Near infrared to blue upconverting Tm3+/Yb3+/Li+:Gd2(MoO4)3 phosphors for light emitting display devices

Tm3+-Yb3+/Tm3+-Yb3+-Li+ codoped/tridoped Gd-2(MoO4)(3) phosphors using chemical co-precipitation method have been synthesized and characterised by XRD, FTIR, diffuse reflectance spectra and FE-SEM analysis. The downconversion emission spectra recorded by using 390 nm radiation shows blue colour emission band due to the (1)G(4) -> H-3(6) transition of Tm3+ ion. Frequency upconversion emission study show overall intense blue, red and NIR upconversion emission bands due to the (1)G(4) -> H-3(6), (1)G(4) -> F-3(4) and H-3(4) -> H-3(6) transitions of Tm3+ ion under 980 nm laser diode excitation. The effect of incorporation of Li+ ions in the codoped phosphors produces small shifting in the XRD peaks towards the higher diffraction angle side and also intensity of the blue upconversion emission bands is enhanced around similar to 510 times in the Tm3+-Yb3+-Li+:Gd-2(MoO4)(3) phosphors as compared to the Tm3+ doped phosphors. The confirmation of overall blue colour emission has been identified by colour co-ordinate analysis. The result shows that the developed tri-doped phosphors show improved blue colour emission and hence could be a proper material for near infrared to blue upconverter and blue colour emitting device fabrications. (C) 2017 Elsevier B.V. All rights reserved.