title: CaMoO4:x%Yb3+: a novel near-infrared quantum-cutting phosphors via cooperative energy transfer.
abstract: An efficient near-infrared (NIR) dowmconversion (DC) has been demonstrated in the CaMoO4:Yb3+ phosphors. Very strong NIR emission around 998 nm from the 2F(7/2) --> 2F(5/2) transition of the Yb3+ has been observed under ultraviolet excitation. A similar broad excitation band due to the absorption of the host CaMoO4 has been recorded when the NIR emission of Yb3+ and the visible molybdate (MoO4(-2)) emission are monitored, which suggests an efficient energy transfer (ET) from the host to the Yb3+. The Yb3+ concentration-dependent luminescence properties and lifetimes of both the visible and NIR emissions have also been studied. The lifetime of the molybdate emission decreases rapidly with the increasing Yb3+ concentration, further verifying the efficient ET from the host to the Yb3+. Moreover, the low temperature measurements have also been carried out to investigate the ET mechanism in the phosphors. A cooperative energy transfer (CET) mechanism has been proposed to rationalize the DC effect. The newly studied CaMoO4:Yb3+ DC phosphors, which can convert the broadband emission of the MoO4(2-) into NIR emission of Yb3+ with a twofold increase in the photon number will have potential application in greatly enhancing the response of silicon-based solar cells with a relatively higher Yb3+ quenching concentration.
authors.affiliation: Department of Physics, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Cao
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Xiantao
authors.initials: X
authors.lastname: Wei
authors.forename: Yonghu
authors.initials: Y
authors.lastname: Chen
authors.forename: Weiping
authors.initials: W
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Yin