Energy Transfer in Mixed Lanthanides Complexes: Toward High‐Performance Pressure Sensors Based on the Luminescence Intensity Ratio

Abstract In this study, a reversible pressure‐sensing material with high sensitivity is presented. Mixed β‐diketonate complexes of Tb³⁺ and Eu³⁺ [(Ln)(acac)₃phen] are synthesized with phenanthroline as an ancillary ligand. The organic ligands provide the antenna effect to make the Ln³⁺ complex excitable at 405 nm. Eu³⁺ emission results from efficient energy transfer (ET) from Tb³⁺. Under 405 nm excitation, the emission intensity of Tb³⁺ decreases whereas the emission intensity of Eu³⁺ increases with pressure, making this complex a potential pressure sensor based on luminescent‐intensity‐ratio (LIR) up to 700 MPa. This study then discusses the application of this Tb³⁺/Eu³⁺ complex for pressure sensing depending on measurement conditions. The addition of the optically neutral ion Y³⁺ to the system can reduce the impact of pressure‐induced structural defects on the emission, thus improving the reversibility of the LIR variation as a function of pressure. Therefore, a self‐calibrating, reliable, and reversible pressure‐sensing material is proposed here, with remarkable pressure sensitivity compared to a peak shift‐based pressure sensor.