Broadband ultraviolet to near infrared conversion in Eu(2+),Nd(3+) co-doped SrAl(2)O(4)

In this study, we investigated the quantum cutting (QC) mechanism in Eu(2+)–Nd(3)-co-doped SrAl(2)O(4) microcrystals by fluorescence spectroscopy and decay lifetime analysis. In this material, the near-infrared (NIR) emissions of Nd(3+) in the range of 800–1200 nm were enhanced under the excitation of the Eu(2+):4f(7) → 4f(6)5d(1) transition radiation. The lifetime of the 5d(1) level of Eu(2+) decreased with the increase in the Nd(3+) concentration. These results verified the occurrence of cooperative energy transfer (CET) from the Eu(2+):5d(1) excited state to the Nd(3+):(4)F(3/2) level, by which one absorbed ultraviolet-visible photon was converted to two NIR photons with an optimal quantum efficiency (QE) of approximately 177.1%. Therefore, this broadband QC material paves the way for a further increase in the conversion efficiency of c-Si solar cells.