Optimizing absorptance in nanostructured thin films

To construct a solar cell with maximal efficiency it is necessary to minimise the remittances of the cell across the solar spectrum. Thin-film solar cells allow for production of solar cells with reduced cost, weight and rare mineral consumption; furthermore, engineering at the nanoscale may achieve the high levels of solar absorption attainable with traditional, thicker cells. Columnar thin films (CTFs) have the potential to fulfil these requirements, as by infiltrating the voids between the column with a fluid and by tailoring the shape of the columns, the optical properties can be tuned. Here we present a mathematical framework for calculating the absorptance of such an infiltrated CTF. Also presented are some preliminary numerical results, based on a titanium oxide CTF. These simulations imply that by decreasing the columnar angle (the angle between the column and the substrate) much higher levels of absorption can be achieved, as compared to a CTF with columns oriented normal to the substrate.