Latest Trends in Temperature Sensing by Molecular Probes

Abstract In this Review, we summarize the work in the last ten years on the development of fluorescent molecular probes with possible applications in microscopic thermometry. We discuss four principal types of temperature‐dependent photoluminescence features: 1) Emission intensity; 2) Ratio of emission intensities; 3) Emission peak shift; and 4) Emission lifetime. We compare the advantages, limitations, and challenges of the different probes using these types of sensing mechanisms. By focusing on molecular probes, rather than nanoparticles or polymers, the mechanisms of temperature dependence are discussed thoroughly, with the most common including twisted intramolecular charge transfer (TICT), aggregation‐induced emission (AIE), and mechanically induced change in emission (MICE). With many different confounding variables associated with each experimental method and mechanism of temperature‐dependent photoluminescence, lanthanide and transition metal complexes seem to be promising candidates for future microscopic thermometry applications.