JP5079231B2 - Thin film, low molecular organic material, and organic electroluminescent device comprising the thin film comprising the low molecular organic material - Google Patents

Description

  The present invention relates to an organic electroluminescent device. More specifically, the present invention relates to an organic electroluminescent device comprising a thin film formed using a specific compound.

  Conventionally, an inorganic electroluminescent element has been used as a panel-type light source such as a backlight. However, in order to drive the light emitting element, an alternating high voltage is required. Recently, an organic electroluminescence element (organic electroluminescence element: organic EL element) using an organic material as a luminescent material has been developed [see, for example, Non-Patent Document 1].

  An organic electroluminescent device has a structure in which a thin film containing a fluorescent organic compound is sandwiched between an anode and a cathode. By injecting electrons and holes into the thin film and recombining them, an exciton (Exington) ) And emits light using light emitted when the exciton is deactivated. The organic electroluminescent element can emit light at a low direct current voltage of several volts to several tens of volts, and various colors (for example, red, blue, green) can be selected by selecting the type of the fluorescent organic compound. ) Can be emitted. The organic electroluminescent device having such characteristics is expected to be applied to various light emitting devices, display devices and the like. However, in general, since the light emission luminance is low and the durability is low, it is not practically sufficient.

In order to improve the light emission luminance and durability of the organic electroluminescent device, methods for increasing the purity of the organic compound used as the light emitting material (for example, Patent Literature 1, Patent Literature 2, Patent Literature 3 and Patent Literature 4) have been proposed. Yes. However, even the material whose purity is increased by the above method is not sufficient in terms of luminous efficiency and durability, and further improvement in luminous efficiency and durability is desired.
Appl.Phys.lett., 51,913 (1987) WO01 / 018149 JP 2002-175895 A JP 2000-048955 A Japanese Patent Laid-Open No. 2000-100522

An object of the present invention is to provide an organic electroluminescent device having improved luminous efficiency and durability.
More specifically, it is to provide an organic electroluminescent device having improved luminous efficiency and durability, a low molecular organic material for forming the organic electroluminescent device, and a thin film formed from the low molecular organic material.

In order to solve the above-mentioned problems, the present inventors have conducted extensive studies on a low-molecular organic material and a thin film formed from the low-molecular organic material for improving luminous efficiency and durability. It came to complete. That is, the present invention
<1>: A thin film formed by a vacuum vapor deposition method and made of a low molecular organic material having a film density of 1.05 g / cm ³ or more,
<2>: The thin film according to <1>, wherein the density of the film is a value measured by an X-ray reflectivity method,
<3>: The thin film according to <1> or <2>, wherein the density of the film is 1.10 g / cm ³ or more,
<4>: The thin film according to <1> to <3>, wherein the low molecular organic material is a condensed hydrocarbon compound, aromatic amine compound, heterocyclic compound and / or organometallic complex compound,
<5>: A low molecular weight organic material satisfying at least two of the following (1), (2) and (3):
(1) A low molecular weight organic material having a deposited film density of 1.05 g / cm ³ or more when a thin film is formed by a vacuum deposition method.
(2) A low molecular weight organic material having an average center-to-center distance of molecules calculated by molecular dynamics simulation of 11.0 mm or less.
(3) A low molecular weight organic material having a reorientation energy value of 1 kJ / mol to 40 kJ / mol in the case of an anion radical and a cation radical calculated using a molecular orbital method program.
<6>: A thin film for which the low molecular weight organic material described in <5> is desired,
<7>: An organic electroluminescent element comprising at least one thin film according to <1> to <4> or <6> between a pair of electrodes,
<8>: The organic electroluminescence device according to <7>, comprising the thin film according to <1> to <4> or <6> as a hole injection layer or a hole transport layer,
<9>: The organic electroluminescence device according to <7> or <8>, comprising the thin film according to <1> to <4> or <6> as a light emitting layer.
<10>: The organic electroluminescence device according to <9>, comprising the thin film according to <1> to <4> or <6> as a light emitting layer, and further the light emitting layer being formed from a host material and a dopant material.
It is about.

  According to the present invention, it is possible to provide an organic electroluminescence device having a long emission life, excellent durability, and high emission luminance.

Hereinafter, the present invention will be described in detail.
The present invention relates to a thin film formed by a vacuum evaporation method, and more particularly to a thin film having a film density of 1.05 g / cm ³ or more.

  Although the measurement of the density of the thin film is not particularly limited, X-ray reflectivity method (Grazing incident X-ray Reflectivity: GIXR), X-ray photoelectron spectroscopy (XPS), medium speed Ion scattering method (Medium Energy Ion Scattering: MEIS), Rutherford backscattering method (Ratherford Backscattering Spectrometry: RBS), nuclear reaction analysis method (Nuclear Reaction Analysis: NRA), neutron reflectometry method (NRA) It is possible to measure with.

  In addition, since it may be difficult to calculate an accurate density due to the influence of the surface contamination layer and the influence of the film surface and the interface depending on each measurement method, the measurement is preferably performed by the X-ray reflectivity method or ellipsometry.

The density of the film is preferably at most 1.10 g / cm ³ or more, more preferably, 1.15 g / cm ³ or more, further preferably 1.17 g / cm ³ or more.
Here, the X-ray specular reflectivity method uses the total reflection phenomenon that occurs when X-rays are incident obliquely on the surface of the thin film, and the thin film is determined from the change in the scattered X-ray intensity near its critical energy or critical angle. And the film thickness, film electron density, and interface roughness of the substrate can be determined simultaneously.
More specifically, when the refractive index of a substance with respect to X-rays is expressed by n = 1−δ−iβ <1, the refraction angle Φ of X-rays irradiated obliquely to the thin film is Φ = (θ ² −δ− 2iβ) When given by ^1/2 and θ is small, total reflection of X-rays occurs. If β (absorption) is ignored, the total reflection angle θ _C ≈ (2δ) ^1/2 . Here, δ is a function of the density of the substance, and the density of the thin film can be measured from θ _C.

