Sensitization of nir emission by tetravalent cerium in K2CeO3:Nd,Yb

Crystalline silicon (c-Si) solar cell is to date the most successfully commercialized solar cell. One of the factors which limit the efficiency of c-Si solar cell is a “spectral mismatch”. The mismatch can be removed by modifying the solar spectrum: converting the near UV and blue region of the spectrum, where solar cell response is poor, to NIR region by using suitable phosphors. In the past, several phosphors based on emission of Yb3+/Nd3+ sensitized by f-d transitions of other divalent, or f-f transitions of trivalent rare earths have been studied. These studies demonstrated the concept. However, an ideal phosphor is still not found. In this work tetravalent rare earth, viz. Ce4+ is studied as the sensitizer. Efficient two-step Ce4+→Nd3+→ Yb3+ energy transfer from CT band of Ce4+ is observed. By virtue of this energy transfer, efficient absorption of near UV light and conversion to NIR is achieved. These results are significant for improving efficiency of c-Si solar cells using spectrum modification.