Multi-photon up-conversion enhancement from Gd2(MoO4)3:Er/Yb thin film via the use of sandwich structure

Lanthanide-doped up-converting nano-particles reveal significant promise for data storage, biological imaging, and temperature sensing, but have not been extensively used due to their low emission intensity. Here, we investigate the up-conversion emissions of Gd2(MoO4)3:Er/Yb thin films that are sandwiched by Gd2(MoO4)3:Yb thin films. Our results show that the sandwiched thin films possess significant enhancement of emission intensities. The enhancement factors of the green and red emissions, radiated from Gd2(MoO4)3:Er/Yb films, reach 9.5 and 5, respectively. Moreover, the ability of sandwich structured thin films in multi-photon up-conversion enhancement is more excellent than that of laser power, attributed to the suppression of undesired radiative/non-radiative recombination of the intermediate states. In addition, the intensity-based temperature absolutely sensitivity of sandwich structured Gd2(MoO4)3:Er3+/Yb3+ reaches 0.013 K−1 at 498 K, which indicate this sandwich structured thin films have larger potential in thermal sensors. This sandwich structure might extend the applications of Ln3+-doped materials in super-resolution imaging and temperature sensing.