When an X-ray electric field is incident on a material having a refractive index n in a vacuum, the relationship of cos θ = n cos θ ′ is established between the incident angle θ and the outgoing angle θ ′ according to Snell's law. in angle _{θ = θ c, cosθ c =} n = 1-δ-iβ ≒ 1-δ , and the more ^{_{1- (θ c 2/2)}} ≒ 1-δ, the relationship θ _c = √2δ is obtained.
δ is from 10 −5 to 10 −6, β is on the order of 10 −7 or less, and these coefficients have the following relationship with the density of materials, the wavelength of X-rays, etc. (essentially the electron density) Related to).

Here, re represents the classical radius of the electron, NA represents the Avogadro number, λ represents the wavelength of the X-ray, ρ represents the density (g / cm ³ ), Zi, Mi, and xi are atoms of i atoms. Number, atomic weight and atomic fraction are represented, and f ′ and f ″ represent dispersion correction and absorption of the atomic scattering factor.

From the above formula, the density can be calculated as the ρ value by using the composition formula of the low molecular weight organic material constituting the thin film.
The X-ray reciprocity analysis method includes a method for obtaining the film thickness from the angular position of the vibration peak, a Fourier analysis method, a simulation calculation, and a curve fitting method by a least square method. It is preferable to carry out by a fitting method.
In principle, it is also possible to calculate the factor corresponding to the density of the thin film of the present invention from the relationship between the film thickness measured by a quartz crystal resonator and the actually measured film thickness in vacuum deposition. However, usually, the position of the crystal unit and the base plate on which the thin film is formed are not the same, and sometimes the positional relationship between the position of the vapor deposition source and the crystal unit is not always constant. As a numerical value, there is a possibility that misunderstanding may occur in obtaining this relationship numerically. Preferably, the film density is obtained by the X-ray reflectivity method.

The density of the thin film varies depending on the type of the low molecular organic material used, and also varies depending on the thin film formation conditions in the vacuum deposition method. The thin film of the present invention can be produced by a simple experiment by setting the thin film formation conditions in the vacuum deposition method so that the film density is 1.05 g / cm ³ or more. At this time, depending on the type of the low molecular weight organic material, it may not be possible to produce a thin film having a thin film density of 1.05 g / cm ³ or more even if the thin film formation conditions are changed. A thin film manufactured from a low molecular weight organic material that cannot form a thin film having a film density of 1.05 g / cm ³ or more is not included in the present invention. The thin film formation conditions in the vacuum deposition method include the vacuum degree of the vacuum chamber, the vapor deposition rate of the low molecular organic material, the temperature of the substrate material, etc. The vacuum degree of the vacuum chamber is preferably 1 × 10 ^{− 4} Pa or more, more preferably 1 × 10 ⁻⁵ Pa or more. Further, the deposition rate of the low-molecular organic material is from 0.05 Å / sec to 50.0 Å / sec.
Preferably, the optimum deposition rate affects the form of the vacuum chamber, the positional relationship between the deposition source and the substrate material, the positional relationship of the vacuum exhaust, etc., so that the density of the thin film is 1.05 g / cm ³ or more. The thin film can be formed according to the obtained conditions.

The temperature of the substrate material may be room temperature, and may be in the range of low temperature (for example, about −30 ° C.) to high temperature (for example, about 150 ° C.). The preferable substrate temperature is the form of the vacuum chamber, the deposition source and the substrate material. Since the positional relationship and the positional relationship of evacuation are also affected, a condition where the density of the thin film is 1.05 g / cm ³ or more can be obtained by a simple experiment, and the thin film can be formed under the obtained condition.

The substrate temperature is preferably lower than the glass transition temperature of the low molecular organic material to be used, and more preferably lower than the glass transition temperature of the low molecular organic material by 10 ° C. or more.
The thin film of the present invention is formed from a specific low molecular organic material, and the low molecular organic material is preferably a compound that meets the following conditions (1) to (8). In the present invention, the molecular weight of the low molecular weight organic material is not strictly limited, but is preferably a molecular weight of 100 to 3000, and more preferably a molecular weight of 200 to 2000.

(1) A low molecular weight organic material having a film density of 1.05 g / cm ³ or more when a thin film is formed by vacuum deposition.
(2) A low molecular weight organic material having a value of the distance between the average centers of gravity of molecules determined by molecular dynamics simulation of 11.0 cm or less
(3) A low molecular weight organic material having a reorientation energy in the case of an anion radical calculated using a molecular orbital method program and a reorientation energy in the case of a cation radical of 1 KJ / mol to 40 KJ / mol.
(4) When a thin film is formed by a vacuum deposition method, the density of the film is 1.05 g / cm ³ or more, and the average distance between the centers of gravity obtained by molecular dynamics simulation is 11.0 cm or less. Low molecular organic materials.
(5) Reorientation energy and cation when the density of the film is 1.05 g / cm ³ or more when the thin film is formed by vacuum vapor deposition, and becomes an anion radical calculated using a molecular orbital method program A low molecular organic material having a reorientation energy of 1 KJ / mol or more and 40 KJ / mol or less when a radical is formed.

(6) The reorientation energy and cation radical when the value of the average center-of-gravity distance of the molecule determined by molecular dynamics simulation is 11.0 cm or less and becomes an anion radical calculated using a molecular orbital method program A low molecular organic material having a reorientation energy of 1 KJ / mol to 40 KJ / mol.
(7) When a thin film is formed by a vacuum evaporation method, the density of the film is 1.05 g / cm ³ or more, and the value of the average distance between centers of gravity obtained by molecular dynamics simulation is 11.0 cm or less. And a low molecular organic material having a reorientation energy in the case of an anion radical and a reorientation energy in the case of a cation radical calculated by using a molecular orbital method program of 1 KJ / mol or more and 40 KJ / mol or less.
(8) When a thin film is formed by a vacuum deposition method, the density of the film is 1.05 g / cm ³ or more, and the value of the average distance between the centers of gravity of the molecules determined by molecular dynamics simulation is 11.0 cm or less. And the reorientation energy in the case of an anion radical and the reorientation energy in the case of a cation radical calculated using a molecular orbital method program are 1 KJ / mol or more and 40 KJ / mol or less, and a condensed hydrocarbon compound , A low molecular weight organic material comprising an aromatic amine compound, a heterocyclic compound and / or an organometallic complex compound.
Preferably, it is a low molecular weight organic material satisfying at least two of the conditions (1), (2), (3), more preferably (4), (5), (7) or (8) And more preferably (7) or (8).

