JP2007084485A - Naphthalene derivative and organic semiconductor material, and light-emitting transistor element and organic electroluminescence element using the same - Google Patents

Abstract

（Ａｒ^１〜Ａｒ^４はそれぞれ独立に置換基を有しても良い芳香環基を表し、少なくともその２つ以上が６π電子系より大きいπ共役系を有する基を表す。なお、Ａｒ^１〜Ａｒ^４の芳香環基が有する置換基同士が結合して環を形成していても良い。）
【選択図】なしAn organic semiconductor material capable of providing high carrier mobility when an organic TFT element is provided.
A naphthalene derivative having a structure represented by the following general formula (V). An organic semiconductor material containing at least one naphthalene derivative.
Embedded image

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)
[Selection figure] None

Description

  The present invention relates to a novel naphthalene derivative, a light-emitting transistor element using the same, an organic electroluminescence element (hereinafter referred to as an organic EL element), and a display device.

  In recent years, with the widespread use of information terminals, there is an increasing demand for flat displays and portable thin displays. Accordingly, liquid crystal films and organic EL elements are attracting attention as display media.

  An organic EL element, which is a typical example of an organic semiconductor device, is a light-emitting element that utilizes a light-emitting phenomenon associated with recombination of electrons and holes in a layer made of an organic phosphor. Specifically, an organic EL element including a light emitting layer made of an organic compound, an electron injection electrode for injecting electrons into the light emitting layer, and a hole injection electrode for injecting holes into the light emitting layer is disclosed in Patent Document 1 and Patents. It is described in Document 2 etc.

  Furthermore, using an organic EL element or film liquid crystal as a display medium, an active drive circuit is considered to be embedded by embedding TFT (Thin Film Transistor), which is effective in ensuring uniformity of screen brightness and screen rewriting speed, in each pixel. Has been. In particular, organic TFTs using organic semiconductors do not require fabrication at a high temperature unlike conventional TFTs using Si semiconductors, and are therefore not limited to glass substrates and can be formed on a flexible plastic substrate at room temperature. It is highly expected in terms of both weight reduction and cost reduction (capital investment and running cost).

  Specific organic TFTs reported so far include pentacene, rubrene and the like, but these have low solubility in organic solvents, and ordinary purification methods (distillation, recrystallization, etc.) cannot be applied. Furthermore, problems remain in the ease of molecular packing, which is a factor for achieving high carrier mobility (easiness of movement of carriers such as electrons and holes, expressed by μ), and control of orientation. (Refer nonpatent literature 1).

  On the other hand, naphthalene derivatives are highly soluble in organic solvents and easy to purify, and have the advantage of being able to produce devices at low cost. The mobility was low and it was impossible to use as an organic TFT.

  Recently, attention has been focused on a light-emitting transistor, which is a composite device in which an organic semiconductor having high carrier mobility is combined with EL light-emitting characteristics as a next-generation display element.

When a display device is configured using this element, the light emitting element and the drive transistor can be configured with the same device as compared with the conventional organic EL display, and the number of parts can be greatly reduced, and further weight reduction and thin film Therefore, development of such a light-emitting transistor material is required.
JP 2003-282256 A JP 2004-311221 A Science 303 (5664), pp.1644-1646 (March 12, 2004)

  In view of the above circumstances, the present invention provides an organic semiconductor material that can obtain high carrier mobility when an organic TFT element is used, a novel naphthalene derivative that is effective as the organic semiconductor material, a light-emitting transistor element having light emitting characteristics using these, and these It is to provide a simpler organic EL element using a light-emitting device, a light-weight display device (display panel) using the light-emitting transistor element or the organic EL element and having an excellent driving speed.

As a result of intensive studies to solve the above problems, the present inventors have found that a specific naphthalene derivative exhibits a high carrier mobility and has a light emitting property, and have completed the present invention.
That is, this invention makes the following a summary.

（Ａｒ^１〜Ａｒ^４はそれぞれ独立に置換基を有しても良い芳香環基を表し、少なくともその２つ以上が６π電子系より大きいπ共役系を有する基を表す。なお、Ａｒ^１〜Ａｒ^４の芳香環基が有する置換基同士が結合して環を形成していても良い。） [1] A naphthalene derivative having a structure represented by the following general formula (V).

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)

[2] An organic semiconductor material comprising at least one naphthalene derivative according to [1].

[3] A light emitting layer capable of transporting holes and electrons as carriers and emitting light by recombination of holes and electrons, a hole injection electrode for injecting holes into the light emitting layer, and electrons into the light emitting layer In a light-emitting transistor element having an electron-injecting electrode to be injected and a gate electrode facing the hole-injecting electrode and the electron-injecting electrode and controlling the distribution of carriers in the light-emitting layer, the light-emitting layer includes: A light-emitting transistor element using the organic semiconductor material described above.

[4] Each of the hole injection electrode and the electron injection electrode has a comb-shaped portion composed of a plurality of comb teeth, and the comb teeth forming the comb-shaped portion of the hole injection electrode and the electrons The light-emitting transistor element according to [3], wherein comb teeth constituting the comb-shaped portion of the injection electrode are alternately arranged with a predetermined interval.

[5] A display device comprising a plurality of light emitting transistor elements according to [3] or [4] arranged on a substrate.

（Ａｒ^１〜Ａｒ^４はそれぞれ独立に置換基を有しても良い芳香環基を表し、少なくともその２つ以上が６π電子系より大きいπ共役系を有する基を表す。なお、Ａｒ^１〜Ａｒ^４の芳香環基が有する置換基同士が結合して環を形成していても良い。） [6] A light emitting layer capable of transporting holes and electrons as carriers and emitting light by recombination of holes and electrons, a hole injection electrode for injecting holes into the light emitting layer, and the light emitting layer An organic electroluminescence device having an electron injection electrode for injecting electrons, comprising at least one naphthalene derivative having a structure represented by the following general formula (V):

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)

[7] A display device comprising a plurality of the organic electroluminescence elements according to [6] arranged on a substrate.

  The naphthalene derivative of the present invention has high carrier mobility when an organic TFT element is used. In addition, since this naphthalene derivative has a light emitting characteristic, it can be used as a light emitting transistor material. By using an organic semiconductor material containing this naphthalene derivative, a simpler organic semiconductor element or a light weight using the same can be obtained. A display panel having excellent driving speed can be provided.

  Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Explanation of words]
In the present invention, the “aromatic ring” means a ring having aromaticity, that is, a ring having a (4m + 2) π electron system (m is a natural number), and therefore, “aromatic hydrocarbon ring” and “aromatic heterocycle”. Ring ". “Hydrocarbon ring” means both “aromatic hydrocarbon ring” and “non-aromatic hydrocarbon ring”, and “heterocycle” means “aromatic heterocycle” and “non-aromatic heterocycle”. "Ring" means both. The skeleton structure of an aromatic ring is usually composed of a 5- or 6-membered monocyclic ring or a 2-6 condensed ring. The aromatic ring includes a monocyclic aromatic hydrocarbon ring, aromatic heterocyclic ring, anthracene. Also included are condensed rings such as rings, carbazole rings, and azulene rings. “......... Ring group” such as “aromatic ring group” is a monovalent substituent obtained by removing one hydrogen atom from such a ring such as an aromatic ring.
In the present invention, “may have a substituent” means that one or more substituents may be present.

（Ａｒ^１〜Ａｒ^４はそれぞれ独立に置換基を有しても良い芳香環基を表し、少なくともその２つ以上が６π電子系より大きいπ共役系を有する基を表す。なお、Ａｒ^１〜Ａｒ^４の芳香環基が有する置換基同士が結合して環を形成していても良い。） [Naphthalene derivatives]
The naphthalene derivative of the present invention has a structure represented by the following general formula (V).

