JP2020042940A - Method of manufacturing charge transporting polymer thin film - Google Patents

Abstract

To provide a manufacturing method capable of manufacturing a charge transporting polymer thin film, excellent in solvent resistance, with reduced driving voltage and improved light emission life.SOLUTION: This is the method of manufacturing a charge transporting polymer thin film of manufacturing a charge transporting polymer thin film, having a composition containing a charge transporting polymer being polymerized and cured, so that a surface area ratio is a surface area ratio Sb satisfying both expressions (1) and (2). When surface area ratios of the charge transporting polymer thin films Pa, Pb, Pc polymerized at respective heating temperatures Ta, Tb, Tc (Ta<Tb<Tc) are defined as Sa, Sb, Sc, Formula (1) Sb/Sa×100<99.95, Formula (2) Sb/Sc×100<99.95. Where, residual film ratios of Pa, Pb, Pc are all 95% or more.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a charge transporting polymer thin film that can be used for an organic electronic device, an organic electroluminescent device, and the like.

  Organic electronic devices are devices that perform electrical operations using organic substances, and are expected to exhibit features such as energy saving, low cost, and flexibility, and are attracting attention as a technology that replaces conventional silicon-based inorganic semiconductors. ing.

  Examples of the organic electronic element include an organic electroluminescent element (hereinafter, also referred to as an “organic EL element”), an organic photoelectric conversion element, an organic transistor, and the like.

  Among organic electronic elements, an organic EL element has been receiving attention as a large-area solid-state light source application, for example, as a substitute for an incandescent lamp or a gas-filled lamp. In addition, it is attracting attention as a leading self-luminous display replacing a liquid crystal display (LCD) in the field of a flat panel display (FPD), and its commercialization is progressing.

  Organic EL elements are roughly classified into two types, a low-molecular-weight organic EL element and a high-molecular-weight organic EL element, according to the organic material used. In the polymer-type organic EL device, a polymer material is used as an organic material, and in the low-molecular-weight organic EL device, a low-molecular material is used. The polymer organic EL element can be easily formed by a wet process such as printing or ink-jet, compared with a low-molecular organic EL element in which film formation is performed mainly in a vacuum system. It is expected as an indispensable element for EL displays. On the other hand, since a polymer organic EL element is formed using a wet process such as printing or ink jet, there is a problem that the lower layer is dissolved when the upper layer is applied. For this reason, it is difficult to form a multilayer structure of the polymer-type organic EL device as compared with the low-molecular-weight organic EL device, and it has not been possible to obtain the effects of improving the luminous efficiency and the lifetime.

  Several approaches have been proposed to address this problem. One is a method using a difference in solubility. For example, the element has a two-layer structure of a hole injection layer containing water-soluble polythiophene: polystyrenesulfonic acid (PEDOT: PSS), and a light-emitting layer formed using an aromatic organic solvent such as toluene. In this case, since the PEDOT: PSS layer does not dissolve in an aromatic solvent such as toluene, a two-layer structure can be manufactured.

  Non-Patent Document 1 proposes a device having a three-layer structure using compounds having greatly different solubilities.

  Patent Document 1 discloses a device having a three-layer structure in which a layer called an interlayer is introduced on PEDOT: PSS.

  Non Patent Literatures 2 to 4 and Patent Literature 2 disclose that the solubility of a compound is changed by using a polymerization reaction of a siloxane compound, an oxetane group, a vinyl group, or the like, and the charge transporting polymer thin film (organic layer) is dissolved in a solvent. A method for insolubilizing is disclosed.

  On the other hand, to improve the conductivity of an organic layer formed by a wet process, there are methods such as changing the molecular structure and changing the film formation process. It has been reported that the morphology of the organic layer is changed by changing the molecular structure or the film forming process, and that the conductivity is changed by the change in the morphology. For the observation of morphology, a contact type surface roughness measuring device, a non-contact type optical roughness measuring device, etc. are used, and the surface shape is average surface roughness Ra, maximum roughness Rz, root mean square surface roughness. rms, surface area ratio S, and the like.

Non-Patent Document 5 reports that the root-mean-square roughness rms increases due to the rearrangement of the polymer caused by heating at a temperature equal to or higher than the melting point, and that the driving voltage changes depending on the heating temperature. However, the relationship between the heating temperature, the root-mean-square roughness rms, and the drive voltage has not been studied in a temperature range exceeding the polymerization initiation temperature.
In Non-Patent Document 6, the root-mean-square roughness rms of a thin film formed from polymers having different structures is examined. This document reports that when a polymer having a small root mean square roughness rms is used as a light emitting layer material, the driving voltage of the organic EL device is reduced. However, the polymer reported here is polymerized. No reaction is involved.

JP 2007-119763 A WO 2008/010487

Y. Goto, T. Hayashida, M. Noto, IDW ‘04 Proceedings of The 11th International Display Workshop, 1343-1346 (2004) H. Yan, P. Lee, N. R. Armstrong, A. Graham, G. A. Evemenko, P. Dutta, T. J. Marks, J. Am. Chem. Soc., 127, 3172-4183 (2005) E. Bacher, M. Bayerl, P. Rudati, N. Reckfuss, C. David, K. Meerholz, O. Nuyken, Macromolecules, 38, 1640 (2005) M.S.Liu, Y.H.Niu, J.W.Ka, H.L.Yip, F.Huang, J. Luo, T.D.Wong, A.K.Y.Jen, Macromolecules, 41, 9570 (2008) Selin Piravadili Mucur, Rifat Kacar, Cagla Meric, Sermet Koyuncu, Organic Electronics, 50, 55-62 (2017) Huan-Chi Yeh, et al, Macromolecules, 41, 3801-3807 (2008)

  In order to increase the efficiency and prolong the life of the organic EL element, it is desirable that the organic layers are multilayered and the functions of the respective layers are separated. In order to form an organic layer into a multilayer using a wet process in which film formation is easy even in a large area, it is necessary to utilize a polymerization reaction so that the lower layer is not dissolved during the formation of the upper layer as described above. In addition, when heating at a high temperature during the formation of the organic layer, solvent resistance can be imparted by a polymerization reaction, but there is a concern about an increase in driving voltage due to decomposition of the polymer. Therefore, a charge transporting polymer thin film that can be used for multilayering is required to have both solvent resistance and reduced driving voltage.

  The present invention seeks to solve the above problems. That is, an object of the present invention is to provide a production method capable of producing a charge transporting polymer thin film having excellent solvent resistance and capable of reducing driving voltage.

Means for solving the above problems are as follows.
[1] A method for producing a charge transporting polymer thin film obtained by polymerizing and curing a composition containing a charge transporting polymer,
A method for producing a charge transporting polymer thin film, which produces a charge transporting polymer thin film such that the surface area ratio satisfies both the following formulas (1) and (2).
The heating temperatures Ta, Tb and Tc satisfy Ta <Tb <Tc,
The surface area ratio of the charge transporting polymer thin film Pa polymerized at the heating temperature Ta is Sa,
The surface area ratio of the charge transporting polymer thin film Pb polymerized at the heating temperature Tb is Sb,
When the surface area ratio of the charge transporting polymer thin film Pc polymerized at the heating temperature Tc is defined as Sc,
Sb / Sa × 100 <99.95 (%) Expression (1)
Sb / Sc × 100 <99.95 (%) Equation (2)
However, the residual film ratios of the charge transporting polymer thin films Pa, Pb and Pc represented by the following formula (3) measured under the following conditions are all 95% or more.
The substrate on which the charge transporting polymer thin film is formed is immersed in a solvent for 1 minute for washing, and the ratio of the absorbance (Abs) of the absorption maximum (λmax) in the UV-vis spectrum before and after washing is defined as the remaining film ratio (%). .
Residual film ratio (%) = Abs after washing / Abs before washing × 100 Equation (3)

[2] The heating temperature Tb is set so that the minimum surface area ratio among the surface area ratios of the charge transporting polymer thin film polymerized at a temperature within the range of the heating temperature Ta to the heating temperature Tc is the surface area ratio Sb. The method for producing a charge transporting polymer thin film according to the above [1].

