fields, and ability to work with high-speed moving objects. [6][7][8][9] A large variety of luminescent thermometers including metal salts, oxides and complexes, [10,11] metalorganic frameworks, [12,13] nanoclusters/ nanocrystals, [14] quantum dots (QDs), [15] organometallics, [16] organic dyes, [17][18][19] and polymers, [20] have already been developed. However, a large portion of the existing luminescent thermometry protocols are dependent on the emission intensity decreasing with the temperature increase as a result of the thermal activation of the nonradiative decay pathways. [12,14a,15,17,20a,21] Regretfully, thermometers developed on the basis of single-emission change are prone to suffering from errors caused by the probe concentration, the excitation, or detection efficiency. In contrast with single-emission-based luminescent thermometers, the ratiometric luminescent ones with change in the intensity ratio of two emission bands when interacting with analytes are more favorable. [6][7][8][9] It is because that ratiometric probing mode can eliminate the intensity fluctuations exerted by the quantity of luminophore, excitation power, detection efficiency, and the sample morphology, displaying a self-calibrating readout. [6-11b,13,18,19] It is therefore highly demanded to devise ratiometric temperaturesensing schemes.There are generally two common approaches for ratiometric sensing, one is referencing the signal of an indicator to that of a temperature-insensitive dye, and the other is taking advantage of probes with intrinsic dual emissions. In the former scenario, careful calibration and complicated preparation process are often required, due to the different physicochemical features between two or more luminogens. From a practical point of view, the latter strategy is even more attractive. In addition, although a few high-performance ratiometric luminescent thermometers have been reported, there still leaves a considerable large room for development: For example, 1) the ratiometric thermometers often involve lanthanides which are rare-earth elements and not readily available, and moreover the lanthanide coordination polymers are unstable in polar solvents, leading to the sensitizers replaced by the solvents; [8-11a,13a,b,c,18d] 2) the luminescence of metal-ligand complexes is usually quenchable by oxygen; [8,11c] 3) the already-developed ratiometric Achieving ratiometric thermometry with a single organic luminophore is a tempting but challenging task. Herein, three dihydrophenazine-based ratiometric thermometers, namely DPC, DPSi-1, and DPSi-2, are facilely developed via the novel vibration-induced emission (VIE) strategy. By elaborately introducing alkyl/siloxane chains to the dihydrophenazine core, these fluorophores exhibit as powder with low melting point or nonvolatile liquids, which emit temperature-sensitive dual emissions: predominantly blue fluorescence (FL) at low temperature and chiefly orange-red FL at high temperature. According to the VIE mechanism, high temperature activates the int...
