Near-Room Temperature Synthesis of Core/Shell-Structured Quantum Dots.

Core/shell-structured quantum dots (QDs) are considered as important active materials for optoelectronic devices. There have been a lot of synthesis procedures developed so far. Real epitaxial growth of shell layer, however, has not been reported yet. Here, a simple method for the synthesis of CdSe/CdS core/shell QDs is presented. Epitaxial growth of CdS shell on CdSe core is carried out by near room temperature successive ion layer adsorption and reaction (RT-SILAR). Our method for shell formation is conducted at room temperature, which facilitates the separation of resulting products from shell growth solution. After full coverage with one monolayer (ML) of CdS on CdSe QDs surface, photoluminescence (PL) quantum yield (QY) reaches up to 60%. Produced CdSe/CdS QDs have an elongated morphology, implying that CdS layers are formed in an epitaxial manner without etching or deteriorating CdSe QDs surface. We believe that our synthesis method for core/shell-structured QDs would be an ideal model for practical implication of QDs as well as fundamental studies.