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US-20260125594-A1 - QUANTUM DOT-CONTAINING COMPOSITION AND METHOD FOR PRODUCING THE SAME

US20260125594A1US 20260125594 A1US20260125594 A1US 20260125594A1US-20260125594-A1

Abstract

A quantum dot-containing composition including quantum dots dispersed in a resin composition, the quantum dots emitting fluorescence by excitation light. The quantum dots include a ligand coordinated to the surface thereof and a surface coating layer bonded to the ligand and containing a siloxane bond, and the surface coating layer contains at least one of substituents of a polymer contained in the resin composition, substituents polymerizable with a polymer contained in the resin composition, and compounds having the same skeleton structure as the polymer. This provides a quantum dot-containing composition that has an enhanced stability and improved compatibility with highly polar solvents and photosensitive resin compositions while maintaining the properties of quantum dots, as well as a method for producing such a quantum dot-containing composition.

Inventors

  • Shinji Aoki
  • Hitoshi Maruyama
  • Yoshihiro Nojima
  • Kazuya TOBISHIMA

Assignees

  • SHIN-ETSU CHEMICAL CO., LTD.

Dates

Publication Date
20260507
Application Date
20230926
Priority Date
20221005

Claims (16)

  1. 1 - 9 . (canceled)
  2. 10 . A quantum dot-containing composition comprising: quantum dots dispersed in a resin composition, the quantum dots emitting fluorescence by excitation light, wherein the quantum dots include a ligand coordinated to a surface thereof and a surface coating layer bonded to the ligand and containing a siloxane bond, and the surface coating layer contains at least one of substituents of a polymer contained in the resin composition, substituents polymerizable with a polymer contained in the resin composition, and compounds having a same skeleton structure as the polymer.
  3. 11 . The quantum dot-containing composition according to claim 10 , wherein the quantum dots contain a quantum dot core selected from the group consisting of II-VI, III-V, IV, IV-VI, I-III-VI and II-IV-V groups, mixed crystals and alloys thereof, and compounds having a perovskite structure.
  4. 12 . The quantum dot-containing composition according to claim 11 , wherein the quantum dots contain a core-shell quantum dot having the quantum dot core coated with a shell with a larger band gap than the quantum dot core.
  5. 13 . The quantum dot-containing composition according to claim 10 , wherein the ligand includes one or more of an amino group, a thiol group, a carboxy group, a phosphino group, a phosphine oxide group, and an ammonium ion.
  6. 14 . The quantum dot-containing composition according to claim 10 , wherein the substituents of a polymer contained in the resin composition are one or more of a vinyl group, an acrylic group, a methacrylic group, a hydroxy group, a phenolic hydroxy group, and an epoxy group.
  7. 15 . The quantum dot-containing composition according to claim 10 , wherein the substituents polymerizable with a polymer contained in the resin composition are one or more of a vinyl group, an acrylic group, a methacrylic group, a hydroxy group, a phenolic hydroxy group, and an epoxy group.
  8. 16 . The quantum dot-containing composition according to claim 10 , wherein the same skeleton structure as the polymer is a skeleton structure derived from acrylic acid, methacrylic acid, acrylic acid esters or methacrylic acid esters, a silphenylene skeleton, a norbornene skeleton, a fluorene skeleton, or an isocyanurate skeleton.
  9. 17 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 10 .
  10. 18 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 11 .
  11. 19 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 12 .
  12. 20 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 13 .
  13. 21 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 14 .
  14. 22 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 15 .
  15. 23 . A wavelength conversion member comprising a cured product of the quantum dot-containing composition according to claim 16 .
  16. 24 . A method for producing the quantum dot-containing composition according to claim 10 containing quantum dots that emit fluorescence by excitation light, the method comprising: a ligand exchange step of mixing a solution in which the quantum dots are dispersed with a ligand having a siloxane bond-forming substituent to thereby coordinate the ligand to an outermost surface of the quantum dots; a surface coating layer formation step of initiating, after the ligand exchange step, a reaction between the siloxane bond-forming substituent and a compound that reacts with the siloxane bond-forming substituent to generate polysiloxane, to thereby form a surface coating layer; and a resin composition mixing step of mixing, after the surface coating layer formation step, the quantum dots coated with the surface coating layer with the resin composition.

