JP2006059791A - Organic device and organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve the service life of an organic device for which a threshold voltage is dropped by forming a dipole molecule layer by connecting molecules each having a dipole to a surface of an electrode. <P>SOLUTION: This organic device is provided with, from the side of a substrate 1, at least a positive electrode 2, the dipole molecule layer 3, one or more organic molecule layers 4, and a negative electrode 5. The problem is solved by providing the organic device wherein the positive electrode 2 is chemically bonded to the dipole molecule layer 3, and the dipole molecule layer 3 satisfies μ/εA>0.20, where ε is a dielectric constant of the dipole molecule layer; A is the average occupation area per molecule constituting the dipole molecule layer; and μ is a dipole moment per molecule constituting the dipole molecule layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic device and an organic electroluminescence device, and more particularly to extending the life and reducing power consumption of an organic device.

  In recent years, the development of organic devices using organic substances has become active in devices such as electroluminescence (hereinafter referred to as EL) elements and solar cells. Advantages of the organic device include being inexpensive, flexible, and relatively easy to manufacture. On the other hand, problems to be solved include improvement of electrode injection efficiency, reduction of threshold voltage, and extension of life.

の構造を有する双極子分子を陽極表面に化学結合させて双極子分子層を形成した有機ＥＬデバイスが報告されている。この双極子分子と基板との結合は化学結合であるため、双極子分子のもつ双極子の向きを固定でき、そのため双極子分子層中に電気二重層を形成することができる。この電気二重層の作用によって陽極の仕事関数が増加してキャリア注入障壁が小さくなり、それにより閾値電圧が低減している。
しかしながら、上記特許文献１の有機ＥＬデバイスにおいて、長寿命化の問題は解決されていない。その理由として、一般のデバイスに印加される程度の高電界において、電極と双極子分子の結合部位に加わる力は非常に大きいものとなってしまい、結合部位が破壊してしまうことが考えられる。つまり、上記デバイスは一般に用いられる程度の電界に対しても比較的脆く、双極子分子層を含まないデバイスと比較して劇的な寿命の延びは見られない。 Aiming at lowering the threshold voltage among the above problems, Patent Document 1 describes the general formula (II):

An organic EL device has been reported in which a dipole molecule layer is formed by chemically bonding a dipole molecule having the following structure to the anode surface. Since the bond between the dipole molecule and the substrate is a chemical bond, the direction of the dipole of the dipole molecule can be fixed, so that an electric double layer can be formed in the dipole molecule layer. This electric double layer increases the work function of the anode and reduces the carrier injection barrier, thereby reducing the threshold voltage.
However, in the organic EL device of Patent Document 1, the problem of extending the life has not been solved. The reason is that, in a high electric field applied to a general device, the force applied to the binding site between the electrode and the dipole molecule becomes very large, and the binding site is destroyed. In other words, the device is relatively fragile even to an electric field that is generally used, and a dramatic increase in lifetime is not seen compared to a device that does not include a dipole molecular layer.

JP 2002-270369 A

Therefore, there is a demand for an organic device having a long lifetime in addition to the reduction in threshold voltage due to having a dipole molecular layer bonded to an electrode in this way.
In an organic device in which the work function of the electrode is changed by bonding a dipole molecular layer to the electrode surface, the amount of change in the work function of the electrode is directly linked to the size of the carrier injection barrier. is connected with. Therefore, knowing the relationship between the work function variation and the lifetime is a shortcut to extending the device lifetime.
However, it is not easy to find a correlation between the lifetime and the amount of work function change obtained from the experimental results. This is because the work function variation obtained in the experiment involves complicated factors such as the interface state of the device.
Therefore, it is useful to express the amount of work function change with a simple formula that removes complex factors such as the interface state, and to know the relationship with the lifetime. There is no.
In view of the above, an object of the present invention is to provide an organic device having a large work function variation based on the derived mathematical formula.

In order to solve the above problems, the present invention expresses a work function variation ΔV of an electrode having a dipole molecule on its surface as a mathematical expression based on electromagnetic considerations, and applies it to the fabrication of an organic device. It is.
Consider a case where dipole molecules are aligned in parallel in the same direction on a plane electrode in a direction perpendicular to the electrode. Here, the origin is the middle point of the dipole molecule, the length of the dipole molecule is L, + q at the end of the dipole on the electrode side, and −q at the other dipole end, and has a dipole. Assuming that the area occupied by one molecule is A, the relative dielectric constant in the dipole molecular layer is ε _s , and the dielectric constant in vacuum is ε ₀ , ΔV at the dipole end opposite to the electrode is given by equation (3) Can be represented.

