核壳结构量子点掺杂玻璃及其光学性能研究

Lead chalcogenide quantum dots doped glasses have important potential applications in the near-infrared wavelength range, but the presence of defects or traps on the surface of quantum dots lowers its quantum efficiency and hinders the research progress. In order to improve the quantum efficiency, this project focuses on the surface passivation of PbS and PbSe quantum dots in glasses, using the all-inorganic passivation method. Based on the silicate and oxyfluoride glasses, current research studies the effects of glass composition on the saturable doping concentrations of alkali-earth chalcogenides and lead chalcogenides. Effects of glass composition and thermal treatment on the controllable, sequential precipitation of lead chalcogenide, alkali-earth chalcogenide or alkali-earth fluoride nanocrystals in the glasses is also emphasized in order to fabricate core/shell structured quantum dots in glasses. High resolution transmission electron microscope, electron energy loss spectroscopy and high temperature in-situ transmission electron microscope will be employed to clarify the nucleation and growth of these core/shell structured quantum dots in glasses. Structural analysis will be combined with optical characterization such as time-resolved photoluminescence spectroscopy, to evaluate the passivation efficiency of quantum dots, understand the passivation mechanism, and demonstrate its effect on the optical properties of these core/shell structured quantum dots in glasses. As a result, this study is not only full of important and practical significance for glasses containing quantum dots, and also valuable for future development of multifunctional glass ceramics.

PbS、PbSe量子点掺杂玻璃在近红外波段有重要的应用前景，但量子点表面缺陷降低了量子点荧光效率，制约了相关应用研究进展。本项目借鉴全无机钝化法，通过制备核壳结构来钝化玻璃中量子点的表面缺陷，提高荧光效率。本项目以硅酸盐及氟氧化物玻璃为基体，研究组成对碱土金属硫族化合物及PbS与PbSe饱和掺杂浓度, 以及热处理对PbS及PbSe量子点与碱土金属硫族化合物纳米晶或碱土金属氟化物纳米晶可控依次析晶的影响规律，制备核壳结构量子点纳米晶；利用高分辨透射电镜、电子能量损失谱以及高温原位高分辨透射电镜等技术手段，研究核壳结构纳米晶体核化、生长过程与机理；采用微观结构分析与时间分辨光谱等手段相结合的方式，研究核壳结构中PbS或PbSe量子点的表面缺陷钝化效果、机制及其对量子点光学性能的影响，研发高荧光效率的量子点掺杂玻璃。该研究对量子点掺杂光功能玻璃有重要的现实意义，对多功能微晶玻璃研发也具参考价值。

PbX（X=S,Se）量子点掺杂玻璃在近红外波段有重要的应用前景，但量子点表面缺陷降低了量子点荧光效率，制约了相关应用研究进展。针对该现状，本项目以量子点表面缺陷钝化为研究目标，采用氟化物与碱土金属硫族化合物等来钝化量子点表面缺陷。第一、阐明了玻璃基质中ZnO的含量对硫族化合物的饱和溶解度有较大的影响，提高玻璃中ZnO的含量能够有效提高硫族化合物的饱和溶解度。玻璃基质中量子点的析晶主要取决于硫族元素的含量，提高X/Pb（X=S, Se）比例能够有效地促进IV-VI量子点的析晶，从而实现了PbS量子点在800-2200 nm波段的可调吸收与荧光。第二、系统研究了PbX量子点在氧氟化物玻璃中析晶性能及其光学性能。研究表面，PbS量子点析晶，能够促进PbF2纳米晶的析晶；同时含PbF2纳米晶的玻璃中，PbS量子点光稳定性能较好。在含有BaF2纳米晶的氧氟化物微晶玻璃中，由于在硫族化合物在氧氟化物玻璃基质与氧氟化物微晶玻璃基质中的饱和溶解度不同，玻璃中所析出的PbSe量子点具有两种不同的粒径分布，从而实现了PbSe量子点掺杂玻璃的双峰荧光，这为量子点掺杂玻璃的在近红外宽光谱可调光源等方面的应用奠定了基础。第三、研究了玻璃基质中量子点禁带宽度调控方法。通过稀土离子掺杂，能够有效控制玻璃基质中量子点的平均粒径；通过Sn2+离子掺杂，有效地降低了掺杂PbSe量子点的禁带宽度，扩大了掺杂量子点的光谱调控范围，实现了量子点在2650 nm波段处的中红外荧光。第四、在玻璃基质中首次合成了PbS/Na2SrSi2O6核壳结构量子点，证明了玻璃中制备核壳结构量子点的可行性。同时在碱土金属掺杂的玻璃体系中，碱土金属离子能够有效地提高量子点荧光效率。