Macromolecular thiol modified three-dimensional network packaged QDs (Quantum Dots) as well as preparation and application thereof

Abstract

Macromolecular mercaptan (such as tetrakis (3-mercaptobutyric acid) pentaerythritol ester, tetrakis (3-mercaptopropionic acid) pentaerythritol ester and the like) is introduced to the surface of the quantum dot with the netted encapsulation layer on the surface for modification, so that the defects on the surface of the quantum dot can be effectively reduced, the quantum dot can maintain higher quantum yield for a long time, and the quantum dot is more suitable for long-term industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of quantum dots of display technology, and specifically relates to a macromolecular thiol-modified three-dimensional mesh-encapsulated QDs and the preparation and application thereof. Background Art

[0002] Quantum dots (QDs for short), also known as nanocrystals, are currently widely used in displays. For example, quantum dot TVs are TVs that use quantum dot technology. The main difference between them and traditional LCD TVs is that they use different backlight sources. Quantum dot TVs use backlight sources containing quantum dot technology, which have more advantages than traditional LED backlight LCD TVs in terms of picture quality, energy saving and environmental protection.

[0003] But at the same time, quantum dots also have certain defects. For example, quantum dots themselves are sensitive to air or water vapor in the air and can be easily damaged by long-term contact. Therefore, more and more technologies are centered around the encapsulation of quantum dots in order to obtain quantum dots with higher air, water and other barrier effects while maintaining the basic stability of luminescence performance.

[0004] In the prior art, patent CN202210738688.8 discloses a quantum dot having a mesh encapsulation layer on the surface and a preparation method thereof, wherein a dithiol compound and a hexahalocyclotriphosphazene are subjected to a condensation reaction to form a mesh encapsulation layer on the surface of the quantum dot; patent CN202211295144.5 also discloses an encapsulated quantum dot and a preparation method thereof, wherein a dithiol compound and a diamide compound are simultaneously used as a linking group to undergo a condensation reaction with hexahalocyclotriphosphazene to form an encapsulation layer on the surface of the quantum dot; although these methods have achieved the relevant technical requirements to a certain extent, it was found in subsequent studies that the quantum dot surface containing the encapsulation layer formed therefrom has defects or gaps, which is specifically manifested in the luminescence aspect that the quantum yield will still decrease significantly under long-term high temperature and high humidity conditions, and technical improvements are still needed. Summary of the invention

[0005] The present invention provides a macromolecular thiol-modified three-dimensional mesh-encapsulated quantum dot, which includes quantum dots dispersed in an encapsulation layer and an encapsulation layer; In the present invention, the encapsulation layer is located on the surface of the quantum dots; In the present invention, the encapsulation layer is obtained by polycondensation reaction of 1,2-propanedithiol and hexahalocyclotriphosphazene; or, The encapsulation layer is obtained by polycondensation reaction of HS(CHOH)2SH, 1,4-phenylenediamine and hexahalocyclotriphosphazene; The macromolecular thiol is modified on the encapsulation layer; The present invention also provides a method for preparing macromolecular thiol-modified three-dimensional mesh-encapsulated quantum dots, the preparation method comprising the following steps: Add 1,2-propanedithiol and hexahalocyclotriphosphazene into an organic solvent, add quantum dots, add a base, carry out polycondensation reaction, add macromolecular thiol to continue the reaction, add distilled water for sedimentation, and centrifuge to obtain encapsulated quantum dots; or, HS(CHOH)2SH, 1,4-phenylenediamine, and hexahalocyclotriphosphazene are added to an organic solvent, quantum dots are added, a base is added, a polycondensation reaction is carried out, a macromolecular thiol is added to continue the reaction, distilled water is added for sedimentation, and encapsulated quantum dots are obtained by centrifugation; In the present invention, the hexahalogenated cyclotriphosphazene is hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, hexabromocyclotriphosphazene or hexaiodocyclotriphosphazene, preferably hexachlorocyclotriphosphazene; Wherein, the molar ratio of 1,2-propanedithiol to hexahalocyclotriphosphazene may be 3:1; Wherein, the molar ratio of HS(CHOH)2SH, 1,4-phenylenediamine and hexahalocyclotriphosphazene can be 2:1:1; In the present invention, the quantum dots are selected from one or more of CdSe / ZnS, InP / ZnS, ZnCdSe, CsPbBr3, CsPbI3, CdSe, PbSe / PbS, CdSe / CdS, CdTe / CdS, CdTe / ZnS, and CdS / ZnS; preferably ZnCdSe; In the present invention, the weight / amount ratio (g / mol) of the quantum dots to the hexahalocyclotriphosphazene may be 40; In the present invention, the macromolecular thiol is selected from one or both of tetrakis(3-mercaptobutyric acid)pentaerythritol ester and tetrakis(3-mercaptopropionic acid)pentaerythritol ester; The molar ratio of the macromolecular thiol to the hexahalocyclotriphosphazene may be 0.1-2:5, preferably 1:5; In some embodiments, the base is selected from sodium hydroxide, potassium hydroxide or triethylamine; In some embodiments, the organic solvent is selected from tetrahydrofuran or xylene, preferably tetrahydrofuran; In some embodiments, the reaction temperature of the polycondensation reaction is 20 to 50°C, preferably 40°C; In some embodiments, the polycondensation reaction time is 10 min to 60 min, preferably 30 min; In some embodiments, the continued reaction time is 5 min to 30 min, preferably 10 min; The present invention also provides an application of macromolecular thiol-modified three-dimensional mesh-encapsulated quantum dots, which is used for making quantum dot optical films or display devices.

