Optical simulations are performed in the research group, where Maxwell’s equations are solved rigorously. Both, two- and three-dimensional systems are taken into consideration. These simulations provide additional insights to the local light trapping in the solar cell, that are not directly accessible by experiment. These information are used to complement the evaluation and interpretation of experimental results from scanning near-field optical microscopy. Furthermore, the surface texture and the layer stack can be modified in the model to optimize the absorption in the solar cell.
The simulations are done by the Finite-Difference Time-Domain (FDTD) method, where the structure is described in a grid with a distance of the grid points much smaller than the wavelength of light. The time-domain of the electromagnetic fields are calculated until reaching a steady state. The structures, considered in the calculations, are real three-dimensional structures, as measured by atomic force microscopy or scanning near-field optical microscopy, or idealized model systems. From these results, the local light intensity, the local absorption and the angular intensity distribution can be obtained. The calculations are done in collaboration with the research group „device simulation“ and performed at Jülich Supercomputing Center.