半导体量子点光学性质研究及湿度传感应用

  半导体量子点作为一种性能优异的光学材料，具有发光波长可调、带隙窄、发光效率高等优点，在太阳能电池、显示以及传感等领域得到了广泛的应用。然而，单壳层的量子点仍然面临发光效率低和光稳定性差等问题。本文将以I型CdSe/ZnS半导体核壳量子点为研究对象，通过微球复合结构提升其发光及稳定性。此外，将CdSe/ZnS量子点应用于光学湿度传感，研究传感特性，讨论传感机制。具体的研究内容如下：

  本文通过激光光谱表征手段研究了CdSe/ZnS核壳量子点的基本光学特性，并利用多孔二氧化硅微球形成复合结构，提升材料性质。由于多孔二氧化硅微球表面凹凸不平，有效地增加了量子点的附着，同时，该结构能够充分增加光在材料的内部散射从而增强荧光。在最优条件下，其荧光强度可增强为原来的6.5倍。这是一种相对于利用配体交换、包覆壳层结构来说更简单的改善量子点发光性能的方法，为优化量子点的光学特性拓展了思路。

  研究发现，CdSe/ZnS量子点的荧光强度随湿度的增加而升高。通过温度依赖性、时间分辨光致发光光谱及PDMS包覆钝化等测试手段证明了在高湿度下，水分子会吸附在量子点的表面形成水膜，钝化了量子点表面相关的缺陷。实验分析了量子点作为光学湿度传感器的传感性能，该传感器具有20-40 s的快速响应与恢复时间，良好的稳定性，选择性及重复性等，并研制出小型的光学湿度传感器。

  本论文基于多种光谱测试手段研究了核壳结构量子点的光学特性，一方面，在不改变量子点本身性质的情况下优化了其发光性能；另一方面，实现了量子点环境光学传感。相关的研究结果对于后续进一步改善低维半导体材料的性质具有指导意义，同时，也推动了量子点在微型环境传感等领域的应用。

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