Controlled Combination of Phosphorescent and Fluorescent Materials to Exploit Energy-Saving Potential in the Built Environment

As global warming accelerates at an alarming rate, there has been growing interest in passive radiative cooling solutions that can spontaneously cool objects without requiring energy consumption. This study investigates the emission performances of combined phosphorescent (P) and fluorescent (F) pigments for use as radiative cooling materials. Previous research has shown the potential of photoluminescence in reducing urban surface temperatures by reflecting and emitting incident solar radiation. P and F pigments were combined in different ratios to achieve a balance between brightness and persistency. The results indicatethat P pigments have higher luminance values but decay more rapidly, while specific ratios of P and F pigments provide reasonable luminance and longer afterglow. This study identifies the optimal "fluorescence-phosphorescence"combination for possible implementation of FP pigments in more complex materials for the built environment. These findings contribute to the development of effective radiative cooling solutions that can mitigate the impacts of global warming.