One-Step Design of a Water-Resistant Green-to-Red Phosphor for Horticultural Sunlight Conversion

As a universal sunlight-conversion agent for agricultural shed films, the green-to-red phosphor CaS:Eu2+ suffers greatly from its poor moisture resistance. Unlike the conventional surface modifications upon application of postprocessing, this work proposes a one-step, two-additive strategy for synthesizing the CaS:Eu2+,CaBr2,CaF2 composite phosphor. For the first time, we realize remarkable improvements in both the chemical stability and the luminescence intensity of a CaS:Eu2+-based material synchronously. The dual halide-modified composite phosphor maintains a stable phase composition against moist air and water immersion. The red emission of the as-obtained CaS:Eu2+,CaBr2,CaF2 phosphor becomes 3 times as intense as that of nonmodified CaS:Eu2+. Moreover, the polymer film fabricated with the modified phosphor presents good weather resistance and brilliant light-conversion performance. Therefore, this one-step method gives the CaS:Eu2+,CaBr2,CaF2 phosphor a great advantage as a long life light-conversion material for agricultural shed films.