Next, a method for calculating the average distance between the centers of gravity of the molecules of the low molecular weight organic material when forming the thin film of the present invention will be described.
The thin film of the present invention is preferably prepared using a low molecular weight organic material having a value of the distance between the average centers of gravity of molecules determined by molecular dynamics simulation of 11.0 cm or less.
In order to calculate the average distance between the center of gravity of a molecule, it is necessary to obtain the structure of the molecule in an amorphous state. For this reason, the simulation process is roughly divided into two parts. The first is a step of obtaining an initial structure as a previous step of obtaining a structure in an amorphous state. In the next step, a structure in an amorphous state is obtained using the initial structure, and an average distance between centers of gravity is calculated.
Here, the molecular dynamics simulation indicates the following series of calculation operations.

Specifically, this represents the following series of operations.
That is, [1] Construction of an amorphous initial structure.
[1-1] A pcff force field is used as a force field, and 15 molecules are placed in a unit cell with periodic boundary conditions. At this time, the initial position and orientation of each molecule are randomly generated. The density of the system is set at 0.8 g / cm ³ , which is slightly smaller than the actual system in order to find a preferable arrangement more efficiently. Corrected by calculation).
[1-2] In this trial calculation, a molecule having a ring structure is checked while avoiding the ring so that the rings are not bound to each other. Then, all possible conformational structures are generated, and the energy increase due to the non-bonded interaction energy of the pcff force field is calculated. Based on the magnitude of these energy increments, a conformation structure that satisfies the probability according to the Boltzmann distribution law is adopted. Here, the set temperature is 300K. The entire structure (arrangement) in the unit cell thus obtained is set as a candidate for the initial structure.
[1-3] By repeating this series of operations, ten initial structure candidates are prepared. For each configuration, the structure is optimized by minimizing the potential energy of the entire system by the steepest descent method. In this calculation, Van der Waals interaction energy and Coulomb interaction energy, which are non-bonded interaction energy components, are calculated by the Cell multipole method. The potential energy of the obtained arrangement is compared, and the arrangement having the lowest energy is selected as the amorphous initial structure.

[2] Structure calculation in an amorphous state and calculation of the distance between the average centers of gravity of molecules.
Using the NVT and NPT ensembles, the molecular state is obtained by molecular dynamics (MD), and the distance between the molecular centers of gravity is calculated.
[2-1] Use a highly reliable compass force field and set the time step to 1.0 femtoseconds. The van der Waals interaction energy is calculated using the atom based method, with a cutoff length of 12 mm, a spline width of 2 mm, and a buffer width of 2 mm. The Ewald method is used to calculate the Coulomb interaction energy.
[2-2] The structure is optimized by minimizing potential energy for the amorphous initial structure. Next, MD calculation of 10,000 steps is performed at a temperature of 600K using an NVT ensemble, and the temperature is shifted to a high temperature state. And the whole system is efficiently balanced by changing temperature and pressure by MD calculation using NPT ensemble. In other words, start from the state of temperature 600K and pressure 1.0MPa until the transition to high temperature (600K) and high pressure (0.1GPa) state. At this time, MD is performed under each pressure while changing the pressure parameterically so that the density change of the system increases smoothly. Then, while lowering the pressure and temperature, it finally shifts to normal temperature and normal pressure and equilibrates to obtain an amorphous state. Specifically, [1] 100,000 steps at 600K ・ 1.0MPa, [2] 100,000 steps at 600K ・ 1.5MPa, [3] 250,000 steps at 600K ・ 0.1GPa, [4] 600K ・ 1.0 After MD calculation in order of 100,000 steps at MPa, [5] 100,000 steps at 600K · 1 atm, [6] 100,000 steps at 450K · 1 atm, [7] 500,000 steps at 298K · 1 atm [8] Finally, MD calculation of 1 million steps is performed at 298 K · 1 atm to equilibrate, and the structure of the final step is taken out to be an amorphous structure. However, when changing the temperature and pressure during the calculation process, before entering each MD stage, the time step of 0.1 femtosecond is performed under the same temperature and pressure conditions as the immediately following MD in order to avoid sudden changes in structure. Insert a short MD calculation of 5,000 steps.
[2-3] The structure of the molecule in the unit cell is analyzed with respect to the obtained amorphous structure, the distance between the centroids of all neighboring molecule pairs is calculated, the average value is calculated, and the average centroid of the molecule is calculated. It is defined as the distance between. Here, a close molecule pair is a molecule-molecule pair in which the van der Waals spheres overlap, or the van der Waals spheres come into contact with each other when the vandi van der Waals radius is considered. It is. The center of gravity of the molecule is calculated as the center of gravity considering the mass of each constituent atom.

In these calculations, the calculation software to be used is not particularly limited. For example, the amorphous initial structure calculation includes an Amorphous_Cell module built in Accelrys Insight II (R) 4.00P +. Can be used.
As for the calculation by the molecular dynamics method, Discover (R) ver. 2002.1 can be used. For the calculation of the distance between the centers of gravity from the obtained amorphous state structure, a self-made program was used.

