Quantum dot light-emitting diode and fabrication method thereof

1 . A quantum dot light-emitting diode (QLED), comprising:

a quantum dot (QD) layer;

an electron transport layer formed on the QD layer, wherein a surface of a side of the QD layer close to the electron transport layer is replaced with an ester substance and is in a polar state; and a rest area of the QD layer remains a non-polar ligand and is in a non-polar state;

a surface the QD layer away from the electron transport layer bonds to a first ligand;

the ester substance is formed through an esterification reaction of a second ligand and a third ligand;

one end of a carbon chain of the second ligand is a sulfhydryl group, and another end is a carboxyl group, and the second ligand bonds to the surface of the QD layer through the sulfhydryl group; and

one end of the carbon chain of the third ligand is a sulfhydryl group, and another end is a hydroxyl group, and the third ligand bonds to the surface of the QD layer through the sulfhydryl group.

2 . The QLED of claim 1 , wherein a carbon chain length of the first ligand is same as a carbon chain length of the second ligand and a carbon chain length of the third ligand forming the ester substance.

3 . The QLED of claim 1 , wherein a molar ratio of the second ligand to the third ligand is 1:1.

4 . The QLED of claim 1 , wherein the first ligand includes at least one of an organic carboxylic acid with 8 or more carbon atoms, a primary amine with 8 or more carbon atoms, a secondary or tertiary amine with 4 or more branched carbon atoms, or an organophosphine with 4 or more branched carbon atoms.

5 . The QLED according to claim 1 , further comprising:

a substrate;

an anode and a cathode formed on the substrate;

a hole injection layer formed between the anode and the QD layer; and

a hole transport layer formed between the hole injection layer and the QD layer;

wherein the electron transport layer is located between the QD layer and the cathode.

6 . The QLED according to claim 4 , wherein the organic carboxylic acid includes at least one of caprylic acid, nonanoic acid, capric acid, undecyl acid, dodecyl acid, tridecyl acid, tetradecyl acid, hexadecyl acid, octadecyl acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, or octadecenoic acid.

7 . The QLED according to claim 4 , wherein the primary amine includes at least one of octylamine, nonylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, or octadecylamine.

8 . The QLED of claim 4 , wherein the secondary or tertiary amine includes at least one of tributylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, or tridecylamine.

9 . The QLED according to claim 4 , wherein the organic phosphine includes at least one of tributylphosphine, trihexylphosphine, triheptylphosphine, trioctylphosphine, trinonylphosphine, or tridecylphosphine.

10 . A fabrication method of quantum dot light-emitting diode (QLED), comprising:

providing a quantum dot (QD) layer having a first ligand bonding to both two surfaces of the QD layer;

under a vacuum condition, using a second ligand and a third ligand to perform ligand exchange with the first ligand located on one of the two surfaces of the QD layer; and

making the second ligand and the third ligand to undergo an esterification reaction to obtain the QD layer having a surface bonding to an ester substance; and

forming an electron transport layer on the surface of the QD layer to which the ester substance bonds, wherein the surface of a side of the QD layer close to the electron transport layer is replaced with the ester substance and is in a polar state; and a rest area of the QD layer remains a non-polar ligand and is in a non-polar state,

wherein one end of a carbon chain of the second ligand is a sulfhydryl group, and another end is a carboxyl group, and the second ligand bonds to the surface of the QD layer through the sulfhydryl group; and

one end of the carbon chain of the third ligand is a sulfhydryl group, and another end is a hydroxyl group, and the third ligand bonds to the surface of the QD layer through the sulfhydryl group.

11 . The fabrication method of the QLED according to claim 10 , wherein a ratio of a total volume of the second ligand and the third ligand to a mass of QDs is 0.01-10:1 mL/mg.

12 . The fabrication method of the QLED according to claim 10 , wherein making the second ligand and the third ligand to undergo the esterification reaction includes:

under a catalysis of an inorganic acid, making the second ligand and the third ligand to undergo the esterification reaction, wherein a temperature of the esterification reaction is 50-180° C., and a time of the esterification reaction is 0.5-4 hour.

13 . The fabrication method of the QLED according to claim 10 , further comprising:

depositing an anode on a substrate;

depositing a hole injection layer on the anode;

depositing a hole transport layer on the hole injection layer;

providing the QD layer having the surface bonding to the ester substance and depositing the QD layer on the hole transport layer;

forming the electron transport layer on the QD layer; and

depositing a cathode on the electron transport layer.

14 . The fabrication method of the QLED according to claim 10 , further comprising:

depositing a cathode on a substrate;

depositing the electron transport layer on the cathode;

providing, on the electron transport layer, the QD layer having the surface bonding to an ester substance;

depositing a hole transport layer on the QD layer,

depositing a hole injection layer on the hole transport layer; and

depositing an anode on the hole injection layer.