Three-Output Naked-Eye High Temperature Organic Film Threshold Thermometers Based on Non-Invasive Chemical Reaction

High-contrast and stably visualized ambient or luminescent color-switching can be achieved by thermal-induced non-invasive chemical reaction for naked-eye threshold temperature indication. The clear and visible output signal of these indicators arises from the large absorption/emission spectral changes upon heating. However, such chemical reactions are difficult to realize in solid-state, especially in the high-temperature region. Herein, a series of naked-eye high-temperature threshold film indicators have been developed based on the solid-state in situ thermal decomposition reaction of difluoroboron beta-diketonate derivative. These thermosensitive films feature three high-contrast visible outputs of ambient thermochromism, fluorescence color change, and luminescence ON/OFF switching, which can be easily detected with the naked eye. The PR-PS film of (E)-4-(2-(6-bromopyren-1-yl)vinyl)-2,2-difluoro-6-phenyl-2H-1 lambda(3),3,2 lambda(4)-dioxaborinine (PR) doped in polystyrene (PS) polymer matrix achieved high sensitivities related to change of ratiometric luminescence and fluorescence intensity up to 230%degrees C-1 and 1.85%degrees C-1, respectively. Furthermore, the polymer matrix with different glass transition temperatures enables programmable tuning of threshold temperature from 120 to 180 degrees C. These thermosensitive films show clear and high-contrast color changes and emission turn-off in real-time with consistent air stability, high photostability, and waterproofing property. This shows considerable potential in outdoor robust high-temperature threshold sensing and information storage.