In the organic electroluminescence device of the present invention, it is preferable that the average center-to-center distance of the molecules obtained by molecular dynamics simulation of all organic compounds forming the organic compound layer is 11.0 mm or less. Has an average distance between the centers of gravity of the molecules of the organic material forming the light emitting layer of 11.0 mm or less, and more preferably, the distance between the average centers of gravity of the molecules of the organic material functioning as the host material of the light emitting layer is 11. 0 or less.
The average distance between the centers of gravity of the molecules is preferably 11.0 mm or less, more preferably 6.0 to 10.5 mm, and still more preferably 8.0 to 10.0 mm.

  Next, the calculation method of the reorientation energy in the case of becoming the anion radical of the low molecular weight organic material used when producing the thin film of the present invention and the reorientation energy in the case of becoming the cation radical will be described.

The reorientation energy value λ _{el in the} case of becoming an anion radical and the reorientation energy value λ _{h in the} case of becoming a cation radical are represented by the following equations, respectively.
λ _el = (E _neut [anion] _{-E neut} [neutral]) + (E _ani [neutral] _{-E ani} [anion]) (1)
λ _h = (E _cat [neutral] _{-E neut} [neutral]) + (E _neut [cation] _{-E cat} [cation]) (2)

Here, when the subscript of E is cat, neut or ani, it represents the total energy of the molecule in the cation state, neutral state and anion state, respectively. In addition, [] shows the stable structure in the charged state. [Neutral], [Cation], and [Anion] indicate the stable structure in the neutral state, cation state, and anion state, respectively. I mean. Thus, for example, E _cat [neutral] is the total energy of the cation molecule in the neutral state stable structure.

In order to calculate the reorientation energy value according to the above formula, the molecular orbital method program Gaussian03 rev.C.02 is used, and the density functional method is used to calculate the stable structure of the molecule and its total energy. be able to. Preferably, for neutral molecules it is calculated by B3LYP / 6-31G ^* and for molecules in the cationic and anionic state it is calculated by UB3LYP / 6-31G ^* . In addition, Gaussian03 rev.C.02 etc. can be used as a molecular orbital method program.

For the stable structure calculation by structure optimization, if the molecules other than C ₁ symmetry, performs vibration analysis, check that there is no imaginary vibrational mode can be determined that it is stable structure. In addition, regarding the calculation of the total energy of the charged state of the cation or anion, if all the <S ² > values are 0.75 to 0.78, it can be confirmed that the other spin states are hardly mixed. Based on these, the reorientation energy value can be calculated by the above two equations.

As the value of the reorientation energy, it is preferable that the reorientation energy l _{el in the} case of an anion radical and the reorientation energy l _{h in the} case of a cation radical are both 1 kJ / mol or more and 40 kJ / mol or less, more preferably. Is 5 kJ / mol or more and 30 kJ / mol or less.

In addition, the ratio of the reorientation energy λ _{el in the} case of becoming an anion radical and the reorientation energy λ _{h in} the case of becoming a cation radical is obtained by using a thin film prepared using the low molecular weight organic material of the present invention as an organic electroluminescent element. When used as a light emitting layer and as a hole injection layer or a hole transport layer of an organic electroluminescent device, the anion radical is used when the thin film of the present invention is used as a light emitting layer of an organic electroluminescent device. The ratio of the reorientation energy λ _{el in the} case of becoming a cation radical to the reorientation energy λ _{h in} the case of becoming a cation radical is preferably 2: 1 to 1: 1.5, and is 2: 1 to 1: 1.2. It is more preferable. Further, when the thin film of the present invention is used as a hole injection layer or a hole transport layer of an organic electroluminescence device, the reorientation energy l _el when it becomes an anion radical and the reorientation energy l when it becomes a cation radical The ratio of _h is preferably 4: 1 to 1: 1, and more preferably 2: 1 to 1.2: 1.

In the thin film of the present invention, specific examples of the low molecular weight organic material corresponding to the above (1) to (8) are not particularly limited. For example, as a light emitting layer host material for forming a light emitting layer. Is preferably a compound having a naphthalene skeleton, anthracene skeleton, benzoanthracene skeleton, bianthracenyl skeleton, trianthracenyl skeleton, phenanthrene skeleton, pyrene skeleton, perylene skeleton, fluorene skeleton, or benzofluorene skeleton as the chromophore. The light emitting layer host material having these chromophores includes compounds that have been used in organic electroluminescent devices so far, but the average distance between the centers of gravity of the molecules is usually 11.0 mm or more. By optimizing the substituents bonded to these chromophores and the stable conformation of the molecules, it becomes possible to reduce the average center-to-center distance of the molecules to 11.0 mm or less. These verifications can be verified by the molecular dynamic simulation described above. Moreover, examples of the low molecular weight organic compound used in the present invention include aromatic amine compounds, aromatic heterocyclic compounds and / or organometallic complex compounds in addition to the above condensed hydrocarbon compounds. .
Preferred examples of the low molecular weight organic material include condensed hydrocarbon compounds and aromatic amine compounds, and more preferred are condensed hydrocarbon compounds.

  Examples of the condensed hydrocarbon compound and aromatic amine compound that can be preferably used in the present invention include the following compounds.

Wherein R, R ′, R ″ and R ″ ′ are a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group and / or a substituted or unsubstituted diaryl. Represents a group selected from amino groups)

[In the formula, Ar, Ar ′, Ar ″ and Ar ″ ′ represent a substituted or unsubstituted aryl group, Ar and Ar ′, and Ar ″ and Ar ″ ′ are bonded to each other to form a cyclic structure containing a nitrogen atom] It may be formed. X represents —O—, —S—, —N (R) — (wherein R represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group), —C (R) (R) — ( R represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group), -C (R) (R) -C (R) (R)-(where R is Represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group)
In the above example, the substituted or unsubstituted aryl group preferably has 6 to 3 nuclear carbon atoms.
Represents an aryl group having 0, more preferably an aryl group having 6 to 26 nuclear carbon atoms.

