image: Timeline of major breakthroughs in the history of the development of luminescence thermometry.
Credit: ©Science China Press
Temperature is a fundamental thermodynamic variable, and its accurate measurement is essential in contexts ranging from cellular metabolism and chemical reactions to the operation of microelectronic devices. Although conventional contact sensors offer high accuracy, they face limitations in applications requiring remote readout or high spatial resolution, as well as in corrosive or biologically sensitive environments and in the presence of electromagnetic noise. Luminescence thermometry uses temperature-dependent changes in emission intensity, luminescence lifetime, peak position, bandwidth or intensity ratios to determine temperature, offering an important route to noncontact and minimally invasive temperature sensing. With their sharp emission lines, microsecond-to-millisecond luminescence lifetimes, high photostability and thermally coupled energy levels (TCLs), trivalent lanthanide ions (Ln³⁺) enable self-referenced ratiometric readout and provide an ideal platform for luminescence thermometry.
A recent review published in Science China Materials, entitled “Lanthanide-based luminescence thermometry: from fundamentals and materials to applications”, systematically summarizes advances in the field, spanning fundamental photophysics, material design and emerging applications.
The fundamentals section describes the electronic structure and energy-level splitting of Ln³⁺ ions, together with upconversion and downshifting luminescence processes. Thermometric mechanisms are systematically classified into TCL-based Boltzmann ratiometric methods, non-TCL strategies, lifetime-based methods and hybrid approaches. The article also establishes standardized performance metrics, including relative sensitivity, temperature uncertainty, spatial and temporal resolution, repeatability and reproducibility, providing an objective basis for comparing different materials and approaches.
The materials section covers six major classes: Ln³⁺-doped inorganic phosphors, upconversion nanoparticles, near-infrared-emitting nanoparticles, lanthanide metal-organic frameworks (Ln-MOFs) and coordination polymers, molecular Ln³⁺ complexes, and composite or hybrid materials. Particular attention is given to anti-thermal-quenching (ATQ) strategies, including defect and trap engineering, lattice rigidity modulation and energy-transfer engineering. The review highlights the field’s shift from evaluating relative sensitivity alone to assessing multiple performance metrics, alongside the increasing integration of emerging platforms such as metal-organic frameworks and hybrid composites.
The applications section highlights the broad prospects for lanthanide-based luminescence thermometry in single-cell metabolic imaging, in vivo temperature imaging, thermal management in microelectronics, chip temperature monitoring, combustion and turbine cooling, hypersonic aerothermal protection, internal battery temperature measurement, remote monitoring, smart textiles and anti-counterfeiting for information security.
The review further examines key challenges, including thermal quenching, quantum efficiency bottlenecks, and insufficient repeatability and reproducibility. It also outlines future directions, including the development of ATQ materials, joint optimization of multiple performance parameters, standardized characterization tailored to specific applications, and artificial intelligence-assisted data analysis. Together, these discussions provide a timely and systematic reference for the design, characterization and deployment of next-generation lanthanide-based luminescent thermometers.