ZnSe量子点制备及光声与光伏特性研究

发布时间：2018-09-19 14:32

【摘要】：本文选取L-半胱氨酸(L-Cys)为配体(修饰剂或保护剂),采用水相合成法制备Zn Se量子点。以制备过程中的回流温度、Zn前体pH值、回流时间、配体L-半胱氨酸的比例分别为单一变量,以光声光谱(PA)和表面光电压谱(SPS)为主要分析手段分析量子点样品的光声与光伏特性。借助X射线衍射(XRD)表征方法鉴定ZnSe量子点样品的晶体结构和粒径大小。分析得出随回流温度、p H值、回流时间和配体比例变化所制得的样品都为立方闪锌矿结构,样品粒子尺寸分别为2.4—3.0nm、2.45—2.52nm、2.48—2.53nm、2.48—2.53nm,粒径总体小于3nm,证实所制的样品确属量子点尺寸范畴。利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)和电子衍射花样分析得到样品近似为球形、分布均匀且为多晶结构。通过傅里叶变换红外光谱(FT-IR)和拉曼光谱(Raman)分析样品的成分与成键情况,实验分析得出,样品为类ZnSe/ZnS/配体的核/壳式结构。主要借助PA、SPS分析样品受调制光照射后的跃迁机制与能量转换行为,通过分析得出,样品在300-400nm、700-800nm光波长范围内受激辐射主要以晶格振动所致的无辐射跃迁释放能量;而在400-550nm光波长范围内则主要以辐射发光的方式释放能量;另外550-700nm光波长范围内,受激辐射为辐射跃迁加无辐射跃迁同时进行释放能量。证明了PA谱与SPS谱呈现能量互补关系,样品具有优异的能量转换效率。借助场诱导表面光电压谱(EFISPS)分析得出样品表现为N型半导体光伏特性。实验以90度制备的量子点为测试样品,测试不同调制频率10-90Hz的光声光谱,分析得出光声响应与调制频率的关系很好地符合光声光热经典理论:R-G理论,并且证明30Hz左右的调制频率为仪器的最适宜调制频率。
[Abstract]:In this paper, L- cysteine (L-Cys) was used as ligand (modifier or protectant) to prepare Zn Se quantum dots by aqueous phase synthesis. The pH value of Zn precursor, the reflux time and the ratio of ligand L- cysteine were single variables, respectively. The photoacoustic and photovoltaic properties of QDs were analyzed by photoacoustic spectrum (PA) and surface photovoltage spectrum (SPS). The crystal structure and particle size of ZnSe quantum dots were identified by X-ray diffraction (XRD) (XRD) characterization. The results show that the samples prepared with the change of reflux temperature, reflux time and ligand ratio are cubic sphalerite structure. The particle sizes of the samples are 2.48-2.53nmmand 2.48-2.53nmm respectively, and the particle size is less than 3nm. it is proved that the samples are in the range of quantum dot size. By means of transmission electron microscope (TEM),) high resolution transmission electron microscope (HRTEM) and electron diffraction pattern analysis, the sample is approximately spherical, uniformly distributed and polycrystalline. Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy (Raman) were used to analyze the composition and bonding of the samples. The experimental results showed that the samples were core-shell structure of ZnSe/ZnS/ like ligands. The transition mechanism and energy conversion behavior of the samples irradiated by modulated light were analyzed by PA,SPS. The results show that the stimulated radiation in the wavelength range of 300-400nm ~ 800nm is mainly due to the non-radiative transition energy caused by lattice vibration. In the range of 400-550nm wavelength, the energy is mainly released in the form of luminescence, and in the range of 550-700nm wavelength, the stimulated radiation is radiative transition and non-radiative transition simultaneously. It is proved that the PA spectrum and the SPS spectrum are energy complementary, and the sample has excellent energy conversion efficiency. Field induced surface photovoltage spectrum (EFISPS) analysis shows that the sample exhibits N-type semiconductor photovoltaic characteristics. The photoacoustic spectra of 10-90Hz with different modulation frequencies were measured by using 90 degree quantum dots as the test sample. The relationship between photoacoustic response and modulation frequency was found to be in good agreement with the classical photoacousto-photothermal theory: R-G theory. It is proved that the modulation frequency of 30Hz is the most suitable modulation frequency of the instrument.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.41

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