Composition-Modulated Strontium Aluminate Phosphors with Continuously Tunable Visible Emission for Advanced Display, Thermometry and Photothermal Conversion

This study demonstrates a single phosphor material system capable of continuously tuning color across the entire visible spectrum while integrating multiple luminescent functionalities. A series of these phosphors was conveniently synthesized with varying Al/Sr ratios in the reactants, enabling the emission color to progress through red, orange, yellow, green and blue. We systematically investigated the photoluminescence mechanisms by correlating crystal phase evolution with europium ion site occupancy and exploiting the resulting multicolor-emitting phosphors in optical display and anti-counterfeiting demonstrations. The relationships between composition, structure, and luminescence were revealed commendably, alongside more functional evaluations of europium-doped strontium aluminate phosphors. Notably, at an equimolar Al/Sr ratio of 1 (with 2 at% Eu doping), the phosphor achieves a high absolute quantum yield of 66.2% and functions as a luminescent optical thermometer with a relative sensitivity of 0.27% K−1 and temperature resolution of ~0.005 K. At a non-equimolar Al/Sr ratio of 2, the Eu-doped phosphor exhibits efficient photothermal conversion, reaching ~72.8 °C under 980 nm laser irradiation (1 W·cm−2) within 10 s. This work introduces a facile composition-regulation strategy for designing multicolor-tunable, multifunctional phosphors, highlighting promising applications in optical displays, anti-counterfeiting, luminescence thermometry and photothermal conversion.