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)

In General Formula (V), Ar ^{1 to} Ar ⁴ are each independently an aromatic ring group that may have a substituent. However, at least two of Ar ^{1 to} Ar ⁴ are groups having a π conjugated system larger than the 6π electron system.

<Ask structure of Ar ^{1 to} Ar ⁴ >
As the aromatic ring group of Ar ^{1 to} Ar ^4, an aromatic such as a furan ring, a thiophene ring, an imidazole ring as a 5-membered monocyclic ring, a benzene ring, a pyridine ring as a 6-membered monocyclic ring, a naphthalene ring, a phenanthrene ring as a condensed ring The thing derived from a ring is mentioned.
However, if the conjugated system is short, performance as a target organic semiconductor material such as mobility reduction cannot be obtained. Therefore, at least two, preferably all ^four of Ar ^{1 to} Ar ⁴ are 6π electrons. It is necessary to have a π-conjugated system larger than the system, for example, a biphenyl group, a naphthyl group, a phenanthryl group, or the like.

<Substituents Ar ^{1 to} Ar ⁴ have>
In the general formula (V), Ar ^{1 to} Ar ⁴ may further have a substituent.
Examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, a hydroxyl group, an alkoxy group, a carbonyl group, an unsubstituted, monosubstituted or disubstituted amino group, and a nitro group. Preferably, they are a C1-C10 alkyl group, a C2-C10 alkenyl group, and a C2-C8 alkynyl group.

  Examples of the alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms include straight chain such as methyl group, ethyl group, propyl group, n-butyl group, i-butyl group and t-butyl group, or Examples thereof include cycloalkyl groups such as branched alkyl groups, cyclobutyl groups, cyclopentyl groups, and cyclohexyl groups, and substituted derivative groups thereof.

  Examples of the alkenyl group having 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms include vinyl group, cis or trans-propenyl group, cis or trans-1-butenyl group, cis or trans-2-butenyl group, 2 -Linear or branched alkenyl groups such as a methyl-1-propenyl group and a 1,2-dimethylpropenyl group.

  Examples of the alkynyl group having 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms include ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2- Examples thereof include linear alkynyl groups such as butynyl group and branched alkynyl groups such as 3-methyl-1-propynyl group.

When Ar ^{1 to} Ar ⁴ have two or more substituents, the substituents may be bonded to each other to form a cyclic structure. ^Further, Ar 1 to Ar ⁴ may form any bets are ring structure by bonding with substituents as ^Ar 1 to Ar ^4, which has.

Ar ^{1 to} Ar ⁴ having these substituents are preferable from the viewpoint of ease of purification of the compound represented by the general formula (V), but those having no substituents. Is preferable from the viewpoint of easy packing between molecules.

  In general, the compound represented by the general formula (V) is preferable in terms of ease of packing between molecules if the symmetry of the molecule is high, and on the contrary, if the asymmetry is high, the amorphousness becomes high. A compound excellent in solubility in a solvent is obtained, which is preferable in terms of application to a coating type device.

<Molecular weight of Ar ^{1 to} Ar ⁴ >
The molecular weights of Ar ^{1 to} Ar ⁴ are easy to handle at the time of synthesis, have high solubility in a solvent at the time of purification, can use various purification methods, and can be deposited at a low temperature during device formation. When it has, it is preferable that it is 1000 or less in total including the substituent.

<Specific Example of Naphthalene Derivative Represented by General Formula (V)>
Preferable specific examples of the naphthalene derivative represented by the general formula (V) include those exemplified below. However, the naphthalene derivative of the present invention is not limited to these as long as the gist is not exceeded.

<Synthesis Method of Naphthalene Derivative Represented by General Formula (V)>

The naphthalene derivative shown in the specific example is 3,6-dibromonaphthalene-2,7- () obtained by brominating naphthalenediol as a raw material to prepare a dibromo derivative, and further converting a hydroxyl group to trifluoromethanesulfonic acid ester. Bistrifluoromethanesulfonic acid ester) or 3,7-dibromonaphthalene-2,6- (bistrifluoromethanesulfonic acid ester) as a raw material.
The resulting dibromonaphthalene-bis (trifluoromethanesulfonate ester) is a variety of 4-substituted symmetrical types by cross-coupling reactions using organometallic compounds such as organomagnesium compounds, organoboron compounds, organotin compounds, and vinyl derivatives as raw materials. Can be converted to naphthalene derivatives.

When performing this coupling reaction, utilizing the fact that trifluoromethanesulfonic acid ester is more reactive than bromine, selectively replacing only trifluoromethanesulfonic acid ester, the remaining bromine has a different substituent from the previous one. Can be introduced to obtain an asymmetric 4-substituted naphthalene derivative.
In addition, the bromine-containing intermediate can be converted to a carbonyl compound after metalation with butyllithium, Grignard reagent or the like. This carbonyl compound can be converted into an imidazole derivative, an oxazole derivative, and a thiazole derivative by reacting with a diamine derivative, aminoalcohol derivative, and aminothiol derivative, respectively.

<Use of naphthalene derivative represented by formula (V)>
The naphthalene derivative of the present invention has high carrier mobility when an organic TFT element is used. Furthermore, since the naphthalene derivative has light emitting characteristics, it can be used as a light emitting transistor material. By using the naphthalene derivative, a simpler organic semiconductor element, or a light-weight display panel using the naphthalene derivative and excellent in driving speed can be used. Can be provided.

In this case, having high carrier mobility means that the carrier mobility evaluated by the DC two-terminal method or the DC four-terminal method, which is a method for evaluating the conductivity of a normal conductive material, is 1.0 × 10 ⁻⁶ cm ² / V. S or more, preferably 4.0 × 10 ⁻⁵ cm ² / V · s or more, more preferably 1.0 × 10 ⁻⁴ cm ² / V · s or more.
In the application of the present invention, the upper limit of the carrier mobility is not particularly limited, but can be practically used if it is substantially 100 cm ² / V · s or less, particularly 10 cm ² / V · s or less.

[Organic semiconductor materials]
The organic semiconductor material of the present invention contains one or more of the naphthalene derivatives of the present invention represented by the above general formula (V). In addition to the naphthalene derivatives, other organic systems may be used as necessary. It may contain a semiconductor material. As other types of organic semiconductor materials that can be contained, those having high mobility are preferable. Specific examples of other organic semiconductor materials include pentacene and oligothiophene. These may be used alone or in combination of two or more.
However, in order to effectively obtain the effect of the naphthalene derivative of the present invention, the content of the naphthalene derivative of the present invention in the organic semiconductor material of the present invention is preferably 30% by weight or more, particularly preferably 50% by weight or more.

[Light emitting layer]
Prior to describing the light-emitting transistor element of the present invention and the organic EL element of the present invention using the naphthalene derivative of the present invention as described above, the light-emitting transistor element and the light-emitting layer constituting the organic EL element will be described.
This light emitting layer is a layer that can transport holes and electrons as carriers and emits light by recombination of holes and electrons.

  The light emitting layer according to the present invention includes one or more of the naphthalene derivatives of the present invention represented by the general formula (V), or one or more of the naphthalene derivatives of the present invention. It contains a semiconductor material.

  In order to form a light emitting layer of a light emitting transistor element or an organic EL element using the organic semiconductor material of the present invention, a vacuum deposition method, a sputtering method, a doctor blade method, a casting method, a spin coating method, a dipping method, etc. are generally performed. The thin film forming method can be used. Of these, spin coating is preferred from the standpoints of mass productivity and cost. When the light emitting layer is formed by spin coating, the rotational speed is preferably 500 to 5000 rpm. After spin coating, a treatment such as heating or exposure to solvent vapor may be performed as necessary.

  Although the film thickness of a light emitting layer is not specifically limited, Usually, 10 nm-5 micrometers, Preferably it is 20 nm-2 micrometers.

