In this paper, we report the thermal-enhanced near-infrared upconversion luminescence (UCL) from thermal-coupled (TC) energy levels of Er³⁺ and a new optical temperature sensing strategy in Er³⁺-doped phosphors. The near-infrared UCL of Er³⁺ in the wavelength range of 750–900 nm due to the transitions from the ²H_11/2 and ⁴S_3/2 TC energy levels to the ⁴I_13/2 metastable energy level showed a thermally enhanced luminescence behavior at elevated temperatures that is related to the enhanced temperature-dependent non-radiative relaxation. The luminescence intensity ratio (LIR) between the near-infrared (²H_11/2/⁴S_3/2 → ⁴I_13/2) and the green (²H_11/2/⁴S_3/2 → ⁴I_15/2) UCL of Er³⁺ was studied as a function of temperature and demonstrated good optical thermometry behavior based on the classic Boltzmann distribution. The absolute sensitivity based on the LIR between near-infrared and green UCL of Er³⁺ was as high as 0.061 K⁻¹, showing a nearly two orders of magnitude improvement compared to that based on the traditional LIR between two green UCL of Er³⁺. It is anticipated that the near-infrared UCL from TC energy levels of Er³⁺ can be used to construct new luminescent thermometry devices with high sensitivity, low temperature uncertainty, and good repeatability.

在本文中，我们从Er ^3+的热耦合（TC）能级报告了热增强的近红外上转换发光（UCL），以及掺Er ^3+的磷光体中的新光学温度传感策略。由于从² H _11/2和⁴ S _3/2  TC能级到⁴ I _13/2亚稳能级的跃迁，Er ³⁺在750-900 nm波长范围内的近红外UCL显示出在高温下热增强的发光行为，这与增强的依赖于温度的非辐射弛豫有关。近红外（² ħ _11/2 / ⁴ š _3/2  →  ⁴我_13/2）和绿色（² ħ _11/2 / ⁴ š _3/2  →  ⁴我_15/2）铒的UCL ³⁺进行了研究作为函数并根据经典的玻尔兹曼分布证明了良好的光学测温行为。尔的近红外和绿色之间UCL基础上，LIR绝对灵敏度³⁺高达0.061ķ ^-1，显示了近两个数量级的提高相比，基于尔的两个绿色UCL之间的传统LIR ^{3 +}。可以预期，Er ^3+的TC能级产生的近红外UCL可用于构建具有高灵敏度，低温不确定性和良好重复性的新型发光测温装置。