Novel Double Light‐Color (Blue and Red) Phosphor Sr9Ca(Li, Na, K)(PO4)7:Eu2+ Excited By NUV Light for Outdoor Plant Cultivation

Abstract Through the conventional high‐temperature state reaction, a series of Sr 9 Ca(Li, Na, K)(PO 4 ) 7 :Eu 2+ phosphors are successfully synthesized. The luminescence of these phosphors can be bifurcated into two distinct regions: blue and red. Upon calculation of their Stokes shifts and comparison of their magnitudes, it is inferred that the blue and red emissions are triggered by the integration of Eu 2+ into the Ca 2+ and Sr 2+ sites, respectively. The disorder of Sr 9 Ca 1.5 (PO 4 ) 7 phosphors in which Ca 2+ is substituted by Li + , Na + , and K + ions is confirmed by Raman spectroscopy. Among the synthesized phosphors, Sr 9 CaNa(PO 4 ) 7 :0.03Eu 2+ demonstrates an emission that aligns with the spectral range required for plant growth, suggesting its potential application in plant cultivation. An exploration is carried out to assess the impact of a light‐conversion film, which is fabricated by embedding the phosphor within the PDMS matrix. The study focuses on Chlorella, a unicellular algal species, to determine the enhancement in growth rates attributable to the light‐conversion properties of the film. Chlorella cultures subject to placement of a film containing 5% phosphor exhibited a 9.21% improvement in growth over those placed on a whiteboard, and a 27.69% increase relative to the control group. These results suggest that the light‐conversion film substantially benefits the proliferation of Chlorella.