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which is excellent in solvent resistance and can manufacture the charge transportable polymer thin film which can aim at reduction of drive voltage can be provided.

FIG. 2 is a schematic cross-sectional view showing one embodiment of the organic EL device of the present embodiment.

  Hereinafter, the present embodiment will be described, but the present embodiment is not limited to the following description.

<Method for producing charge transporting polymer thin film>
The method for producing a charge transporting polymer thin film of the present embodiment is a method for producing a charge transporting polymer thin film obtained by polymerizing and curing a composition containing a charge transporting polymer. The present invention is characterized in that a charge transporting polymer thin film is manufactured so as to have a surface area ratio Sb satisfying both of the following expressions (2).
The heating temperatures Ta, Tb and Tc satisfy Ta <Tb <Tc,
The surface area ratio of the charge transporting polymer thin film Pa polymerized at the heating temperature Ta is Sa,
The surface area ratio of the charge transporting polymer thin film Pb polymerized at the heating temperature Tb is Sb,
When the surface area ratio of the charge transporting polymer thin film Pc polymerized at the heating temperature Tc is defined as Sc,
Sb / Sa × 100 <99.95 (%) Expression (1)
Sb / Sc × 100 <99.95 (%) Equation (2)
However, the residual film ratios of the charge transporting polymer thin films Pa, Pb and Pc represented by the following formula (3) measured under the following conditions are all 95% or more.
The substrate on which the charge transporting polymer thin film is formed is immersed in a solvent for 1 minute for washing, and the ratio of the absorbance (Abs) of the absorption maximum (λmax) in the UV-vis spectrum before and after washing is defined as the remaining film ratio (%). .
Residual film ratio (%) = Abs after washing / Abs before washing × 100 Equation (3)

  In the present embodiment, the surface area ratio is the ratio of the actual surface area S to the area S0 assuming that the surface whose surface shape is measured is completely flat. The surface area ratio S can be measured using a contact type surface roughness measuring device, a non-contact type optical roughness measuring device, or the like.

  In the manufacturing method of the present embodiment, the surface area ratio of the desired charge transporting polymer thin film to be manufactured is the surface area ratio Sb satisfying both the formulas (1) and (2), and the remaining film ratio is 95. Set to be at least%. In order to make such a setting, first, within the heating temperature range where the residual film ratio of the charge transporting polymer thin film is 95% or more, the surface area ratio of the formed thin film is determined by using both the formulas (1) and (2). The three heating temperatures Ta, Tb and Tc to be satisfied are determined. After the temperature is determined, the composition containing the charge transporting polymer is polymerized and cured at the heating temperature Tb, so that the charge transporting polymer thin film having a surface area ratio Sb satisfying both the formulas (1) and (2) is obtained. Can be formed. As a result, it is possible to obtain a charge transporting polymer thin film capable of reducing driving voltage and improving luminous efficiency. In addition, since the charge transporting polymer thin film has a residual film ratio of 95% or more, it has excellent solvent resistance.

  The heating temperatures Ta, Tb, and Tc determined as described above are temperatures at which the remaining charge ratio of the formed charge transporting polymer thin film becomes 95%. Ta <Tb <Tc, but the difference between them is preferably 5 to 60 ° C., and more preferably 5 to 35 ° C.

  The smaller the surface area ratio of the charge transporting polymer thin film is, the lower the driving voltage is. Therefore, the smaller the surface area ratio is, the better. Therefore, it is preferable to set the heating temperature Tb so that the minimum surface area ratio becomes the surface area ratio Sb among the surface area ratios of the charge transporting polymer thin film polymerized at a temperature within the range of the heating temperature Ta to the heating temperature Tc. In other words, it is preferable that the heating temperature Tb be set so that the surface area ratio Sb becomes a minimum between the surface area ratios Sa and Sc while satisfying the expressions (1) and (2).

On the other hand, the upper limit of the formula (1) is 99.95%, preferably 99.90%, and more preferably 99.85%. The lower limit is preferably 80%.
Similarly, the upper limit of the formula (2) is 99.95%, preferably 99.90%, and more preferably 99.85%. The lower limit is preferably 80%.

On the other hand, when measuring the residual film ratio, the substrate on which the charge transporting polymer thin film is formed is immersed in a solvent for one minute and washed. Then, the absorbance (Abs) of the absorption maximum (λmax) in the UV-vis spectrum before and after washing is measured, and the remaining film ratio is determined from the above equation (3). Here, the solvent used for immersion of the charge transporting polymer thin film has a high solubility in the charge transporting polymer before polymerization and curing. As one guide, a hydrophobic solvent can be used if the charge transporting polymer is hydrophobic, and a hydrophilic solvent can be used if the charge transporting polymer is hydrophilic. That is, the charge-transporting polymer is easily dissolved in a hydrophobic solvent if it is hydrophobic, and is easily dissolved in a hydrophilic solvent if it is hydrophilic.In the first place, a hydrophobic one is a hydrophilic solvent, and a hydrophilic one is a hydrophilic one. It tends to be difficult to dissolve in a hydrophobic solvent. Therefore, the fact that the residual film ratio of the charge transporting polymer is 95% or more indicates that it is difficult to dissolve in any solvent.
Here, “high solubility” of the charge transporting polymer in the solvent before the polymerization and curing means that the solubility in 100 g of the solvent at 23 ° C. is 3 g or more.

  In the present embodiment, an organic layer described later can be used as the charge transporting polymer thin film, and the formation method is the same as the method described later. The thickness of the organic layer is not particularly limited, and the organic layer may be formed to have a thickness whose surface shape can be easily measured, or may be formed to have a thickness that does not easily cause a short circuit of the element. Hereinafter, the charge transporting polymer thin film may be simply referred to as “organic layer”.

  Hereinafter, the charge transporting polymer used in the present embodiment and the composition containing the same will be described. Note that the charge transporting polymer thin film according to the present embodiment has the ability to transport charges.

[Charge transporting polymer]
(Construction)
Examples of the partial structure contained in the charge transporting polymer include the following. The charge transporting polymer is not limited to those having the following partial structures. In the partial structure, “L” represents a structural unit L, “T” represents a structural unit T, and “B” represents a structural unit B. In the present specification, “*” in the formula represents a binding site to another structural unit. In the following partial structures, a plurality of Ls may be the same structural unit or different structural units. The same applies to T and B.

