JP7172238B2 - Ink and light emitting element - Google Patents

Description

The present invention relates to inks and light emitting devices.

Devices utilizing electroluminescence, such as LEDs and organic EL devices, are widely used as light sources for various display devices. In recent years, attention has been paid to light-emitting devices using semiconductor nanocrystals having light-emitting properties such as quantum dots and quantum rods as light-emitting materials. Light emission obtained from semiconductor nanocrystals has a narrower spectrum width and a wider color gamut than organic EL devices, and is therefore excellent in color reproducibility.

The light-emitting layer of such a light-emitting device can be obtained by applying an ink in which semiconductor nanocrystals are dispersed in a dispersion medium onto a substrate by a coating method to form a coating film, and then drying the coating film. In some cases, a surface tension modifier such as an organic acid is added to the ink for the purpose of imparting a viscosity suitable for the coating method (see, for example, Patent Document 1).

In addition, in order to obtain good light emission characteristics of the light emitting layer (light emitting device), it is important that the semiconductor nanocrystals exist uniformly and densely in the light emitting layer. This requires good wetting of the ink on the substrate (support). However, according to the studies of the present inventors, it has been found that the ink described in Patent Document 1 does not sufficiently wet and spread on the substrate.

U.S. Patent Application Publication No. 2017/0174921

An object of the present invention is to provide an ink that has a viscosity suitable for a coating method and that can sufficiently wet and spread on a support (substrate), and a light-emitting element with high luminous efficiency.

Such objects are achieved by the present invention of the following (1) to (7).
(1) a luminescent semiconductor nanocrystal;
a fluorine-containing compound having a boiling point of less than 300° C. under atmospheric pressure, comprising a main skeleton containing a fluorine atom and a functional group bonded to the main skeleton and capable of being supported by the semiconductor nanocrystal;
a dispersion medium for dispersing the semiconductor nanocrystals;
An ink comprising 0.001 to 40 parts by mass of the fluorine-containing compound with respect to 100 parts by mass of the semiconductor nanocrystals.

(2) The ink according to (1) above, wherein the main skeleton has 5 to 15 carbon atoms.

（式中、Ｚ_１、Ｚ_２およびＺ_３は、それぞれ独立して、水素原子、水酸基またはアルコキシル基である。） (3) The ink according to (1) or (2) above, wherein the functional group is at least one selected from the group consisting of the following chemical formulas.

(In the formula, Z ₁ , Z ₂ and Z ₃ are each independently a hydrogen atom, a hydroxyl group or an alkoxyl group.)

(4) the main skeleton comprises a linear aliphatic hydrocarbon structure in which at least some of the hydrogen atoms are substituted with fluorine atoms;
The ink according to any one of (1) to (3) above, wherein the functional group is at least one selected from the group consisting of a thiol group, a carboxyl group and an amino group.

(5) The ink according to any one of (1) to (4) above, wherein the substitution ratio of hydrogen atoms with fluorine atoms in the main skeleton is 50% or more.

(6) The ink according to any one of (1) to (5) above, wherein the boiling point of the dispersion medium under atmospheric pressure is equal to or higher than the boiling point of the fluorine-containing compound under atmospheric pressure and 350° C. or lower.

(7) a pair of electrodes;
a light-emitting layer provided between the pair of electrodes and made of the dried ink according to any one of (1) to (6);
A light emitting device comprising: the light emitting layer; and a charge transport layer provided between at least one of the pair of electrodes.

According to the present invention, a luminescent layer with high luminous efficiency can be formed by sufficiently spreading the ink on the substrate.

1 is a cross-sectional view showing an embodiment of a light emitting device of the present invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The ink and light-emitting element of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
<Ink>
The ink of the present invention contains luminescent semiconductor nanocrystals, a fluorine-containing compound, and a dispersion medium for dispersing the semiconductor nanocrystals.
In addition, the ink of the present invention may contain, for example, a charge transport material, a surfactant, and the like, if necessary.

<<Semiconductor nanocrystals>>
Semiconductor nanocrystals (hereinafter sometimes simply referred to as “nanocrystals”) are nano-sized crystals (nanocrystal particles) that absorb excitation light and emit fluorescence or phosphorescence. It is a crystal having a maximum particle size of 100 nm or less as measured by a microscope or scanning electron microscope.
Nanocrystals can be excited, for example, by light energy or electrical energy of a given wavelength to fluoresce or phosphoresce.

The nanocrystals may be red-emitting crystals that emit light with an emission peak in the wavelength range of 605-665 nm (red light), and emit light with an emission peak in the wavelength range of 500-560 nm (green light). It may be a green light-emitting crystal, or a blue light-emitting crystal that emits light (blue light) having an emission peak in the wavelength range of 420 to 480 nm. Also, in one embodiment, the ink preferably comprises at least one of these nanocrystals.
The wavelength of the emission peak of the nanocrystal can be confirmed, for example, in the fluorescence spectrum or phosphorescence spectrum measured using an ultraviolet-visible spectrophotometer.

red-emitting nanocrystals are 665 nm or less, 663 nm or less, 660 nm or less, 658 nm or less, 655 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, 635 nm or less; It preferably has an emission peak in a wavelength range of 632 nm or less or 630 nm or less, and may 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 limits can be combined arbitrarily. In addition, in the following similar description, the upper limit value and the lower limit value described individually can be combined arbitrarily.

Green-emitting nanocrystals have an emission peak in the wavelength range of 560 nm or less, 557 nm or less, 555 nm or less, 550 nm or less, 547 nm or less, 545 nm or less, 543 nm or less, 540 nm or less, 537 nm or less, 535 nm or less, 532 nm or less, or 530 nm or less. It preferably has 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.

The blue-emitting nanocrystals have an emission peak 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, 465 nm or less, 463 nm or less, 460 nm or less, 457 nm or less, 455 nm or less, 452 nm or less, or 450 nm or less. It preferably has 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.

According to the solution of the Schrödinger wave equation of the well-type potential model, the wavelength (emission color) of the light emitted by the nanocrystal depends on the size of the nanocrystal (e.g., particle diameter), but the energy gap of the nanocrystal also affects Dependent. Therefore, by changing the constituent materials and sizes, the emission color of the nanocrystals can be selected (tuned).

Nanocrystals may be composed of a semiconductor material and may have various structures. For example, a nanocrystal may consist solely of a core of the first semiconductor material, with a core of the first semiconductor material covering at least a portion of the core and the first semiconductor A configuration having a shell made of a second semiconductor material different from the material is also possible. In other words, the structure of the nanocrystal may be a structure consisting of only a core (core structure) or a structure consisting of a core and a shell (core/shell structure).

In addition to the shell made of the second semiconductor material (first shell), the nanocrystals also cover at least a portion of this shell and comprise a third semiconductor different from the first and second semiconductor materials. It may further have a shell (second shell) made of material. In other words, the structure of the nanocrystal may be a structure consisting of a core, a first shell and a second shell (core/shell/shell structure).
Furthermore, each of the core and shell may be composed of a mixed crystal containing two or more semiconductor materials (eg, CdSe+CdS, CIS+ZnS, etc.).

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 preferably composed of

Specific semiconductor materials include, for example, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, ＣｄＺｎＳｅ、ＣｄＺｎＴｅ、ＣｄＨｇＳ、ＣｄＨｇＳｅ、ＣｄＨｇＴｅ、ＨｇＺｎＳ、ＨｇＺｎＳｅ、ＣｄＨｇＺｎＴｅ、ＣｄＺｎＳｅＳ、ＣｄＺｎＳｅＴｅ、ＣｄＺｎＳＴｅ、ＣｄＨｇＳｅＳ、ＣｄＨｇＳｅＴｅ、ＣｄＨｇＳＴｅ、ＨｇＺｎＳｅＳ、ＨｇＺｎＳｅＴｅ、ＨｇＺｎＳＴｅ、ＧａＮ、ＧａＰ、ＧａＡｓ、ＧａＳｂ、ＡｌＮ、ＡｌＰ、ＡｌＡｓ、ＡｌＳｂ、 InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb; SnPbSeTe, SnPbSTe, Si, Ge, SiC, SiGe, AgInSe2, _CuGaSe2 , _CuInS2 , _CuGaS2 , _CuInSe2 , _AgInS2 , _AgGaSe2 , _AgGaS2 and _C , and the like.