In other words, the work function change ΔV is the dielectric constant ε (= ε _s ε ₀ ) of the dipole molecular layer when a molecule having a certain dipole (including a compound) is attached to the electrode, and per dipole molecule. It can be seen that control can be performed with the area A occupied by and the dipole moment μ (= + ql). Here, the relationship between the size V of the carrier injection barrier and the amount of change ΔV in the work function of the electrode is represented by the equation (4).

V ₀ is a carrier injection barrier when there is no change in the work function of the electrode. In general, the value of [Delta] V is about one order of magnitude smaller than the V _0, [Delta] V is not required to be taken into account if it is larger than V _0, can reduce the carrier injection barrier as those [Delta] V is greater from the above equation (3) . As described above, if A and ε are small and μ is large, ΔV increases and it is considered that a device having a long lifetime can be obtained. In other words, in order to obtain a long-life device, it is considered necessary to produce an organic device having a dipole molecular layer having a larger μ / εA. In addition, it may be necessary to extend the life of the device by making the bond between the electrode and the dipole molecule a chemical bond having a high durability.

（式中、εは双極子分子層の誘電率、Aは双極子分子層を構成する１分子あたりの平均占有面積、μは双極子分子層を構成する１分子あたりの双極子モーメントを表す。）を満足する有機デバイスが提供される。 Thus, in order to solve the above-described problem, according to the present invention, at least a first electrode, a dipole molecular layer, a monolayer or multilayer organic molecular layer, and a second electrode are sequentially stacked, and the first electrode The electrode and the dipole molecular layer are chemically bonded, and the dipole molecular layer has the formula (1):

(In the formula, ε represents the dielectric constant of the dipole molecular layer, A represents the average occupied area per molecule constituting the dipole molecular layer, and μ represents the dipole moment per molecule constituting the dipole molecular layer. ) Is provided.

According to another aspect of the present invention, there is provided an organic electroluminescence device including the organic device having the above structure.
According to still another aspect of the present invention, there is provided a method for producing the above organic device, including a step of chemically bonding molecules for forming a dipole molecular layer by performing a gas phase reaction with a first electrode, In this process, by controlling the reaction time and the reaction temperature, an organic device that forms a monomolecular film that forms a single layer by chemically bonding with the first electrode in a state where a plurality of the same molecules are closely packed is formed. A manufacturing method is provided.

According to the organic device of the present invention, the dipole molecular layer having μ / εA> 0.20 (unit: voltage V) is provided, and the dipole molecular layer is chemically bonded (particularly covalent bond) on the electrode. As a result, the life can be extended.
Moreover, according to the organic EL device of the present invention, it is possible to drive with low power consumption as the threshold voltage decreases in addition to extending the life.
In addition, according to the method for producing an organic device of the present invention, by controlling the reaction time and the reaction temperature, a single layer is formed by chemically bonding with the first electrode in a state of being packed most closely with the same molecule. Can produce a monomolecular film that reduces the resistance of the entire dipole molecular layer and reduces the number of pinholes in the dipole molecular layer. And the manufacturing cost of the device can be reduced.

  In the organic device of the present invention, an anode (first electrode), a dipole molecular layer, a monolayer or multilayer organic molecular layer, and a cathode (second electrode) are sequentially formed on a substrate. The layers are chemically bonded, and the dipole molecular layer is μ / εA> 0.20 (unit: voltage V) (ε is the dielectric constant of the dipole molecular layer, and A is the per molecule constituting the dipole molecular layer. Of the average occupying area, μ satisfies the dipole moment per molecule constituting the dipole molecular layer. Preferably, [mu] / [epsilon] A> 0.30 (V). By using this dipole molecular layer, the lifetime can be further extended.

In the organic device of the present invention, it is preferable that the dipole molecular layer is made of a silane coupling compound in addition to the above configuration. Since the silane coupling compound can be stably covalently bonded to the electrode as a molecule to be bonded to the electrode, there is an effect that the lifetime of the manufactured organic device is further extended.
In the silane coupling compound satisfying μ / εA> 0.20 (V), the dielectric constant ε is 4 to 30 × 10 ⁻¹¹ F / m, the average occupation area A is 30 to 70 ² , and the bipolar The child moment μ is 2 to 6 Debye.

（式中、X1,X2,X3,X4およびX5は同一又は異なって、X1〜X５のうち何れか１〜３個がハロゲン原子、ニトロ基、低級アルキル基、ハロゲン化低級アルキル基、シアノ基、アシル基、アミノ基、イソシアノ基、チオシアノ基、−COOR4（R4は水素原子もしくは低級アルキル基）、‐ＯR5（R5は水素原子もしくは低級アルキル基）およびビフェニル基で、かつ、残りが水素原子を表し、Yは２価の脂肪族または芳香族炭化水素基を表し、R1,R2およびR3は水素原子もしくは低級アルキル基を表す。） Of the silane coupling compounds that satisfy each of the above conditions, a compound having a structure represented by the following general formula (III) or (IV) is preferably used. In other words, the silane coupling compound according to the present invention has a structure represented by the following general formula (III) or (IV) and satisfies the above μ / εA> 0.20 (V). Compounds are preferred.

