Efficient green up-conversion emission in Yb3+/Ho3+ co-doped CaIn2O4

(a) UCL spectra of CaIn2O4: 0.005Ho3+, 0.1Yb3+ prepared by sol-gel process and solid state method. Insets show the CIE chromaticity coordinates with the UCL photograph of CaIn2O4: 0.005Ho3+, 0.1Yb3+ dispersed in ethanol under 980 nm excitation and the enlarged red emission band at 650 nm, respectively; (b) the temporal evolution of the green emission at 542 nm under 980 nm pulsed laser excitation and (c) UC energy efficiency of CaIn2O4: 0.005Ho3+, 0.1Yb3+ phosphors under different excitation power.