Efficient Visible-to-NIR Spectral Conversion for Polycrystalline Si Solar Cells and Revisiting the Energy Transfer Mechanism from Ce3+ to Yb3+ in Lu3Al5O12 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 Ce3+ and Yb3+ codoped Lu3Al5O12. Moreover, the underlying energy transfermechanism from Ce3+ to Yb3+ 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 Ce3+ to nearby Yb3+ is the dominant energy transfermechanism. Finally, we provide new evidence that Ce4+-Yb2+ charge-transfer state is responsible for the relatively low quantum efficiency of NIR emission in Ce3+ and Yb3+ codoped system.