Wu Di, Li Yan, Liao Yu, Pan Xixiang, Liu Songbin, Zou Wanfang, Peng Jiaqing, Ye Xinyu
Faculty of Materials Metallurgy and Chemistry, Collage of Rare earth, Jiangxi University of Science and Technology, Ganzhou 341000, P.R. China.
School of Materials Science and Engineering, Peking University, Beijing 100083, P.R. China.
Dalton Trans. 2023 Sep 13;52(35):12526-12533. doi: 10.1039/d3dt01996a.
Sunlight-like full-spectrum phosphor-converted light-emitting diodes (pc-LEDs) require near-infrared (NIR) emission bands to fill the spectrum gap and consequently propel their widespread applications. Although fluoride NIR phosphors have been increasingly investigated, balancing high quantum efficiency (QE), high thermal stability, and wideband NIR emission to obtain excellent overall performance in a single system is still a challenge for Cr-doped fluoride NIR phosphor and is significant for direct utilization. Herein, a high-efficiency and thermally stable broadband NIR emission was realized in a novel LiSrGaF:Cr fluoride phosphor benefitting from a relatively weak crystal field and electron-phonon coupling effect. Upon blue light excitation, the ultra-broad NIR luminescence ranging from 650 to 1150 nm can be achieved with an FWHM of 149 nm peaking at ∼813 nm. Furthermore, this system possesses a high QE of up to 76.88% and its emission intensity at 423 K still maintains 61.62% of its initial intensity at room temperature. An NIR output power of 42.82 mW and photoelectric conversion efficiency of 14.27% of NIR pc-LED devices have also been presented based on this NIR phosphor, demonstrating its possible application in compact nonvisible light sources. In addition, a highly continuous sunlight-like vis-NIR pc-LED was further constructed by employing a blue chip with commercial cyan (BaSiON:Eu), yellow (YAlO:Ce), red (CaAlSiN:Eu), and this LiSrGaF:Cr NIR phosphor. The as-obtained pc-LED exhibits an ultra-broad spectrum ranging from 400 nm to 1000 nm, exhibiting a higher color reproduction with a color rendering index (CRI) of 95.1 and luminous efficiency (LE) of 50.22 lm W. These results indicate that LiSrGaF:Cr phosphor can be a promising NIR phosphor candidate for high-quality sunlight-like full-spectrum lighting and infrared night vision technology.
类太阳光全光谱荧光粉转换发光二极管（pc-LED）需要近红外（NIR）发射带来填补光谱间隙，从而推动其广泛应用。尽管氟化物近红外荧光粉已得到越来越多的研究，但在单一体系中平衡高量子效率（QE）、高热稳定性和宽带近红外发射以获得优异的整体性能，对于掺铬氟化物近红外荧光粉来说仍是一项挑战，且对于直接应用具有重要意义。在此，通过一种新型的LiSrGaF:Cr氟化物荧光粉实现了高效且热稳定的宽带近红外发射，这得益于相对较弱的晶体场和电子 - 声子耦合效应。在蓝光激发下，可实现650至1150 nm的超宽带近红外发光，半高宽为149 nm，峰值位于约813 nm处。此外，该体系具有高达76.88%的高量子效率，其在423 K时的发射强度仍保持室温下初始强度的61.62%。基于这种近红外荧光粉，还展示了近红外pc-LED器件的42.82 mW近红外输出功率和14.27%的光电转换效率，证明了其在紧凑型不可见光源中的潜在应用。此外，通过采用具有商用青色（BaSiON:Eu）、黄色（YAlO:Ce）、红色（CaAlSiN:Eu）的蓝色芯片以及这种LiSrGaF:Cr近红外荧光粉，进一步构建了高度连续的类太阳光可见 - 近红外pc-LED。所获得的pc-LED呈现出400 nm至1000 nm的超宽带光谱，显色指数（CRI）为95.1，发光效率（LE）为50.22 lm/W，具有更高的色彩再现性。这些结果表明，LiSrGaF:Cr荧光粉有望成为用于高质量类太阳光全光谱照明和红外夜视技术的近红外荧光粉候选材料。