Linear charge transport polymer

  Charge transporting polymer having branched structure

(Example of each structural unit)
(Structural unit L)
The structural unit L is a divalent structural unit, and preferably has a charge transporting property. The structural unit L having charge transportability is not particularly limited as long as it contains an atomic group capable of transporting charges. For example, the structural unit L is a substituted or unsubstituted aromatic amine structure, carbazole structure, thiophene structure, fluorene structure, benzene structure, biphenylene structure, terphenylene structure, naphthalene structure, anthracene structure, tetracene structure, phenanthrene structure, dihydro Phenanthrene structure, pyridine structure, pyrazine structure, quinoline structure, isoquinoline structure, quinoxaline structure, acridine structure, diazaphenanthrene structure, furan structure, pyrrole structure, oxazole structure, oxadiazole structure, thiazole structure, thiadiazole structure, triazole structure, benzol Thiophene structure, dibenzothiophene structure, benzoxazole structure, benzoxadiazole structure, benzothiazole structure, benzothiadiazole structure, benzotriazole structure And it is selected from the structures containing one or two or more of these. The aromatic amine structure is preferably a triarylamine structure, and more preferably a triphenylamine structure.

  In one embodiment, the structural unit L is a substituted or unsubstituted aromatic amine structure, a carbazole structure, a thiophene structure, a fluorene structure, a benzene structure, a pyrrole structure, and a Is preferably selected from a structure containing one or more of the following, and is selected from a substituted or unsubstituted aromatic amine structure, a carbazole structure, and a structure containing one or more of these. Is more preferred. In another embodiment, the structural unit L is a substituted or unsubstituted fluorene structure, a benzene structure, a phenanthrene structure, a pyridine structure, a quinoline structure, and one or two of these, from the viewpoint of obtaining excellent electron transportability. Preferably, it is selected from a structure containing more than one species.

Specific examples of the structural unit L include the following. The structural unit L is not limited to the following.

R represents a hydrogen atom or a substituent each independently. Preferably, R is ^{independently, -R 1, -OR 2, -SR} 3, -OCOR 4, -COOR 5, -SiR 6 R 7 R 8, -NR 9 R 10, a halogen atom, and, later Selected from the group consisting of groups containing a polymerizable functional group. R ^{1 to} R ¹⁰ each independently represent a hydrogen atom; a linear, cyclic or branched alkyl group having 1 to 22 carbon atoms; or an aryl group or a heteroaryl group having 2 to 30 carbon atoms. An aryl group is an atomic group obtained by removing one hydrogen atom from an aromatic hydrocarbon. A heteroaryl group is an atomic group obtained by removing one hydrogen atom from an aromatic heterocyclic ring. The alkyl group may be further substituted with an aryl group or a heteroaryl group having 2 to 20 carbon atoms, and the aryl group or the heteroaryl group may further have a linear, cyclic or branched group having 1 to 22 carbon atoms. It may be substituted by an alkyl group. R is preferably a hydrogen atom, an alkyl group, an aryl group, or an alkyl-substituted aryl group. Ar represents an arylene group having 2 to 30 carbon atoms or a heteroarylene group. Ar is preferably an arylene group, more preferably a phenylene group. A heteroarylene group is an atomic group obtained by removing two hydrogen atoms from an aromatic heterocyclic ring.

(Arylamine structural unit)
In the present embodiment, the structural unit L preferably includes an arylamine structural unit having a substituent having 8 to 16 carbon atoms (hereinafter, also referred to as “structural unit L1”). The arylamine structural unit means a unit having an aromatic amine structure in which an aryl group is substituted on a nitrogen atom of an amine. As the aromatic amine structure, a diarylamine structure or a triarylamine structure is preferable, and as the aryl group, a phenyl group is preferable. Among them, a triphenylamine structure is most preferable.

The triphenylamine structural unit preferably contains, for example, one or more of the following. In each structural formula, R ¹ represents, for example, a substituent having 8 to 16 carbon atoms. The position of the substituent on the aryl group may be any position. From the viewpoint of the effect of lowering the driving voltage, the position of the substituent is para, meta and ortho based on the bonding position to the nitrogen atom. Formulas (a1), (a2), and (a3) are preferred in this order. It is also possible to combine two or more arylamines having different substituent substitution positions, such as a combination of formulas (a1) and (a2).

When the number of carbon atoms of the substituent R ¹ is 16, there is a tendency that an increase in driving voltage can be suppressed. Therefore, the number of carbon atoms is preferably 16 or less, more preferably 14 or less, and 12 or less. It is more preferred that: Further, the substituent R ¹ may be a polar substituent, a halogen atom, an alkyl halide having 16 or less carbon atoms, or a haloalkane having 16 or less carbon atoms. Good. In this case, the substituent R ¹ more preferably contains fluorine, and further preferably is a haloalkane containing fluorine having 12 or less carbon atoms. Substituents R ¹ may have an ether structure, an ester structure. The substituent R ¹ may be a substituent containing nitrogen, and may have a phenyl structure. Besides substituents R ^1, it may be substituents are present on the benzene ring to which the substituent R ¹ is attached.

(Structural unit B)
When the charge transporting polymer has a branched structure, the structural unit B is a trivalent or higher valent structural unit constituting a branched portion. The structural unit B is preferably hexavalent or less, more preferably trivalent or tetravalent, from the viewpoint of improving the durability of the organic electronic element. The structural unit B is preferably a unit having a charge transporting property. For example, the structural unit B is a substituted or unsubstituted aromatic amine structure, a carbazole structure, a condensed polycyclic aromatic hydrocarbon structure, and one or two of these, from the viewpoint of improving the durability of the organic electronic element. It is selected from structures containing more than one species. The structural unit B may have the same structure as the structural unit L, or may have a different structure, or may have the same structure as the structural unit T, or have a different structure. You may have.

  The following are specific examples of the structural unit B. The structural unit B is not limited to the following.

  W represents a trivalent linking group, for example, an alentolyl group or a heteroarenetriyl group having 2 to 30 carbon atoms. As described above, the arenetriyl group is an atomic group obtained by removing three hydrogen atoms from an aromatic hydrocarbon. A heteroarenetriyl group is an atomic group obtained by removing three hydrogen atoms from an aromatic heterocyclic ring. Ar represents a divalent linking group independently, for example, each independently represents an arylene group having 2 to 30 carbon atoms or a heteroarylene group. Ar is preferably an arylene group, more preferably a phenylene group. Y represents a divalent linking group, for example, a group having at least one hydrogen atom among R (excluding a group containing a polymerizable functional group) in the structural unit L, and one more hydrogen atom And a divalent group excluding. Z represents any of a carbon atom, a silicon atom and a phosphorus atom. In the structural unit, the benzene ring and Ar may have a substituent, and examples of the substituent include R in the structural unit L.

(Structural unit T)
The structural unit T is a monovalent structural unit constituting the terminal of the charge transporting polymer. The structural unit T is not particularly limited, and is selected from, for example, a substituted or unsubstituted aromatic hydrocarbon structure, an aromatic heterocyclic structure, and a structure containing one or more of these. The structural unit T may have the same structure as the structural unit L. In one embodiment, the structural unit T is preferably a substituted or unsubstituted aromatic hydrocarbon structure from the viewpoint of imparting durability without lowering the charge transportability, and is preferably a substituted or unsubstituted benzene. More preferably, it is a structure. In another embodiment, as described later, when the charge transporting polymer has a polymerizable functional group at a terminal portion, the structural unit T has a polymerizable structure (for example, a polymerizable functional group such as a pyrrol-yl group). ). Regarding other than the valence, the structural unit T may have the same structure as the structural unit L, or may have a different structure, or may have the same structure as the structural unit B, Alternatively, they may have different structures.

  The following are specific examples of the structural unit T. The structural unit T is not limited to the following.

