Up-conversion luminescence enhancement and tunable emission color of Y₂O₃: Tm/Yb@Y₂O₃: Yb@Y₂O₃: Er/Yb multilayer thin films

The Y₂O₃: Tm/Yb, Y₂O₃: Tm/Yb@Y₂O₃: Yb and Y₂O₃: Tm/Yb@Y₂O₃: Yb@Y₂O₃: Er/Yb thin films are successfully prepared via spin-coating method. The surface grain size of the thin films is changed by multiple calcinations. The up-conversion luminescence emission of the thin films under 980 nm excitation is improved through two methods, including the increase of surface grain size and the structure of Y₂O₃: Tm/Yb@Y₂O₃: Yb bilayer. When the emission intensity of the Y₂O₃: Tm/Yb@Y₂O₃: Yb thin films are maximized by adjusting the Yb³⁺ concentration of the coating layer, the bilayer thin film continually undergoes multiple calcinations, thus further increasing the enhancement effect of each band emission. Besides, the Y₂O₃: Tm/Yb@Y₂O₃: Yb@Y₂O₃: Er/Yb multilayer thin films are designed to realize the modulation of up-conversion emission color, meaning that its luminescence emission color can change from blue to white and finally to orange by adjusting the thickness of the top Y₂O₃: Er/Yb luminescence layer and the number of calcination. With the capabilities of up-conversion emission enhancement and multicolor luminescence modulation, this multilayer thin film can promote the application of rare earth doped materials in the fields of fluorescence detection and color displaying.