Semiconductor materials include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, InP, InAs, InSb, GaP, GaAs, GaSb, _AgInS2 , _AgInSe2 , _AgInTe2 , _AgGaS2 , _AgGaSe2 , _AgGaTe2 , _CuInS2 , _CuInSe2 , _CuInTe2 , _CuGaS2 , _CuGaSe2 , _CuGaTe2 , Si, C, _Ge and _Cu2ZnSnS4 .
Nanocrystals composed of these semiconductor materials can easily control the emission spectrum, and can reduce production costs and improve mass productivity while ensuring reliability.

Red-emitting nanocrystals include, for example, nanocrystals of CdSe; rod-like nanocrystals of CdSe; rod-like nanocrystals with a shell of CdS and a core of CdSe; Rod-shaped nanocrystals; nanocrystals with a shell of CdS and a core of CdSe; nanocrystals with a shell of CdS and a core of ZnSe; nanocrystals with a shell of ZnS and a core of InP; CdSe and ZnS mixed crystal nanocrystals; CdSe and ZnS mixed crystal rod-shaped nanocrystals; InP nanocrystals; InP rod-shaped nanocrystals; a mixed crystal of CdSe and CdS; a mixed crystal of ZnSe and CdS; a mixed crystal of ZnSe and CdS; a mixed crystal of ZnSe and CdS.

Green-emitting nanocrystals include, for example, CdSe nanocrystals; CdSe rod-like nanocrystals; nanocrystals with a ZnS shell and an InP core; nanocrystals with a ZnS shell and a CdSe core; Nanocrystals of mixed crystals of CdSe and ZnS; rod-like nanocrystals of mixed crystals of CdSe and ZnS;

Blue-emitting nanocrystals include, for example, ZnSe nanocrystals; ZnSe rod-like nanocrystals; ZnS nanocrystals; ZnS rod-like nanocrystals; nanocrystals comprising a ZnSe shell and a ZnS core; rod-shaped nanocrystals with a ZnSe shell and a ZnS core; CdS nanocrystals; CdS rod-shaped nanocrystals;

Even if the nanocrystals have the same chemical composition, by designing the average particle size of the nanocrystals themselves, the color to be emitted from the nanocrystals can be changed to red or green.
Moreover, it is preferable that the nanocrystal itself has as little adverse effect on the human body as possible. Therefore, nanocrystals containing as little cadmium, selenium, etc. as possible are selected and used alone, or when nanocrystals containing the above elements (cadmium, selenium, etc.) are used, other is preferably used in combination with nanocrystals of

The shape of the nanocrystals is not particularly limited and may be any geometric shape or any irregular shape. Examples of the shape of the nanocrystal include spherical, regular tetrahedral, ellipsoidal, pyramidal, disk-like, branch-like, net-like, and rod-like. However, as the shape of the nanocrystal, a shape with less directionality (eg, spherical shape, regular tetrahedral shape, etc.) is preferable. By using nanocrystals having such a shape, the uniformity and fluidity of the ink can be further enhanced.

The average particle diameter (volume average diameter) of the nanocrystals is preferably 40 nm or less, more preferably 30 nm or less, and even 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 even more preferably 2 nm or more. Nanocrystals having such an average particle size are preferable because they not only easily emit light of a desired wavelength, but also can improve dispersibility in ink and storage stability.
The average particle diameter (volume average diameter) of nanocrystals is obtained by measuring with a transmission electron microscope or scanning electron microscope and calculating the volume average diameter.

By the way, nanocrystals are highly reactive because they have surface atoms that can serve as coordination sites. Since nanocrystals have such high reactivity and have a larger surface area than general pigments, they tend to aggregate.
Nanocrystals produce luminescence through quantum size effects. For this reason, when nanocrystals aggregate, a quenching phenomenon occurs, resulting in a decrease in fluorescence quantum yield and a decrease in luminance and color reproducibility. That is, the ink in which nanocrystals are dispersed in a dispersion medium, such as the present invention, is likely to cause deterioration in light-emitting properties due to aggregation, unlike ink in which an organic light-emitting material is dissolved in a solvent. Therefore, in the ink of the present invention, it is important to prepare the ink from the viewpoint of ensuring the dispersion stability of the nanocrystals.

For this reason, in one embodiment, a dispersant (organic ligand) that is compatible with the dispersion medium is supported (held) on the surface of the nanocrystals, in other words, the surface of the nanocrystals is dissipated by the dispersant. may be activated. The presence of this dispersant can improve the dispersion stability of the nanocrystals in the ink.
In this case, the dispersant is supported on the nanocrystal surface by, for example, a covalent bond, a coordinate bond, an ionic bond, a hydrogen bond, a Van der Waals bond, or the like. As used herein, “supported” is a generic term for the state in which a dispersant is adsorbed, attached, or bonded to the surface of nanocrystals. In addition, the dispersing agent can be detached from the surface of the nanocrystals, and the loading by the nanocrystals and the detachment from the nanocrystals are in equilibrium, and these can be repeated.

The dispersant is not particularly limited as long as it is a compound capable of improving the dispersion stability of nanocrystals in ink. Dispersants are classified into low molecular weight dispersants and polymeric dispersants. As used herein, "low molecular weight" means molecules with a weight average molecular weight (Mw) of 5,000 or less, and "high molecular weight" means molecules with a weight average molecular weight (Mw) of greater than 5,000. means
In the present specification, "weight average molecular weight (Mw)" shall be a value measured using gel permeation chromatography (GPC) using polystyrene as a standard substance.

Low-molecular-weight dispersants include, for example, oleic acid; triethyl phosphate, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), octylphosphine phosphorus atom-containing compounds such as acid (OPA); nitrogen atom-containing compounds such as oleylamine, octylamine, trioctylamine, hexadecylamine; sulfur atoms such as 1-decanethiol, octanethiol, dodecanethiol, amyl sulfide containing compounds and the like.

As the polymer dispersant, for example, a polymer compound having a functional group that can be supported by nanocrystals can be used.
Examples of such functional groups include primary amino groups, secondary amino groups, tertiary amino groups, phosphoric acid groups, phosphoric acid ester groups, phosphonic acid groups, phosphonic acid ester groups, phosphinic acid groups, phosphinate ester groups, 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, borate ester group, boronic acid and the like.

Among these, a primary amino group, a secondary amino group, a tertiary amino group, a carboxylic acid ester group, a A phosphate group, a phosphate ester group, a phosphonic acid group, a phosphonic acid ester group, and a carboxylic acid group are preferable because the hydroxyl group and the ether group, even when used alone, have a sufficient ability to support nanocrystals.
Further, primary amino groups, secondary amino groups, tertiary amino groups, phosphoric acid groups, phosphonic acid groups, and carboxylic acid groups are more preferred from the viewpoint of having high carrying capacity on nanocrystals in ink.

Examples of polymeric dispersants having a primary amino group include linear amines such as polyalkylene glycol amines, polyester amines, urethane-modified polyester amines, polyalkylene glycol diamines, polyester diamines, and urethane-modified polyester diamines; ) A comb-shaped polyamine having an amino group on the side chain of an acrylic polymer.
Polymeric dispersants having secondary amino groups include, for example, comb-shaped dispersants having a main chain containing a linear polyethyleneimine skeleton having a large number of secondary amino groups and side chains of polyester, acrylic resin, polyurethane, or the like. block copolymers, and the like.

Polymeric dispersants having a tertiary amino group include, for example, star-shaped amines such as tri(polyalkyleneglycol)amine.
Further, as a polymer dispersant having a primary amino group, a secondary amino group and a tertiary amino group, for example, JP-A-2008-037884, JP-A-2008-037949, JP-A-2008-03818 , a polymer compound having a linear or multibranched polyethyleneimine block and a polyethylene glycol block described in JP-A-2010-007124.

Polymeric dispersants having a phosphoric acid group include, for example, polyalkylene glycol monophosphate, polyalkylene glycol monoalkyl ether monophosphate, perfluoroalkylpolyoxyalkylene phosphate, perfluoroalkylsulfonamide polyoxyalkylene phosphorus, Homopolymers obtained from monomers such as acid esters, acid phosphooxyethyl mono(meth)acrylate, acid phosphooxypropyl mono(meth)acrylate, acid phosphooxypolyoxyalkylene glycol mono(meth)acrylate or these monomers and other a copolymer obtained from a comonomer; and a (meth)acrylic polymer having a phosphoric acid group obtained by the method described in Japanese Patent No. 4,697,356.
The polymer dispersing agent having a phosphate group can be reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide to form a salt and adjust the pH.