R is the same as R ¹ in the structural unit L. When the charge transporting polymer has a polymerizable functional group at the terminal, the structural unit T preferably has a polymerizable functional group. That is, at least one of Rs in the above formula is preferably a group containing a polymerizable functional group.

(Polymerizable functional group)
The charge transporting polymer has a polymerizable substituent (polymerizable functional group) from the viewpoint of being cured by a polymerization reaction and changing the solubility in a solvent. “Polymerizable functional group” refers to a functional group capable of forming a bond with each other by applying heat and / or light.

  Examples of the polymerizable functional group include groups having a carbon-carbon multiple bond (for example, vinyl group, allyl group, butenyl group, ethynyl group, acryloyl group, acryloyloxy group, acryloylamino group, methacryloyl group, methacryloyloxy group, methacryloylamino group). Groups, vinyloxy groups, vinylamino groups, etc.), groups having a small ring (eg, cyclic alkyl groups such as cyclopropyl group and cyclobutyl group; cyclic ether groups such as epoxy group (oxiranyl group) and oxetane group (oxetanyl group)) A diketene group; an episulfide group; a lactone group; a lactam group); and a heterocyclic group (eg, a furan-yl group, a pyrrole-yl group, a thiophen-yl group, a silole-yl group). As the polymerizable functional group, particularly, a vinyl group, an acryloyl group, a methacryloyl group, an epoxy group, and an oxetane group are preferable, and from the viewpoint of reactivity and characteristics of the organic electronic element, a vinyl group, an oxetane group, or an epoxy group is more preferable. preferable.

  From the viewpoint of increasing the degree of freedom of the polymerizable functional group and facilitating the polymerization reaction, the main skeleton of the charge transporting polymer and the polymerizable functional group may be, for example, a linear alkylene chain having 1 to 8 carbon atoms. Preferably they are connected. Further, for example, when an organic layer is formed on an electrode, from the viewpoint of improving the affinity with a hydrophilic electrode such as ITO, it is preferable that the organic layer is connected by a hydrophilic chain such as an ethylene glycol chain or a diethylene glycol chain. preferable. Further, from the viewpoint of facilitating the preparation of the monomer used for introducing the polymerizable functional group, the charge transporting polymer is used as the terminal portion of the alkylene chain and / or the hydrophilic chain, that is, the chain is polymerized with these chains. An ether bond or an ester bond may be present in the link between the functional group and / or the link between these chains and the skeleton of the charge transporting polymer. The above-mentioned “group containing a polymerizable functional group” means a polymerizable functional group itself or a group obtained by combining a polymerizable functional group with an alkylene chain or the like. As the group containing a polymerizable functional group, for example, a group exemplified in WO 2010/140553 can be suitably used.

  The polymerizable functional group may be introduced into the terminal portion (ie, the structural unit T) of the charge transporting polymer, or may be introduced into a portion other than the terminal portion (ie, the structural unit L or B). And a moiety other than the terminal. From the viewpoint of curability, it is preferably introduced at least at the terminal portion, and from the viewpoint of achieving both curability and charge transportability, it is preferably introduced only at the terminal portion. Further, when the charge transporting polymer has a branched structure, the polymerizable functional group may be introduced into the main chain of the charge transporting polymer or may be introduced into the side chain. May be introduced.

  From the viewpoint of contributing to a change in solubility, it is preferable that the polymerizable functional group be contained in the charge transporting polymer in a large amount. On the other hand, from the viewpoint of not hindering the charge transporting property, it is preferable that the amount contained in the charge transporting polymer is small. The content of the polymerizable functional group can be appropriately set in consideration of these.

  For example, the number of polymerizable functional groups per molecule of the charge transporting polymer is preferably 2 or more, more preferably 3 or more, from the viewpoint of obtaining a sufficient change in solubility. In addition, the number of polymerizable functional groups is preferably 1,000 or less, and more preferably 500 or less, from the viewpoint of maintaining charge transportability.

(Number average molecular weight)
The number average molecular weight of the charge transporting polymer can be appropriately adjusted in consideration of solubility in a solvent, film formability, and the like. The number average molecular weight is preferably 500 or more, more preferably 1,000 or more, and still more preferably 2,000 or more, from the viewpoint of excellent charge transportability. Further, the number average molecular weight is preferably 1,000,000 or less, more preferably 100,000 or less, and 50,000 from the viewpoint of maintaining good solubility in a solvent and facilitating preparation of the ink composition. The following are more preferred.

(Weight average molecular weight)
The weight average molecular weight of the charge transporting polymer can be appropriately adjusted in consideration of solubility in a solvent, film formability, and the like. The weight average molecular weight is preferably 1,000 or more, more preferably 5,000 or more, and still more preferably 10,000 or more, from the viewpoint of excellent charge transportability. Further, the weight average molecular weight is preferably 1,000,000 or less, more preferably 700,000 or less, and 400,000, from the viewpoint of maintaining good solubility in a solvent and facilitating the preparation of the ink composition. The following is more preferable, and the most preferable is 300,000 or less.

  The number average molecular weight and the weight average molecular weight can be measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

(Ratio of structural units)
The proportion of the structural units L contained in the charge transporting polymer is preferably 10 mol% or more, more preferably 20 mol% or more, and more preferably 30 mol% or more, based on all structural units, from the viewpoint of obtaining sufficient charge transportability. Is more preferred. Further, in consideration of the structural unit T and the structural unit B introduced as necessary, the proportion of the structural unit L is preferably 95 mol% or less, more preferably 90 mol% or less, and further preferably 85 mol% or less.

  The ratio of the structural units B contained in the charge transporting polymer is based on all structural units, from the viewpoint of improving the characteristics of the organic electronic element, or suppressing the increase in viscosity and favorably synthesizing the charge transporting polymer. 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more. In addition, the proportion of the structural unit B is preferably 60 mol% or less, and more preferably 55 mol% or less, from the viewpoint of suppressing the increase in viscosity and favorably synthesizing the charge transporting polymer, or from the viewpoint of obtaining sufficient charge transportability. Is more preferable, and 50 mol% or less is further preferable.

  The ratio of the structural units T contained in the charge transporting polymer is based on all structural units, from the viewpoint of improving the characteristics of the organic electronic element, or suppressing the rise in viscosity and favorably synthesizing the charge transporting polymer. 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more. In addition, the proportion of the structural unit T is preferably 60 mol% or less, more preferably 55 mol% or less, and still more preferably 50 mol% or less, from the viewpoint of obtaining a sufficient charge transporting property.

  When the charge transporting polymer contains a polymerizable functional group, the proportion of the polymerizable functional group is preferably 0.1 mol% or more based on all structural units from the viewpoint of efficiently curing the charge transporting polymer, 1 mol% or more is more preferable, and 3 mol% or more is further preferable. In addition, the proportion of the polymerizable functional group is preferably 70 mol% or less, more preferably 60 mol% or less, and still more preferably 50 mol% or less, from the viewpoint of obtaining good charge transportability. Here, the “ratio of the polymerizable functional group” means the ratio of the structural unit having the polymerizable functional group.

  In consideration of the balance of charge transportability, durability, productivity, and the like, the ratio (molar ratio) of the structural units L and T is preferably L: T = 100: 1 to 70, and more preferably 100: 3 to 50. Preferably, 100: 5-30 is more preferable. When the charge transporting polymer contains the structural unit B, the ratio (molar ratio) of the structural unit L, the structural unit T, and the structural unit B is L: T: B = 100: 10 to 200: 10 to 100. Preferably, 100: 20-180: 20-90 is more preferable, and 100: 40-160: 30-80 is still more preferable.

