Efficient conversion of broad UV-visible light to near-infrared emission in Mn4+/Yb3+ co-doped CaGdAlO4 phosphors

Mn4+/Yb3+ co-doped CaGdAlO4 are prepared to achieve efficient spectral conversion. XRD Rietveld refinement analysis is performed to obtain the structural information of the synthesized materials. The results indicate the Al3+ and Gd3+ sites are substituted by the Mn4+ and Yb3+ ions, respectively. Intense NIR emission within the most sensitive response region of c-Si solar cells is observed under UV-visible excitation, indicating the existence of efficient energy transfer from Mn4+ to Yb3+ ions. The dipole-dipole interaction is verified to be the dominant energy transfer mechanism among the Mn4+-Yb3+ pair. The linear dependence of energy transfer rate on the Yb3+ concentration indicates that one NIR photon is generated with the absorption of one UV-visible photon. The broad excitation spanning from 250 to 600 nm monitored at NIR emission demonstrates that the Mn4+ ions in the CaGdAlO4 host can be efficient sensitizers for Yb3+ ions to enhance the performance of c-Si cells.