Materials Chemistry and Physics, Vol.147, No.3, 860-866, 2014
Enhanced near-infrared quantum cutting in CaMoO4:Yb3+ phosphors induced by doping with Li+ ions for improving solar cells efficiency
The near-infrared (NIR) quantum cutting (QC) CaMoO4:Yb3+ phosphors co-doped with Li+ ions were synthesized by the sol gel methods. The dependence of the structure, morphology, photoluminescence (PL) and downconversion (DC) quantum efficiency on the Li+ doping concentration have been investigated in details. It was demonstrated that the CaMoO4:Yb3+ phosphors with appropriate concentration of the Li+ ions show improved crystallinity and remarkable increase of the NIR emission from the Yb3+ ions, if compared with the Li+-free samples. The enhancement of the NIR emission and DC quantum efficiency was suggested to be a consequence of the improved crystallinity and stronger absorption of the host due to the [MoO4] tetrahedra distortion induced by the Li+ ions. Cooperative energy transfer (CET) from the host to the Yb3+ ions is discussed as a possible mechanism for the NIR emission enhancement. Excellent luminescence properties of the Li+ doped CaMoO4:Yb3+ phosphor demonstrate its potential application as a better QC layer to increase the energy conversion efficiency of the Si-based solar cells. (C) 2014 Elsevier B.V. All rights reserved.