The ratio of the structural units can be calculated as an average value by using the integrated value of the spectrum derived from each structural unit in the ¹ H NMR spectrum of the charge transporting polymer.

(Production method)
The charge transporting polymer can be produced by various synthetic methods and is not particularly limited. For example, a known coupling reaction such as Suzuki coupling, Negishi coupling, Sonogashira coupling, Stille coupling, Buchwald-Hartwig coupling and the like can be used. Suzuki coupling causes a cross-coupling reaction using a Pd catalyst between an aromatic boronic acid derivative and an aromatic halide. According to the Suzuki coupling, a charge transporting polymer can be easily produced by bonding desired aromatic rings.

  In the coupling reaction, for example, a Pd (0) compound, a Pd (II) compound, a Ni compound, or the like is used as a catalyst. Further, a catalyst species generated by mixing tris (dibenzylideneacetone) dipalladium (0), palladium (II) acetate or the like with a phosphine ligand can also be used. For the method of synthesizing the charge transporting polymer, for example, the description in WO 2010/140553 can be referred to.

[Composition Containing Charge-Transporting Polymer]
The charge transporting polymer described above is usually used in the form of a composition by mixing with other components. Hereinafter, components contained in the composition will be described. In the following, the composition containing the charge transporting polymer is also referred to as a charge transporting material.

(Dopant)
The charge transporting material may contain any additive, and may further contain a dopant, for example.The dopant expresses a doping effect by being added to the charge transporting material, and improves charge transportability. There is no particular limitation as long as it can be obtained. There are two types of doping: p-type doping and n-type doping. In p-type doping, a substance that acts as an electron acceptor is used as a dopant, and in n-type doping, a substance that acts as an electron donor is used as a dopant. It is preferable to perform p-type doping for improving the hole transporting property and to perform n-type doping for improving the electron transporting property. The dopant used for the charge transporting material may be a dopant that exhibits either p-type doping or n-type doping. Further, one kind of dopant may be added alone, or a plurality of kinds of dopants may be mixed and added.

The dopant used for the p-type doping is an electron-accepting compound, and examples thereof include a Lewis acid, a proton acid, a transition metal compound, an ionic compound, a halogen compound, and a π-conjugated compound. Specifically, as the Lewis acid, FeCl ₃ , PF ₅ , AsF ₅ , SbF ₅ , BF ₅ , BCl ₃ , BBr ₃ or the like; As the protonic acid, HF, HCl, HBr, HNO ₅ , H ₂ SO ₄ , inorganic acids such as HClO _4, benzenesulfonic acid, p- toluenesulfonic acid, dodecylbenzenesulfonic acid, polyvinyl sulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, 1-butane sulfonic acid, vinyl phenyl sulfonate , organic acids such as camphorsulfonic acid; the transition metal _{compound, FeOCl, TiCl 4, ZrCl 4} , HfCl 4, NbF 5, AlCl 3, NbCl 5, TaCl 5, MoF 5; as ionic compounds include tetrakis (pentafluorophenyl Phenyl) borate ion, tris (trifluo) Methanesulfonyl) Mechidoion, bis (trifluoromethanesulfonyl) imide ion, hexafluoroantimonate ion, AsF ₆ ^- (hexafluoro arsenic acid ions), BF ₄ ^- (tetrafluoroborate), PF ₆ ^- (hexafluorophosphate) Such as salts having a perfluoroanion, such as a salt having a conjugate base of the above-mentioned protonic acid as an anion; and halogen compounds such as Cl ₂ , Br ₂ , I ₂ , ICl, ICl ₃ , IBr, IF, etc .; π-conjugated compounds Examples include TCNE (tetracyanoethylene) and TCNQ (tetracyanoquinodimethane). Further, it is also possible to use the electron-accepting compounds described in JP-A-2000-36390, JP-A-2005-75948, JP-A-2003-213002 and the like. Preferred are Lewis acids, ionic compounds, π-conjugated compounds and the like.

The dopant used for the n-type doping is an electron donating compound, for example, an alkali metal such as Li or Cs; an alkaline earth metal such as Mg or Ca; an alkali metal such as LiF or Cs ₂ CO ₃ and / or Alkaline earth metal salts; metal complexes; electron donating organic compounds, and the like.

  Since the above-described charge transporting polymer has a polymerizable functional group, it is preferable to use a compound that can act as a polymerization initiator for the polymerizable functional group as a dopant in order to easily change the solubility of the organic layer. .

(Other optional components)
The charge transporting material may further contain a charge transporting low molecular compound, another polymer, or the like.

(Content)
The content of the charge transporting polymer in the charge transporting material is preferably 50% by mass or more, more preferably 70% by mass or more based on the total mass of the charge transporting material, from the viewpoint of obtaining good charge transporting properties. Is more preferable, and 80 mass% or more is still more preferable. The upper limit of the content of the charge transporting polymer is not particularly limited, and may be 100% by mass. The content of the charge transporting polymer may be set to, for example, 95% by mass or less, 90% by mass or less in consideration of including an additive such as a dopant.

  When a dopant is contained, the content is preferably 0.01% by mass or more, and more preferably 0.1% by mass, based on the total mass of the charge transporting material, from the viewpoint of improving the charge transporting property of the charge transporting material. More preferably, the content is 0.5% by mass or more. In addition, from the viewpoint of maintaining good film formability, the amount is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less based on the total mass of the charge transporting material.

<Ink composition>
An ink composition can be obtained by dissolving or dispersing each of the above components in a solvent. By using the ink composition, the organic layer can be easily formed by a simple method such as a coating method. The ink composition may contain a polymerization initiator as needed. When an ink composition containing no polymerization initiator is used, it is preferable that the lower organic layer contains a polymerization initiator because the ink composition in the upper layer can be cured.

[solvent]
As the solvent, water, an organic solvent, or a mixed solvent thereof can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, and isopropyl alcohol; alkanes such as pentane, hexane, and octane; cyclic alkanes such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, and diphenylmethane; Aliphatic ethers such as dimethyl ether, ethylene glycol diethyl ether and propylene glycol-1-monomethyl ether acetate; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene; Aromatic ethers such as 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole; ethyl acetate, n-butyl acetate, ethyl lactate, n-butyl lactate Aliphatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate; N, N-dimethylformamide, N, N-dimethylacetamide and the like Amide solvents; dimethyl sulfoxide, tetrahydrofuran, acetone, chloroform, methylene chloride and the like. Preferred are aromatic hydrocarbons, aliphatic esters, aromatic esters, aliphatic ethers, aromatic ethers and the like.

[Polymerization initiator]
When the charge transporting polymer has a polymerizable functional group, the ink composition preferably contains a polymerization initiator. As the polymerization initiator, known radical polymerization initiators, cationic polymerization initiators, anionic polymerization initiators, and the like can be used. From the viewpoint that the ink composition can be easily prepared, it is preferable to use a substance having both a function as a dopant and a function as a polymerization initiator.
Such substances include, for example, the ionic compounds described above.

[Additive]
The ink composition may further contain an additive as an optional component. Examples of the additives include a polymerization inhibitor, a stabilizer, a thickener, a gelling agent, a flame retardant, an antioxidant, a reduction inhibitor, an oxidizing agent, a reducing agent, a surface modifier, an emulsifier, an antifoaming agent, Dispersants, surfactants and the like can be mentioned.

