Quantum dot material and preparation method, quantum dot light-emitting diode and preparation method

1 . A quantum dot material, comprising:

quantum dot particles, and

a first ligand directly bonded to a surface of the quantum dot particles, wherein

the first ligand is an organic monomer used to form a metal-organic framework (MOF), and the organic monomer comprises at least three first active groups bonded to the quantum dot particles, whereby forming superlattice structure quantum dots with a framework structure similar to the MOF;

the quantum dot material further comprises: a second ligand bonded to the surface of the quantum dot particles, wherein the second ligand is selected from at least one of 2-aminoanthracene, biphenylmonoacetic acid, 4,4-stilbene dicarboxylic acid, biphenylmonoacetic acid, or 4,4-stilbene dicarboxylic acid, the second ligand comprises a second active group bonded to the quantum dot particles, and a molar ratio of the first ligand to the second ligand is about 1:0.95~1.05.

2 . The quantum dot material according to claim 1 , wherein:

the first ligand is selected from compounds having a structure shown in following Formula 1, wherein X 1 , X 2 , and X 3 are first active groups and are same or different:

and

the first active group is selected from one of a hydroxyl group, a carboxyl group, a mercapto group, and an amino group.

3 . The quantum dot material according to claim 1 , further comprising:

a third ligand bonded to the surface of the quantum dot particles, wherein the third ligand is a compound with a general structural formula shown in Formula 5, X 7 is a third active group bonded to the quantum dots, R 1 is —(CH 2 ) m —, m is a positive integer, and m is approximately in the range of 1-10, and

4 . The quantum dot material according to claim 3 , wherein:

the third active group is selected from one of a hydroxyl group, a carboxyl group, a mercapto group, and an amino group; and/or

the third ligand is selected from at least one of suberic acid, pimelic acid, or azelaic acid.

5 . The quantum dot material according to claim 1 , further comprising:

a fourth ligand bonded to the surface of the quantum dot particles, wherein the fourth ligand is a compound with a general structural formula shown in Formula 6, R 2 is selected from carbon having number of atoms ranging approximately from 1 to 6, one end of R 2 includes a substituent of a fourth active group bonded to the quantum dot particles, the fourth ligand is cross-linked by a double-bond polymerization reaction to form a network structure, and

6 . The quantum dot material according to claim 5 , wherein:

the fourth active group is selected from one of a hydroxyl group, a carboxyl group, a mercapto group, and an amino group; and/or

the fourth ligand is selected from at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, or hydroxybutyl methacrylate.

7 . A quantum dot light-emitting diode, comprising:

an anode;

a cathode arranged opposite to the anode;

a quantum dot light-emitting layer disposed between the anode and the cathode; and

an electron transport layer disposed between the quantum dot layer and the cathode;

wherein a material of the quantum dot light-emitting layer is the quantum dot material according to claim 1 .

8 . A method for preparing the quantum dot material according to claim 1 , the method comprising:

in an inert gas atmosphere, providing a fatty acid solution of a first ligand, and first quantum dots;

mixing the fatty acid solution of the first ligand and the first quantum dots to form a mixed solution system, and performing a ligand exchange reaction under a first heating condition to prepare second quantum dots with the first ligand bonded to a surface of the second quantum dots; and

mixing the second quantum dots with the first ligand bonded to the surface of the second quantum dots and the fatty acid solution of a second ligand, and performing the ligand exchange reaction under a second heating condition to prepare third quantum dots with the first ligand and the second ligand bonded to a surface of the third quantum dots at the same time;

wherein a reactivity between the second active group and quantum dots is less than a reactivity between the first active group and the quantum dots.

9 . The method for preparing the quantum dot material according to claim 8 , wherein:

the first ligand is selected from compounds having a structure shown in Formula 1 below, wherein X 1 , X 2 , and X 3 are first active groups and are same or different,

10 . The method for preparing the quantum dot material according to claim 8 , wherein:

when mixing the fatty acid solution of the first ligand and the first quantum dots to form the mixed solution system, the mixed solution system is configured according to a molar ratio of the first ligand to the first quantum dots in the range of 50~100:1; and

mixing the fatty acid solution of the first ligand and the first quantum dots to form the mixed solution system includes separately configuring a fatty acid solvent of the first ligand and a non-polar solution of the first quantum dots, and mixing them to obtain the mixed solution system; and/or performing the ligand exchange reaction under the first heating condition, wherein a temperature of the first heating condition is approximately between 100° C. and 200° C., and a reaction time of the ligand exchange reaction is approximately between 20 min and 40 min.

