Efficient Visible-to-NIR Spectral Conversion for Polycrystalline Si Solar Cells and Revisiting the Energy Transfer Mechanism from Ce³⁺ to Yb³⁺ in Lu₃Al₅O₁₂ Host

Abstract

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.