The substituted or unsubstituted aryloxy group includes a substituted or unsubstituted aryloxy group derived from a substituted or unsubstituted aryl group.
Examples of the substituted or unsubstituted arylthio group include a substituted or unsubstituted arylthio group derived from a substituted or unsubstituted aryl group.
Substituted or unsubstituted diarylamino groups include substituted or unsubstituted diarylamino groups derived from substituted or unsubstituted aryl groups, and the two aryl groups may be the same or different, In addition, each aryl group may be bonded to each other to form a heterocyclic structure containing a nitrogen atom.
In the above example, the substituted or unsubstituted alkyl group preferably represents a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms. Represents.

  The thin film of the present invention may be any one of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer, or may be a thin film of a plurality of layers.

  Next, the organic electroluminescent element of the present invention will be described. The organic electroluminescent element of the present invention comprises the thin film of the present invention between a pair of electrodes. An organic electroluminescent element is usually formed by sandwiching at least one light emitting layer containing at least one light emitting component between a pair of electrodes. A hole injection / transport layer and / or an electron injection containing a hole injection component as desired, considering the functional level of the hole injection and hole transport, electron injection and electron transport of the compound used in the light emitting layer. An electron injecting and transporting layer containing a transporting component can also be provided. For example, when the hole injection function, the hole transport function and / or the electron injection function, and the electron transport function of the compound used in the light emitting layer are good, the light emitting layer is a hole injection transport layer and / or an electron injection transport layer. As a type of element configuration that also serves as a single layer type element configuration. Further, when the light emitting layer is poor in the hole injection function and / or the hole transport function, a two-layer device configuration in which a hole injection transport layer is provided on the anode side of the light emitting layer, the light emitting layer has an electron injection function and / or Alternatively, when the electron transport function is poor, a two-layer device structure in which an electron injection transport layer is provided on the cathode side of the light emitting layer can be obtained. Furthermore, a three-layer device structure in which the light-emitting layer is sandwiched between a hole injection transport layer and an electron injection transport layer can be used. The organic electroluminescent element of the present invention may contain the thin film of the present invention as a light emitting layer, may be contained as a hole injection layer, a hole transport layer, or contained as an electron transport layer. You may do it. Preferably, the thin film of the present invention is contained as a light emitting layer. The organic electroluminescent device prepared by containing the thin film of the present invention exhibits excellent characteristics in terms of luminous efficiency and luminescent lifetime as compared with the organic electroluminescent device using a conventionally known thin film. .

  In addition, each of the hole injecting and transporting layer, the electron injecting and transporting layer, and the light emitting layer may have a single layer structure or a multilayer structure, and the hole injecting and transporting layer and the electron injecting and transporting layer The layer having an injection function and the layer having a transport function can be separately provided.

  In the organic electroluminescent device of the present invention, the thin film of the present invention is preferably used as a constituent component of the hole injecting and transporting layer and / or the luminescent layer, and more preferably used as a constituent component of the luminescent layer.

  In the organic electroluminescent element of the present invention, the thin film of the present invention may be formed of a single low molecular organic compound or may be formed of a plurality of low molecular organic compounds.

  The configuration of the organic electroluminescent device of the present invention is not particularly limited. For example, (EL-1) anode / hole injection transport layer / light emitting layer / electron injection transport layer / cathode type device (FIG. 1). ), (EL-2) anode / hole injection transport layer / light emitting layer / cathode type device (FIG. 2), (EL-3) anode / light emitting layer / electron injection transport layer / cathode type device (FIG. 3), EL-4) Anode / light emitting layer / cathode type element (FIG. 4), and the like. Further, an EL (EL-5) anode / hole injection / transport layer / electron injection / transport layer / light-emitting layer / electron injection / transport layer / cathode-type device (FIG. 5) in which the light-emitting layer is sandwiched between electron injection / transport layers. You can also. In addition, the (EL-5) type element configuration may be an element type in which a single light emitting component is formed as a single layer as a light emitting layer, or a combination of two or more types of light emitting components. Any of the formed elements may be used. Further, the hole injection / transport layer can be divided into a hole injection layer and a hole transport layer to efficiently inject and transport holes.

  The organic electroluminescent device of the present invention is not limited to these device configurations, and each type of device can be provided with a plurality of hole injection / transport layers, light emitting layers, and electron injection / transport layers. In each type of device, an electron blocking layer may be provided between the hole injection transport layer and the light emitting layer, or a hole blocking layer may be provided between the light emitting layer and the electron transport layer.

  A preferable configuration of the organic electroluminescent element is an (EL-1) type element, an (EL-2) type element or an (EL-5) type element, and more preferably an (EL-1) type element or (EL-). 2) A type element.

  Hereinafter, the components of the organic electroluminescence device of the present invention will be described in detail. As an example, (EL-1) anode / hole injection / transport layer / light emitting layer / electron injection / transport layer / cathode type device shown in FIG. 1 will be described.

In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injecting and transporting layer, 4 is a light emitting layer, 5 is an electron injecting and transporting layer, 6 is a cathode, and 7 is a power source.
The organic electroluminescent element of the present invention is preferably supported by the substrate 1, and the substrate is not particularly limited, but a transparent or translucent substrate is preferable, and the material is soda lime glass, Examples thereof include glass such as borosilicate glass and transparent polymers such as polyester, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethyl methacrylate, polypropylene, and polyethylene. Further, a substrate made of a translucent plastic sheet, quartz, transparent ceramics, or a composite sheet in which these are combined can also be used. Furthermore, for example, a color filter film, a color conversion film, and a dielectric reflection film can be combined with the substrate to control the emission color.
As the anode 2, it is preferable to use a metal, an alloy or a conductive compound having a relatively large work function as an electrode material. Examples of the electrode material used for the anode include gold, platinum, silver, copper, cobalt, nickel, palladium, vanadium, tungsten, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide, ITO ( Indium tin oxide (Indium Tin Oxide), polythiophene, polypyrrole, etc. can be mentioned. These electrode materials may be used alone or in combination.
For the anode, these electrode materials can be formed on the substrate by a method such as vapor deposition or sputtering.

