NaLaMgWO:Mn/Pr/Bi bifunctional phosphors for optical thermometer and plant growth illumination matching phytochrome P and P.

Phytochromes P and P distributed in different organs of plant can effectively absorb red and far-red light, respectively. Therefore, plant growth can be controlled by changing the ratio of red light to far-red light. The emission of Pr (transition from P→F) and Mn(transition from E→A) is located at the red and far-red range which matches with the absorption band of P and P, respectively. Herein, NaLaMgWO:Mn/Pr/Bi phosphors with improving luminescence properties via Bi doping have been successfully prepared by the sol-gel method. With the variation of temperature, the photoluminescence (PL) of Pr/Mn (corresponding to P/P) of titled phosphors can be tuned, which is very useful for controlling the plant growth. Moreover, based on the fluorescence intensity ratios (FIR) of the two activator Mn and Pr, the maximum relative sensitivity was approximately 3.39%/K at 298 K. All the results indicated that the titled phosphor is a bifunctional material for plant growth illumination with high matching phytochrome (P and P) and temperature sensing with high sensitivity.