  The light emitting layer may contain a binder in order to improve film properties. As the binder, one kind of known materials such as polyvinyl alcohol, polyvinyl pyrrolidone, ketone resin, nitrocellulose, cellulose acetate, polyvinyl butyral, and polycarbonate can be used alone or in admixture of two or more. If the ratio of the binder in the light emitting layer is too high, the light emission luminance is remarkably lowered. Therefore, when using the binder, and further various additives and organic semiconductor materials of other systems described later, the naphthalene of the present invention in the formed light emitting layer is used. The ratio of the derivative is usually 60% by weight or more, preferably 70% by weight or more, particularly preferably 80% by weight or more.

  An additive may be added to the light emitting layer for improving the light emission efficiency. The additive is not particularly limited, for example, condensed ring derivatives such as phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopylene, dibenzopyrene, rubrene, benzoxazole derivatives, benzthiazole derivatives, benzimidazole derivatives, Benztriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, stilbene derivatives, thiophene derivatives, tetraphenylbutadiene derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives and distyrylbenzene Derivatives such as bisstyryl derivatives, diazaindacene derivatives, furan derivatives, benzofuran derivatives, phenyl esters Isobenzofuran derivatives such as benzofuran, dimesitylisobenzofuran, di (2-methylphenyl) isobenzofuran, di (2-trifluoromethylphenyl) isobenzofuran, phenylisobenzofuran, dibenzofuran derivatives, 7-dialkylaminocoumarin derivatives, 7 -Piperidinocoumarin derivatives, 7-hydroxycoumarin derivatives, 7-methoxycoumarin derivatives, 7-acetoxycoumarin derivatives, 3-benzthiazolylcoumarin derivatives, 3-benzimidazolylcoumarin derivatives, 3-benzoxazolylcoumarin derivatives, etc. Coumarin derivatives, dicyanomethylenepyran derivatives, dicyanomethylenethiopyran derivatives, polymethine derivatives, cyanine derivatives, oxobenzanthracene derivatives, xanthene derivatives, rhodamine derivatives, Olesein derivatives, pyrylium derivatives, carbostyryl derivatives, acridine derivatives, bis (styryl) benzene derivatives, oxazine derivatives, phenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives, 1,2,5-thiadiazolopyrene derivatives Perinone derivatives, pyrrolopyrrole derivatives, squarylium derivatives, violanthrone derivatives, phenazine derivatives, acridone derivatives, diazaflavin derivatives, and the like. These additives may be used alone or in combination of two or more. These additives are usually used in an amount of about 0.1 to 20% by weight based on the naphthalene derivative of the present invention.

  In the light emitting layer, organic semiconductor materials of other systems can be used in combination as required. As other types of organic semiconductor materials that can be used in combination, those having high mobility are preferable. Specific examples of other organic semiconductor materials include pentacene and oligothiophene. These may be used alone or in combination of two or more.

  When the light emitting layer is formed by a doctor blade method, a cast method, a spin coating method, a dipping method, etc., first, the organic semiconductor material of the present invention or the naphthalene derivative of the present invention, a binder, various additives, and other organic semiconductors The material is dissolved in a solvent to prepare a coating solution. The solvent is not particularly limited as long as it does not attack the substrate, and ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolv solvents such as methyl cellosolve and ethyl cellosolve Chain hydrocarbon solvents such as n-hexane and n-octane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t-butylcyclohexane and cyclooctane, Ether solvents such as diisopropyl ether and dibutyl ether, perfluoroalkyl alcohol solvents such as tetrafluoropropanol (TFP), octafluoropentanol and hexafluorobutanol, and solvents such as methyl lactate, ethyl lactate and methyl isobutyrate. Roxyester solvents and the like can be mentioned, but perfluoroalkyl alcohol solvents such as TFP, octafluoropentanol, hexafluorobutanol and the like are more preferable from the industrial aspect, and are solvents generally used industrially at present. It is particularly preferable to use TFP. In addition, these solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The concentration of the naphthalene derivative of the present invention in the coating solution is appropriately determined according to the solubility of the solvent, but is usually 0.1% by weight or more, preferably 10% by weight or more and 50% by weight or less. If the concentration of the naphthalene derivative of the present invention in the coating solution is too low, the formation efficiency of the light emitting layer is deteriorated. If the concentration of the naphthalene derivative of the present invention in the coating solution is excessively high, problems such as crystallization of the naphthalene derivative occur in the film forming step.

  Further, in order to efficiently recover the excess naphthalene derivative after spin coating, the naphthalene derivative of the present invention is applied even when the concentration is usually 1.5 times or more, preferably 2 times or more the concentration of the coating solution. It is preferable that it is soluble in a solvent.

[Light emitting transistor element]
The light-emitting transistor element of the present invention is capable of transporting holes and electrons as carriers and emits light by recombination of holes and electrons, a hole-injecting electrode that injects holes into the light-emitting layer, In a light emitting transistor element having an electron injection electrode for injecting electrons into a light emitting layer, and a gate electrode facing the hole injection electrode and the electron injection electrode and controlling the distribution of carriers in the light emitting layer, the light emitting layer includes: The organic semiconductor material containing the naphthalene derivative of the present invention described above is used.

An example of the light emitting transistor element is an element having a basic structure of a field effect transistor (FET) as shown in FIG. The light-emitting transistor element 10 shown in FIG. 4 is capable of transporting holes and electrons as carriers, and emits light by recombination of holes and electrons. The light-emitting layer 1 is mainly composed of the naphthalene derivative of the present invention. Opposite to the hole injection electrode for injecting holes into the light emitting layer 1, the so-called source electrode 2, the electron injection electrode for injecting electrons into the light emitting layer 1, the so-called drain electrode 3, and the source electrode 2 and the drain electrode 3. The gate electrode 4 made of an N ⁺ silicon substrate that controls the distribution of carriers in the light emitting layer 1. The gate electrode 4 may be composed of a conductive layer made of an impurity diffusion layer formed on the surface layer portion of the silicon substrate. Specifically, as shown in FIG. 4, an insulating film 5 made of silicon oxide or the like is provided on the gate electrode 4, and the source electrode 2 and the drain electrode 3 are provided on the insulating film 5 with a gap therebetween. A light emitting layer 1 is provided so as to cover the source electrode 2 and the drain electrode 3 and to enter between the electrodes 2 and 3.

  In order for the element to exhibit the function of a light-emitting transistor, the difference between the HOMO energy level and the LUMO energy level of the organic phosphor constituting the light-emitting layer 1, particularly the naphthalene derivative of the present invention which is the main component, It is preferable that mobility or luminous efficiency satisfy a predetermined range. In addition, when the naphthalene derivative of this invention is used, it becomes possible to make each function higher by adding the above-mentioned additive.

  First, the smaller the difference between the HOMO energy level and the LUMO energy level, the more easily electrons move and light emission and semiconductivity (that is, electron or hole conductivity in one direction) are more likely to occur. ,preferable. Specifically, the energy level difference is preferably 5 eV or less, more preferably 3 eV or less, and even more preferably 2.7 eV or less. In addition, since this difference is so preferable that it is small, the minimum of this difference is 0 eV.

In addition, the higher the carrier mobility of the naphthalene derivative of the present invention, the higher the semiconductivity, which is preferable. Specifically, it is preferably 1.0 × 10 ⁻⁶ cm ² / V · s or more, more preferably 4.0 × 10 ⁻⁵ cm ² / V · s or more, and 1.0 × 10 ⁻⁴ cm ² / s. V · s or more is more preferable. Note that the upper limit of the carrier mobility is not particularly limited, and is approximately 1 cm ² / V · s.

