Colloidal Crystals as Templates for Light Harvesting Structures in Solar Cells

Monolayer colloidal crystals are formed using silica- and polystyrene beads and used as etch masks for the formation of regular, _m period hexagonal arrays of indentations in a silicon wafer. Such patterns can be used as di_raction gratings or as seeds for further processing, for example by pit-catalysed electrochemical etching. In another experiment, multilayer colloidal crystals are infiltrated with titania before subsequent removal of the beads, forming inverse opals displaying tuneable reflectivities which are interesting for use as selective reflectors.