Heat Resistant Organic Dyes for High Temperature Luminescent Temperature Sensing

Compliant and large-area high-temperature gradient sensing is essential for scientific and industrial applications but remains a big challenge. Although organic luminophores have intrinsic advantages of flexibility and solution processability, they generally suffer from significant emission quenching at high temperatures due to thermally facilitated nonradiative decay. Herein, a heat-resistant blue emitter of C3 based on triarylphosphine oxide has been developed, due to the thermal population of the higher emissive state from its lowest excited state. Based on this, hybridization of C3 with a faster thermally-deactivated yellow dye of T4AC which exhibits a large Stokes shift enables blocking of energy transfer and independent thermal response of the two respective emitters. Thus, sensitive ratiometric film thermometers for high-temperature sensing can be constructed. The relative sensitivity (S_r) reaches 1.27%°C⁻¹ at 128 °C and the temperature resolution is < 0.77 °C in a wide sensing range of 20–240°C. Moreover, naked-eye thermal mapping and multiple anti-counterfeiting of these ratiometric films have also been demonstrated.