Luminous efficiency is the ratio of light generated by inserting photons and electrons. The ratio of emitted light energy to injected optical energy is called PL luminous efficiency (or PL quantum efficiency). The ratio of the number of emitted photons to the number is referred to as EL emission efficiency (or EL quantum efficiency). The injected and excited electrons emit light by recombining with holes, but this recombination does not necessarily occur with a probability of 100%. For this reason, when comparing the organic compound which comprises the said light emitting layer 1, by comparing EL luminous efficiency, the ratio of the light energy discharge | release amount with respect to the injected light energy, and the ratio of the recombination of an electron and a hole The synergistic effects can be compared.
On the other hand, by comparing the PL luminous efficiency, it is possible to compare the ratio of the amount of emitted light energy to the injected light energy. Therefore, by comparing both the PL luminous efficiency and the EL luminous efficiency, It is also possible to compare the rate of recombination with holes.

The PL emission efficiency of the naphthalene derivative of the present invention is preferably as the degree of light emission is larger, preferably 20% or more, and more preferably 30% or more. Note that the upper limit of the PL luminous efficiency is 100%. Further, the EL luminous efficiency is preferably as the degree of light emission is larger, preferably 1 × 10 ⁻³ % or more, and more preferably 5 × 10 ⁻³ % or more. Note that the upper limit of the EL luminous efficiency is 100%.

In addition to the above, the light-emitting transistor element 10 shown in FIG. 4 has a wavelength of emitted light. This wavelength is within the range of visible light, but has different wavelengths depending on the type of the organic phosphor used, particularly the naphthalene derivative of the present invention which is the main component. Various colors can be developed by combining organic phosphors having different wavelengths. For this reason, the wavelength of the emitted light exhibits its characteristics. Moreover, since the light emitting transistor element 10 is characterized by light emission, it should have a certain level of light emission luminance. This light emission luminance refers to the amount of light emission corresponding to the brightness of an object that humans feel when looking at the object. The emission luminance is preferably as high as possible in the measurement method using a photocounter, preferably 1 × 10 ⁴ CPS (count per sec) or more, more preferably 1 × 10 ⁵ CPS or more, and more preferably 1 × 10 ⁶ CPS or more.

The light emitting layer 1 is formed by vapor-depositing (or co-depositing when there are a plurality of types) the constituent organic phosphors, or spin coating. The thickness of the light emitting layer may be at least about 70 nm.
The source electrode 2 and the drain electrode 3 are electrodes for injecting holes and electrons into the light emitting layer 1 and are formed of gold (Au), magnesium-gold alloy (MgAu), or the like. The two are formed so as to face each other with a minute gap of 0.4 to 50 μm or the like.

  Specifically, as shown in FIG. 5, the source electrode 2 and the drain electrode 3 are formed so as to have comb-shaped portions 2 a and 3 a each composed of a plurality of comb teeth, and the comb-shaped portion of the source electrode 2 is formed. 2a and the comb teeth constituting the comb-shaped portion 3a of the drain electrode 3 are alternately arranged at predetermined intervals, thereby more efficiently exerting the function as the light emitting transistor element 10. Can be made. At this time, the distance between the source electrode 2 and the drain electrode 3, that is, the distance between the comb-shaped portion 2a and the comb-shaped portion 3a is preferably 50 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. When this interval exceeds 50 μm, sufficient semiconductor properties cannot be exhibited.

  The light emitting transistor element 10 emits light by applying a voltage to the source electrode 2 and the drain electrode 3 to move both holes and electrons in the source electrode 2 and recombining both in the light emitting layer 1. Can be made. At this time, the amount of holes and electrons moving between the electrodes 2 and 3 through the light emitting layer 1 depends on the voltage applied to the gate electrode 4. For this reason, it is possible to control the conduction state between the source electrode 2 and the drain electrode 3 by controlling the voltage applied to the gate electrode 4 and its change.

  Since the light emitting transistor element 10 performs P-type driving, a negative voltage is applied to the drain electrode 3 with respect to the source electrode 2, and a negative voltage is applied to the gate electrode 4 with respect to the source electrode 2. . Specifically, by applying a negative voltage to the gate electrode 4 with respect to the source electrode 2, holes in the light emitting layer 1 are attracted to the gate electrode 4 side, and holes in the vicinity of the surface of the insulating film 5 are attracted. The density becomes high. When the voltage between the source electrode 2 and the drain electrode 3 is appropriately set, holes are injected from the source electrode 2 to the light emitting layer 1 depending on the control voltage applied to the gate electrode 4, and electrons are injected from the drain electrode 3 to the light emitting layer 1. Will be injected. That is, the source electrode 2 functions as a hole injection electrode, and the drain electrode 3 functions as an electron injection electrode. Thereby, in the light emitting layer 1, recombination of a hole and an electron arises and light emission accompanying this will arise. This light emission state can be turned on / off or the light emission intensity can be changed by changing the control voltage applied to the gate electrode 4.

The theory that the above recombination of holes and electrons occurs in the light emitting layer 1 can be explained as follows.
By applying a negative voltage to the gate electrode 4 with respect to the source electrode 2, a hole channel 11 is formed in the light emitting layer 1 near the interface of the insulating film 5, as shown in FIG. The pinch-off point 12 reaches the vicinity of the drain electrode 3. Then, a high electric field is formed between the pinch-off point 12 and the drain electrode 3, and the energy band is greatly bent as shown in FIG. As a result, electrons in the drain electrode 3 cause an FN (Fowler-Nordheim) tunnel effect that penetrates the potential barrier between the drain electrode 3 and the light emitting layer 1, and are injected into the light emitting layer 1 to recombine with holes. Is done. In addition to the theory that the recombination of holes and electrons is due to the above-described FN tunnel effect, the following theory is also possible. That is, as shown in FIG. 6C, the electrons at the HOMO energy level of the organic phosphor in the light emitting layer 1 are excited to the LUMO energy level by a high electric field, and the excited electrons are positive in the light emitting layer 1. Recombine with the hole. At the same time, electrons are injected from the drain electrode 3 to make up for the HOMO energy level vacated by excitation to the LUMO energy level.

[Display device]
A plurality of the light-emitting transistor elements 10 are two-dimensionally arranged on a substrate to constitute a display device.
An electric circuit diagram of this display device is shown in FIG. That is, in this display device 21, the light emitting transistor elements 10 as described above are arranged in pixels P11, P12,..., P21, P22,. Two-dimensional display is enabled by selectively causing the light-emitting transistor element 10 to emit light and controlling the light emission intensity (luminance) of the light-emitting transistor element 10 of each pixel.

  The substrate 20 may be, for example, a silicon substrate in which the gate electrode 4 is integrated. That is, the gate electrode 4 may be constituted by a conductive layer made of an impurity diffusion layer patterned on the surface of the silicon substrate. Further, a glass substrate may be used as the substrate 20.

  Since each light emitting transistor element 10 is P-type driven, a bias voltage Vd (<0) is applied to its drain electrode 3 (D), and its source electrode 2 (S) is set to the ground potential (= 0). . A selection transistor Ts for selecting each pixel and a data holding capacitor C are connected in parallel to the gate electrode 4 (G).

  The gates of the selection transistors Ts of the pixels P11, P12,..., P21, P22,... Aligned in the row direction are connected to the common scanning lines LS1, LS2,. In addition, common data lines LD1, LD2,... For each column are provided on the side opposite to the light emitting transistor element 10 in the selection transistors Ts of the pixels P11, P21,. Each is connected. For the scanning lines LS1, LS2,..., The pixels P11, P12,...; P21, P22,. A scanning drive signal for selecting pixels at a time is provided. In other words, the scanning line driving circuit 22 sets each row as a sequentially selected row, and conducts the selection transistors Ts of a plurality of pixels in the selected row at a time, thereby bringing the selection transistors Ts of a plurality of pixels in the non-selected row together. Thus, a scanning drive signal for blocking can be generated. On the other hand, signals from the data line driving circuit 23 are input to the data lines LD1, LD2,. A control signal corresponding to the image data is input from the controller 24 to the data line driving circuit 23. The data line driving circuit 23 outputs light emission control signals corresponding to the light emission gradations of the respective pixels in the selected row at the timing when the plurality of pixels in each row are collectively selected by the scanning line driving circuit 21. Supply to… in parallel. As a result, in each pixel in the selected row, a light emission control signal is given to the gate electrode 4 (G) via the selection transistor Ts, so that the light emitting transistor element 10 of the pixel has a gradation corresponding to the light emission control signal. Light is emitted (or turned off). Since the light emission control signal is held in the capacitor C, the potential of the gate electrode G is held even after the selected row by the scanning line driving circuit 22 moves to another row, and the light emitting state of the light emitting transistor element 10 is held. The In this way, two-dimensional display becomes possible.

