【作者】 王琦；

【导师】 张道礼；

【作者基本信息】 华中科技大学 ， 微电子与固体电子学， 2015， 硕士

【摘要】 纳米尺度的PbS胶体量子点的能带从近红外区域蓝移到可见光区,这一特点使其呈现出与体相材料不同的光学性质和电学性质,因而被广泛应用于非线性光学器件、红外探测器以及太阳能电池等领域。这些器件一般可以通过掺杂来调整其载流子浓度。然而,实现PbS胶体量子点的稳定掺杂目前仍然是一个挑战。PbS胶体量子点在未经掺杂处理时通常表现为p型,如果PbS胶体量子点可以有n型特性,就可以与p型的PbS胶体量子点组合来制备同质结,从而避免高温烧结制备TiO2电极以及很多因为烧结所带来的问题。同时,同质结也可以避免异质结所产生的界面效应。另外钝化或掺杂还可以使量子点在呈现n型特性的同时拥有更好的电学性能。本文首先介绍了相关背景知识。包括量子点的基本概念及其物性,量子点掺杂的由来,目前发展的现状以及所存在的问题;然后阐明了量子点合成以及掺杂钝化的微观机理;接着介绍了一种以硫化氢(H2S)气体为硫源制备硫化铅(PbS)量子点的方法,分析温度和生长时间对粒径的影响;随后详细描述了阳离子置换法制备PbS胶体量子点以及后续四丁基碘化铵(TBAI)处理等掺杂过程。样品测试和数据分析工作包括:通过紫外-可见吸收峰判断粒子粒径的变化;通过傅里叶变换红外光谱判断处理前后有机键的变化情况;运用X射线衍射仪测试生成的PbS胶体量子点的结构。根据上述测试所得数据分析量子点性能与合成条件的关系,不断优化实验方案,并最终制备出掺杂良好、性能优异的单分散PbS胶体量子点。更多还原

【Abstract】 Nano-scale PbS quantum dots’ energy band shows a blue shift from the near infrared region to the visible region, which makes it exhibits different optical properties and electrical properties compared to the bulk material, and thus the material applications of nonlinear optical devices, infrared detectors and solar cells have attracted widespread research. Usually,the electronic material used in these devices can use doping methods to adjust the carrier concentration. However, PbS quantum dots’ stable doping process still remains a challenge.PbS quantum dots show p-type character without doping process. If PbS quantum dots can possibly have n-type character, it can be used as an n-type layer to prepare homo-junction.Then we can avoid the process of sintering TiO2 electrode at a high temperature, a lot of consequent problems caused by high temperature sintering can also be solved. Preparing homo-junction can also avoid the interface effect caused by hetero-junction preparation. The passivation or doping process can also make quantum dots have better electrical properties.This paper first introduces the basic concepts and physical properties of quantum dots.Then we explain the origin of the quantum dots’ doping process, the current status of the development and the problems that exist in this process. Later we clarified the microscopic mechanism of quantum dots’ synthesis and doping process. After that we introduced our laboratory’s traditional PbS quantum dots’ preparation method which takes H2 S gas as the sulfur source. We analyze the effect of the reaction temperature and time on the particle size growth at the meantime. A detailed description of the cation-exchange method to prepare PbS quantum dots and the subsequent TBAI doping process will be given later.We then do some tests on the prepared samples: the UV-Vis spectrophotometer(UV)absorption test to determine its particle size changes, the Fourier transform infrared spectrophotometer(FTIR) to judge whether the TBAI treated PbS quantum dots still contain organic bond as untreated ones, the X-ray diffraction(XRD) to view the prepared samples’ structure. Taking advantage of these characterization and test methods to help us analyze quantum dot performance and do more job to optimize the experimental program, change the experimental conditions etc. At last, we can prepare appropriate size, good performance and good mono-dispersity PbS QDs.更多还原