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WO2019065435A1 - Encre et élément électroluminescent - Google Patents

Encre et élément électroluminescent Download PDF

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Publication number
WO2019065435A1
WO2019065435A1 PCT/JP2018/034772 JP2018034772W WO2019065435A1 WO 2019065435 A1 WO2019065435 A1 WO 2019065435A1 JP 2018034772 W JP2018034772 W JP 2018034772W WO 2019065435 A1 WO2019065435 A1 WO 2019065435A1
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Prior art keywords
ink
dispersion medium
light emitting
nanocrystals
group
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PCT/JP2018/034772
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English (en)
Japanese (ja)
Inventor
徹 鶴田
栄志 乙木
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Dic株式会社
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Priority to JP2019545021A priority Critical patent/JP6849089B2/ja
Publication of WO2019065435A1 publication Critical patent/WO2019065435A1/fr

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source

Definitions

  • the present invention relates to an ink and a light emitting device.
  • Devices utilizing electroluminescence are widely used as light sources for various display devices and the like.
  • a light emitting element using a semiconductor nanocrystal having a light emitting property such as a quantum dot or a quantum rod as a light emitting material has attracted attention.
  • the light emission obtained from the semiconductor nanocrystal has a smaller spectrum width and a wider color gamut than the organic EL element, and thus is excellent in color reproducibility.
  • the light emitting layer in this light emitting element is formed by discharging a dispersion liquid in which semiconductor nanocrystals are dispersed in a dispersion medium as droplets from the nozzle hole (see, for example, Patent Document 1).
  • semiconductor nanocrystals generally carry an organic ligand on their surface, but the bonding strength of the organic ligand to the semiconductor nanocrystal is not so great. Therefore, when peroxide is formed in the dispersion, the organic ligand is easily detached from the semiconductor nanocrystal by the action of the peroxide. As a result, the semiconductor nanocrystals aggregate and a phenomenon (self-absorption phenomenon) occurs in which the semiconductor nanocrystals absorb light emitted by the adjacent semiconductor nanocrystals. As a result, the light emission efficiency of the obtained light emitting layer is lowered.
  • An object of the present invention is to provide an ink capable of preventing a decrease in light emission efficiency due to a self absorption phenomenon, and a light emitting device having high light emission efficiency.
  • the second dispersion medium is at least one compound selected from the group consisting of an aromatic ester compound, an aromatic ether compound and an aliphatic ester compound each having a surface tension of more than 32 mN / m ((4) The ink according to any one of 1) to 3).
  • the dispersion medium having the highest boiling point at atmospheric pressure is the first dispersion medium according to any one of the above (1) to (4) ink.
  • a light emitting layer which is provided between the pair of electrodes and is made of the dried product of the ink according to any one of the above (1) to (5);
  • a light emitting device comprising: the light emitting layer; and a charge transport layer provided between at least one of the pair of electrodes.
  • a light emitting layer having high light emission efficiency can be formed.
  • FIG. 1 is a cross-sectional view showing an embodiment of a light emitting device of the present invention.
  • the ink of the present invention comprises a semiconductor nanocrystal having a light-emitting property, a particle composed of a dispersant supported by the semiconductor nanocrystal, and a first dispersion medium having a specific chemical structure for dispersing the particle. And a dispersion medium containing the first dispersion medium and a second dispersion medium different from the first dispersion medium.
  • the ink of the present invention may contain, for example, a charge transport material, a surfactant, and the like, as necessary.
  • the particles are composed of semiconductor nanocrystals and a dispersant supported by the semiconductor nanocrystals.
  • Semiconductor nanocrystals (hereinafter, sometimes simply referred to as “nanocrystals”) are nanosized crystals (nanocrystal particles) that absorb excitation light and emit fluorescence or phosphorescence, and, for example, transmission type electrons It is a crystalline form having a maximum particle diameter of 100 nm or less measured by a microscope or a scanning electron microscope.
  • the nanocrystals can be excited, for example, by light energy or electrical energy of a predetermined wavelength to emit fluorescence or phosphorescence.
  • the nanocrystal may be a red light emitting crystal that emits light (red light) having an emission peak in the wavelength range of 605 to 665 nm, and emits light (green light) having an emission peak in the wavelength range of 500 to 560 nm It may be a green light emitting crystal, or may be a blue light emitting crystal which emits light (blue light) having an emission peak in the wavelength range of 420 to 480 nm. Also, in one embodiment, the ink preferably contains at least one of these nanocrystals. Note that the wavelength of the emission peak of the nanocrystal can be confirmed, for example, in a fluorescence spectrum or a phosphorescence spectrum measured using an ultraviolet-visible spectrophotometer.
  • Red light emitting nanocrystals have a wavelength of 665 nm or less, 663 nm or less, 660 nm or less, 658 nm or less, 653 nm or less, 651 nm or less, 650 nm or less, 647 nm or less, 645 nm or less, 643 nm or less, 640 nm or less, 637 nm or less, It is preferable to have an emission peak in a wavelength range of 632 nm or less or 630 nm or less, and have an emission peak in a wavelength range of 628 nm or more, 625 nm or more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or more, 607 nm or more, or 605 nm or more preferable.
  • These upper and lower limit values can be arbitrarily combined. Also in the following similar descriptions, the upper limit value and the lower limit value individually described can be
  • Green light-emitting nanocrystals have emission peaks in the wavelength range of 560 nm or less, 557 nm or less, 555 nm or less, 547 nm or less, 545 nm or less, 543 nm or less, 537 nm or less, 535 nm or less, 532 nm or less It is preferable to have an emission peak in a wavelength range of 528 nm or more, 525 nm or more, 523 nm or more, 520 nm or more, 515 nm or more, 510 nm or more, 507 nm or more, 505 nm or more, 503 nm or more, or 500 nm or more.
  • Blue light-emitting nanocrystals have emission peaks in the wavelength range of 480 nm or less, 477 nm or less, 475 nm or less, 470 nm or less, 467 nm or less, 463 nm or less, 460 nm or less, 457 nm or less, 455 nm or less It is preferable to have an emission peak in a wavelength range of 450 nm or more, 445 nm or more, 440 nm or more, 435 nm or more, 430 nm or more, 428 nm or more, 425 nm or more, 422 nm or more, or 420 nm or more.
  • the wavelength (emission color) of light emitted by the nanocrystals depends on the size (for example, particle diameter) of the nanocrystals according to the solution of the Schrodinger wave equation of the well potential model, but the energy gap of the nanocrystals is also Dependent. Therefore, the emission color of the nanocrystal can be selected (adjusted) by changing the constituent material and the size.
  • the nanocrystals may be formed of a semiconductor material and can have various structures.
  • the nanocrystal may be composed only of the core composed of the first semiconductor material, and the core composed of the first semiconductor material and at least a part of the core are covered with the first semiconductor It may be configured to have a material and a shell composed of a second semiconductor material different from the material.
  • the nanocrystal structure may be a structure consisting only of the core (core structure) or a structure consisting of the core and the shell (core / shell structure).
  • the nanocrystal covers at least a part of the shell and is a third semiconductor different from the first and second semiconductor materials. It may further have a shell (second shell) composed of a material.
  • the structure of the nanocrystals may be a structure (core / shell / shell structure) composed of the core, the first shell and the second shell.
  • each of the core and the shell may be composed of a mixed crystal (for example, CdSe + CdS, CIS + ZnS, etc.) containing two or more semiconductor materials.
