【作者】 王娟；

【导师】 韩欣欣；

【作者基本信息】 广西大学 ， 物理学， 2024， 硕士

【摘要】 随着科技发展,近红外光谱技术在多个领域发挥着关键作用。然而,传统的近红外光源在发光效率、稳定性以及光谱可调性等方面存在诸多不足,已无法满足现代测量技术对于光源性能的高标准需求。相比之下,近红外pc-LED以其体积小、发光效率高、发射光谱可调等优势受到了广泛的关注和应用。为了促进近红外pc-LED器件的进一步发展,合成更多具有高效和稳定发光性能的近红外荧光粉十分重要。氟化物具有声子能量低,电子-声子耦合作用弱的特点,有望合成高效稳定的近红外荧光粉。因此,本文以氟化物为基质材料,引入过渡金属离子Cr³⁺作为激活剂离子,采用溶剂热法制备了Rb Al F₄:Cr³⁺、Cs₂KIn_1-yAl_yF₆:Cr³⁺、Cs_2-yRb_yKIn F₆:Cr³⁺一系列近红外荧光粉,对其物相结构、发光性能进行了深入的研究。同时还积极探索了宽带近红外荧光粉在夜视、智能识别、无损检测和静脉血管成像等多个领域的应用潜力。主要从以下三个方面开展工作:（1）采用溶剂热法合成了宽带长波长发射的Rb Al F₄:Cr³⁺近红外荧光粉。该荧光粉在蓝光激发下可产生宽带近红外发射,在839 nm处达到峰值,半峰宽为151 nm。结合晶体结构、电子-声子耦合作用和发光性能之间的关系研究,发现较强的电-声子耦合强度有利于产生较宽的发射,同时其扭曲的晶格结构易造成能级分裂,从而产生较长的发射波长。最后演示了NIR pc-LED光源在无损检测、生物成像以及夜视等领域中的应用。（2）采用阳离子取代策略合成了具有优异热稳定性的Cs₂KIn_1-yAl_yF₆:Cr³⁺（y=0.01-0.15）宽带近红外荧光粉。Al³⁺的掺入明显改善了荧光粉的微观形貌,有效地增强了荧光粉的综合发光强度,使得荧光粉的内量子效率增加到88.06%,同时结构刚性的增强也使热稳定性提高到了71.64%。最后,采用制备的近红外pc-LED光源进行照射,展示了该光源在瞳孔跟踪、防伪、智能识别和生物成像等方面的应用。（3）采用邻位原子取代策略合成了具有优异量子效率的Cs_2-yRb_yKIn F₆:Cr³⁺（y=0.01-0.20）宽带近红外荧光粉。详细分析了荧光粉的晶体结构及其发光性能,并进一步探讨了Cs⁺和Rb⁺的相对含量对Cr³⁺发光特性的影响。优化后的Cs_1.97Rb_0.03KIn F₆:0.10Cr³⁺荧光粉在700到1000 nm范围内展现出高效的近红外发射（IQE=91.67%,AE=37.56%,EQE=40.98%）,归因于结构刚性的增强以及Cr³⁺和基质的弱耦合效应。最后,基于所制备pc-LED优良的光电特性,进一步展示了近红外pc-LED在食品质量监测和无损检测等领域中的实际应用潜力。更多还原

【Abstract】 With the rapid development of science and technology,near-infrared（NIR）spectroscopy plays a significant function in various fields.However,the traditional NIR light source in terms of luminous efficiency,stability and spectral tunability is hardly to meet the demands of modern measurement technology on the performance of the light source.Comparatively,near-infrared phosphor-converted light-emitting diodes（NIR pc-LED）have received widespread attention and applications owing to their small size,high luminous efficiency,and tunable emission spectra.With the aim of promoting the further development of NIR pc-LED devices,synthesizing more NIR phosphors with efficient and stable luminescence performance is necessary.The fluoride has low phonon energy and weak electron-phonon coupling,which is expected to synthesize efficient and stable NIR phosphors.Accordingly,this paper uses fluoride as the matrix material and introduces the transition metal ion Cr³⁺as the activator ion.A series of NIR phosphors of Rb Al F₄:Cr³⁺,Cs₂KIn_1-yAl_yF₆:Cr³⁺,and Cs_2-yRb_yKIn F₆:Cr³⁺were synthesized by solvothermal method.Moreover,the crystal structures and luminescent properties have been thoroughly studied.It also explores the application potential of broadband near-infrared phosphors in various fields including night vision,intelligent identification,nondestructive analysis and vein imaging.The main work is carried out in the following three aspects:（1）The broadband long-wavelength-emitting Rb Al F₄:Cr³⁺NIR phosphor has been synthesized by solvothermal method.Under blue light excitation,the phosphor exhibits broadband NIR emission,peaking at 839 nm with a full width at half maximum（FWHM）of 151 nm.Combined with the crystal structure and electron-phonon coupling of Rb Al F₄:Cr³⁺,it is found that the stronger electro-phonon coupling strength is favorable to the wider emission.At the same time,its distorted lattice structure is prone to energy level splitting,which produces a longer emission wavelength.Finally,we demonstrate the application of NIR pc-LED light source in the fields of nondestructive testing,bio-imaging,and night vision.（2）The broadband NIR phosphor of Cs₂KIn_1-yAl_yF₆:Cr³⁺（y=0.01-0.15）with excellent thermal stability has been synthesized by using a cation substitution strategy.The doping of Al³⁺significantly improved the microscopic morphology and therefore effectively enhances the integrated luminescence intensity of the phosphors.It also resulted in the phosphor’s internal quantum efficiency increasing to 88.06%.The enhanced structural rigidity made the thermal stability increase to 71.64%.Finally,the prepared NIR pc-LED light source was used for irradiation to demonstrate the applications of the phosphor in pupil tracking,anti-counterfeiting,intelligent identification,and bio-imaging.（3）The broadband NIR phosphors of Cs_2-yRb_yKIn F₆:Cr³⁺（y=0.01-0.20）with superior quantum efficiency have been synthesized by neighboring atom substitution strategy.The crystal structures of the phosphors and their luminescent properties were investigated in detail.We also further explored the effects of the relative contents of Cs⁺and Rb⁺on the luminescence properties of Cr³⁺.The optimized Cs_1.97Rb_0.03KIn F₆:0.10Cr³⁺phosphor exhibited NIR emission in the range of 700 to 1000 nm.It showed excellent luminescence efficiency（IQE=91.67%,AE=37.56%,EQE=40.98%）,which was attributed to the enhancement of structural rigidity together with the weak coupling effect of Cr³⁺and matrix.Finally,based on the excellent optoelectronic properties of the prepared pc-LED,we demonstrate the practical application potential of NIR pc-LED in the fields of food quality monitoring and nondestructive testing.更多还原