[0006] The present invention introduces macromolecular thiol to modify the surface of quantum dots having a mesh encapsulation layer, which can effectively reduce the defects on the surface of the quantum dots, so that the quantum dots can maintain a high quantum yield for a long time and are more suitable for long-term industrial applications. DETAILED DESCRIPTION

[0007] Comparative Example 1 1) Selenium powder (11.9 mg, 0.15 mmol) was placed in 1.5 mL of trioctylphosphine (TOP) and subjected to ultrasonic oscillation to obtain a selenium precursor solution. Cadmium oxide (12.8 mg, 0.1 mmol) and zinc laurate (46.4 mg, 0.1 mmol) were used as precursors, 3 mL of oleic acid, 3 mL of oleylamine and 3 mL of octadecene were used as solvents, the mixture was heated to 150 °C under nitrogen protection and mixed to form a precursor solution. The selenium precursor solution was quickly injected into the above precursor solution, the mixture was heated to 250 °C, reacted for 15 min, cooled to room temperature naturally, 55 mL of ethyl acetate was added for precipitation, and the mixture was centrifuged to obtain ZnCdSe alloy core QDs.

[0008] 2) In a nitrogen box, add 1,2-propanedithiol (81.1 mg, 0.75 mmol) and hexachlorocyclotriphosphazene (87.0 mg, 0.25 mmol) to 20 mL of tetrahydrofuran, add 10 mg of the ZnCdSe alloy core QDs prepared in step 1), add 65 mg of sodium hydroxide, stir well at 40 ° C and 1500 rpm for 30 min, cool to room temperature, add 20 mL of distilled water for precipitation, and centrifuge to obtain quantum dots with a mesh encapsulation layer on the surface.

[0009] Comparative Example 2 1) Selenium powder (11.9 mg, 0.15 mmol) was placed in 1.5 mL of trioctylphosphine (TOP) and subjected to ultrasonic oscillation to obtain a selenium precursor solution. Cadmium oxide (12.8 mg, 0.1 mmol) and zinc laurate (46.4 mg, 0.1 mmol) were used as precursors, 3 mL of oleic acid, 3 mL of oleylamine and 3 mL of octadecene were used as solvents, the mixture was heated to 150 °C under nitrogen protection and mixed to form a precursor solution. The selenium precursor solution was quickly injected into the above precursor solution, the mixture was heated to 250 °C, reacted for 15 min, cooled to room temperature naturally, 55 mL of ethyl acetate was added for precipitation, and the mixture was centrifuged to obtain ZnCdSe alloy core QDs.

[0010] 2) In a nitrogen box, HS(CHOH)2SH (126.0 mg, 1.0 mmol), 1,4-phenylenediamine (54.1 mg, 0.5 mmol), and hexachlorocyclotriphosphazene (173.8 mg, 0.5 mmol) were added to 40 mL of tetrahydrofuran, and 20 mg of the ZnCdSe alloy core QDs prepared in step 1) was added. Then, 130 mg of sodium hydroxide was added, and the mixture was stirred at 40 °C and 1500 rpm for 30 min. The mixture was cooled to room temperature, and 40 mL of distilled water was added for precipitation. The encapsulated quantum dots were obtained by centrifugation.

