Enhancing the efficiency of solar cells by down shifting YAG: Ce3+ phosphors

Ce3+-doped yttrium aluminum garnet (YAG:Ce3+) is a luminescent down shifting material, and can convert ultraviolet (UV) and blue lights into yellow light. In this paper, the YAG:Ce3+ phosphors are applied on the surface of a monocrystalline silicon solar cell. Although the number of total photons after the down shifting conversion does not increase, the quantum efficiency of the solar cell in short wavelength range has been improved. The reason is that the UV and blue photons can hardly generate carriers in the depletion region of the p-n junction because most of them are absorbed before getting there, while the yellow photons emitted from the YAG:Ce3+ phosphors can generate electron-hole pairs in the region. Experimental results show that the down shifting phosphors have enhanced the energy conversion efficiency of the solar cell from 15.30% to 15.46%. Although the efficiency increase is small, the down-shifting phosphors provide a possible way to reduce the energy loss in the short wavelength range.