CdS纳米晶的稳定化处理及介质极性对荧光光谱的影响

Stabilization of CdS Nanocrystals and Influence of Solvent Polarization on Fluorescent Excitation/Emission Wavelength

用硫脲、聚乙烯吡咯烷酮、L-半胱氨酸水溶液对水热法合成的硫化镉纳米晶进行稳定化处理,发现L-半胱氨酸和聚乙烯吡咯烷酮(PVP)能有效地稳定硫化镉纳米晶,荧光发射强度比处理前增强了五十倍以上。以氯仿、氧化三(正)辛基膦(TOPO)氯仿溶液以及3-巯基丙酸为萃取(或处理)剂,对水热法合成的水溶性CdS半导体纳米晶进行处理,经过荧光光谱分析,发现介质水、氯仿、氧化三(正)辛基膦(TOPO)氯仿溶液以及3-巯基丙酸会对CdS纳米晶的最大荧光激发峰与发射峰的位置产生不同影响,极性大的水分子使得荧光峰蓝移,极性小的氯仿、氧化三(正)辛基膦(TOPO)氯仿溶液以及3-巯基丙酸使得荧光峰红移,最大位移为31nm左右。

High-quality CdS semiconductor nanocrystallites of wurtzite structure synthesized via hydrothermal method were characterized by a combination of transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, X-ray powder diffraction （XRD） pattern. The fluorescence intensity emitted by the nanocrystals is surprisingly enhanced after being treated using thiourea, polyvinylpyrrolidone and L-cysteine respectively. Fluorescence spectra indicated that intensity of fluorescence increases more than Fifty times after stabilization treatment by polyvinylpyrrolidone and L- cysteine. Fluorescence excitation and emission wavelengths were found to change when the water-soluble CdS nanocrystallites were treated with solvents or extractants with different polarization such as chloroform, trioctylphosphine oxide in chloroform solution and 3-mercaptopropionic acid respectively. The maximal shift of wavelength is about 31 nm in 3-mercaptopropionic acid.