11 . The method for preparing the quantum dot material according to claim 8 , further comprising after preparing the second quantum dots with the first ligand bonded to the surface of the second quantum dots:

mixing the second quantum dots with the first ligand bonded to the surface of the second quantum dots and the fatty acid solution of a second ligand, and performing the ligand exchange reaction under a second heating condition to prepare third quantum dots with the first ligand and the second ligand bonded to a surface of the third quantum dots at the same time;

wherein the second ligand is a compound having at least two benzene rings, the second ligand includes a second active group bonded to quantum dot particles of the third quantum dots, and a reactivity between the second active group and quantum dots is less than a reactivity between the first active group and the quantum dots.

12 . The method for preparing the quantum dot material according to claim 8 , wherein:

when mixing the second quantum dots with the first ligand bonded to the surface and the fatty acid solution of the second ligand, the second quantum dots and the second ligand are mixed according to a molar ratio of the second ligand to the second quantum dots in the range of 1:1~10:1; and/or

when performing the ligand exchange reaction under the first heating condition, the reaction temperature of the first heating condition is in the range of 100° C.~200° C., and the reaction time of the ligand exchange reaction is in the range of 4 h~8 h, and when performing the ligand exchange reaction under the second heating condition, the reaction temperature of the first heating condition is in the range of 100° C.~150° C., and the reaction time of the ligand exchange reaction is in the range of 8 h~16 h.

13 . The method for preparing the quantum dot material according to claim 8 , further comprising after performing the ligand exchange reaction under the second heating condition:

dispersing the obtained reaction system in a polar solvent and collecting the third quantum dot precipitation;

dissolving the obtained third quantum dots in a non-polar solvent and repeating at least once and collecting the third quantum dots; and

providing a third quantum dot solution and adding the second ligand into the third quantum dot solution.

14 . The method for preparing the quantum dot material according to claim 8 , wherein:

the first quantum dots are bonded with a third ligand to a surface of the first quantum dots, and the second quantum dots are bonded with the first ligand and the second ligand to the surface of the second quantum dots at the same time, wherein the third ligand is a compound with a general structural formula shown in Formula 5, X 7 is a third active group bonded to the quantum dots, R 1 is —(CH 2 ) m —, m is a positive integer, and m is approximately in the range of 1-10, and

and preparing the first quantum dots includes:

in the inert gas atmosphere, providing a mixed solution system of a fatty acid solution of compound A and initial quantum dots, and performing a ligand exchange reaction under a third heating condition to prepare quantum dots with compound A bonded to a surface of the quantum dots, wherein the general formula of the structure of compound A is as follows, X 7 is the third active group bonded to the quantum dot, R 1 is —(CH 2 ) m —, R 3 is a linear C s H 2s+1 , m and s are positive integers, s+m is in the range of 2~12, and

and

hydrolyzing the compound A on the surface of the quantum dots to obtain the first quantum dots with the third ligand bonded to the surface.

15 . The method for preparing the quantum dot material according to claim 14 , wherein:

when performing the ligand exchange reaction under the third heating condition, the reaction temperature of the first heating condition is in the range of 100° C.~150° C., and the reaction time of the ligand exchange reaction is in the range of 1 h~2 h, and when performing the ligand exchange reaction under the first heating condition, the reaction temperature of the first heating condition is in the range of 100° C.~200° C., and the reaction time of the ligand exchange reaction is in the range of 8 h~16 h; and/or

providing the mixed solution system of the fatty acid solution of the compound A and the initial quantum dots includes: separately configuring a fatty acid solvent of the compound A and a non-polar solution of the initial quantum dots, and mixing them to obtain the mixed solution system.

16 . The method for preparing the quantum dot material according to claim 8 , wherein:

the first quantum dots are bonded with a fourth ligand to the surface of the first quantum dots, and the second quantum dots are bonded with the first ligand and the fourth ligand to the surface of the second quantum dots at the same time, wherein the fourth ligand is a compound with a general structural formula shown in Formula 6, R 2 is selected from carbon having number of atoms ranging approximately from 1 to 6, one end of R 2 includes a substituent of a fourth active group bonded to the quantum dot particles, the fourth ligand is cross-linked by a double-bond polymerization reaction to form a network structure, and

preparing the first quantum dots includes: in the inert gas atmosphere, providing a mixed solution system of a fatty acid solution of the fourth ligand and initial quantum dots, and performing a ligand exchange reaction under a fourth heating condition to prepare the first quantum dots with the fourth ligand bonded to the surface of the first quantum dots; and

after performing the ligand exchange reaction under the fourth heating condition, the method further includes: adding a mixed solution including an initiator and a cross-linking agent, and polymerizing the fourth ligand on the surface of the second quantum dots through heating to prepare the second quantum dots bonded with the first ligand and the fourth ligand at the same time.