Optimal design of periodic nanostructures formed in solar cells as an antireflective layer

Recently, periodic nanostructures with a rectangular profile have been widely used in the backside layer of solar cells to reduce the reflectance and to enhance the performance. In this paper, we design solar cells by applying two-dimensional periodic nanostructures with a trapezoidal profile as an antireflective layer. Through intensive simulations using rigorous coupled-wave analysis (RCWA), we attempt to optimize the profile parameters, including the sidewall angle (SWA), the pitch, and the height. Simulation results indicate that the rectangular profile displays a lower reflectance than the trapezoidal profile. Moreover, when the pitch is almost double of the width and the height is 1~2 times of the width, the total reflectance is reduced by 25~35%.