Further, the anode may have a single layer structure or a multilayer structure. Sheet resistance of the anode is preferably several hundreds Omega / cm ² or less, more preferably, set to about 5~50Ω / cm ^2.

The thickness of the anode is generally about 5 to 1000 nm, more preferably about 10 to 500 nm, although it depends on the material of the electrode material used.
The hole injection transport layer 3 is a layer containing a compound having a function of facilitating the injection of holes from the anode and a function of transporting the injected holes.
The hole injecting and transporting layer is a compound having a hole injecting and transporting function (for example, phthalocyanine derivative, aromatic amine derivative, triarylmethane derivative, oxazole derivative, hydrazone derivative, stilbene derivative, pyrazoline derivative, polysilane derivative, polyphenylene vinylene and its Derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole, etc.) can be used. The compounds having a hole injecting and transporting function may be used alone or in combination.

  Examples of aromatic amine derivatives include 4,4′-bis [N-phenyl-N- (4 ″ -methylphenyl) amino] biphenyl, 4,4′-bis [N-phenyl-N- (3 ″- Methylphenyl) amino] biphenyl, 4,4′-bis [N-phenyl-N- (3 ″ -methoxyphenyl) amino] biphenyl, 4,4′-bis [N-phenyl-N- (1 ″ -naphthyl) Amino] biphenyl, 3,3′-dimethyl-4,4′-bis [N-phenyl-N- (3 ″ -methylphenyl) amino] biphenyl, 1,1-bis [4 ′-[N, N-di (4 ″ -methylphenyl) amino] phenyl] cyclohexane, 9,10-bis [N- (4′-methylphenyl) -N- (4 ″ -n-butylphenyl) amino] phenanthrene, 3,8-bis ( N, N-diphenyl Mino) -6-phenylphenanthridine, 4-methyl-N, N-bis [4 ", 4" '-bis [N', N'-di (4-methylphenyl) amino] biphenyl-4-yl] Aniline, N, N′-bis [4- (diphenylamino) phenyl] -N, N′-diphenyl-1,3-diaminobenzene, N, N′-bis [4- (diphenylamino) phenyl] -N, N′-diphenyl-1,4-diaminobenzene, 5,5 ″ -bis [4- (bis [4-methylphenyl] amino] phenyl-2,2 ′: 5 ′, 2 ″ -terthiophene, 1,3 , 5-tris (diphenylamino) benzene, 4,4 ', 4 "-tris (N-carbazolyl) triphenylamine, 4,4', 4" -tris [N, N-bis (4 "'-tert- Butylbiphenyl-4 ""-yl) amino Triphenylamine, etc. 1,3,5-tris [N-(4'-diphenylamino] benzene, polythiophene and derivatives thereof, poly -N- vinylcarbazole and its derivatives are more preferred.

When the thin film of the present invention is composed of a plurality of low molecular organic materials, the proportion is preferably 50% by weight or more of the low molecular organic compound of the present invention, more preferably 60 to 60% of the low molecular organic compound of the present invention. 99.9% by weight, more preferably 60 to 99% by weight.
The light emitting layer 4 is a layer containing a compound having a function of injecting holes and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons.
The light emitting layer is preferably formed of the thin film of the present invention, and the thin film of the present invention may be formed of one kind of low molecular organic material or a plurality of low molecular organic materials. When the thin film of the present invention is formed from a plurality of low molecular organic materials, it is usually formed from a host material and a guest (dopant) material.

Examples of the low molecular weight organic material (guest material / host material) having a light emitting function for forming the organic electroluminescent element of the present invention include an acridone derivative, a quinacridone derivative, a diketopyrrolopyrrole derivative, a condensed hydrocarbon compound [ For example, rubrene, anthracene, tetracene, pyrene, perylene, chrysene, decacyclene, coronene, tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, 9,10-diphenylanthracene, 9,10-bis (phenylethynyl) anthracene, 1,4- Bis (9′-ethynylanthcenyl) benzene, 4,4′-bis (9 ″ -ethynylanthracenyl) biphenyl, dibenzo [f, f] diindeno [1,2,3-cd: 1 ′, 2 ′ , 3'-lm] perylene derivatives], aromatic amine compounds (for example, hole injection and transport functions) And the like, and organometallic complex compounds [for example, tris (8-quinolinolato) aluminum, bis (10-benzo [h] quinolinolato) beryllium, 2- (2′-hydroxyphenyl)] Zinc salt of benzothiazole, zinc salt of 4-hydroxyacridine, zinc salt of 3-hydroxyflavone, beryllium salt of 5-hydroxyflavone, aluminum salt of 5-hydroxyflavone], phosphorescent organometallic complex [for example, phenylpyridine series Iridium complex, fluorine-substituted phenylpyridine iridium complex, tetraazaporphyrin platinum complex] stilbene derivative [eg 1,1,4,4-tetraphenyl-1,3-butadiene, 4,4′-bis (2,2 -Diphenylvinyl) biphenyl, 4,4'-bis (1,1,2-triphenyl) ethenyl] biphenyl], coumarin derivatives (eg, coumarin 1, coumarin 6, coumarin 7, coumarin 30, coumarin 106, coumarin 138, coumarin 151, coumarin 152, coumarin 153, coumarin 307, Coumarin 311, coumarin 314, coumarin 334, coumarin 338, coumarin 343, coumarin 500), pyran derivatives (eg, DCM1, DCM2), oxazone derivatives (eg, Nile Red), benzothiazole derivatives, benzoxazole derivatives, benzimidazole derivatives, Pyrazine derivatives, cinnamic acid ester derivatives, poly-N-vinylcarbazole and derivatives thereof, polythiophene and derivatives thereof, polyphenylene and derivatives thereof, polyfluorene and derivatives thereof, Examples include rephenylene vinylene and derivatives thereof, polybiphenylene vinylene and derivatives thereof, polyterphenylene vinylene and derivatives thereof, polynaphthylene vinylene and derivatives thereof, and polythienylene vinylene and derivatives thereof. Preferably, an acridone derivative, a quinacridone derivative, a condensed hydrocarbon compound, an aromatic amine compound, a stilbene compound, a polyphenylene compound, an aromatic heterocyclic compound and / or an organometallic complex compound are preferable, and a condensed hydrocarbon compound An organometallic complex compound is more preferable.

