Efficient Visible-to-NIR Spectral Conversion for Polycrystalline Si Solar Cells and Revisiting the Energy Transfer Mechanism from Ce to Yb in LuAlO Host.

The so-called Shockley-Queisser converting efficiency limit of Si solar cells is believed to be surpassed by using the spectral converter. However, searching for efficient spectral converting materials is still a challenging task. In this paper, efficient visible-to-NIR spectral conversion for polycrystalline Si solar cells has been demonstrated in Ce and Yb codoped LuAlO. Moreover, the underlying energy transfermechanism from Ce to Yb is systematically re-investigated by the detailed excitation and emission spectra as well as fluorescent decay curves, and our results demonstrate that fast metal-to-metal charge transfer from Ce to nearby Yb is the dominant energy transfermechanism. Finally, we provide new evidence that Ce-Yb charge-transfer state is responsible for the relatively low quantum efficiency of NIR emission in Ce and Yb codoped system.