Zhong Jiyou, Zeng Liwei, Zhao Weiren, Brgoch Jakoah
School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou510006, China.
Department of Chemistry, University of Houston, Houston, Texas77204, United States.
ACS Appl Mater Interfaces. 2022 Nov 16;14(45):51157-51164. doi: 10.1021/acsami.2c17902. Epub 2022 Nov 6.
Broadband near-infrared (NIR) phosphors are in high demand for creating "smart" NIR phosphor-converted light-emitting diode (pc-LED) sources. In this work, a series of Cr-substituted NIR-emitting materials with highly efficient, broad, tunable emission spectra are achieved by modifying the simple oxide GaO using [Mg-Ge] and [Ga-Ga] co-unit substitution. The results show that the emission peak can be shifted from 726 to 830 nm while maintaining a constant excitation peak in the blue light region, enabling extensive application. The optical properties stem from changes in the Cr crystal field environment upon substitution. Intriguingly, the temperature-dependent photoluminescence emission peak position shows virtually no change in the [Mg-Ge] co-substituted materials. This abnormal phenomenon is found to be a comprehensive embodiment of a weakening crystal field environment (red-shift) as the temperature increases and reduced local structure distortion (blue-shift) with increasing temperature. The high quantum yield, NIR emission, and net-zero emission shift as a function of temperature make this phosphor class optimal for device incorporation. As a result, their performance was studied by coating the phosphor on a 450 nm emitting LED chip. The fabricated device demonstrates an excellent NIR output power and NIR photoelectric conversion efficiency. This study provides a series of efficient, tunable, broadband NIR materials for spectroscopy applications and contributes to the basic foundation of Cr-activated NIR phosphors.
宽带近红外（NIR）磷光体对于制造“智能”近红外磷光体转换发光二极管（pc-LED）光源有很高的需求。在这项工作中，通过使用[Mg-Ge]和[Ga-Ga]共单元取代来修饰简单氧化物GaO，获得了一系列具有高效、宽带、可调发射光谱的Cr取代近红外发光材料。结果表明，发射峰可以从726nm移动到830nm，同时在蓝光区域保持恒定的激发峰，从而实现广泛应用。光学性质源于取代后Cr晶体场环境的变化。有趣的是，在[Mg-Ge]共取代材料中，与温度相关的光致发光发射峰位置几乎没有变化。发现这种异常现象是温度升高时晶体场环境减弱（红移）和温度升高时局部结构畸变减小（蓝移）的综合体现。高量子产率、近红外发射以及发射峰随温度的净零移动使得这类磷光体非常适合用于器件集成。因此，通过将磷光体涂覆在450nm发光的LED芯片上来研究它们的性能。制造的器件展示出优异的近红外输出功率和近红外光电转换效率。这项研究为光谱学应用提供了一系列高效、可调、宽带近红外材料，并为Cr激活近红外磷光体的基础研究做出了贡献。
