CdSe/CdS量子点聚合物复合材料的水致荧光可逆特性

Water-driven Photoluminescence Reversibility in CdSe/CdS Quantum Dots Polymer Composite

量子点由于其优异的光学和电学特性,在新型光电器件领域是一种极具前景的明星材料。本文通过将核壳CdSe/CdS量子点封装到聚二甲基硅氧烷-聚脲(PDMS-PUa)聚合物基质中制备CdSe/CdS@PDMS-PUa复合材料,发现了其光致发光强度和荧光量子产率的水致增强现象,经荧光衰减曲线和漫反射光谱分析,解释了该现象是来自于水中的H_(3)O^(+)和OH^(-)对量子点表面缺陷的有效钝化,使得量子点的晶胞更趋于理想化。进一步通过实验发现,当复合材料从水中取出干燥后,由于量子点表面缺陷态又重新暴露,光致发光强度和荧光量子产率又恢复到初始值。受所发现的荧光可逆现象的启发,本文基于CdSe/CdS@PDMS-PUa复合材料提出了一种具有荧光响应的液体高度传感器,通过荧光亮度的变化可以判断容器内液体的高度值。这些发现不仅揭示了CdSe/CdS量子点水致荧光可逆特性,同时拓宽了量子点聚合物复合材料在光电领域的应用,具有重要的科学意义和应用前景。

Quantum dots are a promising star material in the field of new optoelectronic devices due to their excellent optical and electrical properties.In this work,we prepare the CdSe/CdS@PDMS-PUa composite by encapsulating core/shell CdSe/CdS quantum dots into an amino-terminated polydimethylsiloxane(PDMS-PUa)polymer matrix,which shows water-driven enhanced photoluminescence(PL)intensity and photoluminescence quantum yield(PLQY).After the analysis of fluorescent decay curve and diffuse reflectance spectrum,the reason for this enhancement is found to be the passivation of the surface defects of the quantum dots by H_(3)O^(+) and OH^(-) in water,making the unit cell of the quantum dots more idealized.However,when the composite is taken out of the water for drying,the defect states are exposed again,and both PL and PLQY return to their original values.Inspired by the water-driven PL reversibility in CdSe/CdS@PDMS-PUa composite,a liquid height sensor with fluorescence response is proposed based on the CdSe/CdS@PDMS-PUa composite,which can judge the liquid height value in the container through the change of fluorescence intensity.These findings not only reveal the reversible characteristics of CdSe/CdS quantum dots,but also broaden the application of quantum dots polymer composites in the field of optoelectronics,which has important scientific significance and application prospects.