In the organic electroluminescent device of the present invention, when the thin film of the present invention is formed from a plurality of low molecular organic compounds, the content of the low molecular organic material (host material) of the present invention in the light emitting layer is preferably 99. 0.9 to 80% by weight, and more preferably 99.9 to 90% by weight.
A host material may be used independently and may be used together.

Moreover, a guest material may be used independently and may be used together.
The electron injection / transport layer 5 is a layer containing a compound having a function of facilitating injection of electrons from the cathode and / or a function of transporting injected electrons.

  Examples of the compound having an electron injecting and transporting function used in the electron injecting and transporting layer include, for example, organometallic complexes, oxadiazole derivatives, triazole derivatives, triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, phenanthroline derivatives. Nitro-substituted fluorenone derivatives, thiopyrandioxide derivatives, and the like. Examples of the organometallic complex include an organoaluminum complex such as tris (8-quinolinolato) aluminum, an organic beryllium complex such as bis (10-benzo [h] quinolinolato) beryllium, a beryllium salt of 5-hydroxyflavone, 5- Examples thereof include an aluminum salt of hydroxyflavone. An organoaluminum complex is preferable, and an organoaluminum complex having a substituted or unsubstituted 8-quinolinolato ligand is more preferable. Examples of the organoaluminum complex having a substituted or unsubstituted 8-quinolylate ligand include compounds represented by general formula (a) to general formula (c).

(Q) ₃ -Al (a)
(Wherein Q represents a substituted or unsubstituted 8-quinolinolate ligand)
(Q) ₂ -Al-OL '(b)
(In the formula, Q represents a substituted or unsubstituted 8-quinolinolate ligand, OL ′ represents a phenolate ligand, and L ′ represents a hydrocarbon group having 6 to 24 carbon atoms having a phenyl group. )
(Q) _2- Al-O-Al- (Q) ₂ (c)
(Wherein Q represents a substituted or unsubstituted 8-quinolinolate ligand)

Specific examples of the organoaluminum complex having a substituted or unsubstituted 8-quinolinolato ligand include, for example, tris (8-quinolinolato) aluminum, tris (4-methyl-8-quinolinolato) aluminum, tris (5-methyl- 8-quinolinolato) aluminum, tris (3,4-dimethyl-8-quinolinolato) aluminum, tris (4,5-dimethyl-8-quinolinolato) aluminum, tris (4,6-dimethyl-8-quinolinolato) aluminum,
Bis (2-methyl-8-quinolinolato) (phenolate) aluminum, bis (2-methyl-8-quinolinolato) (2-methylphenolato) aluminum, bis (2-methyl-8-quinolinolato) (3-methylphenolate) ) Aluminum, bis (2-methyl-8-quinolinolato) (4-methylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (2-phenylphenolato) aluminum, bis (2-methyl-8-quinolinolato) ) (3-phenylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (4-phenylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (2,3-dimethylphenolate) aluminum, Bis (2-methyl-8-quinolinolate) ( , 6-Dimethylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (3,4-dimethylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolate) aluminum Bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (2,6-diphenylphenolato) aluminum, bis (2 -Methyl-8-quinolinolato) (2,4,6-triphenylphenolate) aluminum, bis (2-methyl-8-quinolinolato) (2,4,6-trimethylphenolato) aluminum, bis (2-methyl- 8-quinolinolato) (2,4,5,6-tetramethylphenolate) aluminum, bi (2-methyl-8-quinolinolato) (1-naphtholato) aluminum, bis (2-methyl-8-quinolinolato) (2-naphtholato) aluminum, bis (2,4-dimethyl-8-quinolinolato) (2-phenyl) Phenolate) aluminum, bis (2,4-dimethyl-8-quinolinolato) (3-phenylphenolate) aluminum, bis (2,4-dimethyl-8-quinolinolato) (4-phenylphenolate) aluminum, bis (2 , 4-dimethyl-8-quinolinolato) (3,5-dimethylphenolate) aluminum, bis (2,4-dimethyl-8-quinolinolato) (3,5-di-tert-butylphenolate) aluminum,
Bis (2-methyl-8-quinolinolato) aluminum-μ-oxo-bis (2-methyl-8-quinolinolato) aluminum, bis (2,4-dimethyl-8-quinolinolato) aluminum-μ-oxo-bis (2, 4-dimethyl-8-quinolinolato) aluminum, bis (2-methyl-4-ethyl-8-quinolinolato) aluminum-μ-oxo-bis (2-methyl-4-ethyl-8-quinolinolato) aluminum, bis (2- Methyl-4-methoxy-8-quinolinolato) aluminum-μ-oxo-bis (2-methyl-4-methoxy-8-quinolinolato) aluminum, bis (2-methyl-5-cyano-8-quinolinolato) aluminum-μ- Oxo-bis (2-methyl-5-cyano-8-quinolinolato) aluminum, bi (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum-μ-oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum.

A compound having an electron injecting and transporting function may be used alone or in combination. As the cathode 6, it is preferable to use a metal, an alloy or a conductive compound having a relatively small work function as an electrode material. Examples of the electrode material used for the cathode include lithium, lithium-indium alloy, sodium, sodium-potassium alloy, calcium, magnesium, magnesium-silver alloy, magnesium-indium alloy, indium, ruthenium, titanium, manganese, yttrium, and aluminum. , Aluminum-lithium alloys, aluminum-calcium alloys, aluminum-magnesium alloys, and graphite thin films. These electrode materials may be used alone or in combination.

