Researchers at the Vienna University of Technology have discovered that a class of materials, called oxide heterostructures, can be used to create a new kind of extremely efficient ultra-thin solar cell.

Professor Karsten Held from the Institute for Solid State Physics at Vienna University of Technology explained that "Single atomic layers of different oxides are stacked, creating a material with electronic properties which are vastly different from the properties the individual oxides have on their own."

The oxides used to create the material are actually isolators. If two appropriate types of isolators are stacked, the surfaces of the material become metallic and conduct electrical current. "This effect allows us to conveniently extract the charge carriers and create an electrical circuit," said Professor Held.

Different oxides can be used to make cells which are sensitive to different wavelengths of light and materials could be combined in cells that absorb a range of different colours.

Although these cells are more complicated to manufacture than conventional solar cells, they could replace silicon cells when extremely high efficiency or extremely thin cells are needed.