LAUSR

Mixed lanthanide metal–organic framework (LnMOF) films are directly grown on a quartz substrate through a wet chemical synthesis. Thermometric properties of the LnMOF films originating from temperature dependent emission intensity ratio of Tb/Eu are systematically investigated in the 298–383 K range. At an optimized Tb/Eu concentration ratio of 98.0:2.0, the ratiometric thermometer registers a high relative sensitivity of 16.14% K−1 at 359 K. As the temperature increases from 298 to 383 K, the LnMOF film thermometer also displays a distinct change in emission color from green to red, corresponding to a shift in Commission International de l'Eclairage (CIE) chromaticity coordinates from (0.3882, 0.5271) to (0.5459, 0.4037). The colorimetric property of the LnMOF film thermometer is exploited for real‐time temperature mapping with a high sensitivity.