  • the nanocrystal is at least one semiconductor material selected from the group consisting of II-VI semiconductors, III-V semiconductors, I-III-VI semiconductors, IV semiconductors and I-II-IV-VI semiconductors. It is preferable to be composed of
  • Specific semiconductor materials include, for example, CdS, CdSe, CdTe, ZnS, ZnTe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, CdSTe, ZnSeTe, ZnSeTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgSe, CdHgSe, CdHgTe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSeCs, CdZnSe: CdHg
  • Semiconductor materials CdS, CdSe, CdTe, ZnS , ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, InP, InAs, InSb, GaP, GaAs, GaSb, AgInS 2, AgInSe 2, AgInTe 2, AgGaS 2, AgGaSe 2 It is preferable that at least one selected from the group consisting of AgGaTe 2 , CuInS 2 , CuInSe 2 , CuInTe 2 , CuGaS 2 , CuGaS 2 , CuGaSe 2 , CuGaTe 2 , Si, C, Ge, and Cu 2 ZnSnS 4 .
  • the nanocrystals composed of these semiconductor materials can easily control the emission spectrum, can reduce the production cost and improve the mass productivity while securing the reliability.
  • red light emitting nanocrystals include nanocrystals of CdSe; rod-like nanocrystals of CdSe; rod-like nanocrystals including a shell of CdS and a core of CdSe; a shell of CdS and a core of ZnSe Rod-like nanocrystals; nanocrystals with CdS shell and CdSe core; nanocrystals with CdS shell and ZnSe core; nanocrystals with ZnS shell and InP core; ZnS shell and CdSe Nanocrystals with a core of CdSe: ZnS mixed crystal nanocrystals; CdSe ZnS mixed crystal rodlike nanocrystals; InP nanocrystals; InP rodlike nanocrystals; CdSe and CdS and Mixed crystal nanocrystals; rod-like nanocrystals of mixed crystals of CdSe and CdS; nanocrystals of mixed crystals of
  • green light emitting nanocrystals include nanocrystals of CdSe; rod-like nanocrystals of CdSe; nanocrystals including a shell of ZnS and a core of InP; nanocrystals including a shell of ZnS and a core of CdSe; Nanocrystals of mixed crystals of CdSe and ZnS; rod-like nanocrystals of mixed crystals of CdSe and ZnS, and the like can be mentioned.
  • blue light emitting nanocrystals include nanocrystals of ZnSe; rod-like nanocrystals of ZnSe; nanocrystals of ZnS; rod-like nanocrystals of ZnS; nanocrystal comprising a shell of ZnSe and a core of ZnS; A rod-like nanocrystal provided with a shell of ZnSe and a core of ZnS; a nanocrystal of CdS; a rod-like nanocrystal of CdS, and the like.
  • nanocrystals are the same chemical composition, the color which should be light-emitted from a nanocrystal can be changed into red or green by designing the average particle diameter of itself.
  • the nanocrystals themselves have minimal adverse effects on the human body and the like. Therefore, if the nanocrystals containing as little as possible cadmium, selenium, etc. are selected and used alone or if the nanocrystals containing the above elements (cadmium, selenium etc.) are used, the above elements can be reduced as much as possible. It is preferable to use in combination with the nanocrystals of
  • the shape of the nanocrystal is not particularly limited, and may be any geometric shape or any irregular shape.
  • Examples of the shape of the nanocrystal include a sphere, a tetrahedron, an ellipsoid, a pyramid, a disc, a branch, a net, and a rod.
  • a shape with less directionality for example, spherical shape, tetrahedral shape, etc.
  • the uniformity and flowability of the ink can be further enhanced by using the nanocrystals of such shape.
  • the average particle diameter (volume average diameter) of the nanocrystals is preferably 40 nm or less, more preferably 30 nm or less, and still more preferably 20 nm or less. Nanocrystals having such an average particle size are preferable because they easily emit light of a desired wavelength.
  • the average particle diameter (volume average diameter) of the nanocrystals is preferably 1 nm or more, more preferably 1.5 nm or more, and still more preferably 2 nm or more.
  • the nanocrystals having such an average particle size are preferable not only because they easily emit light of a desired wavelength, but also because they can improve the dispersibility in ink and storage stability.
  • the average particle diameter (volume average diameter) of a nanocrystal is measured by a transmission electron microscope or a scanning electron microscope, and is obtained by computing a volume average diameter.
  • nanocrystals have high reactivity because they have surface atoms that can be coordination sites. Nanocrystals are prone to aggregation due to such high reactivity and large surface area as compared to common pigments. Nanocrystals produce luminescence due to quantum size effects. Therefore, when nanocrystals aggregate, a quenching phenomenon occurs, leading to a decrease in fluorescence quantum yield, and a decrease in luminance and color reproducibility. That is, the ink formed by dispersing the nanocrystals in the dispersion medium as in the present invention is likely to cause deterioration of the light emission characteristics due to aggregation unlike the ink formed by dissolving the organic light emitting material in the solvent. For this reason, in the ink of the present invention, preparation from the viewpoint of securing dispersion stability of nanocrystals is important.
  • a dispersant (organic ligand) compatible with the dispersion medium is supported (held) on the surface of the nanocrystal, in other words, the surface of the nanocrystal is inactive due to the dispersant. It has been The presence of the dispersant can improve the dispersion stability of the nanocrystals in the ink.
  • the dispersant is supported on the surface of the nanocrystal by, for example, covalent bond, coordinate bond, ionic bond, hydrogen bond, van der Waals bond, or the like.
  • the term "supported” is a general term for the state in which the dispersing agent is adsorbed, attached or bonded to the surface of the nanocrystal.
  • the dispersing agent can be detached from the surface of the nanocrystal, and the support by the nanocrystal and the detachment from the nanocrystal are in an equilibrium state, and these can be repeated.
  • the dispersant is not particularly limited as long as it is a compound that can improve the dispersion stability of the nanocrystals in the ink.
  • Dispersants are classified into low molecular weight dispersants and high molecular weight dispersants.
  • low molecular weight means a molecule having a weight average molecular weight (Mw) of 5,000 or less
  • polymer means a molecule having a weight average molecular weight (Mw) of more than 5,000.
  • Weight average molecular weight (Mw)” is a value measured using gel permeation chromatography (GPC) using polystyrene as a standard substance.
  • low molecular weight dispersants examples include TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphone Acids (HPA), tetradecylphosphonic acid (TDPA) and octylphosphinic acid (OPA).
  • TOP trioctylphosphine
  • TOPO trioctylphosphine oxide
  • oleic acid oleylamine
  • octylamine trioctylamine
  • hexadecylamine octanethiol
  • dodecanethiol dodecanethiol
  • HPA hexylphosphone Acids
  • TDPA tetradecyl
  • a polymer compound having a functional group that can be supported on the surface of nanocrystals can be used.
  • functional groups primary amino group, secondary amino group, tertiary amino group, phosphoric acid group, phosphoric acid ester group, phosphonic acid group, phosphonic acid ester group, phosphinic acid group, phosphinic acid ester group, Thiol group, thioether group, sulfonic acid group, sulfonic acid ester group, carboxylic acid group, carboxylic acid ester group, hydroxyl group, ether group, imidazolyl group, triazinyl group, pyrrolidonyl group, isocyanuric acid group, boric acid ester group, boronic acid And the like.
  • a primary amino group, a secondary amino group, a tertiary amino group, a carboxylic acid ester group from the viewpoint of easy synthesis of a polymer compound having a plurality of functional groups combined to enhance the ability to support nanocrystals.
  • a phosphoric acid group, a phosphoric acid ester group, a phosphonic acid group, a phosphonic acid ester group, and a carboxylic acid group are preferable in that the hydroxyl group and the ether group have sufficient ability to support nanocrystals even if they are singly.
  • primary amino group, secondary amino group, tertiary amino group, phosphoric acid group, phosphonic acid group, and carboxylic acid group are more preferable in that they have high ability to support nanocrystals appropriately in the ink.
  • polymer dispersant having a primary amino group examples include linear amines such as polyalkylene glycol amines, polyester amines, urethane-modified polyester amines, polyalkylene glycol diamines, polyester diamines, urethane-modified polyester diamines, A comb-type polyamine having an amino group in the side chain of the acrylic polymer) may, for example, be mentioned.