[0011] Example 1 1) Selenium powder (11.9 mg, 0.15 mmol) was placed in 1.5 mL of trioctylphosphine (TOP) and subjected to ultrasonic oscillation to obtain a selenium precursor solution. Cadmium oxide (12.8 mg, 0.1 mmol) and zinc laurate (46.4 mg, 0.1 mmol) were used as precursors, 3 mL of oleic acid, 3 mL of oleylamine and 3 mL of octadecene were used as solvents, the mixture was heated to 150 °C under nitrogen protection and mixed to form a precursor solution. The selenium precursor solution was quickly injected into the above precursor solution, the mixture was heated to 250 °C, reacted for 15 min, cooled to room temperature naturally, 55 mL of ethyl acetate was added for precipitation, and the mixture was centrifuged to obtain ZnCdSe alloy core QDs.

[0012] 2) In a nitrogen box, 1,2-propanedithiol (81.1 mg, 0.75 mmol) and hexachlorocyclotriphosphazene (87.0 mg, 0.25 mmol) were added to 20 mL of tetrahydrofuran, 10 mg of the ZnCdSe alloy core QDs prepared in step 1) was added, and 65 mg of sodium hydroxide was added. The mixture was stirred at 40 °C and 1500 rpm for 30 min, and a solution of pentaerythritol tetrakis(3-mercaptobutyrate) (27.2 mg, 0.05 mmol) in tetrahydrofuran (5 mL) was added. The mixture was stirred for 10 min, cooled to room temperature, and 20 mL of distilled water was added for precipitation. The quantum dots with a mesh encapsulation layer on the surface were obtained by centrifugation.

[0013] Fluorescence detection was performed, and the fluorescence emission peak was 521 nm and the half-peak width was 18 nm.

[0014] Example 2 According to the method of Example 1, only the tetrahydrofuran (5 mL) solution of pentaerythritol tetrakis(3-mercaptobutyrate) (27.2 mg, 0.05 mmol) was replaced with the tetrahydrofuran (5 mL) solution of pentaerythritol tetrakis(3-mercaptopropionate) (24.4 mg, 0.05 mmol) to obtain quantum dots with a mesh encapsulation layer on the surface.

[0015] Fluorescence detection was performed, and the fluorescence emission peak was 523 nm, with a half-peak width of 20 nm.

[0016] Example 3 1) Selenium powder (11.9 mg, 0.15 mmol) was placed in 1.5 mL of trioctylphosphine (TOP) and subjected to ultrasonic oscillation to obtain a selenium precursor solution. Cadmium oxide (12.8 mg, 0.1 mmol) and zinc laurate (46.4 mg, 0.1 mmol) were used as precursors, 3 mL of oleic acid, 3 mL of oleylamine and 3 mL of octadecene were used as solvents, the mixture was heated to 150 °C under nitrogen protection and mixed to form a precursor solution. The selenium precursor solution was quickly injected into the above precursor solution, the mixture was heated to 250 °C, reacted for 15 min, cooled to room temperature naturally, 55 mL of ethyl acetate was added for precipitation, and the mixture was centrifuged to obtain ZnCdSe alloy core QDs.

[0017] 2) In a nitrogen box, HS(CHOH)2SH (126.0 mg, 1.0 mmol), 1,4-phenylenediamine (54.1 mg, 0.5 mmol), and hexachlorocyclotriphosphazene (173.8 mg, 0.5 mmol) were added to 40 mL of tetrahydrofuran, 20 mg of the ZnCdSe alloy core QDs prepared in step 1) were added, and 130 mg of sodium hydroxide was added. The mixture was stirred at 40 °C and 1500 rpm for 30 min, and a solution of pentaerythritol tetrakis(3-mercaptobutyrate) (54.4 mg, 0.1 mmol) in tetrahydrofuran (10 mL) was added. The mixture was stirred for 10 min, cooled to room temperature, 40 mL of distilled water was added for precipitation, and the encapsulated quantum dots were obtained by centrifugation.

[0018] Fluorescence detection was performed, and the fluorescence emission peak was 519 nm and the half-peak width was 21 nm.

[0019] Example 4 According to the method of Example 3, only the tetrahydrofuran (10 mL) solution of pentaerythritol tetrakis(3-mercaptobutyrate) (54.4 mg, 0.1 mmol) was replaced with the tetrahydrofuran (10 mL) solution of pentaerythritol tetrakis(3-mercaptopropionate) (48.8 mg, 0.1 mmol) to obtain quantum dots with a mesh encapsulation layer on the surface.

[0020] Fluorescence detection was performed, and the fluorescence emission peak was 522 nm and the half-peak width was 19 nm.

