Building a highly concentration responsive optical thermometer via tunable electron transfer pathways supported by...

The thermal-coupled levels (TCLs) of lanthanides have attracted great attention in the field of optical thermometer, offering an efficient method to achieve non-contect temperatuer feedback in complex environment. However, the iner 4f electrons are shielded, which becomes the core obstacle in improving the sensing performance. This issue is now circumvented by constructing an electron transfer pathway between Tm³⁺(¹D₂) and Eu³⁺(⁵D₀) configurations. As a result, the electron transfer barrier is related to the relative temperature sensitivity, giving an insight into the modulation mechanism. Compared to the conventional TCLs systems, the relative temperature sensitivity of this strategy is highly concentration-responsive, increasing from 5.56 to 10.1 % K^-1 as the Eu³⁺ molar concentration rises from 0.3 to 0.5 mol%. This work reveals the inner emission mechanism based on IVCT-supported emission mode, and presents the highly adjustability of sensing performance.