[Organic EL device]
The organic EL device of the present invention is capable of transporting holes and electrons as carriers, emits light by recombination of holes and electrons, a hole injection electrode that injects holes into the light emitting layer, and An electron injection electrode for injecting electrons into the light emitting layer, preferably a hole transport layer for transporting holes as carriers from the hole injection electrode to the light emitting layer, and a carrier from the electron injection electrode to the light emitting layer. An organic electroluminescence device having an electron transport layer for transporting the electrons includes at least one of the naphthalene derivatives of the present invention described above.

Specific examples of the organic EL element include an element as shown in FIG.
The organic EL element 30 is a laminate in which a hole injection electrode layer 32, a hole transport layer 33, a light emitting layer 34, an electron transport layer 35, and an electron injection electrode layer 36 are sequentially stacked on a substrate 31. A voltage is applied between the hole injection electrode layer 32 and the electron injection electrode layer 36 by a DC power source 37.

  The substrate 31 supports the organic EL element 30. The substrate 31 is made of a transparent material such as a glass substrate when light generated in the light emitting layer 34 is allowed to pass outside.

  The hole injection electrode layer 32 is a layer that receives a positive voltage applied from the DC power source 37. The material is not particularly limited as long as it has conductivity, but when the light generated in the light emitting layer 34 is emitted to the outside through the substrate 31, the hole injection electrode layer 32 also needs to have transparency. As a material of such a hole injection electrode layer 32, indium tin oxide (ITO) or the like can be used.

  On the other hand, the electron injection electrode layer 36 is a layer that receives a negative voltage applied from the DC power source 37. The material is not particularly limited as long as it has conductivity, and for example, aluminum or the like is used. When the light generated in the light emitting layer 34 is emitted from the electron injection electrode layer 36 side, it is preferable to use a material having transparency such as ITO as the material of the electron injection electrode layer 36.

  The hole transport layer 33 is a layer for sending holes generated in the hole injection electrode layer 32 to the light emitting layer 34, and the electron transport layer 35 emits electrons generated in the electron injection electrode layer 36. This is a layer for sending to the layer 34. Although the hole injection electrode layer 32 and the electron injection electrode layer 36 may be directly laminated with the light emitting layer 34, the hole injection electrode layer 32 or the electron injection electrode layer 36 and the light emitting layer are formed due to the problem of their bonding properties. 34, a layer having good bonding properties and good hole or electron mobility is provided as the hole transport layer 33 or the electron transport layer 35. For this reason, depending on the combination of the hole injection electrode layer 32 or the electron injection electrode layer 36, the light emitting layer 34, and the material, the hole transport layer 33 and the electron transport layer 35 may be omitted.

  Examples of the material constituting the hole transport layer 33 include N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (TPD). Can be mentioned. Examples of the material constituting the electron transport layer 35 include 3- (4-biphenyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole (TAZ). .

  The light-emitting layer 34 is the same as the light-emitting layer 10 of the light-emitting transistor element, and is a layer using the naphthalene derivative of the present invention as a constituent component, and the aforementioned additives are used in combination as necessary.

  As described above, the hole transport layer 33 and the electron transport layer 35 are selected so that the mobility of holes and electrons and the bonding property between the hole injection electrode 32 and the electron injection electrode 36 and the light emitting layer 34 are good. However, when it is difficult to satisfy both of these characteristics, a hole injection layer is further provided between the hole injection electrode layer 32 and the hole transport layer 33, or the electron injection electrode layer 36 and the electron transport layer are provided. An electron injection layer may be provided between the first and second layers. As a result, materials can be selected for the hole transport layer 33 and the electron transport layer 35 with more emphasis on the mobility of holes and electrons, and the bonding property can be improved as the hole injection layer and the electron injection layer. Since material can be selected with emphasis, the range of material selection is expanded.

  In order for such an element to function as an organic EL element, the naphthalene derivative of the present invention is used as a main constituent of the organic phosphor constituting the light emitting layer 34, or Alq3 (Tris ( It is preferable to use the naphthalene derivative of the present invention as a dopant using 8-hydroxyquinolate)) or the like. In the light emitting layer 34, it is preferable that the difference between the HOMO energy level and the LUMO energy level, light emission luminance, PL light emission efficiency, and external light emission efficiency satisfy predetermined ranges. In addition, when the naphthalene derivative of the present invention having each of the above characteristics is used, each function can be further enhanced by adding subcomponents such as the dopant.

The difference between the HOMO energy level and the LUMO energy level is the same as that of the light emitting transistor element.
That is, the light emission luminance is the amount of light emission corresponding to the brightness of an object that a person feels when looking at the object. This emission luminance can be measured using a Si photodiode. According to this method, the light emission luminance (cd / m ² ) generated by the applied current (or voltage) is different. For example, when multiplied by 10 mA / cm ² current (voltage 6.0V) is, 50 cd / ^{m 2} or more is good, preferably 75 cd / ^{m 2} or more, 100 cd / ^{m 2} or more is more preferable. Also, when subjected to 100 mA / cm ² current (voltage 8.0 V) is, 600 cd / ^{m 2} or more is good, preferably 1000 cd / ^{m 2} or more, 2000 cd / ^{m 2} or more is more preferable.

  The PL luminous efficiency is as described above, and the external luminous efficiency is the luminous efficiency observed outside. The external luminous efficiency is usually 5% as the upper limit in the fluorescent dyes used.

  In the organic EL element, it is particularly necessary that the degree of light emission is large, and the PL light emission efficiency is preferably 80% or more, and more preferably 85% or more. Note that the upper limit of the PL luminous efficiency is 100%. Moreover, in external luminous efficiency, 1% or more is good, 1.4% or more is preferable, and 2% or more is more preferable. Note that the upper limit of EL luminous efficiency is 5%.

  In addition to the above, the characteristic of the illustrated organic EL element 30 is the wavelength of the emitted light. This wavelength is within the range of visible light, but has a wavelength that varies depending on the type of organic phosphor used, particularly the naphthalene derivative of the present invention. Various colors can be developed by combining organic phosphors having different wavelengths. For this reason, the wavelength of the emitted light exhibits its characteristics.

  The organic EL element 30 can be formed by forming a hole injection electrode layer 32 on a substrate 31 and sequentially vacuum-depositing or spin-coating each layer thereon. The film thickness of the light emitting layer 34 of the obtained organic EL element 30 should just be about 10-100 nm, and the film thickness of the said hole transport layer 33 and the electron transport layer 35 should just be about 10-50 nm. The hole injection electrode layer 32 and the electron injection electrode layer 36 may have a film thickness of about 5 to 30 nm.

  In this organic EL element 30, when a voltage is applied between the hole injection electrode layer 32 and the electron injection electrode layer 36 by the DC power source 37, holes generated in the hole injection electrode layer 32 are transmitted through the hole transport layer 33. The electrons sent to the light emitting layer 34 and generated in the electron injection electrode layer 36 are sent to the light emitting layer 34 through the electron transport layer 35, and holes and electrons recombine in the light emitting layer 34 to emit light.

