飞秒激光流动烧蚀制备ZnSe有机复合量子点

采用飞秒激光流动烧蚀法制备了聚乙烯亚胺(PEI)包覆的ZnSe量子点水相分散液。水相分散液外观呈现亮黄色透明液体状。多个ZnSe有机复合量子点在水中聚集形成球形胶束,通过扫描电子显微镜(SEM)检测发现,胶束粒径为40~100 nm。利用高分辨透射电子显微镜(HRTEM)和X射线衍射(XRD)研究ZnSe晶体学特性变化,结果表明制得的ZnSe量子点保持了块体ZnSe的立方闪锌矿晶型。该ZnSe有机复合量子点的水分散液在365 nm紫外光照射下显示出明亮的绿色荧光,荧光中心波长约在500 nm处。采用光致发光光谱和紫外可见吸收光谱研究了该有机复合量子点的pH值响应特性,结果表明随着分散液中pH值由9降低到4,光致发光光谱显示出蓝移特性,波长最大蓝移量为25 nm。讨论了绿色荧光的来源与荧光波长调谐的可能机理。

Fabrication of polyethyleneimine-coated ZnSe quantum dots based on femtosecond laser ablation in fluid

Polyethyleneimine(PEI)-coated ZnSe quantum dots dispersed in water were fabricated by femtosecond laser ablation in fluid.The dispersion liquid exhibites an appearance of bright yellowish transparent liquid.A few quantum dots aggregated in water and formed spherical micelles.From the scanning electron microscope(SEM) test,the micelles have an average diameter about 40~100 nm.High resolution transmission electron microscopy(HRTEM) and X-ray diffraction(XRD) were used to study the crystallographic characteristics of ZnSe.Test results show that the quantum dots remained the Zinc blende crystal structure of the bulk materials.This PEI-coated ZnSe quantum dots dispersion liquid shows bright green fluorescence under irradiation of 365 nm UV light.The fluorescence center wavelength is about at 500 nm.Photoluminescence spectra and UV-Vis absorption spectra were used to study the pH response property of the PEI-coated ZnSe quantum dots.Results indicate that with the decrease of pH value from 9 to 4,the photoluminescence spectra peak show a blue shift to a short band and the maximum value of the blue shift is 25 nm.A possible mechanism for the origin and the tunability of the green fluorescence was discussed.