All of the samples were synthesized by sol-gel methods.Two approaches to charge compensation,(i) 2Ca2+→yb3++M+,where M+ is an alkali ion like Li+,Na+ and K+,and (ii) indirect charge compensation:3Ca2+→2Yb3++vacancy,were studied in detail.It was found that charge compensation would be very beneficial for the growth of the grains,especially in Li+ ions added samples.All the grains were homogeneously spherical with less boundaries; in addition,a great variety of the absorption ability in different charge compensation samples were observed:in comparison with the phosphors without charge compensation,indirectly charge compensated and Li+ ions added phosphors showed much stronger absorption strength in the ultraviolet (UV) region whereas that of Na+ and K+ ions added samples was much weaker;moreover,measurements of the emission intensities showed that:in comparison with the phosphors without charge compensation,the visible emission intensity from MoO42- decreased a lot in indirectly charge compensated and Li+ ions added phosphors,whereas there was a remarkable increase of the near infrared (NIR) emission intensity from Yb3+ ions in the two types of samples under 266 nm excitation,implying more efficient energy transfer (ET) from MoO42-toYb3+ ions; at last,measurements and analysis of the decay curves of the visible 495 nm emission were carried out,and it was found that the energy transfer from MoO42- to Yb3+ ions were more efficient in the two above types of phosphors.The theoretical quantum cutting (QC) efficiency was also improved greatly.Overall,the addition ofLi+ ions would be very beneficial for the morphology of the powders in addition to the growth of the grains.It was advantageous to increase the downconversion (DC)quantum efficiency; however,indirect charge compensation would enhance the NIR emission intensity to the most for its strongest absorption ability in the UV region.