High-sensitive temperature sensing based on thermal-enhanced emission and non-thermally coupled energy levels of white upconversion luminescence system.

NaY(VO):Nd,Yb,Ho,Tm phosphors present significantly improved sensitivity of optical temperature sensing based on thermal-enhanced upconversion luminescence and non-thermally coupled energy levels. Under 808 nm excitation, white upconversion luminescence is successfully achieved in Nd-sensitized system. In addition, the emissions intensities originated from G→I transition of Nd and F→H transition of Tm gradually increase with elevating temperature owning to the thermal population effects, as opposed to the blue (G→H transition of Tm), green (S,F→I transition of Ho) and red (F→I transition of Ho) emissions intensities show continuous decreasing trend. The temperature sensing behaviors are investigated by employing multiple non-thermally coupled energy levels. Based on non-thermally coupled energy levels of G (Nd)/G (Tm), the absolute and relative sensitivities are obtained to be 0.433 K and 2.81 % K. These results demonstrate that the NaY(VO):Nd,Yb,Ho,Tm phosphors with superior optical thermometry performance and white luminescence within a relatively wide temperature range can achieve optical applications in many fields.