  • a polymer dispersant having a secondary amino group for example, a comb type having a main chain including a linear polyethyleneimine skeleton having a large number of secondary amino groups, and a side chain of polyester, acrylic resin, polyurethane or the like Block copolymers and the like can be mentioned.
  • polymer dispersant having a tertiary amino group examples include star-shaped amines such as tri (polyalkylene glycol) amines, and the like.
  • polymer dispersants having a primary amino group for example, JP-A 2008-037884, JP-A 2008-037949, and JP-A 2008-03818.
  • polymer dispersant having a phosphoric acid group for example, polyalkylene glycol monophosphate ester, polyalkylene glycol monoalkyl ether monophosphate ester, perfluoroalkyl polyoxyalkylene phosphate ester, perfluoroalkyl sulfonamide polyoxyalkylene phosphorus Homopolymers obtained from monomers such as acid esters, acid phosphoxyethyl mono (meth) acrylates, acid phosphoxy propyl mono (meth) acrylates, acid phosphoxy polyoxyalkylene glycol mono (meth) acrylates, or these monomers and other monomers Copolymers obtained from comonomers and (meth) acrylic polymers having a phosphoric acid group obtained by the method described in Japanese Patent No. 4697356.
  • the polymer dispersant having a phosphoric acid group can also be adjusted in pH by forming a salt by reacting an alkali metal hydroxide or an alkaline earth metal
  • polymer dispersant having a phosphonic acid group for example, polyalkylene glycol monoalkyl phosphonate, polyalkylene glycol monoalkyl ether monoalkyl phosphonate, perfluoroalkyl polyoxyalkylene alkyl phosphonate, perfluoroalkyl sulfone Amide polyoxyalkylene alkyl phosphonates, polyethylene phosphonic acid; monomers such as vinyl phosphonic acid, (meth) acryloyl oxyethyl phosphonic acid, (meth) acryloyl oxy propyl phosphonic acid, (meth) acryloyl oxy polyoxy alkylene glycol phosphonic acid And homopolymers obtained from the monomers and copolymers obtained from the monomers and other comonomers.
  • the polymer dispersant having a phosphonic acid group can also be adjusted in pH by forming a salt by reacting an alkali metal hydroxide or an alkaline earth metal hydroxide
  • polymer dispersant having a phosphinic acid group for example, polyalkylene glycol dialkyl phosphinate ester, perfluoroalkyl polyoxyalkylene dialkyl phosphinate ester, perfluoroalkyl sulfonamide polyoxyalkylene dialkyl phosphinate ester, polyethylene phosphinic acid; Homopolymers obtained from monomers such as vinylphosphinic acid, (meth) acryloyloxydialkylphosphinic acid, (meth) acryloyloxypolyoxyalkylene glycol dialkylphosphinic acids or copolymers obtained from this monomer and other comonomers .
  • the polymer dispersant having a phosphinic acid group can also be adjusted in pH by forming a salt by reacting an alkali metal hydroxide or an alkaline earth metal hydroxide.
  • polymer dispersant having a thiol group examples include polyvinyl thiol, polyalkylene glycol ethylene thiol and the like.
  • polymer dispersant having a thioether group examples include polyalkylene glycol thioethers obtained by reacting mercaptopropionic acid and glycidyl-modified polyalkylene glycol described in JP-A-2013-60637.
  • polymer dispersant having a sulfonic acid group for example, polyalkylene glycol monoalkyl sulfonic acid ester, polyalkylene glycol monoalkyl ether monoalkyl sulfonic acid ester, perfluoroalkyl polyoxyalkylene alkyl sulfonic acid ester, perfluoroalkyl sulfone Amide polyoxyalkylene alkyl sulfonic acid ester, polyethylene sulfonic acid; homopolymer obtained from monomers such as vinyl sulfonic acid, (meth) acryloyloxy alkyl sulfonic acid, (meth) acryloyloxy polyoxy alkylene glycol sulfonic acid, polystyrene sulfonic acid Or the copolymer etc.
  • the polymer dispersant having a sulfonic acid group can also be adjusted in pH by forming a salt by reacting an alkali metal hydroxide or an alkaline earth metal hydroxide.
  • polymer dispersant having a carboxylic acid group for example, polyalkylene glycol carboxylic acid, perfluoroalkyl polyoxyalkylene carboxylic acid, polyethylene carboxylic acid, polyester monocarboxylic acid, polyester dicarboxylic acid, urethane modified polyester monocarboxylic acid, urethane Homopolymers obtained from monomers such as modified polyester dicarboxylic acids; vinyl carboxylic acids, (meth) acryloyloxyalkyl carboxylic acids, (meth) acryloyloxy polyoxyalkylene glycol carboxylic acids or copolymers obtained from this monomer and other comonomers Etc.
  • the polymer dispersant having a carboxylic acid group can also be adjusted in pH by forming a salt by reacting an alkali metal hydroxide or an alkaline earth metal hydroxide.
  • the polymer dispersant having an ester group can be obtained, for example, by dehydration condensation of a monoalkyl alcohol to the polymer dispersant having a carboxylic acid group.
  • Examples of the polymer dispersant having a pyrrolidonyl group include polyvinyl pyrrolidone and the like.
  • the polymer dispersant having a specific functional group may be a synthetic product or a commercially available product.
  • a commercial item for example, DISPERBYK-102, DISPERBYK-103, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-110, DISPERBYK-111, DISPERBYK-118, DISPERBYK-118, DISPERBYK-140, DISPERBYK-140 included in the DISPERBYK series manufactured by Bick Chemie Ltd.
  • FLORENE flow Len series
  • FLOWLEN DOPA-15BHF Flowlen DOPA-33
  • Flowlen DOPA-44 include Flowlen DOPA-44, and the like.
  • One of these polymer dispersants may be used alone, or two or more thereof may be used in combination.
  • the dispersant as described above may be supported in a state in which almost the whole molecule is in contact with the nanocrystal, or may be supported in a state in which only a part of the molecule is in contact with the nanocrystal. In any state, the dispersant suitably exerts a dispersing function to disperse the nanocrystals stably in the dispersion medium.
  • the weight average molecular weight (Mw) of the dispersant is preferably 50,000 or less, and more preferably about 100 to 50,000.
  • Mw weight average molecular weight
  • the mass of the compound which is not a polymer among low molecular weight dispersing agents it replaces with a "weight average molecular weight" and uses "molecular weight.”
  • a dispersant having a weight average molecular weight equal to or more than the lower limit is excellent in the ability to support nanocrystals, and therefore, the dispersion stability of the nanocrystals in the ink can be sufficiently ensured.
  • a dispersant having a weight average molecular weight equal to or less than the above upper limit has a sufficient number of functional groups per unit weight and does not become too high in crystallinity, so that the dispersion stability of nanocrystals in the ink can be enhanced. it can.
  • the weight average molecular weight of the dispersant is not too high, the inhibition of charge transfer in the obtained light emitting layer can be prevented or suppressed.
  • the amount of the dispersant (in particular, the polymer dispersant) relative to the nanocrystals is preferably 50% by mass or less relative to 100% by mass of the nanocrystals.
  • the amount of the dispersant with respect to nanocrystals is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more with respect to 100% by mass of nanocrystals. . Thereby, sufficient dispersion stability of the nanocrystals in the ink can be maintained.
  • the charge transport material usually has a function of transporting holes and electrons injected into the light emitting layer.
  • the charge transport material is not particularly limited as long as it has a function of transporting holes and electrons.
  • Charge transport materials are classified into polymeric charge transport materials and low molecular charge transport materials.