Polymeric dispersants having phosphonic acid groups include, for example, polyalkylene glycol monoalkyl phosphonate, polyalkylene glycol monoalkyl ether monoalkyl phosphonate, perfluoroalkyl polyoxyalkylene alkyl phosphonate, and perfluoroalkyl sulfone. Monomers such as amide polyoxyalkylene alkyl phosphonic acid esters, polyethylene phosphonic acid; vinyl phosphonic acid, (meth) acryloyloxyethyl phosphonic acid, (meth) acryloyloxypropyl phosphonic acid, (meth) acryloyloxy polyoxyalkylene glycol phosphonic acid and copolymers obtained from this monomer and other comonomers.
The polymeric dispersant having a phosphonic acid group can be reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide to form a salt and adjust the pH.

Polymeric dispersants having phosphinic acid groups include, for example, polyalkylene glycol dialkylphosphinate, perfluoroalkylpolyoxyalkylenedialkylphosphinate, perfluoroalkylsulfonamide polyoxyalkylenedialkylphosphinate, polyethylene phosphinic acid; Examples include homopolymers obtained from monomers such as vinylphosphinic acid, (meth)acryloyloxydialkylphosphinic acid, (meth)acryloyloxypolyoxyalkylene glycol dialkylphosphinic acid, and copolymers obtained from these monomers and other comonomers. . The polymer dispersant having a phosphinic acid group can be reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide to form a salt and adjust the pH.

Polymeric dispersants having a thiol group include, for example, polyvinyl thiol and polyalkylene glycol ethylene thiol.
Examples of the polymer dispersant having a thioether group include polyalkylene glycol thioether obtained by reacting mercaptopropionic acid and glycidyl-modified polyalkylene glycol described in JP-A-2013-60637.

Polymeric dispersants having sulfonic acid groups include, for example, polyalkylene glycol monoalkyl sulfonates, polyalkylene glycol monoalkyl ether monoalkyl sulfonates, perfluoroalkyl polyoxyalkylene alkyl sulfonates, and perfluoroalkyl sulfones. Homopolymers derived from monomers such as amidopolyoxyalkylenealkylsulfonic acid esters, polyethylenesulfonic acid; vinylsulfonic acid, (meth)acryloyloxyalkylsulfonic acid, (meth)acryloyloxypolyoxyalkylene glycolsulfonic acid, polystyrenesulfonic acid Alternatively, copolymers obtained from this monomer and other comonomers may be mentioned.
In addition, the polymer dispersant having a sulfonic acid group can be reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide to form a salt and adjust the pH.

Polymer dispersants having carboxylic acid groups include, for example, polyalkylene glycol carboxylic acid, perfluoroalkylpolyoxyalkylene carboxylic acid, polyethylene carboxylic acid, polyester monocarboxylic acid, polyester dicarboxylic acid, urethane-modified polyester monocarboxylic acid, urethane Modified polyester dicarboxylic acids; homopolymers obtained from monomers such as vinylcarboxylic acid, (meth)acryloyloxyalkylcarboxylic acid, (meth)acryloyloxypolyoxyalkylene glycol carboxylic acid or copolymers obtained from this monomer with other comonomers etc.
The polymeric dispersant having a carboxylic acid group can also be reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide to form a salt and adjust the pH.

A polymeric dispersant having an ester group can be obtained by dehydrating and condensing a polymeric dispersant having a carboxylic acid group with, for example, a monoalkyl alcohol.
Polymer dispersants having a pyrrolidonyl group include, for example, polyvinylpyrrolidone.

Incidentally, the polymer dispersant having a specific functional group may be a synthetic product or a commercial product.
Commercially available products include, for example, DISPERBYK-102, DISPERBYK-103, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-118, DISPERBYK-140, and DISPERBYK- included in the DISPERBYK series manufactured by BYK-Chemie. DISPERBYK-145, DISPERBYK-161, DISPERBYK-164, DISPERBYK-168, DISPERBYK-168, DISPERBYK-180, DISPERBYK-182, DISPERBYK-184, DISPERBYK-185, DISPERBYK-190, DISPERBYK-191, DISPERBYK-2000, DISPERBYK-2000, DISPERBYK-2008, DISPERBYK-2009, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2022, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2060, DISPERBYK-9070 manufactured by DISPERBYK-9070 DISPERBONIC, DISPER90PERBYK DISPERBONIC;シリーズに含まれるＴＥＧＯ Ｄｉｓｐｅｒｓ ６１０、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６３０、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６５０、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６５１、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６５２、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６５５、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６６０Ｃ、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６６２Ｃ、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６７０、ＴＥＧＯ Ｄｉｓｐｅｒｓ ６８５、ＴＥＧＯ Ｄｉｓｐｅｒｓ ７００、ＴＥＧＯ Ｄｉｓｐｅｒｓ 710, TEGO Dispers 715W, TEGO Dispers 740W, TEGO Dispers 750W, TEGO Dispers 752W, TEGO Dispers 755W, TEGO Dispers 760W; , EFKA-4010, EFKA-4050, EFKA-4055, EFKA-4020, EFKA-4015, EFKA-4060, EFKA-4300, EFKA-4330, EFKA-4400, EFKA-4406, EFKA- 4510, EFKA-4800; SOLSPERS-3000, SOLSPERS-9000, SOLSPERS-16000, SOLSPERS-17000, SOLSPERS-18000, SOLSPERS-13940, SOLSPERS-20000, SOLSPERS-24000, which are included in the SOLSPERSE series manufactured by Nippon Lubrizol Co., Ltd. -32550, SOLSPERS-71000; AJISPUR PB-821, AJISPUR PB-822, AJISPUR PB-823 included in the Ajinomoto Fine Techno Ajinomoto series; DISPARLON DA325, DISPARLON included in the DISPARLON series made by Kusumoto Kasei DA375, DISPARLON DA1800, DISPARLON DA7301; FLORENE DOPA-17HF, FLORENE DOPA-15BHF, FLORENE DOPA-33, FLORENE DOPA-44 included in the FLORENE series manufactured by Kyoeisha Chemical Co., Ltd., and the like.
These polymeric dispersants may be used singly or in combination of two or more.

The dispersant as described above may be carried with almost all of its molecules in contact with the nanocrystals, or may be carried with only a portion of its molecules in contact with the nanocrystals. In either state, the dispersant suitably exhibits a dispersing function of stably dispersing the nanocrystals in the dispersion medium.
From this point of view, the weight average molecular weight (Mw) of the dispersant is preferably 50,000 or less, more preferably about 100 to 50,000. When the mass of a low-molecular-weight dispersant that is not a polymer is expressed, "molecular weight" is used instead of "weight-average molecular weight."

A dispersant having a weight-average molecular weight equal to or higher than the lower limit value has an excellent ability to support nanocrystals, so that it is possible to sufficiently secure the dispersion stability of nanocrystals in the ink. On the other hand, 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 have an excessively high crystallinity, so that the dispersion stability of nanocrystals in ink can be improved. can. Moreover, since the weight-average molecular weight of the dispersant is not too high, it is possible to prevent or suppress the inhibition of charge transfer in the resulting light-emitting layer.

When a dispersant is used, the amount of the dispersant (especially polymer dispersant) relative to the nanocrystals is preferably 50 parts by mass or less with respect to 100 parts by mass of the nanocrystals. This makes it difficult for unnecessary organic substances to remain or precipitate on the surface of the nanocrystals when the nanocrystals carry the dispersing agent. Therefore, the dispersing agent layer is unlikely to become an insulating layer that inhibits the transfer of electric charges, and deterioration of the light emission characteristics can be prevented.
On the other hand, the amount of the dispersant to the nanocrystals is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more with respect to 100 parts by mass of the nanocrystals. . Thereby, sufficient dispersion stability of the nanocrystals in the ink can be maintained.

<<Charge transport material>>
A charge-transporting material usually has the 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 small molecule charge transport materials.

Examples of polymeric charge transport materials include, but are not limited to, 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.

Examples of low-molecular-weight charge transport materials include, but are not limited to, 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 ,4-dimethylbenzene (DCB), carbazole derivatives such as 5,11-diphenyl-5,11-dihydroindolo[3,2-b]carbazole; bis(2-methyl-8-quinolinolate)-4- aluminum complexes such as (phenylphenolato)aluminum (BAlq); phosphine oxide derivatives such as 2,7-bis(diphenylphosphine oxide)-9,9-dimethylfluorene (P06); 3,5-bis(9- silane derivatives such as carbazolyl)tetraphenylsilane (SimCP), 1,3-bis(triphenylsilyl)benzene (UGH3); 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl triphenylamine derivatives such as (α-NPD), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9H-carbazole, 9-(2,6-diphenylpyrimidine-4 -yl)-9H-carbazole, heterocyclic derivatives such as derivatives of these compounds, and the like.

