Engineering of Mixed Eu<sup>3+</sup>/Tb<sup>3+</sup> Metal‐Organic Frameworks Luminescent Thermometers with Tunable Sensitivity
Virgile Trannoy, Albano N. Carneiro Neto, Carlos D. S. Brites, Luís D. Carlos, Hélène Serier‐Brault
Abstract
Abstract In the last decade, numerous Ln‐bearing metal‐organic frameworks (MOFs) have been reported for luminescence thermometry applications. Although the Ln 3+ composition is always thoroughly determined, this parameter is never optimized to improve thermometric performances. Here, the optimization of thermometric performances of luminescent probes is tackled by reporting a series of mixed Eu 3+ –Tb 3+ metal‐organic frameworks. The thermometric performances are accessed as a function of the Eu 3+ content yielding a maximum relative sensitivity between 0.19 and 0.44% K −1 registered at temperatures between 340 and 240 K, respectively. A meticulous theoretical investigation of the Tb 3+ ‐to‐Eu 3+ energy transfer in the series of mixed Eu 3+ –Tb 3+ MOFs is also performed to determine the predominant pathway of the energy transfer. For the first time, a clear evidence of the significant influence of the Eu/Tb ratio on the energy transfer between Ln 3+ emitting centers is presented that definitively determines the operating temperature range and the maximum relative sensitivity of the luminescent thermal probes.