(Wherein X1, X2, X3, X4 and X5 are the same or different, and any one to three of X1 to X5 are a halogen atom, a nitro group, a lower alkyl group, a halogenated lower alkyl group, a cyano group, An acyl group, an amino group, an isocyano group, a thiocyano group, -COOR4 (R4 is a hydrogen atom or a lower alkyl group), -OR5 (R5 is a hydrogen atom or a lower alkyl group) and a biphenyl group, and the remainder represents a hydrogen atom. Y represents a divalent aliphatic or aromatic hydrocarbon group, and R1, R2 and R3 represent a hydrogen atom or a lower alkyl group.)

In the general formula (III) or (IV), examples of the halogen atom include F, Cl, Br, and the like. Examples of the lower alkyl group include methyl, ethyl, propyl, and butyl groups having 1 to 4 carbon atoms. Examples of the halogenated lower alkyl group include chloromethyl, chloroethyl, bromomethyl, and bromoethyl groups. The acyl group HCO-, CH ₃ CO-, include C ₂ H ₅ CO- or the like. The -COOR4 -COOH, -COOCH _3, include -COOC ₂ H ₅ and the like. The -OR5 -OH, -OCH _3, include -OC ₂ H ₅ and the like.

Preferred examples of the molecule having the structure represented by the general formula (III) include p-nitrophenyltriethoxysilane represented by the structural formula (V).

Preferred examples of the molecule having the structure of the general formula (IV) include 1-trimethoxysilylethynyl-4-nitrobenzene of the structural formula (I).

Moreover, in the organic device of the present invention, in addition to the above-described configuration, the dipole molecular layer is a monomolecular film (a thin film having a thickness of one molecule or less of the molecules constituting the same) that forms one layer from a plurality of identical molecules. Some are preferred. Here, the thickness of the monomolecular film is maximum when each dipole molecule is bonded in a direction perpendicular to the electrode, and when each dipole molecule is bonded in an oblique direction to the electrode, Thinner. In general, organic substances have a high electric resistance, which also affects the short life, but by using a monolayer dipole molecular layer, the resistance of the entire dipole molecular layer can be minimized, The lifetime of the entire device is improved as compared with a non-molecular film.
Further, in the organic device of the present invention, in addition to the above configuration, the dipole molecular layer is more preferably a monomolecular film in which a plurality of the same molecules are closely packed to form one layer. One possible cause of device degradation is the presence of pinholes in the dipole molecular layer. Close-packed monolayers have a dense structure that can minimize the presence of pinholes. Therefore, there is an effect that the deterioration of the device derived from the pinhole is suppressed and the lifetime of the manufactured organic device is further extended.

  Hereinafter, the organic device of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment.

(Embodiment 1)
FIG. 1 is a sectional view showing a schematic structure of an organic device according to the present invention. The organic device has a structure in which an anode 2, a dipole molecular layer 3 composed of dipole molecules bonded to the anode 2, a single or multilayer organic molecular layer 4, and a cathode 5 are sequentially laminated on a substrate 1.

The substrate 1 serves as a support for the organic device, and quartz, glass, metal, or the like is used. In general, a conductive material having a large work function such as indium tin oxide (ITO), Au, or Ag is used as the anode 2.
The dipole molecular layer 3 is composed of molecules having a dipole covalently bonded to the anode. As the dipole molecule, when there is a hydroxyl group on the surface of the anode 2, a silane coupling compound, an acid chloride compound, or a hypophosphite compound that easily reacts with the hydroxyl group to form a covalent bond with the anode is used. However, among these, it is preferable to use a silane coupling compound that can form a stronger covalent chemical bond than an acid chloride compound or a hypophosphite compound.
Here, examples of the silane coupling compound include compounds of Compound No. 1 (Structural Formula (I)) and Compound No. 3 (Structural Formula (V)) shown in Table 1 below. An example of the chloride compound is trans-4-nitrocinnamoyl chloride of Compound No. 2.

In addition, examples of hypophosphorous acid-based molecules include 4-chlorophenyl dichlorophosphate represented by the structural formula (VI).

When the anode is a metal having a large work function such as Au or Ag, a dipole molecule having a thiol group that can be directly bonded to a metal atom, for example, 4-nitrothiophenol of the structural formula (VII) can be mentioned. .