<<Surfactant>>
As the surfactant, for example, one or a combination of two or more of fluorine-based surfactants, silicone-based surfactants, hydrocarbon-based surfactants, and the like can be used. Among these, silicone-based surfactants and/or hydrocarbon-based surfactants are preferable because they are difficult to trap charges.

Low-molecular-weight or high-molecular-weight surfactants can be used as the silicone-based surfactant and the hydrocarbon-based surfactant.
Specific examples thereof include BYK series manufactured by BYK Chemie, Surfynol manufactured by Nissin Chemical Industry Co., Ltd., and the like. Among these, a silicone-based surfactant comprising an organically modified siloxane can be preferably used because a highly smooth coating film can be obtained when the ink is applied.

<<dispersion medium>>
Nanocrystals (or particles composed of nanocrystals carrying a dispersing agent) as described above are dispersed in a dispersion medium.
The dispersion medium is not particularly limited, but for example, aromatic hydrocarbon compounds, aromatic ester compounds, aromatic ether compounds, aromatic ketone compounds, aliphatic hydrocarbon compounds, aliphatic ester compounds, aliphatic ether compounds, aliphatic group ketone compounds, alcohol compounds, amide compounds, other compounds, and the like, and one or more of these can be used in combination.

Aromatic hydrocarbon compounds include toluene, xylene, ethylbenzene, cumene, mesitylene, tert-butylbenzene, indane, diethylbenzene, pentylbenzene, 1,2,3,4-tetrahydronaphthalene, naphthalene, hexylbenzene, heptylbenzene, cyclohexyl Benzene, 1-methylnaphthalene, biphenyl, 2-ethylnaphthalene, 1-ethylnaphthalene, octylbenzene, diphenylmethane, 1,4-dimethylnaphthalene, nonylbenzene, isopropylbiphenyl, 3-ethylbiphenyl, dodecylbenzene and the like.

Examples of aromatic ester compounds include phenyl acetate, methyl benzoate, ethyl benzoate, phenyl propionate, isopropyl benzoate, methyl 4-methylbenzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, ethyl p-anisate, dimethyl phthalate and the like.

Aromatic ether compounds include dimethoxybenzene, methoxytoluene, ethylphenyl ether, dibenzyl ether, 4-methylanisole, 2,6-dimethylanisole, ethylphenyl ether, propylphenyl ether, 2,5-dimethylanisole, 3, 5-dimethylanisole, 4-ethylanisole, 2,3-dimethylanisole, butylphenyl ether, 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 compounds include acetophenone, propiophenone, 4′-methylacetophenone, 4′-ethylacetophenone, butylphenylketone and the like.
Examples of aliphatic hydrocarbon compounds include pentane, hexane, octane, cyclohexane, and the like.

Examples of aliphatic ester compounds include ethyl acetate, butyl acetate, ethyl lactate, hexyl acetate, butyl lactate, isoamyl lactate, amyl valerate, ethyl levylate, γ-valerolactone, ethyl octanoate, γ-hexalactone, isoamyl hexa amylhexanate, nonyl acetate, methyl decanoate, diethyl glutarate, γ-heptalactone, ε-caprolactone, octalactone, propylene carbonate, γ-nonanolactone, hexyl hexanoate, diisopropyl adipate, δ-nonanolactone, glycerol Acetic acid, δ-decanolactone, dipropyl adipate, δ-undecalactone and the like.

Aliphatic ether compounds include 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 and the like.

Aliphatic ketone compounds include diisobutyl ketone, cycloheptanone, isophorone, 6-undecanone and the like.
Alcohol compounds include 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. Glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol, cyclohexanol, 2-butoxyethanol and the like.

Amide compounds include N,N-dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone, N,N-dimethylacetamide and the like.
Other compounds include water, dimethylsulfoxide, acetone, chloroform, methylene chloride, and the like.

The viscosity of the above dispersion medium at 25° C. is preferably about 1 to 20 mPa·s, more preferably about 1.5 to 15 mPa·s, and more preferably about 2 to 10 mPa·s. More preferred. If the viscosity of the dispersion medium at room temperature is within the above range, the droplets ejected from the nozzle holes of the droplet ejection head are separated into main droplets and small droplets when the ink is ejected by the droplet ejection method. It is possible to prevent or suppress the occurrence of the phenomenon (satellite phenomenon). Therefore, it is possible to improve the landing accuracy of the droplets on the adherend (support).

<<Fluorine-containing compound>>
Here, if the ink cannot wet and spread on the support, the nanocrystals will be unevenly distributed in the formed light-emitting layer, resulting in a decrease in the light-emitting efficiency of the light-emitting layer (light-emitting element). Resulting in.
As a result of intensive studies by the present inventors in order to solve this problem, it has been found that the addition of a fluorine-containing compound to the ink enables the ink to sufficiently wet and spread on the support. One of the main reasons for this is thought to be that the addition of the fluorine-containing compound lowers the surface tension of the ink.

In the present invention, as the fluorine-containing compound, a compound containing a fluorine atom-containing main skeleton and a functional group bonded to the main skeleton and capable of being carried by the nanocrystal is used. By using a fluorine-containing compound having such a functional group, the fluorine-containing compound is supported on the nanocrystals, and in addition to the effect of improving the wetting and spreadability of the ink, the effect of improving the dispersion stability of the nanocrystals in the ink. is also demonstrated.
As a result, the non-uniformity of the distribution of nanocrystals in the formed light-emitting layer is further reduced, and the light-emitting efficiency of the light-emitting layer is improved.

Although the number of carbon atoms in the main skeleton is not particularly limited, it is preferably 5-15, more preferably 6-13, even more preferably 7-11. A fluorine-containing compound having a main skeleton having such a number of carbon atoms can prevent an extreme decrease in affinity with a dispersion medium.

The main skeleton includes a linear aliphatic hydrocarbon structure, a branched aliphatic hydrocarbon structure, a cyclic aliphatic hydrocarbon structure, an aromatic hydrocarbon structure, or a combination thereof. Among them, the main skeleton preferably contains a linear aliphatic hydrocarbon structure. If the main skeleton contains a straight-chain aliphatic hydrocarbon structure, when the fluorine-containing compound is supported on the nanocrystal, it will expand in the radial direction of the nanocrystal. Therefore, the dispersion stability of the nanocrystals in the ink is further improved.

A linear aliphatic hydrocarbon structure may or may not have an unsaturated bond.
In the main skeleton, the substitution rate of hydrogen atoms with fluorine atoms (hereinafter sometimes referred to as "fluorine substitution rate") is not particularly limited, but is preferably 50% or more, and 60% or more. more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. By using a fluorine-containing compound having such a fluorine substitution rate, the wetting and spreadability of the ink can be further improved. Note that the fluorine substitution rate may be 100%.

The functional group that can be carried on the nanocrystal is preferably at least one selected from the group consisting of the following chemical formulas, and at least one selected from the group consisting of a thiol group, a carboxyl group and an amino group. more preferred.

（式中、Ｚ_１、Ｚ_２およびＺ_３は、それぞれ独立して、水素原子、水酸基またはアルコキシル基である。）

(In the formula, Z ₁ , Z ₂ and Z ₃ are each independently a hydrogen atom, a hydroxyl group or an alkoxyl group.)

The functional groups represented by the above chemical formulas have high affinity with nanocrystals, and thiol groups, carboxyl groups, and amino groups are preferred because they have particularly high affinity with nanocrystals.
For this reason, the fluorine-containing compound is a main skeleton containing a linear aliphatic hydrocarbon structure in which at least some hydrogen atoms are substituted with fluorine atoms, and a thiol group, a carboxyl group, or an amino group. Compounds with functional groups are preferred.

Furthermore, in the present invention, a fluorine-containing compound having a boiling point of less than 300° C. under atmospheric pressure (1 atm) (hereinafter also simply referred to as “boiling point”) is used. By using such a fluorine-containing compound, the fluorine-containing compound can be sufficiently and reliably removed from the light-emitting layer (nanocrystals) even when the drying conditions for the coating film are set to mild conditions when forming the light-emitting layer. can be done.
Therefore, thermal deterioration of the nanocrystals can be prevented. In addition, the fluorine-containing compound, which hinders electron transfer during light emission, does not remain in the light-emitting layer, or if it remains, the amount can be extremely small. As a result, the luminous efficiency of the light emitting element can be further enhanced.

