Effect of Zn2+ and Li+ ions doped on microstructure and upconversion luminescence of Y2O3: Er3+-Yb3+ thin films

The Y2O3 up-conversion luminescent films were prepared with sol-gel and spin coating. The effects of Li+ doping, Zn2+ doping and Li+-Zn2+ co-doping on the structure and upconversion luminescence property of the samples were investigated. The results show that the doping improved the film's crystallinity, and the effect of co-doping was better than that of single doping. Pumped with 980-nm laser, there were three emission bands in the up-conversion spectrum of each sample, 553-nm and 563-nm green lights, and 683-nm red light, corresponding to Er3+: (H11/2I15/2)-H-2-I-4, S-4(3/2) -> I-4(15/2), F-4(9/2) -> (4)I(15/2 )transitions, respectively. Although the ion concentration of the single-doped Li+ (3.0 mol%) or the singledoped Zn2+ (3.0 mol%) was the same as that of the Li+-Zn(2+ )co-doped (1.5 mol%+1.5 mol%), the 563-nm green light emission intensities of the three doped films were about 3.2, 6.4 and 18 times of that of the undoped, respectively. The doped Li+ or Zn2+ ions further broken the symmetry of the Y2O3 crystal field, restrained the fluorescence quenching, and increased the fluorescence lifetime, therefore improved greatly the luminescence intensity. When Li+ and Zn2+ ions were co-doped, their charge compensation effect further improved the fluorescence lifetime and the luminescence intensity. (C) 2019 Elsevier B.V. All rights reserved.