Quantum dot structure with excellent stability and method for making the same

A method for making a quantum dot structure, comprising the steps of:

• a) mixing a solution containing a precursor of M1 with a solution containing a precursor of C1, and reacting the precursor of M1 with the precursor of C1 to obtain a first mixture solution containing a core that is a single crystal of a compound M1C1, the core having a core surface that has a first region and a second region, the first region being inactive with oxygen, the second region being oxidized by oxygen present in the first mixture solution to form an oxide layer thereon;
• b) adding a solution containing a precursor of M2 and a solution containing a precursor of C2 into the first mixture solution and growing a compound M2C2 on the first region of the core surface so as to obtain a second mixture solution containing a first quantum dot that has the core and an inner shell of the compound M2C2 formed only on the first region of the core;
• c) adding dropwise an etchant into the second mixture solution to selectively etch the oxide layer formed on the second region;
• d) diluting the etchant in the second mixture solution to terminate etching of the oxide layer;
• e) filtering the second mixture solution to obtain the first quantum dot that has the core and the inner shell formed on the core;
• f) adding the first quantum dot obtained in step e) into a dispersant-containing solution to obtain a third mixture solution;
• g) settling the third mixture solution;
• h) after step g), filtering the third mixture solution to remove residue of the etchant from the first quantum dot so as to obtain a fourth mixture solution containing the first quantum dot;
• and
• i) mixing the fourth mixture solution with the solution containing the precursor of M2 and the solution containing the precursor of C2, and growing an outer shell of a single crystal of a compound M2C2 on the second region of the core surface and the inner shell, the outer shell including a first portion and a second portion, the first portion being grown on the inner shell, the second portion being grown on the second region of the core surface and being connected to the first portion,
• wherein
• M1 is an element selected from the group consisting of Al, Ga, and In, and Cl is an element selected from the group consisting of P, As, and combinations thereof, and M2 is an element selected from the group consisting of Zn, Pb, Ag, Cu, Mn, Cd, and Mg, and C2 is an element selected from the group consisting of S, Se, O, F, Cl, Br, I, Te, and combinations thereof.

A method for making a quantum dot structure, comprising the steps of:

• a) mixing a solution containing a precursor of M1 with a solution containing a precursor of C1, and reacting the precursor of M1 with the precursor of C1 to obtain a first mixture solution containing a core that is a single crystal of a compound M1C1, the core having a core surface that has a first region and a second region, the first region being inactive with oxygen, the second region being oxidized by oxygen present in the first mixture solution to form an oxide layer thereon;
• b) adding a solution containing a precursor of M2 and a solution containing a precursor of C2 into the first mixture solution and growing a compound M2C2 on the first region of the core surface so as to obtain a second mixture solution containing a first quantum dot that has the core and an inner shell of the compound M2C2 formed on the first region of the core, said inner shell having a thickness ranging from 1 Å-10 Å;
• c) adding dropwise an etchant into the second mixture solution to selectively etch the oxide layer formed on the second region;
• d) diluting the etchant in the second mixture solution to terminate etching of the oxide ager;
• e) filtering the second mixture solution to obtain the first quantum dot that has the core and the inner shell formed on the core;
• f) adding the first quantum dot obtained in step e) into a dispersant-containing solution to obtain a third mixture solution;
• g) settling the third mixture solution;
• h) after step g), filtering the third mixture solution to remove residue of the etchant from the first quantum dot so as to obtain a fourth mixture solution containing the first quantum dot;
• and
• i) mixing the fourth mixture solution with the solution containing the precursor of M2 and the solution containing the precursor of C2, and growing an outer shell of a single crystal of a compound M2C2 on the second region of the core surface and the inner shell, the outer shell including a first portion and a second portion, the first portion being grown on the inner shell, the second portion being grown on the second region of the core surface and being connected to the first portion,
• wherein
• M1 is an element selected from the group consisting of Al, Ga, and In, and Cl is an element selected from the group consisting of P, As, and combinations thereof, and
• M2 is an element selected from the group consisting of Zn, Pb, Ag, Cu, Mn, Cd, and Mg, and C2 is an element selected from the group consisting of S, Se, O, F, Cl, Br, I, Te, and combinations thereof.