The organic molecular layer 4 is composed of a single layer or multiple layers of organic molecules. Taking an organic EL device as an example, tris (8-hydroxyquinaldine) aluminum (Alq ₃ ) or 10-benzo [h] quinolinol-beryllium complex (BeBq ₂ ) is a light-emitting layer if the organic molecular layer 4 is a single layer. If there are two layers, N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (TPD) with hole transport layer added to the light-emitting layer And Alq ₃ are used. In the present invention, Alq ₃ and TPD can be commercially available products (for example, manufactured by Aldrich), and BeBq ₂ can be synthesized by the method described in the document Chem. Lett. 1993, 905-906. As the 10-hydroxybenzo [h] quinoline necessary for this synthesis, a commercially available product (for example, manufactured by Tokyo Chemical Industry Co., Ltd.) can be used.
As the cathode 5, Al, MgIn, or the like having a small work function is used.

  The method for producing the organic device of the present invention will be described in detail. According to the method of forming the anode 2 on the substrate 1 by vacuum deposition or sputtering and then bringing the formed anode 2 into contact with a dipole molecule to cause a chemical reaction. A dipole molecular layer 3 covalently bonded to the anode 2 is obtained. Furthermore, the organic molecular layer 4 is formed on the dipole molecular layer 3 by vacuum vapor deposition, and finally the cathode 5 is formed by vacuum vapor deposition, sputtering, etc., and the target organic device can be produced.

  In the present invention, the dipole moment can be obtained by performing quantum chemical calculations on the target molecule. For details, the objective is to use the PM3 method (J. Comp. Chem. 10,209 (1989), J. Comp. Chem. 10,221 (1989)), which is one of the semi-empirical methods of the Gaussian03 package, which is a molecular orbital calculation program. Optimize the structure of the molecule and calculate the exact dipole moment by calculating the Hartree-Fock (HF) method, one of the ab initio molecular orbital methods, using the optimized structure. be able to. In the present invention, the basis function of the HF method is 6-31 + G (d, p). The average occupied area per dipole molecule is calculated by measuring the absorbance of the ultraviolet absorption spectrum, estimating the number of dipole molecules per unit area of the anode surface from the absorption peak intensity, and taking the reciprocal of this. be able to. The dielectric constant can be calculated based on these values obtained by measuring the film thickness of the dipole molecular layer from AFM measurement and the capacitance of the dipole molecular layer by capacitance measurement.

(Synthesis Example 1) Synthesis of 1-trimethoxysilylethynyl-4-nitrobenzene (Compound No. 1) 1-trimethoxysilylethynyl-4-nitrobenzene was synthesized by the following method. The reaction formula (a) is shown below.
A two-necked flask equipped with a dropping funnel with a side tube and a three-way cock was replaced with nitrogen, and 19.6 g (133 mmol) of 1-ethynyl-4-nitrobenzene (made by Aldrich) in 8.2 ml (128 mmol) of 20 ml of dry tetrahydrofuran. ) Was added dropwise at -78 ° C, and the temperature of the reaction solution was raised to -40 ° C over 30 minutes. Subsequently, 20.5 g (131 mmol) of trimethoxychlorosilane (manufactured by fluorochem) was added, and the reaction solution was heated to 0 ° C. and stirred for a while. After removing the insoluble part by Celite filtration, refining from tetrahydrofuran / hexane mixed solution: v / v = 3/7, approx. 200ml, it was purified, and the target compound was obtained in 30% yield (10.7g, 39.9mmol). Obtained. Moreover, it was identified as the target compound from ¹ H-NMR and ¹³ C-NMR.

Synthesis Example 2 Synthesis of p-nitrophenyltriethoxysilane (Compound No. 3) p-nitrophenylethynyltrimethoxysilane was synthesized by the following method. The reaction formula (b) is shown below.
Put a magnesium chip 2.43g (100mmol) into a three-necked flask equipped with a thermometer, a Jimroh condenser, and a dropping funnel, and replace with nitrogen. Add 100ml of dry tetrahydrofuran and 23.9g (120mmol) of triethoxychlorosilane (made by fluorochem) and stir well. did. Next, 70 ml of a dry tetrahydrofuran solution of 20.2 g (100 mmol) of 1-bromo-4-nitrobenzene (Aldrich) was slowly added dropwise at 0 ° C., and the temperature of the reaction solution was raised to room temperature over 2 hours. The mixture was stirred overnight at room temperature and then refluxed for 4 hours to complete the reaction. The solution was filtered under a nitrogen atmosphere to remove insoluble matters, and then the filtrate was concentrated under reduced pressure to 20 ml and purified from recrystallization by adding 150 ml of dry hexane to obtain the desired compound in a yield of 41% (9.97 g, 41.0 mmol). Moreover, it was identified as the target compound from ¹ H-NMR and ¹³ C-NMR.