[0021] Test Case The changes in quantum yield of the quantum dots of Comparative Examples 1-2 and Examples 1-4 were tested under high temperature and high humidity conditions for a long time (720 hours); The high temperature and high humidity conditions are: 85°C and 95% relative humidity; In the present invention, the quantum yield is measured by an absolute fluorescence quantum yield spectrometer; The measurement results are shown in Table 1 below: Through the above tests, it can be found that when preparing quantum dots with a mesh encapsulation layer on the surface, introducing macromolecular thiols (such as pentaerythritol tetrakis (3-mercaptobutyrate), pentaerythritol tetrakis (3-mercaptopropionic acid), etc.) into the system for modification can effectively reduce the defects on the surface of the quantum dots, so that they can maintain a high quantum yield for a long time. For example, the quantum yield of Examples 1-4 is significantly higher than that of the unmodified comparative example 1-2 after a long period of high temperature and high humidity; and it is also found that the modification method has a better effect on the mesh encapsulated quantum dots constructed with a binary system of dithiols and hexahalocyclotriphosphazenes than the mesh encapsulated quantum dots constructed with a ternary system of dithiols, diamides and hexahalocyclotriphosphazenes, for example, the effect of Example 1-2 is better than that of Example 3-4 as a whole; in addition, for macromolecular thiols, the overall effect of using pentaerythritol tetrakis (3-mercaptobutyrate) is better than that of using pentaerythritol tetrakis (3-mercaptopropionic acid), etc., for example, the effect of Example 3 is better than that of Example 4.

[0022] The embodiments described above are only preferred implementations of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principles of the present invention, and these improvements should also be regarded as within the scope of protection of the present invention.

Claims

1. A macromolecular thiol-modified three-dimensional network-encapsulated quantum dot, comprising quantum dots dispersed in an encapsulation layer and an encapsulation layer; The encapsulation layer is located on the surface of the quantum dots; The encapsulation layer is obtained by polycondensation reaction of 1,2-propanedithiol and hexahalocyclotriphosphazene; or, The encapsulation layer is obtained by polycondensation reaction of HS(CHOH)2SH, 1,4-phenylenediamine and hexahalocyclotriphosphazene; The macromolecular thiol is modified on the encapsulation layer; The macromolecular thiol is selected from one or both of tetrakis(3-mercaptobutyric acid)pentaerythritol ester and tetrakis(3-mercaptopropionic acid)pentaerythritol ester.

2. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 1, wherein: The molar ratio of 1,2-propanedithiol to hexahalocyclotriphosphazene is 3:1; or, The molar ratio of HS(CHOH)2SH, 1,4-phenylenediamine and hexahalocyclotriphosphazene is 2:1:

1.

3. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 1, wherein: The quantum dots are selected from one or more of CdSe / ZnS, InP / ZnS, ZnCdSe, CsPbBr3, CsPbI3, CdSe, PbSe / PbS, CdSe / CdS, CdTe / CdS, CdTe / ZnS, and CdS / ZnS.

4. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 1, wherein: The molar ratio of the macromolecular thiol to the hexahalocyclotriphosphazene is 0.1-2:

5.

5. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 4, wherein: The molar ratio of the macromolecular thiol to the hexahalocyclotriphosphazene is 1:

5.

6. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 4, wherein: The hexahalogenated cyclotriphosphazene is hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, hexabromocyclotriphosphazene or hexaiodocyclotriphosphazene.

7. The macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to claim 6, wherein: The hexahalogenocyclotriphosphazene is hexachlorocyclotriphosphazene.

8. A method for preparing macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to any one of claims 1 to 7, the method comprising the following steps: Add 1,2-propanedithiol and hexahalocyclotriphosphazene into an organic solvent, add quantum dots, add a base, carry out polycondensation reaction, add macromolecular thiol to continue the reaction, add distilled water for sedimentation, and centrifuge to obtain encapsulated quantum dots; or, HS(CHOH)2SH, 1,4-phenylenediamine, and hexahalocyclotriphosphazene are added to an organic solvent, quantum dots are added, a base is added, a polycondensation reaction is carried out, a macromolecular thiol is added to continue the reaction, distilled water is added for sedimentation, and encapsulated quantum dots are obtained by centrifugation.

9. Use of the macromolecular thiol-modified three-dimensional network-encapsulated quantum dots according to any one of claims 1 to 7 or the macromolecular thiol-modified three-dimensional network-encapsulated quantum dots prepared according to claim 8 for making quantum dot optical films or display devices.

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