  • the polymer charge transport material is not particularly limited, and examples thereof include vinyl polymers such as poly (9-vinylcarbazole) (PVK); poly [N, N′-bis (4-butylphenyl) -N, N '-Bis (phenyl) -benzidine] (poly-TPA), polyfluorene (PF), poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) -benzidine (Poly- TPD), poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 '-(N-(-sec-butylphenyl) diphenylamine)] (TFB), polyphenylene vinylene ( Conjugated compound polymers such as PPV), copolymers containing these monomer units, and the like can be mentioned.
  • PVK poly (9-vinylcarbazole)
  • PVK poly [N,
  • the low molecular charge transport material is not particularly limited.
  • CBP 4,4′-bis (9H-carbazol-9-yl) biphenyl
  • CBP 9,9 ′-(p-tert-butylphenyl) -3 , 3-Biscarbazole, 1,3-dicarbazolylbenzene (mCP), 4,4'-bis (9-carbazolyl) -2,2'-dimethylbiphenyl (CDBP), N, N'-dicarbazolyl-1
  • Carbazole derivatives such as 2,4-dimethylbenzene (DCB), 5,11-diphenyl-5,11-dihydroindolo [3,2-b] carbazole; bis (2-methyl-8-quinolinolate) -4- Aluminum complexes such as (phenylphenolato) aluminum (BAlq), 2,7-bis (diphenylphosphine oxide) -9,9-dimethylfluorene ( Phosphine oxide derivatives such as P06
  • surfactant for example, one or more of a fluorine-based surfactant, a silicone-based surfactant, a hydrocarbon-based surfactant and the like can be used in combination. Among these, silicone surfactants and / or hydrocarbon surfactants are preferable because they are difficult to trap charges.
  • silicone surfactant and the hydrocarbon surfactant low molecular weight or high molecular weight surfactants can be used. Specific examples thereof include, for example, BYK series manufactured by Big Chemie Co., Ltd., and Surfynol manufactured by Nisshin Chemical Industry Co., Ltd. Among these, since a coating film having high smoothness can be obtained when the ink is applied, a silicone-based surfactant made of organically modified siloxane can be suitably used.
  • Dispersion medium Particles of nanocrystals carrying such a dispersing agent are dispersed in a dispersion medium.
  • the dispersion medium is not particularly limited, and examples thereof include aromatic hydrocarbon compounds, aromatic ester compounds, aromatic ether compounds, aromatic ketone compounds, aliphatic hydrocarbon compounds, aliphatic ester compounds, aliphatic ether compounds, and fats. Group ketone compounds, alcohol compounds, amide compounds, other compounds, etc. may be mentioned, and one or more of these may be used in combination.
  • aromatic hydrocarbon compound As an aromatic hydrocarbon compound, toluene, xylene, ethylbenzene, cumene, mesitylene, tert-butylbenzene, indane, diethylbenzene, pentylbenzene, 1,2,3,4-tetrahydronaphthalene, naphthalene, hexylbenzene, heptylbenzene, cyclohexyl Examples thereof include benzene, 1-methylnaphthalene, biphenyl, 2-ethylnaphthalene, 1-ethylnaphthalene, octylbenzene, diphenylmethane, 1,4-dimethylnaphthalene, nonylbenzene, isopropylbiphenyl, 3-ethylbiphenyl, dodecylbenzene and the like.
  • aromatic ester compound phenyl acetate, methyl benzoate, ethyl benzoate, phenyl propionate, isopropyl benzoate, methyl 4-methylbenzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, ethyl p-anisate, Dimethyl phthalate etc. are mentioned.
  • aromatic ether compounds dimethoxybenzene, methoxytoluene, ethylphenyl ether, dibenzyl ether, 4-methylanisole, 2,6-dimethylanisole, ethylphenyl ether, propylphenylether, 2,5-dimethylanisole, 3, 5-dimethylanisole, 4-ethylanisole, 2,3-dimethylanisole, butylphenylether, p-dimethoxybenzene, p-propylanisole, m-dimethoxybenzene, methyl 2-methoxybenzoate, 1,3-dipropoxybenzene Diphenyl ether, 1-methoxynaphthalene, 3-phenoxytoluene, 2-ethoxynaphthalene, 1-ethoxynaphthalene and the like.
  • aromatic ketone compound examples include acetophenone, propiophenone, 4′-methylacetophenone, 4′-ethylacetophenone, butylphenyl ketone and the like.
  • aliphatic hydrocarbon compounds include pentane, hexane, octane and cyclohexane.
  • aliphatic ester compounds include ethyl acetate, butyl acetate, ethyl lactate, hexyl acetate, butyl lactate, isoamyl lactate, amyl valerate, ethyl levrilate, ⁇ -valerolactone, ethyl octanoate, ⁇ -hexalactone, isoamyl hexahydrate , Amyl hexanate, nonyl acetate, methyl decanoate, diethyl glutarate, ⁇ -heptalactone, ⁇ -caprolactone, octalactone, propylene carbonate, ⁇ -nonanolactone, hexyl hexanoate, diisopropyl adipate, ⁇ -nonanolactone, glycerol tri Acetic acid, ⁇ -decanolactone, dipropyl adipate, ⁇ -undecal
  • aliphatic ether compounds tetrahydrofuran, dioxane, propylene glycol-1-monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, propylene glycol diacetate, diethylene glycol isopropyl methyl ether, diethylene glycol diethyl ether, diethylene glycol diacetate, diethylene glycol butyl methyl ether Diethylene glycol monoethyl ether acetate, dihexyl ether, 1,3-butanediol diacetate, 1,4-butanediol diacetate, diethylene glycol monobutyl ether acetate, diethylene glycol dibutyl ether, diheptyl ether, dioctyl ether, etc. And the like.
  • aliphatic ketone compounds examples include diisobutyl ketone, cycloheptanone, isophorone, 6-undecanone and the like.
  • alcohol compounds methanol, ethanol, isopropyl alcohol, 1-heptanol, 2-ethyl-1-hexanol, propylene glycol, ethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethyl 3-hydroxyhexanate, triethylene
  • examples include glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol, cyclohexanol and the like.
  • amide compound examples include N, N-dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone, N, N-dimethylacetamide and the like.
  • Other compounds include water, dimethyl sulfoxide, acetone, chloroform, methylene chloride and the like.
  • the viscosity at 25 ° C. of the dispersion medium as described above is preferably about 1 to 20 mPa ⁇ s, more preferably about 1.5 to 15 mPa ⁇ s, and about 2 to 10 mPa ⁇ s. More preferable. If the viscosity of the dispersion medium at normal temperature is within the above range, the droplets ejected from the nozzle holes of the droplet ejection head are separated into the main droplets and the small droplets when the ink is ejected by the droplet ejection method. Occurrence of the phenomenon (satellite phenomenon) can be prevented or suppressed. Therefore, it is possible to improve the landing accuracy of the droplets on the adherend.
  • the ink of the present invention when there is a possibility that particles containing nanocrystals are inactivated by oxygen, water, etc. and do not function stably, dissolved gas and water were removed as much as possible when preparing the ink.
  • a post-treatment to remove dissolved oxygen and water as much as possible from the ink.
  • the post-treatment include degassing treatment, treatment to saturate or supersaturate an inert gas, heat treatment, dehydration treatment to be performed by passing a drying agent, and the like.
  • the dissolved oxygen and moisture in the ink are preferably 200 ppm or less, more preferably 100 ppm or less, and still more preferably 10 ppm or less.
  • the content of particles contained in the ink is preferably about 0.01 to 20% by mass, more preferably about 0.01 to 15% by mass, and about 0.1 to 10% by mass Is more preferred.
  • the amount of particles contained in the ink within the above range, when the ink is discharged by the droplet discharge method, the discharge stability can be further improved.
  • the particles (nanocrystals) are less likely to be aggregated with each other, and the light emission efficiency of the obtained light emitting layer can be enhanced.