Synthesis Example 3 Synthesis of 3,5-bis (trifluoromethyl) phenyltrimethoxysilane (Compound No. 6) 3,5-bis (trifluoromethyl) phenyltrimethoxysilane was synthesized by the following method. The reaction formula (c) is shown below.
Put a magnesium chip 2.43g (100mmol) into a three-necked flask equipped with a thermometer, a Jimroh condenser, and a dropping funnel, and replace with nitrogen. Add 100ml of dry tetrahydrofuran and 18.8g (120mmol) of trimethoxychlorosilane (made by fluorochem) and stir well. did. Next, 70 ml of a dry tetrahydrofuran solution of 29.3 g (100 mmol) of 3,5-bis (trifluoromethyl) bromobenzene (Aldrich) was slowly added dropwise at 0 ° C, and the temperature of the reaction solution was raised to room temperature over 2 hours. It was. Thereafter, the reaction was completed overnight by stirring at room temperature and refluxing for 4 hours. The solution was filtered to remove insoluble matter, and then purified by recrystallization from tetrahydrofuran / hexane mixed solution: v / v = 2/8, about 100 ml to obtain the desired compound in a yield of 35% (11.7 g, 35.1 mmol). ). Moreover, it was identified as the target compound from ¹ H-NMR and ¹³ C-NMR.

(Example 1)
An organic EL device having the structure shown in FIG. 1 was produced by the following method.
First, ITO was deposited to a thickness of 150 nm on a glass substrate measuring 25 mm long × 25 mm wide × 0.7 mm thick to form an anode. Next, a resist pattern was formed on the ITO anode surface, and the anode was patterned into a desired shape by etching with hydrochloric acid using the resist pattern as a mask. Subsequently, the anode was ultrasonically cleaned in chloroform, and further, the anode was ultrasonically cleaned in acetone and ethanol, respectively. Thereafter, oxygen plasma ashing treatment (using Branson / IPC 4000) was performed on the ITO anode surface at 150 ° C. for 15 minutes to expose the clean anode surface and generate oxygen radicals on the anode surface. Thereafter, the anode surface was immersed in ultrapure water for 5 minutes to change oxygen radicals to hydroxyl groups, thereby forming an anode surface having many hydroxyl groups that are likely to form covalent bonds.

Subsequently, the substrate with anode and the 1-trimethoxysilylethynyl-4-nitrobenzene (silane coupling compound) of Compound No. 1 shown in Table 1 synthesized as in Synthesis Example 1 have heat and pressure resistance. Place in a Teflon (registered trademark) container, and heat the container at 150 ° C. in an explosion-proof oven to volatilize the silane coupling compound and perform a gas phase reaction with the anode surface until the saturation time. Trimethoxysilylethynyl-4-nitrobenzene was covalently bonded to form a 1.0 nm-thick dipole molecular layer. The film thickness was estimated by AFM measurement (using NanoScope III manufactured by Digital Instruments). Here, the saturation time is defined as the time during which the average occupied area with respect to the anode surface per molecule of the dipole does not change, and in this case it was 150 minutes. Specifically, an ultraviolet absorption spectrum measurement (using Shimadzu UV-3100PC) of a dipole molecular layer vapor-grown every 15 minutes was performed, and an absorption peak indicated by 1-trimethoxysilylethynyl-4-nitrobenzene It was considered that a dipole monolayer was formed because there was no change between 150 minutes and 165 minutes, and from this, the saturation time was estimated to be 150 minutes. Here, the monomolecular layer means a thin film whose thickness corresponds to the size of one molecule. The average area occupied per molecule of dipole molecules layer when reacted until saturation time was 35.9A ² as calculated by UV absorption spectrometry. From the molecular orbital calculations, the dipole moment of 1-trimethoxysilylethynyl-4-nitrobenzene was estimated to be 5.01 Debye. Furthermore, the relative dielectric constant calculated by capacitance measurement (using Agilent 4284A Precision LCR meter) and AFM measurement was 14.6, and from this, the value of μ / εA was estimated to be 0.360V.

