摘要
制备了壳层厚度可以精确控制的CdTe/CdS核壳量子点,利用紫外-可见吸收光谱、光致发光光谱、透射电镜和时间分辨光谱等技术,分析了CdS壳层厚度对CdTe量子点的荧光量子产率和光谱结构的影响规律.发现了不同于CdSe/CdS,CdSe/ZnS,CdTe/ZnS等核壳量子点的荧光峰展宽、大幅度红移以及荧光寿命大幅度增加现象.根据能带的位置关系,随着CdS厚度的增加,CdTe从Ⅰ型结构逐渐过渡到Ⅱ型核壳结构.对于Ⅱ型CdTe/CdS核壳量子点,不仅存在CdTe核区导带电子与价带空穴间的直接复合,还存在CdS壳层导带电子与CdTe核价带空穴界面处的间接复合,发光机制的变化导致荧光峰的展宽、明显红移和荧光寿命的增加.当壳层过厚时,壳层表面新引入的缺陷会阻碍荧光寿命和量子产率的进一步提高.
Water-soluble CdTe/CdS core-shell quantum dots（QDs） with the different shell thickness capped with 3-mercaptopropionic acid were synthesized following the synthetic method of successive ion layer adsorption and reaction. UV-Vis absorption spectroscopy, photoluminescence（PL） spectroscopy, transmission electron microscopy（TEM） and time-resolved luminescence were employed to analyze optical characters of QDs. The CdTe/CdS QDs exhibited a significant red shift of emission peak, FWHM increasing and PL lifetime lengthening when the shell layer grew. The experiments revealed that the CdTe/CdS QDs evolve from type-Ⅰ to type- Ⅱcore-shell structure with the increase of the shell thickness. The lack of PL lifetime lengthening and quantum yield increasing was ascribed to the surface influence of the shell.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第9期1789-1792,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:10674034,60478015,60771051,60601014,20603035)
国家“八六三”计划(批准号:2006AA03Z335)
黑龙江省教育厅项目(批准号:11533047)资助
