Temperature is a key parameter for both scientific and technological communities. [1-5] In particular, real-time and in situ spatial thermo-detection in a large area is essential and highly required in modern and intelligence industries. [4,6-10] Many types of thermometers utilize various temperature-dependent physical properties to detect environmental and physiological temperatures, such as volume, potential, and conductivity. [4] These sensors based on thermocouples and thermal resistance are commonly used due to their reliable performance and relatively low manufacturing costs; however, these traditional thermometers have difficulty in achieving large-area spatial temperature measurements, except when using costexpensive and complicated element array techniques. [11] Infrared thermometers based on blackbody radiation are easy to handle with thermal imaging but have the drawbacks of low spatial resolution, high noise, low image contrast, blurred visual effect, and a narrow grayscale. In recent years, luminescent thermometry has become increasingly appealing due to its non-invasive detection, fast response, high sensitivity, high spatial resolution, resistance to electrical/magnetic fields, and the ability to work with fast moving objects. [12-15] Luminescent thermometers are generally operated utilizing temperature-dependent photophysical parameters, such as emission lifetime, [16] emission intensity, [4] peak position, [17] and ratiometric emission intensities. [18] Among them, ratiometric thermometry, which is based on the temperature-dependent intensity ratios of two separate transitions, presents a more reliable and accurate measurement due to its self-referencing characteristics, i.e., independence on luminophore concentration, fluctuation of excitation source or detector, and luminescence background. [19,20] More importantly, this method is cost-effective and does not require expensive instruments as lifetime measurements. To date, most high-performance ratiometric luminescent thermometers applicable to wide-range and high-temperature sensing are generally based on inorganic metal-contained complexes, clusters, coordination polymers, and metal-organic frameworks. [18,21-24] However, these inorganic metal-based Large-area thin-film thermometers for high-temperature and wide-range gradient thermosensing and thermomapping are difficult to realize, although they are crucial for scientific and industrial applications. Most luminophores encounter significant emission quenching at heating, and among them, inorganic metal-based materials have difficulty forming uniform and large-areacompliant films. Herein, a series of heat-resistant blue luminophores based on carbazolyl-pyrene-substituted triarylphosphine oxides is developed. At a high temperature of 260 °C, their films still maintain high brightness (up to 79% of the original luminous intensity at-196 °C) due to the thermo-populating of the bright high-lying excited states. By hybridizing with a thermosensitive yellow chromophore presenting both excited state ...