Rare earth ions doped phosphors for improving efficiencies of solar cells

• Spectrum modification for efficiency enhancement of solar cells is reviewed.
• Downshifting, downconversion and upconversion are three modifying processes, whose fundamental theories are discussed.
• Development of materials for enhancing efficiency of solar cells is presented.
• Outlook for lanthanide-doped spectrum-converter is presented.

This paper discusses lanthanide doped luminescent materials which can modify the solar spectrum to reduce the spectral losses encountered by PV (photovoltaic) devices and enhance the conversion efficiency. High cost owing to low conversion efficiency is a limiting factor for contribution of PV devices. Thermalization, recombination, and transmission, resulted from spectral mismatch are three major losses. Many efforts have been made on spectral modification to circumvent these losses. Spectral modification is to modify the incident photons to appropriate energy by upconversion, downconversion or downshifting to better match with the bandgap of semiconductors. Recently, many lanthanide doped spectral modifiers in variety of hosts have been prepared and used to reduce the spectral losses. These materials will be discussed in this paper and the challenges of development and application of such materials is presented as well.