High-efficiency CdTe/CdS core/shell nanocrystals in water enabled by photo-induced colloidal hetero-epitaxy of CdS shelling at room temperature  

作　　者：Hakimeh Zare Maziar Marandi Somayeh Fardindoost Vijay Kumar Sharma Aydan Yeltik Omid Akhavan Hilmi Volkan Demir Nima Taghavinia 

机构地区：[1]Institute for Nanoscience and Nanotechnology, Shafif University of Technology, Tehran 14588, Iran [2]Department of Physics, Faculty of Sciences, Arak University, Arak 38156-8-8349, Iran [3]Department of Physics, Department of Electrical and Electronics Engineering, and UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey [4]Luminous, Center of Excellence for Semiconductor Lighting and Displays, Microelectronics Division, School of Electrical and Electronics Engineering, and Physics and Applied Physics Division, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798, Singapore [5]Physics Department, ShafifUniversity of Technology, Tehran 14588, Iran

出　　处：《Nano Research》2015年第7期2317-2328,共12页纳米研究（英文版）

摘　　要：We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature, enabled by the controlled release of S species under low-intensity ultraviolet （UV） light illumination. The resulting photo-induced dissociation of S2O2- ions conveniently triggers the formation of critical two-dimensional CdS epitaxy on the CdTe surface at room temperature, as opposed to initiating the growth of individual CdS core-only nanocrystals. This controlled colloidal hetero-epitaxy leads to a substantial increase in the photoluminescence （PL） quantum yield （QY） of the shelled nanocrystals in water （reaching 64%）. With a systematic set of studies, the maximum PL QY is found to be almost independent of the illuminating UV intensity, while the shell formation kinetics required for reaching the maximum QY linearly depends on the illuminating UV intensity. A stability study of the QD films in air at various temperatures shows highly improved thermal stability of the shelled QDs （up to 120 ℃ in ambient air）. These results indicate that the proposed aqueous CdTe/CdS core/shell nanocrystals hold great promise for applications requiring efficiency and stability.

关 键 词：CdTe/CDs core/shell nanocrystal thermal stability PHOTOCHEMICAL 

分 类 号：O[理学]