Engineering a novel role for Yb3+ to overcome thermal quenching and improve photothermal conversion efficiency as well as temperature sensing performance

In this paper, two types of phosphors, Cs 3 GdGe 3 O 9 :Er 3+ and Cs 3 GdGe 3 O 9 :Yb 3+ /Er 3+ , were synthesized using the high-temperature solid-state method, and a new role for Yb 3+ was successfully achieved. The presence of low phonon energy in the matrix and the low energy level mismatch between the 2 F 5/2 and the 4 I 11/2 enables the construction of a phonon-assisted channel between Yb 3+ and Er 3+ through doping with Yb 3+ ions. This channel overcomes thermal quenching and achieves thermal enhancement at high temperatures. Additionally, Yb 3+ increases the chance of non-radiative transition within the matrix, effectively converting the 980 nm laser into heat energy. This leads to a significant change in the surface temperature of the sample, greatly improving the photothermal conversion efficiency. Moreover, Yb 3+ greatly enhances the emission intensity of green light, resulting in a maximum relative sensitivity of 1.11 % K −1 for temperature measurements in the Er 3+ single-doped system and 1.28 % K −1 in the Yb 3+ /Er 3+ co-doped system, based on the Er 3+ thermally coupled energy level. These results demonstrate that this paper provides a new idea for materials to overcome thermal quenching and improve the efficiency of photothermal conversion and temperature sensing performance.