absorption of these cells while making the silicon layer even thinner. This will boost the electrical performance and increase the industrial production yield as well as reduce manufacturing costs. By implementing a smart geometric design of the solar cell, light is managed such that the absorption is optimized. Apart from geometric optics, plasmonic effects can further enhance the absorption. In this study, improved light management is shown by interaction of light with the dielectric contrast of nanoholes in the Ag back reflector of the cell. The following investigated physical phenomena can be induced by the nanoholes and lead to improved absorption: near field enhancement, light scattering, and surface plasmons. Angular resolved measurements of the quantum efficiency are compared with finite-difference time-domain (FDTD) simulations. This is compared with experimental devices comprising these nanoholes. The presentation will be concluded by remaining challenges and new ways to endeavor. © 2012 OSA.