On the other hand, when a fluorine-containing compound having a boiling point of 300° C. or higher is used, the conditions for drying the coating film must be set to severe conditions, and there is concern about deterioration of the nanocrystals. On the other hand, if the drying conditions are set to mild conditions, many fluorine-containing compounds remain without being removed from the light-emitting layer. For this reason, the luminous efficiency of the light emitting element is lowered.

The boiling point of the fluorine-containing compound may be less than 300°C, preferably about 80 to 250°C, more preferably about 100 to 250°C. As a result, the fluorine-containing compound can be sufficiently removed from the light-emitting layer even under mild drying conditions. In addition, since the fluorine-containing compound is not excessively removed from the ink during storage or the like, it is possible to prevent deterioration in the wetting and spreading properties of the ink over time.

Examples of fluorine-containing compounds that satisfy the above conditions include difluoroacetic acid, dodecafluorosuberic acid, 4,4-difluorocyclohexanecarboxylic acid, 2,2-difluoro-2-(fluorosulfonyl)acetic acid, and heptafluorobutyric acid. , hexafluoroglutaric acid, heptadecafluorononanoic acid, hexadecafluorosebacic acid, heneicosafluoroundecanoic acid, 2-amino-4,4,4-trifluoro-3-(trifluoromethyl)butyric acid, 4,4 ,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanoic acid, nonafluorovaleric acid, nonadecafluorodecanoic acid, octafluoroadipine acid, pentadecafluorooctanoic acid, pentafluoropropionic acid, 3,3,3-trifluoropropionic acid, 4-(trifluoromethyl)cyclohexanecarboxylic acid, tricosafluorododecanoic acid, 2-hydroxy-2,2-bis (Trifluoromethyl)acetic acid, 4,4,4-trifluorobutyric acid, 2,2-difluoroethylamine, heptafluorobutyramide, 1H,1H-perfluorobutylamine, 1-aminomethyl-4-trifluoromethylcyclohexane, 1H , 1H-undecafluorohexylamine, perfluorododecanethiol, 4,4,5,5,6,6,6-heptafluoro-1-hexanamine, 1,1,2,2-tetrahydroperfluorododecanethiol, Aliphatic compounds such as perfluorododecanethiol and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7-pentadecafluoro-1-heptanethiol etc. These may be used individually by 1 type, and may be used in combination of 2 or more types.

Other fluorine-containing compounds include 4-fluorobenzoic acid, 4-fluoro-3-(trifluoromethyl)benzoic acid, trans-3,5-difluorocinnamic acid, tetrafluorophthalic acid, pentafluorobenzoic acid, 4 - aromatics such as fluoroaniline, 4,5-difluoro-1,2-phenylenediamine, 4-aminononafluorobiphenyl, pentafluoroaniline, 4-fluorobenzenethiol, 3,4-difluorobenzenethiol, pentafluorobenzenethiol Group compounds and the like can also be suitably used. These may be used individually by 1 type, and may be used in combination of 2 or more type. Further, these aromatic compounds may be used as fluorine-containing compounds instead of aliphatic compounds, or may be used in combination with aliphatic compounds.

Similar to the dispersing agent, the fluorine-containing compound as described above is in equilibrium between being supported by the nanocrystals and being released from the nanocrystals, and these can be repeated.
Therefore, when a dispersant is used, the fluorine-containing compound in the ink may replace part of the dispersant and be supported on the nanocrystals, or replace the entire dispersant and be supported on the nanocrystals. good.

In addition, as described above, the fluorine-containing compound also exhibits a function (that is, a function similar to that of a dispersant) to enhance the dispersion stability of the nanocrystals in the ink. Therefore, depending on the amount of the fluorine-containing compound used, the use of the dispersant may be omitted.
The amount of the fluorine-containing compound contained in the ink is 0.001 to 40 parts by weight with respect to 100 parts by weight of the nanocrystals. If it is less than the above lower limit, the effect of lowering the surface tension of the ink by the fluorine-containing compound cannot be sufficiently obtained. On the other hand, when the above upper limit is exceeded, the surface tension is too low, resulting in a low-viscosity ink unsuitable for the coating method (particularly, the droplet discharge method).

The amount of the fluorine-containing compound contained in the ink may be 0.001 to 40 parts by mass, preferably about 0.001 to 30 parts by mass, with respect to 100 parts by mass of the nanocrystals. 001 to 20 parts by mass is more preferable. The lower limit of the amount of the fluorine-containing compound contained in the ink is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more with respect to 100 parts by mass of the nanocrystals. When the amount of the fluorine-containing compound contained in the ink is within the above range, the surface tension of the ink can be moderately lowered while maintaining the viscosity suitable for various coating methods.

In the ink of the present invention, if there is a possibility that the nanocrystals (or particles containing nanocrystals) are deactivated by oxygen, water, etc. and do not function stably, dissolved gas or moisture It is preferable to use a dispersion medium from which as much as possible has been removed, or to perform a post-treatment to remove dissolved oxygen and moisture from the ink as much as possible after preparation of the ink. Examples of the post-treatment include degassing, inert gas saturation or supersaturation, heat treatment, and dehydration by passing a desiccant.
The dissolved oxygen and water content in the ink is preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 10 ppm or less.

The amount of nanocrystals 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. By setting the amount of nanocrystals contained in the ink within the above range, the ejection stability can be further improved when the ink is ejected by a droplet ejection method. In addition, the particles (nanocrystals) are less likely to agglomerate, and the luminous efficiency of the resulting luminescent layer can be increased.

In this specification, "the amount of nanocrystals contained in the ink" means that when the ink is composed of nanocrystals, a fluorine-containing compound, and a dispersion medium, the total amount of these is 100 parts by mass. , refers to the mass ratio (%) of nanocrystals, and when the ink is composed of nanocrystals, a fluorine-containing compound, other nonvolatile components and a dispersion medium, the total amount of nanocrystals when the total of these is 100 parts by mass Refers to mass ratio (%).

As described above, the present invention uses a fluorine-containing compound having a boiling point of less than 300° C., that is, a fluorine-containing compound that volatilizes at relatively low temperatures. Therefore, it is preferable to use a compound whose boiling point is equal to or higher than the boiling point of the fluorine-containing compound and equal to or lower than 350° C. as the dispersion medium. By using such a dispersant, the fluorine-containing compound is preferentially removed from the coating film before the dispersion medium is removed from the coating film when the coating film is dried during the formation of the light-emitting layer. Therefore, the amount of the fluorine-containing compound remaining in the obtained light-emitting layer can be further reduced, and the light-emitting efficiency of the light-emitting device can be further increased.

The boiling point of the dispersion medium is not particularly limited because it is appropriately selected according to the boiling point of the fluorine-containing compound, but it is more preferably about 180 to 350°C, more preferably about 200 to 350°C. By using a dispersion medium having such a boiling point, the above effects can be further enhanced.

Moreover, the dispersion medium preferably contains a polar compound. In the coating film during the drying process, the dispersing agent and/or the fluorine-containing compound may detach from the surface of the nanocrystals, exposing the surface of the nanocrystals. In this case, aggregation of the nanocrystals (particles) can be prevented by solvating the polar compound on the surface of the nanocrystals. Therefore, since the nanocrystals are uniformly distributed in the obtained light-emitting layer, it is possible to prevent or suppress the deterioration of the light-emitting efficiency of the light-emitting layer due to the self-absorption phenomenon of the nanocrystals.

The amount of the polar compound contained in the dispersion medium is preferably about 20 to 80% by mass, more preferably about 30 to 70% by mass. By using a dispersion medium containing a polar compound in such an amount range, the effects described above can be exhibited more remarkably.

