Silicon solar cells with monolithic rare-earth oxide upconversion layer

A ternary rare-earth oxide (REO) up-conversion layer was deposited on monocrystalline thin film solar cells to demonstrate up-conversion of sub-band-gap solar radiation into the spectral range of silicon. Laser radiation from 1520 nm to 1560 nm was shown to generate an additional photocurrent in the underlying silicon solar cell. Through combinations of rare-earth ions, portions of the sub-band-gap solar spectrum can conceivably be upconverted to light of shorter wavelength, thereby increasing the efficiency of existing silicon solar cells. The REO films form a stable optically active dielectric that is compatible with standard semiconductor processing techniques.