  • the mass of the particles refers to the sum of the mass of the nanocrystals and the mass of the dispersant supported by the nanocrystals.
  • the amount of particles contained in the ink means, when the ink is composed of particles and a dispersion medium, the sum of the particles and the dispersion medium is 100% by mass.
  • the ink is composed of particles, nonvolatile components other than particles, and dispersion medium, it refers to mass% of particles when the total of particles, nonvolatile components, and dispersion medium is 100% by mass. .
  • a compound containing a methylene group directly bonded to an aromatic ring or a hetero atom (hereinafter, also referred to as “reducing compound”) is selected as the first dispersion medium.
  • the use of such a compound can improve the wettability of the ink to the substrate that supplies the ink. For this reason, since the ink can spread smoothly and uniformly on the support, the uniform thickness can be obtained regardless of the method of supplying the ink on the support, the drying conditions of the coating film formed by the ink, and the like.
  • a light emitting layer that is, a flat light emitting layer) can be obtained. Such a light emitting layer has high luminance uniformity.
  • the hetero atom constituting the ester group or the amido group is removed from the hetero atom to which the methylene group is directly bonded.
  • the ester group includes an ester group derived from a carboxylic acid, an ester group derived from a sulfuric acid, an ester group derived from a phosphoric acid, an ester group in a urethane group, and the like.
  • the amido group includes amido group itself, amido group in imide group, amido group in urethane group and the like.
  • the amide group also includes an amide group derived from a carboxylic acid, an amide group derived from a sulfuric acid, an amide group derived from a phosphoric acid, and the like.
  • Such a first dispersion medium has the property that a methylene group directly bonded to an aromatic ring or a hetero atom is oxidized and easily converted to a peroxide.
  • this peroxide acts on the dispersing agent supported on the nanocrystals, causing the dispersing agent to be detached from the nanocrystals.
  • the nanocrystals aggregate in the ink, in the light emitting layer formed using such an ink, the luminous efficiency is lowered due to the self-absorption phenomenon of the particles (nanocrystals).
  • the present inventors diligently studied to solve such a problem. As a result, it has been found that by appropriately setting the amount of the first dispersion medium contained in the ink, the adverse effect of the peroxide can be prevented or suppressed without reducing the wettability of the ink to the support.
  • the present invention has been completed. That is, in the present invention, the amount of the first dispersant contained in the ink is set to 20 to 50% by mass. Thereby, the said effect is exhibited suitably and the light emitting layer obtained comes to have the outstanding brightness uniformity and high luminous efficiency.
  • the amount of the first dispersant contained in the ink may be about 20 to 50% by mass, preferably about 20 to 40% by mass, and more preferably about 20 to 30% by mass .
  • the first dispersion medium preferably has a boiling point (hereinafter, also simply referred to as "boiling point") under atmospheric pressure (1 atm) of about 200 to 340 ° C, and preferably about 210 to 320 ° C. More preferable.
  • the first dispersion medium having a boiling point in such a temperature range is difficult to evaporate (vaporize). Therefore, by using the ink containing the first dispersion medium, when the ink is discharged by the droplet discharge method, the ink is suitably prevented from being dried in the vicinity of the nozzle hole of the droplet discharge head. , The nozzle hole is not clogged. As a result, the ejection stability of the ink can be maintained for a long time, and the formation efficiency of the light emitting layer can be improved.
  • the surface tension of the first dispersion medium is preferably 32 mN / m or less, more preferably 25 to 32 mN / m.
  • the first dispersion medium include, for example, aromatic linear alkyl compounds such as hexylbenzene, heptylbenzene, octylbenzene, nonylbenzene, dodecylbenzene, 2-ethylnaphthalene, 1-ethylnaphthalene, tetralin, and benzo.
  • aromatic cyclic alkyl compounds such as cyclooctane
  • aliphatic ether compounds such as diethylene glycol butyl methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and diethylene glycol dibutyl ether. These compounds can be used alone or in combination of two or more.
  • the first dispersion medium is preferably at least one compound selected from the group consisting of aromatic linear alkyl compounds (especially octylbenzene and nonylbenzene) and aliphatic ether compounds. These compounds are excellent in the effect of improving the wettability of the ink to the support, and are relatively difficult to convert to peroxides. Therefore, by setting the amount of the first dispersion medium contained in the ink within the above range, it is possible to obtain a light emitting layer having particularly excellent luminance uniformity and particularly high luminous efficiency.
  • aromatic linear alkyl compounds especially octylbenzene and nonylbenzene
  • aliphatic ether compounds are excellent in the effect of improving the wettability of the ink to the support, and are relatively difficult to convert to peroxides. Therefore, by setting the amount of the first dispersion medium contained in the ink within the above range, it is possible to obtain a light emitting layer having particularly excellent luminance uniformity and particularly high luminous efficiency.
  • the surface tension of the second dispersion medium is preferably more than 32 mN / m, and more preferably about 32 to 45 mN / m.
  • the second dispersion medium include, for example, aromatic hydrocarbon compounds such as 1-methylnaphthalene and 1,4-dimethylnaphthalene; butyl benzoate, ethyl p-anisole, butyl benzoate, isopentyl benzoate, Aromatic ester compounds such as dimethyl phthalate; aromatic ether compounds such as diphenyl ether and 3-phenoxytoluene; aromatic ketone compounds such as 4'-methylacetophenone; isoamyl lactate, amyl valerate, ethyl levrilate, ⁇ -valerolactone, ethyl octanoate, ⁇ -hexalactone, isoamyl hexanate, amyl hexanate, nonyl acetate, methyl decanoate, diethyl glutarate, ⁇ -heptalactone, ⁇ -caprolactone, octalactone, propylene carbonate,
  • the second dispersion medium is preferably at least one compound selected from the group consisting of an aromatic ester compound, an aromatic ether compound and an aliphatic ester compound.
  • the first dispersion medium and the second dispersion medium as described above can be used in combination of two or more compounds as the first dispersion medium and one compound as the second dispersion medium.
  • the first dispersion medium can also be used in combination with one compound and two or more compounds as the second dispersion medium, and two or more compounds as the first dispersion medium and two or more as the second dispersion medium.
  • the compounds of the above can also be used in combination.
  • the ink of the present invention may further contain another dispersion medium different from the first dispersion medium and the second dispersion medium.
  • the dispersion medium having the highest boiling point is preferably the first dispersion medium. Therefore, when the ink contains two dispersion media of the first dispersion medium and the second dispersion medium, the boiling point of the first dispersion medium is preferably higher than the boiling point of the second dispersion medium.
  • the first dispersant having high wettability to the support is finally evaporated from the coating film.
  • the ink wets and spreads sufficiently on the support, and the particles are more uniformly present on the support.
  • the brightness uniformity and the light emission efficiency of the obtained light emitting layer are further improved.
  • the light emitting device of the present invention comprises an anode and a cathode (a pair of electrodes), and a light emitting layer provided between them and comprising the dried product of the ink of the present invention, and at least one of the light emitting layer and the anode and the cathode And a charge transport layer provided therebetween.
  • the charge transport layer preferably includes at least one layer selected from the group consisting of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.
  • the light emitting device of the present invention may further include a sealing member or the like.
  • FIG. 1 is a cross-sectional view showing an embodiment of a light emitting device of the present invention.
  • FIG. 1 for convenience, the dimensions of the respective parts and the ratio thereof are shown exaggeratingly, and may differ from the actual one.
  • the materials, dimensions, and the like described below are merely examples, and the present invention is not limited thereto, and can be appropriately changed without changing the gist of the invention.
  • the upper side of FIG. 1 will be referred to as “upper side” or “upper side” and the upper side as “lower side” or “lower side”.