Subsequently, the substrate obtained through the above steps was transferred to a vacuum vapor deposition device (ELORA-100 manufactured by ULVAC Kiko Co., Ltd.), and a vacuum degree of 5 × 10 ⁻⁶ Torr was set, followed by TPD (Aldrich Corporation) placed on a metal boat. The TPD hole transport layer having a film thickness of 100 nm was formed on the dipole molecular layer by heating so that the deposition rate was maintained at 1.0 Å / s. The film thickness was measured with a quartz resonator. Subsequently, Alq ₃ (manufactured by Aldrich) having a film thickness of 100 nm was deposited as a light emitting layer on the hole transport layer in the same manner as TPD. At this time, the deposition rate was kept at 1.0 Å / s, and the degree of vacuum was 5 × 10 ⁻⁶ Torr. Finally, an organic EL device was fabricated by vacuum-depositing Al having a film thickness of 200 nm on the light-emitting layer at a temperature maintaining a vacuum degree of 5 × 10 ⁻⁶ Torr and a deposition rate of 2.0 Å / s.

A direct current is applied to the organic EL device so that the initial luminance is 100 cd / m ^2, and then the luminance is measured at a constant current at regular intervals, and the lifetime when the emission luminance becomes 50% of the initial luminance is determined. It was. As shown in Table 1, the lifetime of this organic EL device was as long as 3000 hours. Moreover, the light emission luminance-voltage curve of the organic EL device of Example 1 is shown in FIG. The voltage reaching the luminance of 100 cd / m ² is as low as 5.3 V, and even the voltage reaching 500 cd / m ² is kept as low as 6.6 V.

(Example 2)
Using trans-4-nitrocinnamoyl chloride (acid chloride compound) of Compound No. 2 shown in Table 1 as a molecule constituting the dipole molecular layer (made by Aldrich), heating temperature (reaction temperature) 120 ° C., saturation time An organic EL device was produced in the same manner as in Example 1 except that the dipole molecular layer was formed in 60 minutes. In the organic EL device of Example 2, the average occupied area per molecule of the dipole molecular layer at the saturation point is estimated to be 61.1Å ² , the dipole moment is 2.91 Debye, and the relative dielectric constant is 7.47. / ΕA was 0.240V. Further, the same lifetime measurement as in Example 1 was performed, and as shown in Table 1, it was 1800 hours. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltage reaching the luminance of 100 cd / m ² is as low as 6.0 V, and the voltage reaching 500 cd / m ² is kept as low as 7.5 V. In addition, other preferable reaction temperature in the formation of a dipole molecular layer by trans-4-nitrocinnamoyl chloride of Compound No. 2 and the saturation time at that time are about 100 ° C. and about 105 minutes.

(Example 3)
As a molecule constituting the dipole molecular layer, p-nitrophenyltriethoxysilane (silane coupling compound) of Compound No. 3 shown in Table 1 synthesized as in Synthesis Example 2 was used. An organic EL device was produced in the same manner as in Example 1 except that the dipole molecular layer was formed in 90 minutes. In the organic EL device of Example 3, the average occupied area per molecule of the dipole molecular layer at the saturation point is estimated to be 42.3Å ² , the dipole moment is 5.66 Debye, and the relative dielectric constant is 23.9. / ΕA was 0.211V. Further, the same lifetime measurement as in Example 1 was performed, and as shown in Table 1, it was 2100 hours. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltage reaching the luminance of 100 cd / m ² is as low as 5.8 V, and even the voltage reaching 500 cd / m ² is kept as low as 6.9 V. In addition, other preferable reaction temperature in the formation of the dipole molecular layer by p-nitrophenyltriethoxysilane of Compound No. 3 and the saturation time at that time are about 100 ° C. and about 195 minutes.

Example 4
Using 1-trimethoxysilylethynyl-4-nitrobenzene (silane coupling compound) of Compound No. 1 shown in Table 1 as the molecule constituting the dipole molecular layer, the reaction time with the anode is 30 minutes, and the dipole molecular layer An organic EL device was produced in the same manner as in Example 1 except that was formed. Similarly, organic EL devices were also produced in the same manner as in Example 1 except that the dipole molecular layer was formed with reaction times of 60, 90, 120, 150 and 180 minutes, respectively.
When the average occupied area A per molecule of the dipole molecular layer of these devices is estimated, as shown in Table 2 and FIG. 3, there is no change after 150 minutes, and thus the reaction temperature (heating temperature) is 150 ° C. In this case, it takes about 150 minutes or more to form a monomolecular film (dipole molecular layer) constituting a single layer chemically bonded to the anode in a state where a plurality of identical molecules are packed in close packing (saturation time) (About 150 minutes) Further, when the same life measurement as in Example 1 was performed, as shown in Table 2, a long life of 3000 hours was obtained in 150 minutes and 180 minutes, respectively.