[Content]
The content of the solvent in the ink composition can be determined in consideration of application to various coating methods. For example, the content of the solvent is preferably such that the ratio of the charge transporting polymer to the solvent is 0.1% by mass or more, more preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. Is more preferable. The content of the solvent is preferably such that the ratio of the charge transporting polymer to the solvent is 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. .

  When the ink composition contains a polymerization initiator, the content of the polymerization initiator is not particularly limited, and can be appropriately determined according to the type and amount of the polymerizable functional group contained in the charge transporting polymer. For example, the content of the polymerization initiator is preferably at least 0.1% by mass, more preferably at least 0.5% by mass, based on the charge transporting polymer.

<Organic layer>
The organic layer according to the present embodiment is a layer formed using the charge transporting material or the ink composition of the above embodiment. By using the ink composition, an organic layer can be favorably formed by a coating method. As a coating method, for example, a spin coating method; a casting method; an immersion method; A known method such as a plateless printing method may be used. The organic layer (coating layer) obtained after the coating is dried using a hot plate or an oven to remove the solvent.

  When the charge transporting polymer has a polymerizable functional group, the polymerization reaction of the charge transporting polymer can be advanced by light irradiation, heat treatment, or the like, and the solubility of the organic layer can be changed. By stacking the organic layers having different solubilities, it is possible to easily achieve a multilayer structure of the organic electronic element. For the method of forming the organic layer, for example, the description in WO 2010/140553 can be referred to.

  The thickness of the organic layer after drying or after curing is preferably 0.1 nm or more, more preferably 1 nm or more, and still more preferably 3 nm or more, from the viewpoint of improving charge transport efficiency. The thickness of the organic layer is preferably 300 nm or less, more preferably 200 nm or less, and still more preferably 100 nm or less, from the viewpoint of reducing electric resistance.

<Organic electronics device>
An organic electronic device according to an embodiment of the present invention has at least one organic layer according to the present embodiment. Examples of the organic electronic element include an organic EL element, an organic photoelectric conversion element, an organic transistor, and the like. The organic electronic element preferably has a structure in which an organic layer is disposed between at least a pair of electrodes.

<Organic EL device>
The organic EL device according to the embodiment of the invention has at least the organic layer according to the embodiment. The organic EL device usually includes a light emitting layer, an anode, a cathode, and a substrate, and may further include, if necessary, other functional layers such as a hole injection layer, an electron injection layer, a hole transport layer, and an electron transport layer. Have. Each layer may be formed by an evaporation method or a coating method. The organic EL device preferably has an organic layer as a light emitting layer or another functional layer, more preferably has a functional layer, and still more preferably has at least one of a hole injection layer and a hole transport layer.

  FIG. 1 is a schematic sectional view showing an embodiment of the organic EL device. The organic EL device of FIG. 1 is a device having a multilayer structure, and includes a substrate 8, an anode 2, a hole injection layer 3 and a hole transport layer 6 including an organic layer of the above embodiment, a light emitting layer 1, an electron transport layer 7, An electron injection layer 5 and a cathode 4 are provided in this order. Hereinafter, each layer will be described.

[Hole injection layer, hole transport layer]
In FIG. 1, the hole injection layer 3 and the hole transport layer 6 are organic layers formed using the charge transporting material or the ink composition, but the organic EL element is not limited to such a structure. Another organic layer may be a layer formed using the charge transporting material or the ink composition. It is preferable that at least one of the hole transport layer and the hole injection layer is an organic layer formed using the charge transporting material or the ink composition, and that at least the hole transport layer is the organic layer. preferable. For example, when the organic EL element has an organic layer formed using the charge transporting material or the ink composition as a hole transport layer, and further has a hole injection layer, a known hole injection layer is used. Material can be used. Further, for example, when the organic EL element has an organic layer formed using the charge transporting material or the ink composition as a hole injecting layer, and further has a hole transporting layer, the hole transporting layer Known materials can be used.

[Light-emitting layer]
As a material used for the light emitting layer, a light emitting material such as a low molecular compound, a polymer, and a dendrimer can be used. Polymers are preferred because they have high solubility in solvents and are suitable for coating methods. Examples of the light emitting material include a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescent material (TADF).

  As fluorescent materials, low molecular weight compounds such as perylene, coumarin, rubrene, quinacridone, stilbene, dyes for dye lasers, aluminum complexes and derivatives thereof; polyfluorene, polyphenylene, polyphenylenevinylene, polyvinylcarbazole, fluorene-benzothiadiazole copolymer , Fluorene-triphenylamine copolymers, and their derivatives; and mixtures thereof.

As the phosphorescent material, a metal complex containing a metal such as Ir or Pt can be used. Examples of the Ir complex include FIr (pic) which emits blue light (iridium (III) bis [(4,6-difluorophenyl) -pyridinate-N, C ² ] picolinate) and Ir (ppy) 3 which emits green light. (Fact tris (2-phenylpyridine) iridium), which emits red light (btp) 2Ir (acac) (bis [2- (2′-benzo [4,5-α] thienyl) pyridinate-N, C3] iridium ( Acetyl-acetonate)), Ir (piq) 3 (tris (1-phenylisoquinoline) iridium) and the like. Examples of the Pt complex include PtOEP (2,3,7,8,12,13,17,18-octaethyl-21H, 23H-forfin platinum) that emits red light.

  When the light emitting layer contains a phosphorescent material, it is preferable that the light emitting layer further contains a host material in addition to the phosphorescent material. As the host material, a low molecular compound, a polymer, or a dendrimer can be used. Examples of the low molecular weight compound include CBP (4,4′-bis (9H-carbazol-9-yl) biphenyl), mCP (1,3-bis (9-carbazolyl) benzene), and CDBP (4,4′- Examples of the polymer include bis (carbazol-9-yl) -2,2′-dimethylbiphenyl) and their derivatives. Examples of the polymer include the charge-transporting material of the above embodiment, polyvinylcarbazole, polyphenylene, polyfluorene, and their derivatives. No.

  Examples of the thermally activated delayed fluorescent material include, for example, Adv. Mater., 21, 4802-4906 (2009); Appl.Phys. Lett., 98, 083302 (2011); Chem. Comm., 48, 9580 (2012) ; Appl. Phys. Lett., 101, 093306 (2012); J. Am. Chem. Soc., 134, 14706 (2012); Chem. Comm., 48, 11392 (2012); Nature, 492, 234 (2012) Adv. Mater., 25, 3319 (2013); J. Phys. Chem. A, 117, 5607 (2013); Phys. Chem. Chem. Phys., 15, 15850 (2013); Chem. Comm., 49, 10385 (2013); Chem. Lett., 43, 319 (2014).

[Electron transport layer, electron injection layer]
Materials used for the electron transport layer and the electron injection layer include, for example, phenanthroline derivatives, bipyridine derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene, condensed ring tetracarboxylic anhydrides such as perylene, carbodiimide Fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, thiadiazole derivatives, benzimidazole derivatives, quinoxaline derivatives, aluminum complexes and the like. Further, the charge transporting material of the above embodiment can also be used.

[cathode]
As the cathode material, for example, a metal or a metal alloy such as Li, Ca, Mg, Al, In, Cs, Ba, Mg / Ag, LiF, and CsF is used.

[anode]
As the anode material, for example, a metal (for example, Au) or another material having conductivity is used. Other materials include, for example, oxides (eg, ITO: indium oxide / tin oxide) and conductive polymers (eg, polythiophene-polystyrene sulfonic acid mixture (PEDOT: PSS)).