  • FIG. 1 in order to avoid that a drawing becomes complicated, the description of the hatching which shows a cross section is abbreviate
  • the light emitting device 1 shown in FIG. 1 includes a hole injection layer 4, a hole transport layer 5, and a light emitting layer 6 sequentially stacked from the anode 2 side between the anode 2, the cathode 3, and the anode 2 and the cathode 3. , The electron transport layer 7 and the electron injection layer 8. Each layer will be sequentially described below.
  • the anode 2 has a function of supplying holes from the external power source toward the light emitting layer 6.
  • the constituent material (anode material) of the anode 2 is not particularly limited.
  • a metal such as gold (Au)
  • a metal halide such as copper iodide (CuI)
  • oxide examples thereof include metal oxides such as tin (SnO 2 ) and zinc oxide (ZnO). These may be used alone or in combination of two or more.
  • the thickness of the anode 2 is not particularly limited, but is preferably about 10 to 1,000 nm, and more preferably about 10 to 200 nm.
  • the anode 2 can be formed by, for example, a dry film forming method such as a vacuum evaporation method or a sputtering method.
  • the anode 2 having a predetermined pattern may be formed by a photolithography method or a method using a mask.
  • the cathode 3 has a function of supplying electrons from an external power source toward the light emitting layer 6.
  • the constituent material (cathode material) of the cathode 3 is not particularly limited, but, for example, lithium, sodium, magnesium, aluminum, silver, sodium-potassium alloy, magnesium / aluminum mixture, magnesium / silver mixture, magnesium / indium mixture, aluminum / Aluminum oxide (Al 2 O 3 ) mixture, rare earth metals, etc. may be mentioned. These may be used alone or in combination of two or more.
  • the thickness of the cathode 3 is not particularly limited, but is preferably about 0.1 to 1,000 nm, and more preferably about 1 to 200 nm.
  • the cathode 3 can be formed by, for example, a dry film forming method such as a vapor deposition method or a sputtering method.
  • the hole injection layer 4 has a function of receiving holes supplied from the anode 2 and injecting the holes into the hole transport layer 5.
  • the hole injection layer 4 may be provided as necessary, and may be omitted.
  • the constituent material (hole injection material) of the hole injection layer 4 is not particularly limited.
  • phthalocyanine compounds such as copper phthalocyanine; 4,4 ', 4' '-tris [phenyl (m-tolyl) amino] Triphenylamine derivatives such as triphenylamine; 1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile, 2,3,5,6-tetrafluoro-7,7,8,8- Cyano compounds such as tetracyano-quinodimethane; metal oxides such as vanadium oxide and molybdenum oxide; amorphous carbon; polyaniline (emeraldine), poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonic acid) (PEDOT -PSS), polymers such as polypyrrole, and the like.
  • the hole injection material is preferably a polymer, and more preferably PEDOT-PSS.
  • the above-described hole injection materials may be used alone or in combination of two or more.
  • the thickness of the hole injection layer 4 is not particularly limited, but is preferably about 0.1 to 500 mm, more preferably about 1 to 300 nm, and still more preferably about 2 to 200 nm.
  • the hole injection layer 4 may have a single-layer structure or a stacked structure in which two or more layers are stacked. Such a hole injection layer 4 can be formed by a wet film formation method or a dry film formation method.
  • the hole injection layer 4 When the hole injection layer 4 is formed by a wet film formation method, an ink containing the above-described hole injection material is usually applied by various coating methods, and the obtained coating film is dried.
  • the application method is not particularly limited, and examples thereof include an inkjet method (droplet discharge method), a spin coat method, a cast method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method and the like.
  • a vacuum evaporation method, a sputtering method or the like can be suitably used.
  • the hole transport layer 5 has a function of receiving holes from the hole injection layer 4 and efficiently transporting the holes to the light emitting layer 6.
  • the hole transport layer 4 may have a function of preventing transport of electrons.
  • the hole transport layer 5 may be provided if necessary, and may be omitted.
  • the constituent material (hole transport material) of the hole transport layer 5 is not particularly limited, and, for example, TPD (N, N'-diphenyl-N, N'-di (3-methylphenyl) -1, 1 ' -Biphenyl-4,4'diamine), ⁇ -NPD (4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), m-MTDATA (4,4 ', 4' '-) Low molecular weight triphenylamine derivatives such as tris (3-methylphenylphenylamino) triphenylamine); polyvinylcarbazole; poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) -Benzidine] (poly-TPA), polyfluorene (PF), poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) -benz
  • the hole transport material is preferably a triphenylamine derivative, or a polymer compound obtained by polymerizing a triphenylamine derivative having a substituent introduced therein, and the substituent having a substituent introduced therein is preferable. More preferably, it is a polymer compound obtained by polymerizing a phenylamine derivative.
  • the above-mentioned hole transport materials may be used alone or in combination of two or more.
  • the thickness of the hole transport layer 5 is not particularly limited, but is preferably about 1 to 500 nm, more preferably about 5 to 300 nm, and still more preferably about 10 to 200 nm.
  • the hole transport layer 5 may have a single-layer structure or a stacked structure in which two or more layers are stacked. Such a hole transport layer 5 can be formed by a wet film formation method or a dry film formation method.
  • the ink containing the above-mentioned hole transport material is applied by various coating methods, and the obtained coating film is dried.
  • the application method is not particularly limited, and examples thereof include an inkjet method (droplet discharge method), a spin coat method, a cast method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method and the like.
  • a vacuum evaporation method, a sputtering method or the like can be suitably used.
  • the electron injection layer 8 has a function of receiving the electrons supplied from the cathode 3 and injecting the electrons into the electron transport layer 7.
  • the electron injection layer 8 may be provided if necessary, and can be omitted.
  • the constituent material (electron injection material) of the electron injection layer 8 is not particularly limited, but, for example, alkali metal chalcogenides such as Li 2 O, LiO, Na 2 S, Na 2 Se, NaO; CaO, BaO, SrO, Alkaline earth metal chalcogenides such as BeO, BaS, MgO, CaSe; alkali metal halides such as CsF, LiF, NaF, KF, LiCl, KCl, NaCl; alkalis such as 8-hydroxyquinolinolatolithium (Liq) Metal salts; alkaline earth metal halides such as CaF 2 , BaF 2 , SrF 2 , MgF 2 , BeF 2 and the like can be mentioned.
  • alkali metal chalcogenides such as Li 2 O, LiO, Na 2 S, Na 2 Se, NaO
  • CaO, BaO, SrO, Alkaline earth metal chalcogenides such as BeO, BaS, Mg
  • alkali metal chalcogenides alkaline earth metal halides and alkali metal salts are preferable.
  • the above-mentioned electron injection materials may be used alone or in combination of two or more.
  • the thickness of the electron injection layer 8 is not particularly limited, but is preferably about 0.1 to 100 nm, more preferably about 0.2 to 50 nm, and still more preferably about 0.5 to 10 nm. preferable.
  • the electron injection layer 8 may have a single-layer structure or a stacked structure in which two or more layers are stacked. Such an electron injection layer 8 can be formed by a wet film formation method or a dry film formation method.
  • the ink containing the above-mentioned electron injection material is applied by various coating methods, and the obtained coating film is dried.
  • the application method is not particularly limited, and examples thereof include an inkjet method (droplet discharge method), a spin coat method, a cast method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method and the like.
  • an inkjet method droplet discharge method
  • a spin coat method a cast method
  • an LB method a letterpress printing method
  • a gravure printing method a screen printing method, a nozzle printing method and the like.
  • the electron transport layer 7 has a function of receiving electrons from the electron injection layer 8 and efficiently transporting it to the light emitting layer 6.
  • the electron transport layer 7 may have a function of preventing the transport of holes.
  • the electron transport layer 7 may be provided as necessary, and may be omitted.
  • the constituent material (electron transport material) of the electron transport layer 7 is not particularly limited.