(Example 5)
Using 1-trimethoxysilylethynyl-4-nitrobenzene (silane coupling compound) of compound number 1 shown in Table 1 as a molecule constituting the dipole molecular layer, the reaction temperature between the anode and this molecule is 180 ° C. An organic EL device was produced in the same manner as in Example 1 except that the dipole molecular layer was formed at 90 minutes and 150 minutes.
The device occupies a reaction time of 90 minutes and the area occupied by each molecule of dipole molecules is 36.1 Å ^{2. A} dipole molecular layer consisting of a monolayer (single layer) constituting one layer was formed. . On the other hand, the average area occupied per dipole molecules 1 molecule of the device that the reaction time was changed to 150 minutes is 18.8A ^2, found that the dipole molecules layer is not the one layer (single layer) in a reaction time of 150 minutes It was. The cause is considered that the silane coupling molecule may be bonded in a three-dimensional network structure, and at high temperatures, the reaction does not stop at the monomolecular film, and further, the molecules are stacked on the multilayer film. It is thought that was formed.
Moreover, when the lifetime measurement was performed for each device with a reaction time of 90 minutes and 150 minutes in the same manner as in Example 1, it was 3000 hours for 90 minutes and 2600 hours for 150 minutes, and the dipole molecular layer was a single layer. The lifetime of the monolayer film was longer.
In addition, other preferable reaction temperature in the formation of the dipole molecular layer by 1-trimethoxysilylethynyl-4-nitrobenzene of Compound No. 1 and the saturation time at that time are about 120 ° C. and about 270 minutes.

(Comparative Example 1)
As a molecule constituting the dipole molecular layer, phenyltrimethoxysilane (silane coupling compound) of Compound No. 4 shown in Table 1 (manufactured by Aldrich) is used, and the dipole molecular layer is heated at 100 ° C. and saturated for 105 minutes. An organic EL device was produced in the same manner as in Example 1 except that was formed. The organic EL device of Comparative Example 1 is estimated to have an average occupied area per molecule of the dipole molecular layer at the saturation point of 38.0Å ² , a dipole moment of 0.457 Debye, and a relative dielectric constant of 5.33, μ / ΕA was 0.085V. Moreover, as a result of performing the lifetime measurement similar to Example 1, as shown in Table 1, it was as short as 450 hours. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltage reaching the luminance of 100 cd / m ² was 10.8 V, which is higher than those in Examples 1 to 3, and the voltage reaching 500 cd / m ² was as high as 12.2 V, and the difference from Examples 1 to 3 was remarkable.

(Comparative Example 2)
Using the bromophenyltrimethoxysilane (silane coupling compound) of Compound No. 5 shown in Table 1 as a molecule constituting the dipole molecular layer (manufactured by fluorochem), the dipole molecule at a heating temperature of 120 ° C. and a saturation point of 120 minutes. An organic EL device was produced in the same manner as in Example 1 except that the layer was formed. The organic EL device of Comparative Example 2 is estimated to have an average occupied area per molecule of the dipole molecular layer at the saturation point of 44.9Å ² , a dipole moment of 1.70 Debye, and a relative dielectric constant of 12.3. / ΕA was 0.116V. Moreover, as a result of performing the lifetime measurement similar to Example 1, as shown in Table 1, it was as short as 600 hours. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltage reaching the luminance of 100 cd / m ² is 9.0 V, which is higher than those of Examples 1 to 3, and the voltage reaching 500 cd / m ² is 10.5 V, which is a significant difference from Examples 1 to 3.

(Comparative Example 3)
As a molecule constituting the dipole molecular layer, 3,5-bis (trifluoromethyl) phenyltrimethoxysilane (silane coupling compound) of Compound No. 6 shown in Table 1 synthesized as in Synthesis Example 3 was used. An organic EL device was produced in the same manner as in Example 1 except that the dipole molecular layer was formed at a heating temperature of 150 ° C. and a saturation point of 90 minutes. The organic EL device of Comparative Example 3 is estimated to have an average occupied area per molecule of the dipole molecular layer at the saturation point of 88.7Å ² , a dipole moment of 4.52 Debye, and a relative dielectric constant of 11.8. / ΕA was 0.162V. Moreover, as a result of performing the lifetime measurement similar to Example 1, as shown in Table 1, it was as short as 750 hours. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltages reaching the luminance of 100 cd / m ² and 500 cd / m ² were 7.3 V and 8.7 V, which were higher than those in Examples 1 to 3, respectively.

(Comparative Example 4)
An organic EL device was produced in the same manner as in Example 1 except that the step of forming a dipole molecular layer was omitted except that no molecules constituting the dipole molecular layer were included. The organic EL device of Comparative Example 4 was subjected to the same lifetime measurement as that of Example 1. As a result, it was as short as 450 hours as shown in Table 1. Moreover, the light emission luminance-voltage curve of this organic EL device is shown in FIG. The voltage reaching the luminance of 100 cd / m ² is 11.2 V, which is higher than those in Examples 1 to 3, and the voltage reaching 500 cd / m ² is as high as 12.4 V, and the difference between Examples 1 to 3 is remarkable.