[substrate]
Glass, plastic, or the like can be used as the substrate. The substrate is preferably transparent and preferably has flexibility. Quartz glass, light transmissive resin film and the like are preferably used.

  Examples of the resin film include films containing polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyether imide, polyether ether ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, cellulose triacetate, cellulose acetate propionate, and the like. No.

  When a resin film is used, the resin film may be coated with an inorganic substance such as silicon oxide or silicon nitride in order to suppress the permeation of water vapor, oxygen, or the like.

[Emission color]
The emission color of the organic EL element is not particularly limited. The white organic EL element is preferable because it can be used for various lighting devices such as home lighting, car lighting, a clock, and a liquid crystal backlight.

  As a method for forming a white organic EL element, a method in which a plurality of light-emitting colors are simultaneously emitted using a plurality of light-emitting materials to mix colors can be used. The combination of a plurality of emission colors is not particularly limited, but a combination containing three emission maximum wavelengths of blue, green and red, and two emission maximum wavelengths such as blue and yellow, yellow green and orange, etc. Combinations to be included. The emission color can be controlled by adjusting the type and amount of the emission material.

<Display element, lighting device, display device>
The display element according to the present embodiment includes the organic EL element according to the above embodiment. For example, a color display element can be obtained by using an organic EL element as an element corresponding to each pixel of red, green, and blue (RGB). Image forming methods include a simple matrix type in which individual organic EL elements arranged in a panel are directly driven by electrodes arranged in a matrix, and an active matrix type in which a thin film transistor is arranged and driven in each element.

  The lighting device according to the present embodiment includes the organic EL element according to the present embodiment. Further, the display device according to the present embodiment includes a lighting device and a liquid crystal element as display means. For example, the display device can be a display device using a lighting device according to an embodiment of the present invention as a backlight and a known liquid crystal element as a display means, that is, a liquid crystal display device.

  Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited thereto.

<Preparation of Pd catalyst>
In a glove box under a nitrogen atmosphere, tris (dibenzylideneacetone) dipalladium (73.2 mg, 80 μmol) was weighed into a sample tube at room temperature, anisole (15 ml) was added, and the mixture was stirred for 30 minutes. Similarly, tris (t-butyl) phosphine (129.6 mg, 640 μmol) was weighed into a sample tube, anisole (5 ml) was added, and the mixture was stirred for 5 minutes. These solutions were mixed and stirred at room temperature for 30 minutes to obtain a catalyst.

<Synthesis of charge transporting polymers 1 to 6>
[Synthesis Example 1: Synthesis of charge transporting polymer 1]
In a three-necked round bottom flask, the following monomer 1 (3.0 mmol), the following monomer 2 (2.0 mmol), the following monomer 3 (2.0 mmol), the following monomer 4 (2.0 mmol), and the following monomer 5 (2.0 mmol) , And anisole (20 mL) were added, and the above-prepared Pd catalyst solution (7.5 mL) was further added. After stirring for 30 minutes, a 10% aqueous solution of tetraethylammonium hydroxide (20 mL) was added. All solvents were used after degassing with nitrogen bubbles for more than 30 minutes. The mixture was heated at reflux for 2 hours. All the operations so far were performed under a nitrogen stream.

  After the completion of the reaction, the organic layer was washed with water. Then, the organic layer was poured into methanol-water (9: 1). The resulting precipitate was suction-filtered and washed with methanol-water (9: 1). The precipitate after washing was dissolved in toluene and reprecipitated from methanol. The obtained precipitate was suction-filtered, dissolved in toluene, added with a metal adsorbent (Triphenylphosphine, polymer-bound on styrene-divinylbenzene copolymer (Strem Chemicals), 200 mg based on the precipitate), and stirred overnight. . After completion of the stirring, the metal adsorbent and insolubles were removed by filtration, and the filtrate was concentrated using a rotary evaporator. After dissolving the concentrate in toluene, it was reprecipitated from methanol-acetone (8: 3). The resulting precipitate was suction-filtered and washed with methanol-acetone (8: 3). The resulting precipitate was dried under vacuum to obtain a charge transporting polymer 1.

  The number average molecular weight of the obtained charge transporting polymer 1 was 9,200, and the weight average molecular weight was 51,300. The number average molecular weight and the weight average molecular weight were measured by GPC (in terms of polystyrene) using tetrahydrofuran (THF) as an eluent. The measurement conditions are as follows.

Liquid pump: L-6050 Hitachi High-Technologies Corporation UV-Vis detector: L-3000 Hitachi High-Technologies Corporation Detection wavelength: 254 nm
Column: Gelpack (registered trademark) GL-A160S / GL-A150S Hitachi Chemical Co., Ltd. Eluent: THF (for HPLC, not containing a stabilizer) Wako Pure Chemical Industries, Ltd. Flow rate: 1 mL / min
Column temperature: room temperature (25 ° C)
Molecular weight standard substance: Standard polystyrene (PStQuick B / C / D) Tosoh Corporation

[Synthesis Example 2: Synthesis of charge transporting polymer 2]
The following monomer 6 (5.0 mmol), monomer 3 (2.0 mmol), monomer 4 (2.0 mmol), monomer 5 (2.0 mmol), and anisole (20 mL) were added to a three-neck round bottom flask, Further, a separately prepared solution (7.5 mL) of a Pd catalyst was added and stirred. Thereafter, the charge-transporting polymer 2 was synthesized in the same manner as in the method described in Synthesis Example 1.
The number average molecular weight of the obtained charge transporting polymer 2 was 14,300, and the weight average molecular weight was 138,000.

[Synthesis Example 3: Synthesis of charge transporting polymer 3]
The monomer 6 (5.0 mmol), the monomer 3 (2.0 mmol), the monomer 5 (4.0 mmol), and anisole (20 mL) were added to a three-necked round bottom flask, and a separately prepared Pd catalyst solution ( (7.5 mL) and stirred. Thereafter, the charge transporting polymer 3 was synthesized in the same manner as in Preparation Example 1.
The number average molecular weight of the obtained charge transporting polymer 2 was 22,900, and the weight average molecular weight was 169,000.

<Preparation of ink composition>
[Ink composition 1]
Ink composition 1 containing charge transporting polymer 1 (7.0 mg), the following polymerization initiator (0.07 mg), and toluene (2.3 mL) was prepared.

[Ink composition 2]
Ink composition 2 was prepared in the same manner as ink composition 1 except that charge transport polymer 1 was changed to charge transport polymer 2.

[Ink composition 3]
Ink composition 3 was prepared in the same manner as ink composition 1 except that charge transporting polymer 1 was changed to charge transporting polymer 3.

<Preparation of organic layer>
[Organic layer P1]
The ink composition 1 was spin-coated on a substrate with ITO at 3,000 rpm, and then heated on a hot plate at 170 ° C. for 30 minutes to perform a polymerization reaction, thereby producing an organic layer P1 (20 nm).

[Organic layer P2]
An organic layer P2 was produced in the same manner as the organic layer P1, except that the heating temperature of the organic layer P1 was changed to 190 ° C.

[Organic layer P3]
An organic layer P3 was produced in the same manner as the organic layer P1, except that the heating temperature of the organic layer P1 was changed to 210 ° C.

[Organic layer P4]
An organic layer P4 was produced in the same manner as the organic layer P1, except that the heating temperature of the organic layer P1 was changed to 230 ° C.