  • an electron transport material it is preferable that they are an imidazole derivative, a pyridine derivative, a pyrimidine derivative, a triazine derivative, and a metal oxide (inorganic oxide).
  • the above-mentioned electron transporting materials may be used alone or in combination of two or more.
  • the thickness of the electron transport layer 7 is not particularly limited, but is preferably about 5 to 500 nm, and more preferably about 5 to 200 nm.
  • the electron transport layer 7 may be a single layer or a stack of two or more. Such an electron transport layer 7 can be formed by a wet film formation method or a dry film formation method.
  • the ink containing the above-mentioned electron transport material is applied by various coating methods, and the obtained coating film is dried.
  • the application method is not particularly limited, and examples thereof include an inkjet method (droplet discharge method), a spin coat method, a cast method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method and the like.
  • a vacuum evaporation method, a sputtering method or the like may be applied.
  • the light emitting layer 6 has a function of generating light emission using energy generated by recombination of holes and electrons injected into the light emitting layer 6.
  • the light emitting layer 6 is composed of the dried product of the ink of the present invention. Therefore, since the nanocrystals are uniformly dispersed and present in the light emitting layer 6, the light emitting layer 6 has excellent light emitting efficiency.
  • the thickness of the light emitting layer 6 is not particularly limited, but is preferably about 1 to 100 nm, and more preferably about 1 to 50 nm.
  • the light emitting layer 8 applies the ink of this invention by various coating methods, and dries the obtained coating film.
  • the coating method is not particularly limited, and examples thereof include inkjet printing (piezo method or thermal droplet discharge method), spin coating, casting, LB method, letterpress printing, gravure printing, screen printing, The nozzle printing method etc. are mentioned.
  • the nozzle printing method is a method of applying ink in the form of stripes from the nozzle holes as liquid columns.
  • the ink of the present invention can be suitably applied by inkjet printing.
  • the ink of the present invention is preferably applied by a piezo inkjet printing method.
  • a preferred apparatus used for applying the ink of the present invention is an inkjet printer having a piezo inkjet head.
  • the light emitting element 1 may further include, for example, a bank (partition wall) that divides the hole injection layer 4, the hole transport layer 5, and the light emitting layer 6.
  • the height of the bank is not particularly limited, but is preferably about 0.1 to 5 ⁇ m, more preferably about 0.2 to 4 ⁇ m, and still more preferably about 0.2 to 3 ⁇ m.
  • the width of the bank opening is preferably about 10 to 200 ⁇ m, more preferably about 30 to 200 ⁇ m, and still more preferably about 50 to 100 ⁇ m.
  • the length of the opening of the bank is preferably about 10 to 400 ⁇ m, more preferably about 20 to 200 ⁇ m, and still more preferably about 50 to 200 ⁇ m.
  • the inclination angle of the bank is preferably about 10 to 100 °, more preferably about 10 to 90 °, and still more preferably about 10 to 80 °.
  • the method of manufacturing a light emitting device is a step of forming a light emitting layer by supplying an ink as described above onto a support to form a coated film, and drying the coated film (hereinafter also referred to as "light emitting layer forming step" )have.
  • the support is the hole transport layer 5 or the electron transport layer 7 in the configuration shown in FIG. 1, but it differs depending on the light emitting element to be manufactured.
  • the support in the case of producing a light emitting device composed of an anode, a hole transport layer, a light emitting layer and a cathode, the support is a hole transport layer or a cathode.
  • the support In the case of producing a light emitting device composed of an anode, a hole injection layer, a light emitting layer, an electron injection layer and a cathode, the support is a hole injection layer or an electron injection layer.
  • the support may be an anode, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer or a cathode.
  • the support is preferably an anode, a hole injection layer or a hole transport layer, more preferably a hole injection layer or a hole transport layer, and still more preferably a hole transport layer.
  • the above-mentioned bank may be formed on the support.
  • the light emitting layer 6 can be formed only at a desired position on the support.
  • the ink of the present invention is intermittently discharged from the nozzle holes of the droplet discharge head onto the support in a predetermined pattern.
  • drawing patterning can be performed with a high degree of freedom.
  • the piezoelectric droplet discharge method the selectivity of the dispersion medium can be enhanced, and the heat load on the ink can be reduced.
  • the ejection amount of the ink is not particularly limited, but is preferably 1 to 50 pL / time, more preferably 1 to 30 pL / time, and still more preferably 1 to 20 pL / time.
  • the opening diameter of the nozzle hole is preferably about 5 to 50 ⁇ m, and more preferably about 10 to 30 ⁇ m.
  • the temperature for forming the coating film is not particularly limited, but is preferably about 10 to 50 ° C., more preferably about 15 to 40 ° C., and still more preferably about 15 to 30 ° C. By discharging droplets at such a temperature, crystallization of various components (such as nanocrystals, dispersants, charge transport materials, and the like) contained in the ink can be suppressed.
  • the relative humidity at the time of forming the coating film is not particularly limited, but is preferably about 0.01 ppm to 80%, more preferably about 0.05 ppm to 60%, and more preferably 0.1 ppm to 15 % Is more preferable, 1 ppm to 1% is particularly preferable, and 5 to 100 ppm is most preferable. It is preferable from the control of the conditions at the time of forming a coating film becoming easy for relative humidity to be more than the said lower limit. On the other hand, it is preferable from the ability to reduce the moisture content adsorbed to the coating film which may exert a bad influence on the light emitting layer 6 obtained as relative humidity is below the said upper limit.
  • the light emitting layer 6 is obtained by drying the obtained coating film. Drying may be carried out by leaving at room temperature (25 ° C.) or by heating. When drying is performed by heating, the drying temperature is not particularly limited, but is preferably about 40 to 150 ° C., and more preferably about 40 to 120 ° C.
  • drying is preferably performed under reduced pressure, and more preferably performed under reduced pressure of 0.001 to 100 Pa.
  • drying time is preferably 1 to 90 minutes, and more preferably 1 to 30 minutes.
  • the ink and light emitting element of this invention were demonstrated, this invention is not limited to the structure of embodiment mentioned above.
  • the ink and the light emitting element of the present invention may have any other optional configuration added to the configuration of the above-described embodiment, or may be replaced with any configuration that exhibits the same function. You may
  • Example A1 A mixed dispersion medium containing the above precipitate as a first dispersion medium, diethylene glycol butyl methyl ether (50 mass%) as a first dispersion medium, and diphenyl ether (50 mass%) as a second dispersion medium so as to be 1.0 mass%
  • the ink was prepared by dispersing in (Example A2, Example A3, Comparative Example A1, Comparative Example A2)
  • An ink was prepared in the same manner as Example A1, except that the mixing ratio of diethylene glycol butyl methyl ether and diphenyl ether was changed as shown in Table 1.
  • Example B1 A mixed dispersion medium containing the above precipitate as the first dispersion medium, diethylene glycol butyl methyl ether (50 mass%) as the first dispersion medium, and acetophenone (50 mass%) as the second dispersion medium so as to be 1.0 mass%
  • the ink was prepared by dispersing in (Example B2, Example B3, Comparative Example B1, Comparative Example B2) An ink was prepared in the same manner as Example B1, except that the mixing ratio of diethylene glycol butyl methyl ether and acetophenone was changed as shown in Table 2.
  • Example C1 To the mixed dispersion medium containing the above precipitate as a first dispersion medium, diethylene glycol dibutyl ether (50 mass%) as a first dispersion medium, and diphenyl ether (50 mass%) as a second dispersion medium so as to be 1.0 mass% The ink was prepared by dispersing. (Example C2, Example C3, Comparative Example C1, Comparative Example C2) An ink was prepared in the same manner as Example C1, except that the mixing ratio of diethylene glycol dibutyl ether and diphenyl ether was changed as shown in Table 3.
