A loss mechanism for solar cells is the incomplete absorption of sunlight. Light trapping aims to remove this loss by both reducing reflection at the front surface of the cell and engineering the light inside the cell so that it cannot escape, thus effectively trapping the light. Light which is trapped will be absorbed by the cell, thereby increasing the cell performance.
With this goal in mind, novel devices are developed using nanoimprint lithography to precisely control the geometry while maintaining excellent scalability. These concepts are then directly applied to liquid phase crystallized thin-film silicon solar cells where light trapping is particularly effective due to the low device thickness.
When researching light trapping structures, simulations can be an invaluable tool to both optimize and understand different device designs. The flexibility in geometry provided for by nanoimprint lithography needs a similarly flexible modelling tool for accurate simulations. Therefore the finite element method is used as it can simulate an arbitrary geometry with a high degree of precision.
A solar cell is not only an optical but also an electrical device. Therefore an area of focus is to optimize light trapping within the constraints posed by charge carrier transport within the cell.