  As is clear from Table 1, Examples 1 to 3 in which μ / εA> 0.20 (V) have a lifetime that is at least twice that of Comparative Examples 1 to 4 that do not satisfy μ / εA> 0.20 (V). It can be said that Examples 1 to 3 having a dipole molecular layer chemically bonded to the anode achieve both a reduction in threshold voltage and a longer life. An increase in the value of μ / εA leads to a decrease in the threshold voltage, and as can be seen from FIG. 2, the organic EL devices of Examples 1 to 3 can be driven with low power consumption. Further, when comparing Compound Nos. 1, 2 and 3 in Table 1, it is clear that Compound Nos. 1 and 3 in which the dipole molecular layer is made of a silane coupling agent have a longer lifetime. In particular, an organic device using Compound No. 1 that satisfies μ / εA> 0.30 (V) has a long lifetime, and the lifetime is more than three times that of Comparative Examples 1 to 4 that do not satisfy μ / εA> 0.20 (V). It can be seen that it extends.

Further, as apparent from Table 2 of Example 4 and FIG. 3, the average occupation area does not change during the time after the formation of the dipole molecular layer composed of a monolayer of monolayers at an appropriate reaction temperature. The device life is the longest. From this, it is necessary to stop the reaction when a dipole molecular layer consisting of a monolayer of monolayers is formed, so that a device with a long lifetime can be obtained and the reaction must be continued for a longer time. Therefore, the reaction time can be reduced, and as a result, the device manufacturing cost can be reduced.
Further, as is clear from the results of Example 5, when the reaction temperature between the anode and the dipole molecule is higher, the time required for forming the dipole molecular layer composed of a monolayer monolayer can be shortened, It is possible to reduce device manufacturing costs. In addition, from the results of Example 5, it is also clear that if the dipole molecular layer is a single layer, the lifetime is longer than that of other layers.

(Embodiment 2)
Examples 1 to 3 are organic EL devices. For example, the substrate is made of glass, the anode is made of ITO, the organic molecular layer is made of p-type molecular copper phthalocyanine (CuPc) and n-type molecule C ₆₀ , and the cathode is made of Al. Thereby, an organic solar cell device can also be comprised.

  The organic device of the present invention can be used for a display organic EL device such as a mobile phone, a television, a personal computer, a car navigation system, an organic solar cell device, and the like.

It is sectional drawing which shows schematic structure of the organic device which concerns on this invention. It is the light-emitting luminance-voltage curve of the organic EL device of Examples 1-3 and Comparative Examples 1-4. 6 is an average occupied area-reaction time curve of the organic EL device of Example 4.

Explanation of symbols

1 Substrate 2 Anode 3 Dipole Molecular Layer 4 Organic Molecular Layer 5 Cathode

Claims (9)

At least a first electrode, a dipole molecular layer, a single-layer or multilayer organic molecular layer, and a second electrode are sequentially stacked, the first electrode and the dipole molecular layer are chemically bonded, and the dipole molecule The layer is of formula (1):

(Wherein ε represents the dielectric constant of the dipole molecular layer, A represents the average occupied area per molecule constituting the dipole molecular layer, and μ represents the dipole moment per molecule constituting the dipole molecular layer. An organic device characterized by satisfying   The organic device according to claim 1, wherein the dipole molecular layer is formed of a silane coupling agent. The organic device according to claim 2, wherein the silane coupling agent has a dielectric constant ε: 4 to 30 × 10 ⁻¹¹ F / m, an average occupied area A: 30 to 70 ² , and a dipole moment μ: 2 to 6 Debye. . The dipole molecular layer has the formula (2):

The organic device according to claim 1, wherein: The silane coupling agent has the structural formula (I):

The organic device as described in any one of Claims 2-4 which has the structure of these.   The organic device according to any one of claims 1 to 5, wherein the dipole molecular layer is a monomolecular film that forms one layer from a plurality of identical molecules.   The organic device according to any one of claims 1 to 5, wherein the dipole molecular layer is a monomolecular film in which a plurality of identical molecules are closely packed to form one layer.   The organic electroluminescent device provided with the organic device as described in any one of Claims 1-7.   The method for producing an organic device according to claim 1, comprising a step of chemically bonding molecules for forming a dipole molecular layer with a first electrode by a gas phase reaction, wherein the reaction time is a reaction time. And controlling the reaction temperature to form a monomolecular film that forms a single layer by chemically bonding with the first electrode in a state of being packed most closely with the same molecule. Method.

Images