  • Example D1 To the mixed dispersion medium containing the above precipitate as a first dispersion medium, diethylene glycol dibutyl ether (50% by mass) as a first dispersion medium, and acetophenone (50% by mass) as a second dispersion medium so as to be 1.0% by mass The ink was prepared by dispersing. (Example D2, Example D3, Comparative Example D1, Comparative Example D2) An ink was prepared in the same manner as Example D1, except that the mixing ratio of diethylene glycol dibutyl ether and acetophenone was changed as shown in Table 4.
  • Example E1 The above precipitate is mixed so as to be 1.0% by mass with diethylene glycol monobutyl ether acetate (50% by mass) as a first dispersion medium and ⁇ -nonanolactone (50% by mass) as a second dispersion medium.
  • the ink was prepared by dispersing in a dispersion medium.
  • Example E2 Example E3, Comparative Example E1, Comparative Example E2
  • An ink was prepared in the same manner as in Example E1, except that the mixing ratio of diethylene glycol monobutyl ether acetate to ⁇ -nonanolactone was changed as shown in Table 5.
  • Example F1 The precipitate is contained so as to be 1.0% by mass, diethylene glycol monobutyl ether acetate (50% by mass) as a first dispersion medium, and ⁇ -valerolactone (50% by mass) as a second dispersion medium.
  • the ink was prepared by dispersing in a mixed dispersion medium.
  • Example F2 Example F3, Comparative Example F1, Comparative Example F2
  • An ink was prepared in the same manner as in Example F1 except that the mixing ratio of diethylene glycol monobutyl ether acetate to ⁇ -valerolactone was changed as shown in Table 6.
  • Example G1 A mixed dispersion containing the precipitate as above, octylbenzene (50% by mass) as a first dispersion medium, and 3-phenoxytoluene (50% by mass) as a second dispersion medium so as to be 1.0% by mass
  • the ink was prepared by dispersing in a medium.
  • Example G2, Example G3, Comparative Example G1, Comparative Example G2 An ink was prepared in the same manner as Example G1, except that the mixing ratio of octylbenzene to 3-phenoxytoluene was changed as shown in Table 7.
  • Example H1 A mixed dispersion containing the precipitate as above, octylbenzene (50% by mass) as a first dispersion medium, and 1-methoxynaphthalene (50% by mass) as a second dispersion medium so as to be 1.0% by mass
  • the ink was prepared by dispersing in a medium.
  • Example H2, Example H3, Comparative Example H1, Comparative Example H2 An ink was prepared in the same manner as in Example H1 except that the mixing ratio of octylbenzene to 1-methoxynaphthalene was changed as shown in Table 8.
  • Example I1 A mixed dispersion medium containing the above precipitate as the first dispersion medium, nonylbenzene (50 mass%) as the first dispersion medium, and dimethyl phthalate (50 mass%) as the second dispersion medium so as to be 1.0 mass%
  • the ink was prepared by dispersing in (Example I2, Example I3, Comparative Example I1, Comparative Example I2) An ink was prepared in the same manner as in Example I1 except that the mixing ratio of nonylbenzene and dimethyl phthalate was changed as shown in Table 9.
  • Example J1 The above precipitate is mixed and dispersed so as to be 1.0 mass%, containing nonylbenzene (50 mass%) as a first dispersion medium and 1-methoxynaphthalene (50 mass%) as a second dispersion medium.
  • the ink was prepared by dispersing in a medium.
  • Example J2, Example J3, Comparative Example J1, Comparative Example J2 An ink was prepared in the same manner as in Example J1 except that the mixing ratio of nonylbenzene to 1-methoxynaphthalene was changed as shown in Table 10.
  • Example K1 A dispersion medium (50 mass%) containing the precipitate in a mass ratio of 50:50 of diethylene glycol dibutyl ether and octylbenzene as a first dispersion medium so as to be 1.0 mass%, and a second dispersion
  • the ink was prepared by dispersing in a mixed dispersion medium containing butyl benzoate (50% by mass) as a medium.
  • Example K2 Example K2, Example K3, Comparative Example K1, Comparative Example K2
  • An ink was prepared in the same manner as in Example K1, except that the mixing ratio of the dispersion medium containing diethylene glycol dibutyl ether and octylbenzene at a mass ratio of 50:50 to 1-methoxynaphthalene was changed as shown in Table 11. Was prepared.
  • the coating film (ink pattern) was dried at 25 ° C. for 30 minutes under a reduced pressure of 0.003 Pa.
  • the support formed up to the light emitting layer was conveyed to a vacuum deposition machine, and an electron transport layer of 40 nm, an electron injection layer of 0.5 nm, and a cathode of 100 nm were sequentially formed by vapor deposition.
  • the electron transporting layer was formed using TPBI
  • the electron injecting layer was formed using lithium fluoride
  • the cathode was formed using aluminum.
  • the support formed up to the cathode was transported to a glove box, and the sealing glass coated with the epoxy resin was attached to the support. Thus, a light emitting element was manufactured.
  • the light emitting element (light emitting layer) obtained using the ink of each Example had excellent luminance uniformity and high light emission efficiency.
  • the effect is further improved.
  • the light emitting element obtained using the ink of each comparative example either the brightness uniformity or the light emission efficiency was inferior.
  • the ink of the present invention is a first ink containing a particle composed of a semiconductor nanocrystal having a light-emitting property, a dispersant supported by the semiconductor nanocrystal, and a methylene group directly bonded to an aromatic ring or a hetero atom.

Landscapes

  • Electroluminescent Light Sources (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)

Abstract

L'invention concerne : une encre capable d'empêcher une réduction de l'efficacité d'émission de lumière provoquée par un phénomène d'auto-absorption ; et un élément électroluminescent ayant une efficacité d'émission de lumière élevée. Cette encre comprend : des particules constituées de nanocristaux semi-conducteurs électroluminescents et d'un agent de dispersion supporté par les nanocristaux semi-conducteurs ; un premier milieu de dispersion comprenant un cycle aromatique ou un groupe méthylène directement lié à un hétéroatome ; et un second milieu de dispersion différent du premier milieu de dispersion. L'encre est caractérisée en ce que la quantité du premier milieu de dispersion inclus dans l'encre est de 20 à 50 % en masse.
PCT/JP2018/034772 2017-09-28 2018-09-20 Encre et élément électroluminescent WO2019065435A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010009995A (ja) * 2008-06-27 2010-01-14 Seiko Epson Corp 吐出液、吐出液セット、薄膜パターン形成方法、薄膜、発光素子、画像表示装置、および、電子機器
JP2014077046A (ja) * 2012-10-10 2014-05-01 Konica Minolta Inc 発光層形成用インク組成物、発光素子の作製方法及びエレクトロルミネッセンスデバイス
WO2017028638A1 (fr) * 2015-08-14 2017-02-23 广州华睿光电材料有限公司 Encre d'impression et dispositif électronique
WO2017080323A1 (fr) * 2015-11-12 2017-05-18 广州华睿光电材料有限公司 Composition d'impression et son application

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010009995A (ja) * 2008-06-27 2010-01-14 Seiko Epson Corp 吐出液、吐出液セット、薄膜パターン形成方法、薄膜、発光素子、画像表示装置、および、電子機器
JP2014077046A (ja) * 2012-10-10 2014-05-01 Konica Minolta Inc 発光層形成用インク組成物、発光素子の作製方法及びエレクトロルミネッセンスデバイス
WO2017028638A1 (fr) * 2015-08-14 2017-02-23 广州华睿光电材料有限公司 Encre d'impression et dispositif électronique
WO2017080323A1 (fr) * 2015-11-12 2017-05-18 广州华睿光电材料有限公司 Composition d'impression et son application

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JP6849089B2 (ja) 2021-03-24

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