Research progress on broadband down-conversion spectral modification based on energy transfering of rare earth ions

Broadband down-conversion spectral modification based on energy transfer of rare earth ions has a possibility to improve the conversion efficiency of solar cell due to the prohibition of the thermal loss of the excess photon energy. Recent developments on the spectral modification were reviewed. Rare-earth ions such as Eu2+, Yb2+ and Ce3+with f-d transitions were chosen as sensitizers, and Yb3+ was selected as luminescent center due to the matching between the energy level difference of Yb3+ and the band-gap of Si. One photon in the high energy region from 300nm to 500nm was split to the more low-energy photons in the near infrared region. The fluorescence decay curves and time-resolved luminescence spectra were used to investigate the energy transfer mechanism. Based on the design of material's micro-structure, some methods for the realization of broadband down-conversion spectral modification with high efficiency were proposed