近年来，近红外荧光粉转换发光二极管（NIR pc-LED）在夜视、生物成像和无损检测等领域引起了广泛关注。然而，获得兼具高量子效率和优异热稳定性的近红外荧光粉仍然是一个巨大挑战。本文利用高温固相法合成了一种新型近红外荧光粉BaY₂Al₂Ga₂SiO₁₂∶Cr³⁺（BYAGSO∶Cr³⁺），并系统研究了材料的结构和发光性质。在440 nm蓝光激发下，BYAGSO∶Cr³⁺荧光粉的发射光谱在650~850 nm范围内呈现锐线和宽带的混合发射，源于Cr³⁺：²E→⁴A₂自旋禁戒跃迁和⁴T₂→⁴A₂自旋允许跃迁发射。该近红外发光表现出可观的量子效率和良好的热稳定性，最优化样品的外量子效率可达30.3%，在200 ℃时样品的发光强度可保持其在室温时强度的99%。通过将BYAGSO∶Cr³⁺荧光粉与450 nm蓝光LED芯片结合，我们封装了一个NIR pc-LED器件。该器件在300 mA驱动电流下，输出功率为70.83 mW；在20 mA驱动电流下，光电转换效率为11.20%。研究结果表明，BYAGSO∶Cr³⁺在NIR pc-LED领域具有良好的应用前景。

间接带隙的Cs₂NaBiCl₆双钙钛矿材料具有近红外宽波段发射特性, 但低发光效率限制了其在近红外发光领域的应用。本工作通过共沉淀法快速制备微米级尺寸的Cs₂Ag_0.1Na_0.9BiCl₆:Tm³⁺双钙钛矿晶体, 实现了近红外荧光增强, 并系统研究了其光学吸收、光致发射(PL)、光致激发(PLE)、时间分辨光致发光和荧光量子效率(PLQY)等光学性能。共沉淀法制备的Cs₂Ag_0.1Na_0.9BiCl₆:Tm³⁺的光学带隙为3.06 eV。在350 nm紫外光激发下, 可以观察到峰值位于680 nm的近红外宽峰发射, 这源于自陷激子发光。通过引入Tm³⁺作为新的发光中心, 实现了810 nm波段的近红外发光增强, 在780~830 nm波段荧光量子效率(PLQY)从1.67%提高到11.77%, 提高了6.05倍。在650~900 nm波段, Cs₂Ag_0.1Na_0.9BiCl₆:Tm³⁺的近红外PLQY高达25.22%。本研究证明了共沉淀法快速制备的Cs₂Ag_0.1Na_0.9BiCl₆:Tm³⁺钙钛矿作为新型近红外光源材料的可行性。

近红外荧光转换型发光二极管（pc-LED）在光谱分析、生物成像、夜视照明等领域有重要应用价值，得到了人们的广泛关注。本文采用高温固相法制备了一系列Ca₂TbHf₂Al₃O₁₂∶Ce³⁺，xCr³⁺（CTHAO∶Ce³⁺，xCr³⁺）近红外荧光材料，通过粉末XRD表征结合结构精修技术确定制备的CTHAO∶Ce³⁺，xCr³⁺为纯相石榴石结构。在该样品中，Tb³⁺作为基质组成，与掺杂离子Ce³⁺共同作为Cr³⁺离子的敏化剂，三者之间存在多种能量传递效应，通过光谱及荧光寿命表征证实存在Ce³⁺→Tb³⁺、Ce³⁺→Cr³⁺、Tb³⁺→Cr³⁺的能量传递过程；重点分析了Tb³⁺向Cr³⁺的能量传递机制，以偶极-四极交互作用为主导，能量传递效率可达79.5%。CTHAO∶Ce³⁺，0.02Cr³⁺在100 ℃时的近红外发射强度能保持初始强度的36%，计算得到活化能为0.30 eV。将该样品与410 nm芯片相结合制成器件，在驱动电流为200 mA时，近红外最大输出功率可达7.5 mW，光电转换效率为1.2%。本工作研究了通过多重能量传递提高Cr³⁺的发光，对于设计和开发Cr³⁺激发的高效近红外发光材料有一定的指导意义。

Organic lasers that emit light in the deep-red and near-infrared (NIR) region are of essential importance in laser communication, night vision, bioimaging, and information-secured displays but are still challenging because of the lack of proper gain materials. Herein, a new molecular design strategy that operates by merging two excited-state intramolecular proton transfer-active molecules into one excited-state double proton transfer (ESDPT)-active molecule was demonstrated. Based on this new strategy, three new materials were designed and synthesized with two groups of intramolecular resonance-assisted hydrogen bonds, in which the ESDPT process was proven to proceed smoothly based on theoretical calculations and experimental results of steady-state and transient spectra. Benefiting from the effective six-level system constructed by the ESDPT process, all newly designed materials showed low threshold laser emissions at approximately 720 nm when doped in PS microspheres, which in turn proved the existence of the second proton transfer process. More importantly, our well-developed NIR organic lasers showed high laser stability, which can maintain high laser intensity after 12000 pulse lasing, which is essential in practical applications. This work provides a simple and effective method for the development of NIR organic gain materials and demonstrates the ESDPT mechanism for NIR lasing.

With the rapid growth of optical communications traffic, the demand for broadband optical amplifiers continues to increase. It is necessary to develop a gain medium that covers more optical communication bands. We precipitated PbS quantum dots (QDs) and BaF2:Tm3+ nanocrystals (NCs) in the same glass to form two independent emission centers. The BaF2 NCs in the glass can provide a crystal field environment with low phonon energy for rare earth (RE) ions and prevent the energy transfer between RE ions and PbS QDs. By adjusting the heat treatment schedule, the emission of the two luminescence centers from PbS QDs and Tm3+ ions perfectly splices and covers the ultra-broadband near-infrared emission from 1200 nm to 2000 nm with bandwidth over 430 nm. Therefore, it is expected to be a promising broadband gain medium for fiber amplifiers.