Tm3+/Yb3+-codoped LuPO4 phosphors were synthesized by the reverse-like co-precipitation method [1].The obtained LuPO4∶Tm3+,Yb3+ phosphors were characterized by X-ray diffraction(XRD),diffuse reflectance and photoluminescence(PL)spectra and decay lifetime measurements to understand the observed near-infrared(NIR)downconversion(DC)phenomena.The XRD results show that all the prepared phosphors can be readily indexed to pure tetragonal phase of LuPO4 and exhibit good crystallinity.The spectral results show that there are the strong visible emission around 649 nm from Tm3+(1G4→3F4)and NIR emission around 1003 nm from Yb3+(2F5/2→2F7/2)of LuPO4∶Tm3+,Yb3+ phosphors under 468nm excitation,respectively.The Yb3+ concentration dependence of the luminescent characters and decay lifetimes of both the visible and NIR emission bands has been investigated.The quenching concentration of Yb3+ ions approaches as high as 30mol%.The DC mechanism was discussed in detail by building up the energy level structures of both two optical centers Yb3+ and Tm3+,as shown in Fig.1.In conclusion,the LuPO4∶Tm3+,Yb3+ phosphors can be suggested as an excellent candidate for NIR DC layers to improve the energy efficiency of solar cells.