Quantum dot composition including a ligand bonded to a surface of a quantum dot, light emitting element including an emission layer containing a quantum dot and ligand residues, and method for manufacturing the same
A quantum dot composition includes a quantum dot, and a ligand bonded to a surface of the quantum dot, wherein the ligand includes a head portion bonded to the surface of the quantum dot and containing a polar solvent dissociative functional group, and a tail portion connected to the head portion. A quantum dot composition according to an embodiment is used to form an emission layer of a light emitting element to enhance luminous efficiency of the light emitting element including an emission layer formed through the quantum dot composition.
1. A quantum dot composition comprising:
a quantum dot; and
a ligand bonded to a surface of the quantum dot,
wherein the ligand comprises:
a head portion bonded to the surface of the quantum dot and containing a polar solvent dissociative functional group; and
a tail portion connected to the head portion, the tail portion containing a non-polar organic material, and
the ligand is represented by any one among Formulae 1 to 19, and 21 to 23:
wherein in Formulae 1 to 19, and 21 to 23,
R 1 and R 2 are each independently a substituted or unsubstituted alkyl group having 7 to 30 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and
x 1 is an integer of 1 to 10.
2. The quantum dot composition of claim 1 , wherein the quantum dot comprises:
a core; and
a shell surrounding the core, and
an interface between the core and the shell having a concentration gradient of an element that decreases toward the core.
3. The quantum dot composition of claim 1 , wherein the tail portion comprises a substituted or unsubstituted alkyl group having 7 to 30 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms.
4. The quantum dot composition of claim 1 , wherein the ligand is a monodentate ligand or a bidentate ligand.
5. The quantum dot composition of claim 1 , wherein the head portion comprises a hydrogen cation, a sodium cation, or a potassium cation.
6. The quantum dot composition of claim 1 , further comprising a non-polar organic solvent.
7. The quantum dot composition of claim 1 , wherein the tail portion has a first end connected to the head portion and a free second end opposite the first end.
8. A light emitting element comprising:
a first electrode;
a hole transport region on the first electrode;
an emission layer on the hole transport region and containing a quantum dot and ligand residues, the ligand residues comprising a head portion and a tail portion connected to the head portion, the tail portion containing a non-polar organic material;
an electron transport region on the emission layer; and
a second electrode on the electron transport region, and
wherein the head portion comprises a polar solvent dissociative functional group, and
the ligand residues are dissociated from the quantum dots.
9. The light emitting element of claim 7 , wherein the quantum dot comprises:
a core; and
a shell surrounding the core, and
an interface between the core and the shell having a concentration gradient of an element that decreases toward the core.
10. The light emitting element of claim 7 , wherein
the ligand residues comprise at least one among a sulfonyl ion, a carbonyl ion, a phosphate ion, an ammonium ion, an oxy group, or an amine group.
11. The light emitting element of claim 7 , wherein
the ligand residues comprise a substituted or unsubstituted alkyl group having 6 to 30 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms.
12. The light emitting element of claim 7 , wherein the ligand residues comprise a hydrogen cation, a sodium cation, or a potassium cation.
13. The light emitting element of claim 7 , wherein the ligand residues comprise aliphatic or aromatic hydrocarbons connected to the polar solvent dissociative functional group.