Na5Y(MoO4)4: Sm3+ red phosphor with good thermal stability and high color rendering index for plant growth lighting and white light emitting diodes

Abstract

To enhance the luminous efficiency of white LEDs and further advance the application of artificial light in controlling plant growth, it is imperative to develop a red phosphor with high luminescence intensity and excellent thermal stability. Our research team has successfully synthesized a Sm3+-activated, high-temperature-resistant Na5Y(MoO4)4 red phosphor through the solid-phase method. Utilizing X-ray diffraction and X-ray photoelectron spectroscopy, we confirmed the successful doping of Sm3+ ions into the Na5Y(MoO4)4 matrix. The synthesized phosphors demonstrate a robust red emission at 645 nm, characterized by an optimal doping concentration of 0.06 and a quantum efficiency of 38.14%. Remarkably, the emission peak intensity and integral area of the sample at 423 K retain 83.24% of their value at room temperature, showcasing exceptional thermal stability. The potential of the prepared phosphors in solid-state lighting and in promoting plant growth was confirmed by encapsulating them within LED devices. The emission spectrum of the encapsulated red LED closely aligns with the absorption spectra of plant chlorophyll a/b and the photosensitive pigment PR, indicating its suitability for enhancing photosynthesis. Additionally, the encapsulated white LED emits a brilliant white light, achieving a high color rendering index with values of Ra (91.7) and R9 (40), significantly outperforming the commercial phosphor standards of 80 (Ra) and 15 (R9). The test results demonstrate the synthesized red phosphor has a promising application in white LED illumination and plant growth enhancement.