Materials emitting near-infrared (NIR) light play a crucial role in the development of phosphor-converted light-emitting diodes (pc-LEDs) for applications ranging from fundamental science like spectroscopic analysis to highly applied uses like night vision and biological imaging. One class of materials that has garnered significant interest for these technical spaces is Cr³⁺-activated garnets due to their high efficiency and ability to operate at relatively high temperatures. However, their limited emission beyond 800 nm impedes their use as optimal blue LED-pumped NIR-emitting materials. In this study, we present a new garnet-type NIR phosphor, Na₂CaZr₂Ge₃O₁₂:Cr³⁺, that addresses this challenge─the material exhibits a long-wavelength emission (λ_em,max = 832 nm) and good thermal quenching resistance while maintaining an excellent internal quantum efficiency (IQE = 98%). These properties are attributed to a crystal environment reconstruction, where a crystal structure distortion is coupled to a weak crystal field, which is uncommon for most rigid garnet-type phosphors. Furthermore, the fabricated NIR pc-LED devices using this material demonstrate superior performance compared with devices employing well-known efficient NIR phosphors operating in this emission range. The light source is subsequently demonstrated in applications spanning night vision, bioimaging, and nondestructive analysis. This study not only provides insights into the luminescence properties of Cr³⁺-activated garnet materials with desirable performance but also highlights the practical application of NIR-emitting garnet phosphors.

中文翻译：

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开发用于夜视和生物成像中的高级 NIR pc-LED 的 Na2CaZr2Ge3O12:Cr3+ 石榴石荧光粉

发射近红外 (NIR) 光的材料在磷光体转换发光二极管 (pc-LED) 的开发中发挥着至关重要的作用，其应用范围从光谱分析等基础科学到夜视和生物成像等高度应用。 Cr ³⁺活化石榴石是这些技术领域引起人们极大兴趣的一类材料，因为它们具有高效率和在相对较高温度下工作的能力。然而，它们在 800 nm 之外的有限发射阻碍了它们作为最佳蓝色 LED 泵浦近红外发射材料的使用。在这项研究中，我们提出了一种新型石榴石型近红外荧光粉 Na ₂ CaZr ₂ Ge ₃ O ₁₂ :Cr ³⁺来解决这一挑战，该材料表现出长波长发射（λ _em,max = 832 nm）并且良好的抗热猝灭性，同时保持出色的内量子效率（IQE = 98%）。这些特性归因于晶体环境重建，其中晶体结构畸变与弱晶体场耦合，这对于大多数刚性石榴石型荧光粉来说并不常见。此外，与采用在此发射范围内工作的众所周知的高效近红外荧光粉的器件相比，使用这种材料制造的近红外 pc-LED 器件表现出卓越的性能。该光源随后在夜视、生物成像和无损分析等应用中得到验证。这项研究不仅深入了解了具有理想性能的Cr ³⁺激活石榴石材料的发光特性，而且突出了近红外发射石榴石荧光粉的实际应用。