The polar group possessed by the polar compound includes, for example, a hydroxyl group, a carbonyl group, a thiol group, an amino group, a nitro group, a cyano group and the like. Among these, the polar group is preferably at least one selected from the group consisting of hydroxyl groups and carbonyl groups. These polar groups should ensure sufficient dispersion stability of the nanocrystals in the ink, and should have an appropriate affinity for the nanocrystals so that they can be easily detached from the nanocrystals when the coating is dried. preferred from

Thus, polar compounds are phenyl acetate, methyl benzoate, ethyl benzoate, phenyl propionate, isopropyl benzoate, methyl 4-methylbenzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, ethyl p-anisate, phthalate Aromatic ester compounds such as dimethyl acid; Aromatic ketone compounds such as acetophenone, propiophenone, 4'-methylacetophenone, 4'-ethylacetophenone, butylphenyl ketone; Ethyl lactate, hexyl acetate, butyl lactate, isoamyl lactate , amyl valerate, ethyl levyrate, γ-valerolactone, ethyl octanoate, γ-hexalactone, isoamylhexanate, amylhexanate, nonyl acetate, methyl decanoate, diethyl glutarate, γ-heptalactone, ε- Caprolactone, octalactone, propylene carbonate, γ-nonanolactone, hexyl hexanoate, diisopropyl adipate, δ-nonanolactone, glycerol triacetic acid, δ-decanolactone, dipropyl adipate, δ-undecalactone, δ-tridecanolactone, δ- dodecalactone, propylene glycol-1-monomethyl ether acetate, propylene glycol diacetate, diethylene glycol diacetate, diethylene glycol monoethyl ether acetate, 1,3-butanediol diacetate, 1,4-butanediol diacetate, diethylene glycol monobutyl ether acetate Aliphatic ester compounds such as; diisobutyl ketone, cycloheptanone, isophorone, 6-undecanone and other aliphatic ketone compounds; 1-heptanol, 2-ethyl-1-hexanol, propylene glycol, ethylene glycol, diethylene glycol monoethyl Alcohol compounds such as ether, triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, ethyl 3-hydroxyhexanate, tripropylene glycol monomethyl ether, diethylene glycol, cyclohexanol, 2-butoxyethanol; 2-aminosulfide, 1-undecanethiol, It is preferably at least one compound selected from the group consisting of thiol compounds such as 1,12-dodecanethiol. By using these polar compounds, the light emission lifetime of the light emitting layer (light emitting device) can be further improved.

<Light emitting element>
The light-emitting element of the present invention comprises an anode and a cathode (a pair of electrodes), a light-emitting layer provided between them and made of the dried ink of the present invention, and at least one electrode of the light-emitting layer and the anode and the cathode. and a charge transport layer provided between.
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. Moreover, 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 one embodiment of the light-emitting device of the present invention.
In addition, in FIG. 1, the dimensions of each part and their ratios are exaggerated for the sake of convenience, and may differ from the actual dimensions. Also, the materials, dimensions, and the like shown below are examples, and the present invention is not limited to them, and can be changed as appropriate without changing the gist of the invention.
For convenience of explanation, the upper side of FIG. 1 is hereinafter referred to as "upper side" or "upper side", and the upper side is referred to as "lower side" or "lower side". In addition, in FIG. 1, hatching indicating a cross section is omitted in order to avoid complication of the drawing.

A light-emitting element 1 shown in FIG. 1 includes an anode 2, a cathode 3, and a hole-injection layer 4, a hole-transport layer 5, and a light-emitting layer 6 which are sequentially laminated from the anode 2 side between the anode 2 and the cathode 3. , an electron transport layer 7 and an electron injection layer 8 .
Each layer will be described below in order.

[Anode 2]
The anode 2 has a function of supplying holes from an external power source toward the light emitting layer 6 .
The constituent material (anode material) of the anode 2 is not particularly limited. Metal oxides such as tin (SnO ₂ ) and zinc oxide (ZnO) are included. These may be used alone or in combination of two or more.

Although the thickness of the anode 2 is not particularly limited, it is preferably about 10 to 1,000 nm, more preferably about 10 to 200 nm.
The anode 2 can be formed, for example, by a dry film-forming method such as a vacuum deposition method or a sputtering method. At this time, the anode 2 having a predetermined pattern may be formed by a photolithography method or a method using a mask.

[Cathode 3]
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 examples include lithium, sodium, magnesium, aluminum, silver, sodium-potassium alloy, magnesium/aluminum mixture, magnesium/silver mixture, magnesium/indium mixture, and aluminum. / aluminum oxide (Al ₂ O ₃ ) mixtures, rare earth metals and the like. These may be used alone or in combination of two or more.

Although the thickness of the cathode 3 is not particularly limited, it is preferably about 0.1 to 1,000 nm, more preferably about 1 to 200 nm.
The cathode 3 can be formed, for example, by a dry film-forming method such as a vapor deposition method or a sputtering method.

[Hole injection layer 4]
The hole injection layer 4 has a function of receiving holes supplied from the anode 2 and injecting them into the hole transport layer 5 . The hole injection layer 4 may be provided as required, and may be omitted.

The constituent material (hole injection material) of the hole injection layer 4 is not particularly limited, but for example, a phthalocyanine compound such as copper phthalocyanine; 4,4′,4″-tris[phenyl(m-tolyl)amino ] triphenylamine derivatives such as triphenylamine; 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile, 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(styrenesulfonic acid) (PEDOT -PSS), polymers such as polypyrrole, and the like.

Among these, the hole injection material is preferably a polymer, more preferably PEDOT-PSS.
Moreover, the above hole injection materials may be used alone or in combination of two or more.

Although the thickness of the hole injection layer 4 is not particularly limited, it is preferably about 0.1 to 500 nm, more preferably about 1 to 300 nm, even more preferably about 2 to 200 nm.
The hole injection layer 4 may have a single layer structure or a laminated structure in which two or more layers are laminated.
Such a hole injection layer 4 can be formed by a wet film formation method or a dry film formation method.

When the hole injection layer 4 is formed by a wet film formation method, usually, an ink containing the hole injection material is applied by various coating methods, and the resulting coating is dried. The coating method is not particularly limited, but examples thereof include an inkjet method (droplet ejection method), a spin coating method, a casting method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method, and the like. be done.
On the other hand, when the hole injection layer 4 is formed by a dry film-forming method, a vacuum vapor deposition method, a sputtering method, or the like can be preferably used.

[Hole transport layer 5]
The hole-transporting layer 5 has a function of receiving holes from the hole-injecting layer 4 and transporting them efficiently to the light-emitting layer 6 . Further, the hole transport layer 4 may have a function of preventing transport of electrons. The hole transport layer 5 may be provided as required, and may be omitted.

The constituent material (hole transport material) of the hole transport layer 5 is not particularly limited, but for example, TPD (N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1' -biphenyl-4,4'diamine), α-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)-benzidine (Poly-TPD), poly[( Conjugated systems such as 9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(sec-butylphenyl)diphenylamine)) (TFB), polyphenylene vinylene (PPV) compound polymers; and copolymers containing these monomer units.

Among these, the hole-transporting material is preferably a polymer compound obtained by polymerizing a triphenylamine derivative or a triphenylamine derivative into which a substituent is introduced. A polymer compound obtained by polymerizing a phenylamine derivative is more preferred.
Moreover, the above hole transport materials may be used alone or in combination of two or more.

Although the thickness of the hole transport layer 5 is not particularly limited, it is preferably about 1 to 500 nm, more preferably about 5 to 300 nm, even more preferably about 10 to 200 nm.
The hole transport layer 5 may have a single layer structure or a laminated structure in which two or more layers are laminated.
Such a hole transport layer 5 can be formed by a wet film formation method or a dry film formation method.

When the hole transport layer 5 is formed by a wet film-forming method, usually, an ink containing the above hole transport material is applied by various coating methods, and the obtained coating film is dried. The coating method is not particularly limited, but examples thereof include an inkjet method (droplet ejection method), a spin coating method, a casting method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method, and the like. be done.
On the other hand, when the hole transport layer 5 is formed by a dry film-forming method, a vacuum vapor deposition method, a sputtering method, or the like can be preferably used.

[Electron injection layer 8]
The electron injection layer 8 has a function of receiving electrons supplied from the cathode 3 and injecting them into the electron transport layer 7 . The electron injection layer 8 may be provided as required, and may be omitted.

The constituent material (electron injection material) of the electron injection layer 8 is not particularly limited, but examples thereof include alkali metal chalcogenides such as Li ₂ O, LiO, Na ₂ S, Na ₂ Se, and NaO; 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-hydroxyquinolinolatritium (Liq) Metal salts; alkaline earth metal halides such as _CaF2 , _BaF2 , _SrF2 , _MgF2 , _BeF2 , and the like.

Among these, alkali metal chalcogenides, alkaline earth metal halides and alkali metal salts are preferred.
Moreover, the electron injection materials described above may be used alone or in combination of two or more.

