Visualization of icing of supercooled water using Tb(III)-based temperature-sensitive paint

•temperature-sensitive paint composed of Tb(hfa)3(tppo)2 and silicon grease/n-heaxne medium was prepared.•The photophysical properties of Tb(hfa)3(tppo)2-based TSP were characterized by spectroscopy.•The high-speed imaging experiments revealed the water/ice phase change of a supercooled water droplet accompanied by latent-heat release. Visualization of icing processes of supercooled water is reported. Tb(hfa)3(tppo)2 composed of a Tb(III) ion, triphenylphosphine oxide (tppo), and hexafluoroacetylacetonato (hfa) ligands was coated on an aluminum surface using silicon grease/n-hexane medium for temperature-sensitive luminescent paint. The prepared Tb(III)-based sensor was characterized by temperature-dependent emission spectral measurements. The icing processes of a supercooled water droplet were observed using a high-speed camera. The time-dependent images clearly showed the water/ice phase change from an original point of physical stimulation to entire droplet. The emission intensity decrease was responsible for the heat-assisted back energy transfer from Tb(III) ions to hfa ligands due to the latent-heat release during the icing processes.