[Display device]
A plurality of the organic EL elements 30 can be two-dimensionally arranged on a substrate to constitute a display device.
As an example of this display device, an example of an electric circuit diagram of a passive display device is shown in FIG. In this display device 41, scanning lines (LS1 ′, LS2 ′,...) And data lines (LD1 ′, LD2 ′,...) Are arranged in a grid pattern on the substrate 40, and an organic EL is formed at each intersection. The element 30 is arranged. Specifically, the organic EL element (1, 1) in the first row and first column has one end connected to the first row scanning line and the other end arranged in the first data line. The organic EL element (j, i) in the j-th row and the i-th column has one end connected to the j-th scanning line and the other end arranged in the i-th data line. The organic EL element (j, i) emits light when a current flows when the data line i is set to the high level and the scanning line j is set to the low level. The light emission gradation can be controlled by adjusting the period during which this current flows. For example, the scanning line driving circuit 42 selects a scanning line corresponding to a row to emit light, sets it to a low level (for example, 0 V), and sets a scanning line corresponding to a row that does not emit light to a high level. Further, a data signal pulse-modulated according to the light emission gradation is supplied from the data line driving circuit 43 to the data line as high level data for a predetermined period. As a result, the selected organic EL element can emit light, and an image can be displayed. In the scanning line driving circuit 42, the selected EL elements emit light in order by switching the scanning lines to be selected in order, so that the images can be changed in order.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

The analysis method employed in the following is as follows.
FAB-MS (Fast Particle Impact Mass Spectrometry): “JMS-700” manufactured by JEOL Ltd. was used and nitrobenzyl alcohol was used as a matrix.
Proton NMR analysis: Analysis was performed in a deuterated chloroform solvent using “AV400M nuclear magnetic resonance spectrometer (400 MHz)” manufactured by Bruker.
DEI-MS (desorption ionization mass spectrometry) analysis: using “JMS-700 MStation mass spectrometer” manufactured by JEOL Ltd., acceleration voltage: 10 kV, temperature rising condition: 0-0.9 A, 1 A / min I went there.
Liquid chromatography (LC):
Shimadzu Pump: LC-20AT
Detector (UV): SPO-6AV
Column: GL Sciences Co., Ltd. (ODS-2, 4.6φ × 150 mm)
Solvent: CH ₃ CN (manufactured by Kanto Chemical Co., Inc.)
Flow rate: 1 ml / min
Absorption wavelength: 254 nm
Thermostatic bath temperature: 40 ° C

[Synthesis Example 1]
Bromination of 2,7-dihydroxynaphthalene was performed by the following method.
<Reference Aust. J. Chem., 1960, (13), 256-260 (RG Cooke, BL Johnson, and WR Owen)>

  A 500 mL three-necked flask was equipped with a reflux condenser, a dropping funnel, and an alkali trap. Into this reactor, 10.04 g of 2,7-dihydroxynaphthalene (Aldrich reagent, purity 97%) and 230 mL of acetic acid (pure chemical reagent) were added and stirred at room temperature. Into this, 80 mL of acetic acid in 13 mL of bromine (Kanto Chemical Reagent, purity 99%) was added dropwise over 40 minutes from the dropping funnel, and after stirring for 15 minutes, 30 mL of pure water was added. The temperature was raised to 80 ° C. over 25 minutes, and after reaching 80 ° C., 15.49 g of tin powder (Kishida Chemical Reagent, purity 99%) was added little by little. After the entire amount of tin powder was charged, the mixture was further heated at 80 ° C. for 5 hours.

At 50 ° C., the reaction solution was filtered with a fold filter paper, 150 mL of pure water was added and the mixture was allowed to stand, and the precipitated needle crystals were collected by suction filtration. The recovered crystals were washed with cold methanol and pure water and then dried under reduced pressure to obtain 12.66 g of an off-white solid.
^{From 1} H NMR, it was confirmed that the recovered solid was the desired 3,6-dibromo-2,7-dihydroxynaphthalene.
Yield: 65.5%
¹ H NMR (400 MHz, CDCl ₃ ):
δ 7.86 (s, 2H), 7.23 (s, 2H), 5.65 (s, 2H)

[Synthesis Example 2]
3,6-Dibromo-2,7-dihydroxynaphthalene was converted to trifluoromethanesulfonic acid ester by the following method.

  A dropping funnel, a three-way cock, and a thermometer were attached to a 100 mL three-necked flask, and the inside of the reactor was replaced with nitrogen. Into this reactor, 3.00 g of 3,6-dibromo-2,7-dihydroxynaphthalene, 20 mL of dichloromethane (Kanto Chemical Reagent) and 3.6 mL of dehydrated pyridine (Aldrich Reagent) were added and stirred in an ice bath. From this dropping funnel, trifluoromethanesulfonic anhydride (Tokyo Kasei Reagent, purity 98%) 3.0 mL of dichloromethane 10 mL solution was added dropwise over 15 minutes, and after completion of the addition, the mixture was stirred in an ice bath for 1 hour. After warming to room temperature and stirring for 1 hour, 1.5 mL of trifluoromethanesulfonic anhydride and 3.6 mL of dehydrated pyridine were further added and stirred at room temperature for 1 hour.

Under reduced pressure, the solvent was removed with a rotary evaporator, and 100 mL of 1N HCl aqueous solution and 100 mL of dichloromethane were added to the residue. The organic layer was separated and washed with 100 mL of 1N aqueous HCl. The organic layer was dehydrated with anhydrous magnesium sulfate and then filtered, and the filtrate was concentrated with an evaporator. The obtained residue was purified by silica gel column chromatography (chloroform-hexane) to obtain 4.24 g of a pale yellow solid.
^{From 1} H NMR, it was confirmed that this solid was the desired 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonate ester.
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.17 (s, 2H), 7.84 (s, 2H)

[Synthesis Example 3]
2,7-bis (4-biphenyl) -3,6-dibromonaphthalene was synthesized from 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonate by the following method.

  A 100 mL three-necked flask was equipped with a reflux condenser, a three-way cock, and a thermometer. To this reactor, 1.50 g of 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonate ester, 1.02 g of 4-biphenylboric acid (Wako Pure Chemical Reagent, purity not stated), sodium carbonate (Kanto Chemical) Reagent) 1.10 g, toluene (pure chemical reagent) 30 mL, ethanol (pure chemical reagent) 10 mL, and pure water 3 mL were added, and the operation of depressurization and nitrogen substitution was performed 5 times with vigorous stirring at room temperature. Further, nitrogen was bubbled through the reaction mixture for 30 minutes, and the entire system was replaced with nitrogen. Next, 0.18 g of tetrakistriphenylphosphinopalladium (0) was added, and the mixture was heated and stirred at 80 ° C. for 4 hours in an oil bath.

After cooling, the reaction solution was separated into oil and water, and the aqueous layer was extracted three times with 30 mL of toluene. The organic layers were combined, dehydrated over anhydrous magnesium sulfate, filtered, and concentrated to obtain a crude product. The crude product was purified by silica gel column chromatography (hexane-toluene), and the first fraction was collected and dried by heating under reduced pressure to obtain 0.38 g of a white solid.
^{From 1} H NMR and mass spectrometry, this white solid was confirmed to be 2,7-bis (4-biphenyl) -3,6-dibromonaphthalene.
Yield: 24.8%.
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.17 (s, 2H), 7.82 (s, 2H), 7.72-7.66 (m, 8H), 7.60-7.56 (m, 4H), 7.51-7. 45 (m, 4H), 7.41-7.36 (m, 2H)
MS (FAB): 590 (M ⁺ )

[Example 1]
2,3,6,7-tetrakis (2-naphthyl) naphthalene was synthesized from 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonate by the following method.

