Optimization of a photocell

Photocells contain a silicon-based solar energy absorbing material. An optimal design of the interface between this material and the exterior medium is desired. The problem is modelled by the Helmholtz equation. The interface is assumed to be periodic and thus only one period is considered. It is shown that the problem has a solution if the interface is not allowed to oscillate too much. An approximation of the solution is computed with the finite element method coupled with an integral Fourier method for the radiation condition. The numerical simulations show fairly large improvements in the efficiency of the photocell.