North Carolina State University researchers have devised a new nanoscale “sandwich” design technique for thin-film solar cells, creating significantly slimmer cells without sacrificing efficiency. A thin, 70 nm, amorphous silicon active layer, which absorbs solar energy for conversion, is sandwiched between two dielectric layers between 200 to 300 nm thick. The design closely resembles a square wave, with elevated nanosurfaces evenly spaced across the film. The nanostructures are key because they act as “efficient optical antennas [...] focusing solar energy into the active material”, allowing a thinner active layer without impairing the solar cell’s efficiency. Current thin-film solar cells on the market require 300 to 500 nm thick active layers to be as effective as 70 nm nanoscale sandwich cells. The new techniques’ importance is twofold: it can be applied to many other solar cell materials and thinner cells should result in decreased manufacturing costs.