  A 200 mL three-necked flask was equipped with a reflux condenser, a three-way cock, and a thermometer. This reactor was charged with 3.05 g of 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonate, 4.52 g of 2-naphthylboric acid (Aldrich reagent, purity not stated), sodium carbonate (Kanto Chemical Reagent) 5 .50 g, 60 mL of toluene (pure chemical reagent), 25 mL of ethanol (pure chemical reagent) and 10 mL of pure water were added, and vacuum degassing and nitrogen replacement were performed 5 times with vigorous stirring at room temperature. Further, nitrogen was bubbled through the reaction mixture for 30 minutes, and the entire system was replaced with nitrogen. Next, 0.46 g of tetrakistriphenylphosphinopalladium (0) was added, and the mixture was heated and stirred in an oil bath at 80 ° C. for 12 hours.

After cooling, the precipitated white solid was collected by suction filtration and washed successively with pure water and methanol. 1.91 g of white solid was obtained by heating and drying under reduced pressure.
^{From 1} H NMR and mass spectrometry, this white solid was confirmed to be the desired 2,3,6,7-tetrakis (2-naphthyl) naphthalene.
Yield: 57.7%
LC: 97.6%
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.13 (s, 4H), 7.96 (s, 4H), 7.82-7.75 (m, 8H), 7.57 (d, J = 8.80, 2H), 7.46- 7.42 (m, 8H), 7.26-7.24 (m, 4H)
MS (FAB): 632 (M ^<+> )

[Example 2]
2,3,6,7-tetrakis (4-biphenyl) naphthalene was synthesized from 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester by the following method.

  A 200 mL three-necked flask was equipped with a reflux condenser, a three-way cock, and a thermometer. This reactor was charged with 3.02 g of 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester, 5.18 g of 4-biphenylboric acid (Wako Pure Chemical Reagent, purity not stated), sodium carbonate (Kanto Chemical) 5. Reagent (5.46 g), toluene (pure chemical reagent) 50 mL, ethanol (pure chemical reagent) 20 mL, and pure water 10 mL were added, and the operation of vacuum degassing and nitrogen substitution was performed 5 times with vigorous stirring at room temperature. Further, nitrogen was bubbled through the reaction mixture for 30 minutes, and the entire system was replaced with nitrogen. Tetrakistriphenylphosphinopalladium (0) (0.75 g) was added, and then the mixture was heated and stirred in an oil bath at 80 ° C. for 11 hours.

After cooling, the precipitated white solid was collected by suction filtration and washed successively with pure water and methanol. The mixture was refluxed with a toluene solvent and filtered hot, and the precipitated crystals were collected and washed 5 times with chloroform. By drying under reduced pressure, 1.60 g of white crystals were obtained.
^{From 1} H NMR and mass spectrometry, this white solid was confirmed to be the desired 2,3,6,7-tetrakis (4-biphenyl) naphthalene.
Yield: 42.0%
LC: 94.1%
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.03 (s, 4H), 7.65-7.61 (m, 8H), 7.57-7.53 (m, 8H), 7.47-7.41 (m, 8H), 7. 41-7.37 (m, 8H), 7.37-7.31 (m, 4H)
MS (FAB): 736 (M ^<+> )

[Example 3]
2,7-bis (4-biphenyl) -3,6-diphenylnaphthalene was synthesized from 2,7-bis (4-biphenyl) -3,6-dibromonaphthalene by the following method.

  In a 20 mL Schlenk tube, 0.37 g of 2,7-bis (4-biphenyl) -3.6-dibromonaphthalene, 0.21 g of phenylboric acid (Aldrich reagent, purity 95%), 0.34 g of sodium carbonate (Kanto Chemical Reagent) Add 5 mL of toluene (pure chemical reagent), 3 mL of ethanol (pure chemical reagent), and 1 mL of pure water, repeat the degassing and nitrogen replacement operations three times while stirring the mixture, and add 1 nitrogen to the mixture. Aerated for hours. Next, 0.12 g of tetrakistriphenylphosphinopalladium (0) was added, and the mixture was heated and stirred at 80 ° C. for 9 hours in an oil bath.

After cooling, the precipitated solid was collected by suction filtration, and the obtained solid was purified by silica gel column chromatography (hexane-chloroform). The white solid recovered by concentrating the distilled solution was washed with acetonitrile, and heated and dried under reduced pressure to obtain a white solid.
^{From 1} H NMR and mass spectrometry, this white solid was confirmed to be 2,7-bis (4-biphenyl) -3,6-diphenylnaphthalene.
Yield: 82.5%
LC: 98.7%
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.00 (s, 2H), 7.96 (s, 2H), 7.63-7.60 (m, 4H), 7.53-7.50 (m, 4H), 7.46-7. 41 (m, 4H), 7.39-7.26 (m, 16H)
MS (DEI): 584 (M ⁺ )

[Comparative Example 1]
2,3,6,7-tetraphenylnaphthalene was synthesized from 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester by the following method.

  A 200 mL three-necked flask was equipped with a reflux condenser, a three-way cock, and a thermometer. To this reactor, 3.00 g of 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester, 3.29 g of phenylboric acid (Tokyo Kasei Reagent, purity 95%), sodium carbonate (Kanto Chemical Reagent) 5. 20 g of toluene (pure chemical reagent) 50 mL, ethanol (pure chemical reagent) 20 mL, and pure water 10 mL were added, and vacuum degassing and nitrogen replacement were performed 5 times while stirring at room temperature. Further, nitrogen was bubbled through the reaction mixture for 30 minutes, and the entire system was replaced with nitrogen. Next, 0.33 g of tetrakistriphenylphosphinopalladium (0) was added, and the mixture was stirred with heating at 80 ° C. for 12 hours in an oil bath.

After cooling, the precipitated white solid was collected by suction filtration and washed successively with pure water and methanol. 1.70 g of white solid was obtained by heating and drying under reduced pressure.
^{From 1} H NMR and mass spectrometry, it was confirmed that this white solid was the desired 2,3,6,7-tetraphenylnaphthalene.
Yield: 80.5%
LC: 99.5%
¹ H NMR (400 MHz, CDCl ₃ ):
δ7.93 (s, 4H), 7.25-7.23 (m, 20H)
MS (FAB): 432 (M ^<+> )

[Comparative Example 2]
2,3,6,7-tetrakis (3-pyridyl) naphthalene was synthesized from 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester by the following method.

  A 200 mL three-necked flask was equipped with a reflux condenser, a three-way cock, and a thermometer. To this reactor, 1.96 g of 3,6-dibromo-2,7-naphthalenediol bistrifluoromethanesulfonic acid ester, 3.56 g of 3-pyridylboronic acid pinacol ester (Aldrich reagent, 97%), sodium carbonate (Kanto Chemical Reagent) 3.59 g, toluene (pure chemical reagent) 40 mL, ethanol (pure chemical reagent) 20 mL, and pure water 5 mL were added, and vacuum degassing and nitrogen replacement were performed 5 times with vigorous stirring at room temperature. Further, nitrogen was bubbled through the reaction mixture for 30 minutes, and the entire system was replaced with nitrogen. Next, 0.31 g of tetrakistriphenylphosphinopalladium (0) was added, and the mixture was heated and stirred in an oil bath at 80 ° C. for 12 hours.

After cooling, the precipitated solid was filtered off, and the filtrate was concentrated and purified by silica gel column chromatography (chloroform-methanol), and further purified by GPC.
¹ H NMR and mass spectrometry confirmed that this white solid was the desired 2,3,6,7-tetrakis (3-pyridyl) naphthalene.
Yield: 6.8%
¹ H NMR (400 MHz, CDCl ₃ ):
δ 8.59 (dd, J = 2.0, 4H), 8.54 (dd, J = 4.8, 4H), 8.02 (s, 4H), 7.50-7.46 (m, 4H) ), 7.24-7.19 (m, 4H)
MS (DEI): 436 (M ⁺ )

[Characteristic evaluation]
The properties of the naphthalene compounds synthesized in Comparative Examples and Examples were evaluated and the results are shown in Table 1.
The transistor elements used for the characteristic evaluation and the evaluation conditions for each characteristic are as follows.

