Design and analysis of spectrally selective patterned thin-film cells

This paper outlines several techniques for systematic and efficient optimization as well as sensitivity assessment to fabrication tolerances of surface texturing patterns in thin film amorphous silicon (a-Si) solar cells. The aim is to achieve maximum absorption enhancement. The joint optimization of several geometrical parameters of a three-dimensional lattice of periodic square silver nanoparticles, and an absorbing thin layer of a-Si, using constrained optimization tools and numerical FDTD simulations is reported. Global and local optimization methods, such as the Broyden-Fletcher-Goldfarb-Shanno quasi-Newton method and simulated annealing, are employed concurrently for solving the inverse near-field radiation problem. The design of the silver-patterned solar panel is optimized to yield maximum average enhancement in photon absorption over the solar spectrum. The optimization techniques are expedited and improved using a novel nonuniform adaptive spectral sampling technique. Furthermore, the sensitivity of the optimally designed parameters of the solar structure is analyzed by postulating a probabilistic model for the errors introduced in the fabrication process. Monte Carlo simulations and unscented transform techniques are used for this purpose.