Description

TECHNICAL FIELD The present invention relates to a quantum dot-containing composition and a method for producing the same. BACKGROUND ART When the crystal size of semiconductor nanoparticle single crystals becomes smaller than or equal to the Bohr radius of excitons, a strong quantum confinement effect occurs, resulting in discrete energy levels discrete. This makes the energy levels dependent on the crystal size, allowing for adjusting the light absorption wavelength and the emission wavelength based on the crystal size. Additionally, the quantum confinement effect enhances the efficiency of light emission resulting from exciton recombination in the semiconductor nanoparticle single crystals, and this emission is basically characterized by emission lines. Thus, achieving a uniform particle size distribution would enable high-brightness, narrow-band emission. This is why semiconductor nanoparticle single crystals are gaining significant attention. The phenomenon caused by such a strong quantum confinement effect in nanoparticles is called the quantum size effect, and semiconductor nanoparticle single crystals that exploit this property, known as quantum dots, have been explored for their applications to a wide range of fields. One application of quantum dots being explored is their use in a fluorescent material for displays. Achieving narrow-band and high-efficiency emission would enable the representation of colors that could not be reproduced with any existing technologies. This is why quantum dots are gaining attention as a next-generation display material. Displays for which the use of quantum dots have been currently promoted include quantum dot liquid crystal displays, which are already being commercialized. Attempts have been made to convert white light or light emitted from a blue LED backlight to green or red by passing it through a quantum dot-containing wavelength conversion member. The surface of quantum dots is active, and the quantum yield gradually decreases due to moisture and oxygen in the atmosphere, so that enhancing the stability is an essential issue to consider for quantum dot-containing wavelength conversion members. Various studies have been conducted on how to improve the stability of quantum dot-containing wavelength conversion members. One example approach is gas barrier sealing. This approach enhances the stability by forming an inner layer in which quantum dots are dispersed in an amphiphilic polymer or compatible polymer and by further dispersing quantum dots in another resin layer with low gas permeability. Patent Document 1 discloses a method of forming polymer beads by dispersing quantum dots (QDs) in a hydrophobic resin layer, modifying the surface of the polymer beads to allow them to be dispersed in a hydrophilic polymer, and dispersing them in the hydrophilic polymer. Hydrophilic polymers tend to have higher gas barrier properties than hydrophobic polymers, so that QDs are dispersed in such a bilayer or multilayer structure. However, the gas barrier properties are insufficient for use in applications where high temperatures and high humidity conditions are expected, such as in liquid crystal display units. Thus, a method is adopted in which the QD film is sandwiched between gas barrier films to remove the effects of oxygen and water vapor. Various studies have also been conducted on how to fabricate polymer beads. Patent Document 2 discloses a method of fabricating QD-containing polymer beads from polysiloxane having an amino group and a polymerizable functional group and mixing them with a polymer having another polymerizable functional group to create an emulsion, followed by further curing it. This method uses a polymer incorporating ligands that coordinate to the surface of the QDs to enhance the adhesion to the QDs, which can increase the concentration of QDs contained in the polymer beads and thus enhance the stability. However, even with this method, the stability is still insufficient, and so the QD layer is sandwiched between barrier films for implementation. Also Patent Document 3 discloses, which explores a method for improving heat and moisture resistance without using barrier films. In this method, silazane coating treatment is further applied to the multilayer resin composition incorporating the polymer beads structure disclosed in Patent Document 1, thereby enhancing the stability. Patent Document 4 discloses still another approach. In this method, ligands coordinate to quantum dots, and reactive substituents such as vinyl and methacrylic groups introduced into the ligands. Then, a Si—H containing silicone resin and a curing agent are mixed, and the mixture is directly spin-coated and heat-cured to fabricate a film with improved heat and moisture resistance. For application to color filters, it is important to create a quantum dot surface condition that is suitable for the patterning method used. Currently, photolithography methods are in practical use for