Synergistic regulation of fluorescence thermometer sensitivity based on LSPR effect and energy transfer

Fluorescence intensity ratio (FIR) thermometry is an ideal non-contact temperature measurement method with rapid response and high sensitivity. Improving sensitivity and stability is always the research hotspot in this field. Energy transfer between the emission centers plays a key role to improve temperature sensitivity. A new method based on synergistic regulation of local surface plasmon resonance (LSPR) effect and energy transfer is introduced in this paper. Tb (TMHD)₃/Eu(dbm)₃phen composite films are prepared by coating method. Silver buffer layers and gold nanorods are used to tune the emissions of Tb³⁺ and Eu³⁺. The energy transfer from Tb³⁺ to Eu³⁺ is present with 40 % energy transfer efficiency. Silver buffer layers have an overall enhancement effect on the emissions of Tb³⁺ and Eu³⁺, and gold nanorods have a preferential enhancement on the emissions of Eu³⁺. With the measurement temperature decreasing, the luminous intensity of the composited film is enhanced by silver layer, but there is no significant influence on the fluorescence intensity ratio. The film covered with Au nanorods presents the highest relative sensitivity of 1.8 % K^-1 and has the widest temperature range. This suggests that LSPR effect is an efficient method to tune the temperature sensing property and has potential application in highly sensitive optical thermometers.