Rare earths are used in many areas of Chinese photovoltaics. According to reports, research on rare-earth luminescent materials for LEDs has progressed, and phosphors will become a new generation of lighting sources. How about specific conditions?
LED solid-state lighting devices have the advantages of high efficiency, energy saving, and environmental protection. After more than ten years of development, they have basically replaced traditional incandescent and fluorescent lamps and become a new generation of lighting sources. The phosphor has a wavelength conversion function and plays an important role in determining the white light performance of the LED, such as color rendering index, color temperature, and efficiency. It is one of the key materials for the LED lighting device. The phosphor with high research and development efficiency and good thermal stability has been It is the goal pursued by people.
The optoelectronic functional materials and device team of the Institute of Advanced Manufacturing Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, developed a new type of Ba9Lu2Si6O24: Ce3+ silicate blue phosphor; its fluorescence quantum efficiency can be maintained at room temperature at 160°C. 94%, showing good thermal stability. The study was awarded a national invention patent and the relevant results were published on Advanced Optical Materials.
Based on the Ba9Lu2Si6O24 material, the team used a Tb3+-Tb3+ quantum trimming and resonance energy transfer effect to obtain a green phosphor with a luminous efficiency of up to 144%. The visible light quantum trimming was achieved. The anomalous red emission of Eu2+ was observed for the first time. Spectral means traced back to the source of red light; on this basis, a single white light was obtained by co-doping of Ce3+/Eu2+/Mn2+. Obtained one of the national invention patents and related basic research results are published in The Journal of Physical Chemistry C, Materials Research Bulletin.
Recently, the team conducted a systematic study on the luminescent properties of Ba9Lu2Si6O24-based cyan phosphors through a combination of theory and experiments. Through the optimization of the process, the internal quantum efficiency of fluorescence is improved to 90%, and the decay of light within 1600 hours at 85°C/85%RH is less than 10%. Only the cyan fluorescent powder and the red powder are compounded, and white light having a color rendering index of 90 or more can be obtained on the NUV chip. Based on the calculation and understanding of the first-principles electronic structure of Ba9Lu2Si6O24, combined with the experimental characterization of spectroscopy, the team proposed a method to calculate the bandgap of the substrate of a wide band gap inorganic non-metallic material, and revealed the thermal stability mechanism of the material's luminescence, except The interaction between heat and phonons can cause luminescence quenching, and the decrease in absorption rate due to heat is another cause of thermal quenching of luminescent materials. The relevant results were published in the Journal of Materials Chemistry C.
In addition, the team raised the steady-state fluorescence quantum efficiency of Gd3Al2Ga3O12:Ce3+ yellow afterglow phosphors to 82%, which provides a potentially valuable rare earth luminescent material for solving the problem of AC LED strobe. The related content has applied for 2 national invention patents, and some research results have been published on Chemical Communications.
The research work was supported by the National Natural Science Foundation of China, the Zhejiang Provincial Philanthropy Technology Fund and the Ningbo Natural Science Foundation.