[Organic layer P5]
The ink composition 2 was spin-coated at 3,000 rpm on a substrate with ITO, and then heated on a hot plate at 190 ° C. for 30 minutes to perform a polymerization reaction, thereby producing an organic layer P5 (20 nm).

[Organic layer P6]
An organic layer P6 was produced in the same manner as the organic layer P5 except that the heating temperature of the organic layer P5 was changed to 210 ° C.

[Organic layer P7]
An organic layer P7 was produced in the same manner as the organic layer P5 except that the heating temperature of the organic layer P5 was changed to 220 ° C.

[Organic layer P8]
An organic layer P8 was produced in the same manner as the organic layer P5 except that the heating temperature of the organic layer P5 was changed to 230 ° C.

[Organic layer P9]
An organic layer P9 was produced in the same manner as the organic layer P5 except that the heating temperature of the organic layer P5 was changed to 250 ° C.

<Measurement of residual film ratio>
The substrate on which the charge transporting polymer thin film was formed was immersed in toluene for 1 minute and washed. The ratio of the absorbance (Abs) of the absorption maximum (λmax) in the UV-vis spectrum before and after washing was defined as the remaining film ratio (%).
Residual film ratio (%) = Abs after washing / Abs before washing × 100 Equation (3)

<Measurement of surface area ratio>
The surface area ratio of the organic layers P2 to P4 and P6 to P9 was measured using a scanning probe microscope (SP400, Yamato Scientific Co., Ltd.). The scanning area was 500 nm ² , and the scanning speed was 500 nm / s. Three measurements were made for each organic layer, and the average was defined as the surface area ratio of the organic layer.

  The residual film ratio and the surface area ratio of the measured organic layers P1 to P9 are shown in Table 1 below.

  The organic layers P1 and P5 had a residual film ratio of less than 95%. Table 2 shows the ratio of the surface area ratios of the organic layers P2 to P4 and P6 to P9 having the remaining film ratio of 95% or more.

P2 to P4 prepared from the ink composition 1 are compared. These heating temperatures are T2 <T3 <T4. The ratio of the surface area ratios was S3 / S2 = 99.82 and S3 / S4 = 99.75, which was smaller than 99.95. Therefore, P3 is the organic layer according to the present embodiment.
P6, P7 and P9 prepared from the ink composition 2 are compared. These heating temperatures are T6 <T7 <T9. The ratio of the surface area ratios was S7 / S6 = 98.93 and S7 / S9 = 99.58, which was smaller than 99.95. Therefore, P7 is the organic layer according to the present embodiment.
Similarly, P6, P8, and P9 are compared. These heating temperatures are T6 <T8 <T9. The ratio of the surface area ratios was S8 / S6 = 98.89 and S8 / S9 = 99.54, which was smaller than 99.95. Therefore, P8 is the organic layer according to the present embodiment.

<Preparation of organic EL element>
(Example 1)
In a nitrogen atmosphere, the ink composition 1 was spin-coated at 3000 rpm on a glass substrate on which ITO was patterned to a width of 1.6 mm, and then cured by heating at 210 ° C. for 30 minutes on a hot plate, followed by hole injection. A layer (20 nm) was formed.

  Next, the ink composition 3 was spin-coated at 3000 rpm on the hole injection layer obtained by the above operation, and then dried by heating at 180 ° C. for 10 minutes on a hot plate to form a hole transport layer (40 nm). ) Formed.

The substrate obtained above was transferred into a vacuum evaporation machine, and CBP: Ir (ppy) ₃ (94: 6, 30 nm), BAlq (10 nm), Alq ₃ (30 nm), LiF (0 .8 nm) and Al (100 nm) in this order by a vapor deposition method, and a sealing treatment was performed to produce an organic EL element.

(Example 2)
In a nitrogen atmosphere, the ink composition 2 was spin-coated at 3000 rpm on a glass substrate on which ITO was patterned to a width of 1.6 mm, and then cured by heating at 220 ° C. for 30 minutes on a hot plate to inject holes. A layer (20 nm) was formed.
Thereafter, an organic EL device was manufactured in the same manner as in Example 1.

(Example 3)
An organic EL device was manufactured in the same manner as in Example 2 except that the heating temperature of the hole injection layer was changed to 230 ° C.

(Comparative Example 1)
An organic EL device was manufactured in the same manner as in Example 1 except that the heating temperature of the hole injection layer was changed to 190 ° C.

(Comparative Example 2)
An organic EL device was manufactured in the same manner as in Example 1 except that the heating temperature of the hole injection layer was changed to 230 ° C.

(Comparative Example 3)
An organic EL device was manufactured in the same manner as in Example 2 except that the heating temperature of the hole injection layer was changed to 210 ° C.

(Comparative Example 4)
An organic EL device was manufactured in the same manner as in Example 2 except that the heating temperature of the hole injection layer was changed to 250 ° C.

<Evaluation of organic EL element>
When voltage was applied to the organic EL devices obtained in Examples 1 to 3 and Comparative Examples 1 to 4, green light emission was confirmed in each case. For each element, emission luminance 1000 cd / ^{m 2} at the drive voltage and luminous efficiency were measured emission lifetime (luminance half-life) in the initial luminance 3000 cd / ^{m 2.} Table 3 shows the measurement results.

  As shown in Table 3, the organic EL devices of Examples 1 to 3 exhibited lower driving voltage, higher luminous efficiency, and longer luminous life than Comparative Examples 1 to 4. That is, from the viewpoint of the constituent material of the hole injection layer, it can be understood that the use of the charge transporting polymer thin film of the present embodiment has the effects of reducing the driving voltage and improving the light emission lifetime.

  As above, the effects of the present embodiment have been shown using the examples. In addition to the charge transporting polymer used in the examples, when a charge transporting polymer thin film having the surface area ratio described above is used, an organic EL device having a low driving voltage can be obtained, and similarly excellent effects can be obtained. It shows.

Claims (2)

A method for producing a charge transporting polymer thin film obtained by polymerizing and curing a composition containing a charge transporting polymer,
A method for producing a charge transporting polymer thin film, which produces a charge transporting polymer thin film such that the surface area ratio satisfies both the following formulas (1) and (2).
The heating temperatures Ta, Tb and Tc satisfy Ta <Tb <Tc,
The surface area ratio of the charge transporting polymer thin film Pa polymerized at the heating temperature Ta is Sa,
The surface area ratio of the charge transporting polymer thin film Pb polymerized at the heating temperature Tb is Sb,
When the surface area ratio of the charge transporting polymer thin film Pc polymerized at the heating temperature Tc is defined as Sc,
Sb / Sa × 100 <99.95 (%) Expression (1)
Sb / Sc × 100 <99.95 (%) Equation (2)
However, the residual film ratios of the charge transporting polymer thin films Pa, Pb and Pc represented by the following formula (3) measured under the following conditions are all 95% or more.
The substrate on which the charge transporting polymer thin film is formed is immersed in a solvent for 1 minute for washing, and the ratio of the absorbance (Abs) of the absorption maximum (λmax) in the UV-vis spectrum before and after washing is defined as the remaining film ratio (%). .
Residual film ratio (%) = Abs after washing / Abs before washing × 100 Equation (3)   The heating temperature (Tb) is set so that a minimum surface area ratio among the surface area ratios of the charge transporting polymer thin film polymerized at a temperature within the range of the heating temperature (Ta) to the heating temperature (Tc) is the surface area ratio (Sb). 2. The method for producing a charge transporting polymer thin film according to 1.

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