<Foundation creation>
FIG. 10 shows a perspective view of a transistor element used for evaluation of physical properties of the material (carrier mobility and EL light emission efficiency measurement).
As the gate electrode (p-Si) 51 and the insulating film (SiO ₂ ) 52, a p-Si (thickness 2 mm) substrate with thermally oxidized SiO ₂ (thickness 300 nm) manufactured by KST was used. A comb-shaped mask having a gate length L: 25 μm, a gate width W: 4 mm, and 20 pins is formed on the substrate using a positive resist (TMSR-8900: Tokyo Ohka Kogyo Co., Ltd.), and then a source electrode 53 and a drain electrode 54 are formed. Was prepared by vapor deposition of Cr (manufactured by Nilaco) 1 nm / Au (manufactured by Nilaco) 40 nm. After removing the mask, the target transistor element is formed by laminating a naphthalene-based compound to a thickness of 100 nm using a vacuum deposition method (deposition rate: 1.0 Å / s, degree of vacuum: 3.0 × 10 ⁻³ Pa or less). Got.

<Measurement of carrier mobility μ (cm ² / V · s)>
The relational expression between the drain voltage (V _d ) and the drain current (I _d ) of the organic semiconductor is expressed by the following formula (1), which increases linearly (straight region), but when V _d increases, the channel pinch · By turning off, _Id is saturated and becomes a constant value (saturation region), and _Id is expressed by the following equation (2).

L: Channel length [cm]
W: Channel width [cm]
C _i : capacitance [F / cm ² ] per unit area of the gate insulating film
μ _sat : mobility in saturation region [cm ² / Vs]
I _d : drain current [A]
V _d : drain voltage [V]
V _g : gate voltage [V]
V _T : gate threshold voltage [V] (drain voltage (V _d ) in the saturation region is constant and drain current (I _d ) is raised to the power of 1/2 (V _dsat ^1/2 ) as gate voltage (V _g ) Plot against the asymptote and show the point where the horizontal axis intersects.)

From the relationship of √I _d and V _g in saturation region, the mobility of the organic semiconductor: mu can be obtained.
In the present invention, the drain voltage is changed from 10 V to -100 V in a -1 V step using a semiconductor parameter analyzer (Agilent, HP4155C) under the conditions where the pressure is a degree of vacuum to 5 × 10 ^-3 Pa and the temperature is room temperature. The gate voltage was operated from 0 V to −100 V in a −20 V step, and the mobility was calculated using the above equation (2).

<EL luminous efficiency (%)>
The external quantum efficiency η _ext is obtained by operating the drain voltage from 10 V to −100 V in a −1 V step and the gate voltage from 0 V to −100 V in a −20 V step using the transistor element, and the light emitted from the element is shown in FIG. The sample 61 is measured by a photon counter (4155C Semiconductor Parameter Analyzer) 60 shown in FIG. 6 and the number of photons [CPS] obtained there is converted into a luminous flux [lw] using the following equation (3). _Was used to calculate EL luminous efficiency η _ext .

Symbols:
N _PC : Number of photons observed by photon counter (PC) [CPS]
X _PC : Value obtained by converting the number of photons into a luminous flux [lw] r: Radius of cone or circle [cm]
h: Distance between photon counter 60 and sample 61 [cm]

<PL luminous efficiency (%)>
The luminous efficiency of PL is determined by using a integrating sphere (IS-060, Labsphere Co.) as excitation light after depositing a naphthalene compound to a thickness of 70 nm on a quartz substrate in a nitrogen atmosphere to form a single layer film. Calculation was performed by irradiating a He—Cd laser (IK5651R-G Kimmon electric Co.) having a wavelength of 325 nm and measuring light emission multi-channel photodiode (PMA-11, Hamamatsu photonics Co.) from the sample.

Note that the transistor characteristics of 2,3,6,7-tetrakis (2-naphthyl) naphthalene are shown in FIG. The emission wavelengths of 2,3,6,7-tetraphenylnaphthalene and 2,3,6,7-tetrakis (2-naphthyl) naphthalene are shown in FIG.
FIG. 2A shows the transistor characteristics of 2,3,6,7-tetrakis (4-biphenyl) naphthalene, and FIG. 2B shows the emission spectrum.
FIG. 3A shows the transistor characteristics of 2,7-bis (4-biphenyl) -3,6-diphenylnaphthalene, and FIG. 3B shows the emission spectrum.

(A) is a graph showing the transistor characteristics of 2,3,6,7-tetrakis (2-naphthyl) naphthalene, (b) is a graph showing 2,3,6,7-tetraphenylnaphthalene and 2,3,6 It is a graph which shows the light emission wavelength of 6,7-tetrakis (2-naphthyl) naphthalene. (A) The figure shows the transistor characteristics of 2,3,6,7-tetrakis (4-biphenyl) naphthalene, and (b) is a graph showing the emission spectrum. (A) The figure shows the transistor characteristics of 2,7-bis (4-biphenyl) -3,6-diphenylnaphthalene, and (b) is a graph showing the emission spectrum. It is typical sectional drawing which shows schematic structure which shows embodiment of the light emitting transistor element of this invention. It is a schematic diagram which shows the electrode shape of the light emitting transistor element shown in FIG. It is explanatory drawing of the recombination mechanism of the hole and electron of the light emitting transistor element shown in FIG. FIG. 5 is an electric circuit diagram showing an embodiment of a display device of the present invention using the light emitting transistor element shown in FIG. 4. It is typical sectional drawing which shows schematic structure which shows embodiment of the organic EL element of this invention. It is an electric circuit diagram which shows embodiment of the display apparatus of this invention using the organic EL element shown in FIG. It is a perspective view of the transistor element used for evaluation (physical mobility and EL luminous efficiency measurement) of the physical property of material. It is a perspective view which shows the photon counter used for the measurement of EL luminous efficiency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting layer 2 Source electrode 3 Drain electrode 4 Gate electrode 5 Insulating film 10 Light emitting transistor element 20 Substrate 21 Display device 30 Organic EL element 31 Substrate 32 Hole injection electrode layer 33 Hole transport layer 34 Light emitting layer 35 Electron transport layer 36 Electron Injection electrode layer 40 Substrate 41 Display device

Claims (7)

A naphthalene derivative having a structure represented by the following general formula (V).

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)   An organic semiconductor material comprising at least one naphthalene derivative according to claim 1.   A light-emitting layer that can transport holes and electrons as carriers and emits light by recombination of holes and electrons, a hole-injection electrode that injects holes into the light-emitting layer, and an electron that injects electrons into the light-emitting layer The light emitting transistor element having an injection electrode and a gate electrode facing the hole injection electrode and the electron injection electrode and controlling the distribution of carriers in the light emitting layer, the organic layer according to claim 2 in the light emitting layer. A light-emitting transistor element using a semiconductor material.   Each of the hole injection electrode and the electron injection electrode has a comb-shaped portion composed of a plurality of comb teeth, and the comb teeth constituting the comb-shaped portion of the hole injection electrode and the electron injection electrode 4. The light-emitting transistor element according to claim 3, wherein the comb teeth constituting the comb-shaped portion are alternately arranged at a predetermined interval.   5. A display device comprising a plurality of light emitting transistor elements according to claim 3 arranged on a substrate. A light emitting layer that can transport holes and electrons as carriers and emits light by recombination of holes and electrons, a hole injection electrode that injects holes into the light emitting layer, and electrons that are injected into the light emitting layer An organic electroluminescent device having an electron injection electrode comprising at least one naphthalene derivative having a structure represented by the following general formula (V):

(Ar ^{1 to} Ar ⁴ each independently represents an aromatic ring group that may have a substituent, and at least two of them represent a group having a π-conjugated system larger than the 6π electron system. Ar ^{1 to} Ar ^The substituents of the aromatic ring group ⁴ may be bonded to each other to form a ring.)   A display device comprising a plurality of the organic electroluminescence elements according to claim 6 arranged on a substrate.

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