Although the thickness of the electron injection layer 8 is not particularly limited, it is preferably about 0.1 to 100 nm, more preferably about 0.2 to 50 nm, and further preferably about 0.5 to 10 nm. preferable.
The electron injection layer 8 may have a single-layer structure or a laminated structure in which two or more layers are laminated.
Such an electron injection layer 8 can be formed by a wet film formation method or a dry film formation method.

When the electron injection layer 8 is formed by a wet film formation method, usually, an ink containing the above electron injection material is applied by various coating methods, and the resulting coating film is dried. The coating method is not particularly limited, but examples thereof include an inkjet method (droplet ejection method), a spin coating method, a casting method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method, and the like. be done.
On the other hand, when the electron injection layer 8 is formed by a dry film-forming method, a vacuum deposition method, a sputtering method, or the like can be applied.

[Electron transport layer 7]
The electron transport layer 7 has a function of receiving electrons from the electron injection layer 8 and efficiently transporting them to the light emitting layer 6 . Further, the electron transport layer 7 may have a function of preventing transport of holes. In addition, the electron transport layer 7 may be provided as required, and may be omitted.

The constituent material (electron transport material) of the electron transport layer 7 is not particularly limited. Quinolines such as 10-hydroxybenzo[h]quinolinato)beryllium (BeBq2), bis(2-methyl-8-quinolinolato)(p-phenylphenolato)aluminum (BAlq), bis(8-quinolinolato)zinc (Znq) metal complexes having a backbone or a benzoquinoline backbone; metal complexes having a benzoxazoline backbone such as bis[2-(2'-hydroxyphenyl)benzoxazolato]zinc (Zn(BOX)2); bis[2-( 2′-Hydroxyphenyl)benzothiazolate]zinc (Zn(BTZ)2), a metal complex having a benzothiazoline skeleton; 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1 ,3,4-oxadiazole (PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ), 1,3- Bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7), 9-[4-(5-phenyl-1,3,4- tri- or diazole derivatives such as oxadiazol-2-yl)phenyl]carbazole (CO11); 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H- benzimidazole) (TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (mDBTBIm-II); quinoline derivatives; perylene derivatives; pyridine derivatives such as 7-diphenyl-1,10 _- phenanthroline (BPhen); pyrimidine derivatives; triazine derivatives; quinoxaline derivatives; metal oxides and the like.

Among these, imidazole derivatives, pyridine derivatives, pyrimidine derivatives, triazine derivatives, and metal oxides (inorganic oxides) are preferred as electron transport materials.
Moreover, the above electron transport materials may be used alone or in combination of two or more.
Although the thickness of the electron transport layer 7 is not particularly limited, it is preferably about 5 to 500 nm, more preferably about 5 to 200 nm.
The electron transport layer 7 may be a single layer or a laminate of two or more layers.
Such an electron transport layer 7 can be formed by a wet film formation method or a dry film formation method.

When the electron transport layer 7 is formed by a wet film-forming method, usually, an ink containing the above-described electron transport material is applied by various coating methods, and the resulting coating film is dried. The coating method is not particularly limited, but examples thereof include an inkjet method (droplet ejection method), a spin coating method, a casting method, an LB method, a letterpress printing method, a gravure printing method, a screen printing method, a nozzle printing method, and the like. be done.
On the other hand, when the electron transport layer 7 is formed by a dry film-forming method, a vacuum deposition method, a sputtering method, or the like can be applied.

[Light emitting layer 6]
The light-emitting layer 6 has a function of emitting light 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 ink of the present invention. Therefore, since the nanocrystals are uniformly dispersed in the light-emitting layer 6, the light-emitting layer 6 has excellent luminous efficiency.

Although the thickness of the light-emitting layer 6 is not particularly limited, it is preferably about 1 to 100 nm, more preferably about 1 to 50 nm.
For the light-emitting layer 8, the ink of the present invention is applied by various coating methods, and the resulting coating film is dried. The coating method is not particularly limited, but includes, for example, an inkjet printing method (piezo method or thermal droplet ejection method), spin coating method, casting method, LB method, letterpress printing method, gravure printing method, screen printing method, Nozzle print printing method and the like can be mentioned.
Here, the nozzle printing method is a method of applying ink from nozzle holes in the form of liquid columns in stripes.

The ink of the present invention can be suitably applied by an inkjet printing method. In particular, the ink of the present invention is preferably applied by a piezo inkjet printing method. As a result, the heat load when ejecting ink can be reduced, and the particles (nanocrystals) themselves are less likely to have problems. Therefore, a suitable apparatus for applying the ink of the present invention is an inkjet printer having a piezoelectric inkjet head.

The light-emitting element 1 may further have banks (partition walls) that partition the hole injection layer 4, the hole transport layer 5, and the light-emitting layer 6, for example.
Although the height of the bank is not particularly limited, it is preferably about 0.1 to 5 μm, more preferably about 0.2 to 4 μm, even more preferably about 0.2 to 3 μm.

The width of the bank opening is preferably about 10 to 200 μm, more preferably about 30 to 200 μm, even more preferably about 50 to 100 μm.
The length of the bank opening is preferably about 10 to 400 μm, more preferably about 20 to 200 μm, even more preferably about 50 to 200 μm.
The inclination angle of the bank is preferably about 10 to 100°, more preferably about 10 to 90°, and even more preferably about 10 to 80°.

<Method for manufacturing light-emitting element>
The method for producing a light-emitting element includes a step of supplying the above-described ink onto a support to form a coating film, and drying the coating film to form a light-emitting layer (hereinafter also referred to as a “light-emitting layer forming step”). )have.
The support is the hole-transporting layer 5 or the electron-transporting layer 7 in the configuration shown in FIG.

For example, when manufacturing a light-emitting device consisting of an anode, a hole-transporting layer, a light-emitting layer and a cathode, the support is either the hole-transporting layer or the cathode. Also, in the case of manufacturing 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 the hole-injection layer or the electron-injection layer.
Thus, the support can 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, still more preferably a hole transport layer.

In addition, banks as described above may be formed on the support. By forming the bank, the light-emitting layer 6 can be formed only at desired locations on the support.
For example, in the droplet ejection method, the ink of the present invention is intermittently ejected from nozzle holes of a droplet ejection head onto a support in a predetermined pattern. According to the droplet discharge method, drawing patterning can be performed with a high degree of freedom. Among them, the piezo droplet ejection method can improve the selectivity of the dispersion medium and reduce the thermal load on the ink.

At this time, the ink ejection amount is not particularly limited, but is preferably 1 to 50 pL/time, more preferably 1 to 30 pL/time, and further preferably 1 to 20 pL/time.
Also, the opening diameter of the nozzle hole is preferably about 5 to 50 μm, more preferably about 10 to 30 μm. As a result, it is possible to improve ejection accuracy while preventing clogging of the nozzle holes.

The temperature at which the coating film is formed is not particularly limited, but is preferably about 10 to 50°C, more preferably about 15 to 40°C, even more preferably about 15 to 30°C. By ejecting droplets at such a temperature, crystallization of various components ((nanocrystals, dispersant, charge transport material, etc.) contained in the ink can be suppressed.

Also, the relative humidity when forming the coating film is not particularly limited, but it is preferably about 0.01 ppm to 80%, more preferably about 0.05 ppm to 60%, and 0.1 ppm to 15 %, more preferably about 1 ppm to 1%, and most preferably about 5 to 100 ppm.
When the relative humidity is equal to or higher than the lower limit, it is preferable because the conditions for forming the coating film can be easily controlled. On the other hand, when the relative humidity is equal to or less than the upper limit, the amount of water adsorbed by the coating film, which may adversely affect the light-emitting layer 6 obtained, can be reduced, which is preferable.

By drying the obtained coating film, the light-emitting layer 6 is obtained. The drying may be performed by leaving it 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, more preferably about 40 to 120°C.

Drying is preferably carried out under reduced pressure, more preferably under reduced pressure of 0.001 to 100 Pa.
Furthermore, the drying time is preferably 1 to 90 minutes, more preferably 1 to 30 minutes.

By drying the coating film under such drying conditions, not only the dispersion medium but also the fluorine-containing compound and/or the dispersing agent are reliably removed from the coating film, and the resulting luminescent layer 6 is substantially nanocrystalline. It will be composed only of
The degree can be confirmed by the amount of the fluorine-containing compound and/or dispersant contained in the light-emitting layer 6. Specifically, the total amount of the fluorine-containing compound and/or dispersant contained in the light-emitting layer 6 The amount is 25 ppm or less, preferably 20 ppm or less, more preferably 10 ppm or less. It can be considered that such a light-emitting layer 6 does not substantially contain a fluorine-containing compound and/or a dispersing agent as impurities, and the light-emitting layer 6 has an increased light-emitting efficiency and a long light-emitting life. become longer.

