A novel promising red phosphor Ca9LiBi0.667(PO4)7:Eu3+ with excellent responsiveness to phytochrome PFR for the indoor plant cultivation

Abstract

A new red luminescent material Ca9LiBi2/3(PO4)7:Eu3+ (CLBPO:Eu3+) was synthesized by high temperature solid state reaction, and characterized by X-ray powder diffraction (XRD), field emission scanning electric microscopy (FESEM) and fluorescence spectroscopy. The XRD patterns indicated that CLBPO:Eu3+ phosphor has been successfully synthesized. The photoluminescence excitation (PLE) spectra and emission (PL) spectra of phosphor, as well as the relationship between PL intensity and concentration were discussed. The results exhibit that the PL peak of CLBPO:Eu3+ phosphor is mainly centered at 616 nm under 395 nm excitation, which is attributed to 5D0→7F2 transition of Eu3+ ions. In addition, the 5D0 → 7F4 transition around 700 nm belongs to the far-red emission, which matches well with the far-red absorption wavelength required for plant photosensitive pigments PFR. Moreover, when the doping concentration of Eu3+ is 80 mol%, the PL intensity of phosphor reaches the maximum. The calculated International Commission on Illumination (CIE) coordinates lie in the red region and the color purity of CLBPO:0.8Eu3+ is determined to be 99.76%. The correlated color temperature (CCT) value of CLBPO:Eu3+ is less than 3500 K, belonging to warm red light. In view of the aforementioned interesting luminescent properties, the prepared phosphor possesses high application potential in the fabrication of phosphor-converted white light emitting diodes (WLED), and plant growth lighting.