Quantum dots having composition gradient shell structure and manufacturing method thereof

A quantum dot comprising a core and a shell, wherein:

• the core comprises a first Group II-VI compound;
• the shell comprises a second Group II-VI compound;
• the second Group II-VI compound has a larger bandgap than the first Group II-VI compound;
• and
• the shell has a gradual composition gradient.

A method of manufacturing quantum dots, comprising:

• mixing a compound comprising a core-forming Group II metal with a compound comprising a shell-forming Group II metal to form a mixture;
• heating the mixture comprising the core-forming Group II metal and the shell-forming Group II metal at a temperature between approximately 100° C. and 350° C.;
• forming a core by mixing the mixture with a compound comprising a core-forming Group VI element and a compound comprising a shell-forming Group VI element;
• and
• forming a shell having a composition gradient by maintaining the mixture at a temperature between approximately 100° C. and 350° C.

A quantum dot comprising:

• a core;
• an outer shell having a predetermined bandgap energy that is higher than that of the core;
• and
• an inner shell that surrounds the core and that is surrounded by the outer shell, wherein the inner shell has a bandgap energy that gradually decreases in a direction from the outer shell towards the core.

A method of manufacturing quantum dots, comprising:

• reacting compounds to form cores;
• and
• reacting remaining compounds to form shells having a gradual composition gradient,
• wherein said reacting compounds and said reacting remaining compounds are sequentially performed due to a difference in reactivity between the compounds.