The LSPR regulation of TiO 2 : W nanocrystals and its application in enhanced upconversion luminescence

The localized surface plasmon resonance (LSPR) absorption peaks of semiconductor nanocrystals are mainly concentrated in the infrared band, and the absorption characteristics can be controlled by the amount of element doping. The coupling of upconversion nanocrystals (UCNPs) and semiconductor nanocrystals can improve the upconversion luminescence (UCL) of rare-earth ions. Here, the LSPR absorption and morphology of the semiconductor nanocrystalline TiO 2 : W were adjusted by using ammonium fluoride during synthesis. Significant absorption enhancement of TiO 2 : W in the near-infrared region was obtained to enhance the UCL of NaYF 4 : Yb 3+, Er 3+. The Glass/NaYF 4 : Yb 3+, Er 3+ /TiO 2 : W@SiO 2 layered structure films were fabricated through spin coating. Compared with Glass/NaYF 4 : Yb 3+, Er 3+, the green and red lights of the Glass/NaYF 4 : Yb 3+, Er 3+ /TiO 2 : W@SiO 2 films were enhanced by 15.9 and 17.8 times, respectively. The UCL enhancement of Glass/NaYF 4 : Yb 3+, Er 3+ /TiO 2 : W@SiO 2 was derived from the LSPR property of TiO 2 : W through the enhancement of the excitation. The present work is important for possible applications of these layered structures as biomarkers, photocatalysts, flexible materials, and photoluminescence display panels.