Comparative Investigation on Upconversion Luminescence Properties of Lu2O3:Er/Yb and Lu2O2S:Er/Yb Phosphors

A series of (Lu 0.99− x Er 0.01 Yb x ) 2 O 3 and (Lu 0.99− x Er 0.01 Yb x ) 2 O 2 S ( x = 0—0.1) phosphor particles are prepared to investigate their upconversion luminescence properties. Under 980 nm pumping laser, the two phosphors both exhibit strong green emission at ≈520—573 nm and weak red emission at ≈648—688 nm arising from 4 S 3/2 / 2 H 11/2 → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions of Er 3+ , respectively. The optimum concentrations of Yb 3+ sensitizers are found to be 1.0 at% in oxide and 0.5 at% in oxysulfide, and their corresponding CIE chromaticity coordinates are (0.29, 0.69) and (0.33, 0.65). The Lu 2 O 2 S:Er/Yb phosphor exhibits ≈42 times higher luminescence intensity than the Lu 2 O 3 :Er/Yb contrast. More Yb 3+ addition further increases the proportion of red emission by the cross‐relaxation between adjacent Yb 3+ and Er 3+ and the multiphonon relaxation. The luminescence intensities of the two phosphors gradually increase as the laser output power increases and the upconversion mechanisms are both identified to be two‐phonon processes. The Lu 2 O 2 S:Er/Yb phosphor has a shorter lifetime than the Lu 2 O 3 :Er/Yb counterpart, whereas the lifetime for the red emission is longer than that for the green emission in each case.