UV photon harvesting and enhanced near-infrared emission in novel quantum cutting Ca2BO3Cl:Ce3+,Tb3+,Yb3+ phosphor

A novel near-infrared (NIR) quantum cutting (QC) Ca2BO3Cl:Ce3+,Tb3+,Yb3+ phosphor promising for luminescent solar concentrators (LSC) with Si solar cells was successfully developed. It can harvest UV photons and exhibits an intense NIR emission of Yb3+ around similar to 1000 nm, perfectly matching the maximum spectral response of Si solar cells. The NIR emission intensity of Ca2BO3Cl:Ce3+,Tb3+,Yb3+ upon broadband excitation of Ce3+ ion at 288, 315 and 369 nm is about 9.1, 10 and 2.8 times as intense as that of GdBO3:Tb3+,Yb3+ with the highest NIR quantum efficiency of about 182% upon narrow excitation of Tb3+ ion at 488 nm. It demonstrates for the first time that Ce3+ ion can be an efficient sensitizer harvesting UV photons and greatly enhancing the NIR emission of Yb3+ ion through efficient energy feeding by the allowed 4f-5d absorption of Ce3+ ion with high oscillator strength. We believe this new NIR QC phosphor may open a new route to the design of advanced NIR QC phosphors for maximizing LSC performance with Si solar cells.