A set (unit pixel) is composed of a red light emitting element 1 that emits red (R) light, a green light emitting element 1 that emits green (G) light, and a blue light emitting element 1 that emits blue (B) light. By arranging a plurality of sets on the substrate in a matrix form, a display device capable of displaying a color image can be configured. In this case, for example, switching elements (for example, TFT elements) electrically connected to each anode 2, gate bus lines, source bus lines, and the like are provided on the substrate.

Although the ink and the light-emitting element of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments.
For example, the ink and the light-emitting element of the present invention may each have any other configuration in addition to the configurations of the embodiments described above, or may be replaced with any configuration that exhibits similar functions. It's okay.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.
1. Removal of Particles Hexane was added to a toluene solution containing particles (5 mg/mL, manufactured by Aldrich; product number 776785-5ML), and after centrifugation, a precipitate containing particles was collected by filtration. The particles consist of nanocrystals with a ZnS shell and an InP core, and oleylamine supported thereon.
In addition, a plurality of samples were taken out from the sediment, each sample was burned with a pyrolysis mass meter, and the amount of weight loss at that time was determined. As a result, the supported amount of oleylamine was 10 to 30 parts by mass with respect to 100 parts by mass of the nanocrystals.

2. Preparation of ink (Example 1)
After dispersing the above precipitate (particles) in butyl benzoate, the following fluorine-containing compound A was added to prepare an ink. The amount of precipitate contained in the ink was set to 1% by mass, and the amount of fluorine-containing compound A was set to 0.05% by mass.
Moreover, the boiling point of the fluorine-containing compound A is 107° C., and the fluorine substitution rate is 85%.

(Example 2)
An ink was prepared in the same manner as in Example 1, except that the fluorine-containing compound A was changed to the fluorine-containing compound B below. The fluorine-containing compound B has a boiling point of 177° C. and a fluorine substitution rate of 100%.

(Example 3)
An ink was prepared in the same manner as in Example 1, except that the fluorine-containing compound A was changed to the fluorine-containing compound C below. Fluorine-containing compound C has a boiling point of 245° C. and a fluorine substitution rate of 100%.

(Comparative example 1)
An ink was prepared in the same manner as in Example 1 except that the fluorine-containing compound A was omitted.

(Comparative example 2)
An ink was prepared in the same manner as in Example 1, except that the fluorine-containing compound A was changed to the fluorine-free compound D below. The boiling point of fluorine-free compound D is 240° C., and the fluorine substitution rate is 0%.

(Comparative Example 3)
An ink was prepared in the same manner as in Example 1, except that the fluorine-containing compound A was changed to the fluorine-containing compound E below. The fluorine-containing compound E has a boiling point of 300° C. and a fluorine substitution rate of 81%.

3. Evaluation The inks obtained in each example and each comparative example were evaluated as follows.
3-1. Fabrication of Light Emitting Device First, a glass substrate (40 mm×70 mm) on which ITO was patterned in stripes was spin-coated with a positive photoresist to which a fluorosurfactant was added. After that, a bank defining pixels of 300 μm in length and 100 μm in width (vertical pitch of 350 μm and horizontal pitch of 150 μm) was formed on the positive photoresist by patterning by photolithography. This gave a banked support.
The thickness of the bank was measured using an optical interference surface profile measuring device (manufactured by Ryoka System Co., Ltd.), and it was confirmed that the bank had a thickness of 2.0 μm.

Next, using an inkjet printer (DMP2831, Cartridge Box DMC-11610, manufactured by FUJIFILM Corporation), a hole injection layer of 45 nm, a hole transport layer of 30 nm, and a hole transport layer of 30 nm are formed in the pixels of the banked support. and a light-emitting layer were sequentially formed.
The hole injection layer was formed using PEDOT/PSS (CLEVIOUS P JET), the hole transport layer was formed using a 1.0% by mass TFB tetralin solution, and the light emitting layer was formed using the ink obtained above. formed.
Moreover, when forming the light-emitting layer, the coating film (ink pattern) was dried at 25° C. for 30 minutes under a reduced pressure of 0.003 Pa.

Next, the support formed up to the light-emitting layer was transported to a vacuum vapor 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 transport layer was formed using TPBI, the electron injection layer was formed using lithium fluoride, and the cathode was formed using aluminum.
Further, the support formed up to the cathode was transported to a glove box, and a sealing glass coated with an epoxy resin was attached to the support. Thus, a light-emitting device was produced.

3-2. Evaluation of Wetting and Spreading Property A current of 10 mA/cm ² was applied to the obtained light-emitting element to emit light, and the luminance distribution within one pixel was measured with a two-dimensional luminance meter (Radiant IC-PMI8). It was evaluated according to the following evaluation criteria.
Note that numerical values in the following evaluation criteria are relative values when the measurement result of the light-emitting element obtained in Comparative Example 1 is set to 1. The larger the numerical value, the better the luminance uniformity. In other words, it indicates that a uniform film thickness and a homogeneous luminescent layer were formed due to the good wetting and spreading properties of the ink.

<Evaluation Criteria>
○: 1.1 or more △: 1.0 or more and less than 1.1 ×: less than 1.0 Table 1 shows the evaluation results.

3-3. Evaluation of Luminous Efficiency A current of 10 mA/cm ² was applied to the obtained light-emitting device to cause it to emit light. The luminance at this time was measured with a luminance meter (Topcon BM-9), and the luminous efficiency was evaluated according to the following criteria.
Note that numerical values in the following evaluation criteria are relative values when the measurement result of the light-emitting element obtained in Comparative Example 1 is set to 1. A larger value indicates better luminous efficiency.

<Evaluation Criteria>
○: 1.5 or more △: 1.0 or more and less than 1.5 ×: less than 1.0 Table 1 shows the evaluation results.

As shown in Table 1, the ink of each example using a fluorine-containing compound having a boiling point of less than 300° C. had good wetting and spreading properties, resulting in excellent luminance uniformity. On the other hand, the ink of Comparative Example 2 had the same wetting and spreadability as the ink of Comparative Example 1 containing no fluorine-containing compound, and had the same luminance uniformity.
Further, in the light-emitting elements of each example, since the fluorine-containing compound hardly remained in the light-emitting layer, the light-emitting efficiency was excellent. On the other hand, in the light-emitting device of Comparative Example 3 using a fluorine-containing compound having a boiling point of 300° C., a large amount of the fluorine-containing compound remained in the light-emitting layer, resulting in a decrease in luminous efficiency.
When the viscosity of each ink of each example and each comparative example was measured, it was confirmed that each had a viscosity suitable for the coating method (printing method).

REFERENCE SIGNS LIST 1 light emitting element 2 anode 3 cathode 4 hole injection layer 5 hole transport layer 6 light emitting layer 7 electron transport layer 8 electron injection layer

Claims (4)

a luminescent semiconductor nanocrystal;
a fluorine-containing compound having a boiling point of less than 300° C. under atmospheric pressure, comprising a main skeleton containing a fluorine atom and a functional group bonded to the main skeleton and capable of being supported by the semiconductor nanocrystal;
a dispersion medium for dispersing the semiconductor nanocrystals;
The main skeleton comprises a linear aliphatic hydrocarbon structure in which at least some hydrogen atoms are substituted with fluorine atoms,
the functional group is at least one selected from the group consisting of a thiol group, a carboxyl group and an amino group;
In the main skeleton, the substitution rate of hydrogen atoms with fluorine atoms is 85% or more,
An ink comprising 0.001 to 40 parts by mass of the fluorine-containing compound with respect to 100 parts by mass of the semiconductor nanocrystals. 2. The ink according to claim 1, wherein the main skeleton has 5 to 15 carbon atoms. 3. The ink according to claim 1, wherein the boiling point of the dispersion medium under atmospheric pressure is equal to or higher than the boiling point of the fluorine-containing compound under atmospheric pressure and 350[deg.] C. or lower. a pair of electrodes;
a light-emitting layer provided between the pair of electrodes and made of the dried ink according to any one of claims 1 to 3 ;
A light emitting device comprising: the light emitting layer; and a charge transport layer provided between at least one of the pair of electrodes.

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