Nanocrystalline copper oxide for selective solar energy absorbers

The high-energy edge of the transparency window in nanocrystalline copper monoxide (CuO) can be shifted to 0.6 eV (against 1.45 eV in single crystals). This shift is related to a modification of the shape of the fundamental absorption edge of CuO without any change in the refractive index. The obtained nanocrystalline CuO is recommended for use as a selective solar energy absorber.