It is also possible to insert an insulating thin film layer between the cathode and the electron injecting and transporting layer for the purpose of improving the electron injection efficiency or preventing defects due to leakage or short circuit.
Examples of the material used for the insulating layer material include lithium fluoride, lithium oxide, cesium fluoride, cesium oxide, magnesium fluoride, calcium fluoride, calcium oxide, aluminum oxide, aluminum nitride, titanium oxide, silicon oxide, and oxide. Examples thereof include germanium, silicon nitride, boron nitride, molybdenum oxide, ruthenium oxide, vanadium oxide and the like. These may be used alone, or may be used in a mixed system or a stacked system.

For the cathode, these electrode materials can be formed on the electron injecting and transporting layer by, for example, vapor deposition, sputtering, ion vapor deposition, ion plating, or cluster ion beam.
The cathode may have a single layer structure or a multilayer structure. The sheet electrical resistance of the cathode is preferably several hundred Ω / cm 2 or less. The thickness of the cathode is usually 5 to 1000 nm, preferably 10 to 500 nm, although it depends on the electrode material used. In order to take out light emitted from the organic electroluminescence device of the present invention with high efficiency, at least one of the anode and the cathode is preferably transparent or translucent, and generally has a transmittance of emitted light of 70% or more. Thus, it is preferable to set the material and thickness of the anode or cathode.

  The organic electroluminescent device of the present invention may contain a singlet oxygen quencher in at least one of the hole injection transport layer, the light emitting layer, and the electron injection transport layer. Although it does not specifically limit as a singlet oxygen quencher, For example, rubrene, a nickel complex, diphenylisobenzofuran is mentioned, Preferably it is rubrene.

The layer containing the singlet oxygen quencher is not particularly limited, but is preferably a light emitting layer or a hole injection transport layer, and more preferably a hole injection transport layer. When a singlet oxygen quencher is contained in the hole injecting and transporting layer, it may be uniformly contained in the hole injecting and transporting layer. May be contained in the vicinity of the electron injecting and transporting layer).
The content of the singlet oxygen quencher is 0.01 to 50% by weight, preferably 0.05 to 30% by weight of the total amount constituting the layer to be contained (for example, hole injection transport layer). Preferably, it is 0.1 to 20% by weight.

When forming each layer such as a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer by a vacuum deposition method, the conditions for vacuum deposition are not particularly limited as long as they are the above-mentioned conditions. Under a vacuum of about ⁻⁴ Pa or less, a boat temperature (deposition source temperature) of about 50 to 500 ° C., a substrate temperature of about −50 to 150 ° C., and a deposition rate of about 0.05 to 50 mm / sec. Is preferred. In this case, each layer such as a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer is preferably formed continuously under vacuum. It becomes possible to manufacture an organic electroluminescent element excellent in various characteristics by forming continuously. When each layer such as hole injection transport layer, light emitting layer, electron injection transport layer, etc. is formed using a plurality of compounds by vacuum deposition, the temperature of each boat containing the compounds is individually controlled and co-evaporated. It is preferable to do.

  The film pressure of each layer such as the hole injecting and transporting layer, the light emitting layer, and the electron injecting and transporting layer is not particularly limited, but is usually 5 nm to 5 μm.

  The organic electroluminescent device of the present invention produced under the above conditions is provided with a protective layer (sealing layer) for the purpose of preventing contact with oxygen, moisture, etc. For example, it can be protected by enclosing it in paraffin, liquid paraffin, silicon oil, fluorocarbon oil, zeolite-containing fluorocarbon oil). Examples of the material used for the protective layer include organic polymer materials (for example, fluorine resin, epoxy resin, silicone resin, epoxy silicone resin, polystyrene, polyester, polycarbonate, polyamide, polyimide, polyamideimide, polyparaxylene, polyethylene, Polyphenylene oxide), inorganic materials (for example, diamond thin film, amorphous silica, electrically insulating glass, metal oxide, metal nitride, metal carbide, metal sulfide), and photocurable resin. The material used for the protective layer may be used alone or in combination. The protective layer may have a single layer structure or a multilayer structure.

The organic electroluminescent element of the present invention can also be provided with an interface layer (intermediate layer) on the surface of the anode. Examples of the material for the interface layer include organic phosphorus compounds, polysilanes, aromatic amine derivatives, phthalocyanine derivatives, fluorocarbon polymers, and the like.
Furthermore, the surface of an electrode, for example, an anode, can be used by treating the surface with acid, ammonia / hydrogen peroxide, UV ozone, oxygen plasma, or the like.

  The organic electroluminescent element of the present invention can be usually used as a DC drive type element, but can also be used as an AC drive type element. Further, the organic electroluminescence device of the present invention may be a segment type, a passive drive type such as a simple matrix drive type, or an active drive type such as a TFT (thin film transistor) type or an MIM (metal-insulator-metal) type. It may be. The driving voltage is usually 2 to 30V. The organic electroluminescent element of the present invention includes a panel-type light source (for example, a backlight for a clock, a liquid crystal panel, etc.), various light-emitting elements (for example, an alternative to a light-emitting element such as an LED), and various display elements [for example, information display Element (PC monitor, mobile phone / mobile terminal display element)], various signs, various sensors, and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

Production Example 1
Formation of thin film The Si substrate was cleaned using ultrapure water, acetone, and isopropanol. Then, it fixed to the board | substrate holder of the vacuum evaporation system, and depressurized the vapor deposition tank (vacuum chamber) to 1 * 10 < ^-5 > Pa. Thereafter, the following compound (A) filled in the resistance heating boat was heated and evaporated by energizing the resistance heating boat. The vapor deposition rate was 8 Å / sec, and a vapor deposition film (thin film) was formed to a thickness of 100 nm.
When the Si substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 1.153 g / cm ³ .

Production Example 2
Formation of Thin Film A glass substrate having an ITO transparent electrode (anode) having a thickness of 150 nm was subjected to ultrasonic cleaning using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. The substrate was dried using nitrogen gas, further washed with UV / ozone, fixed to a substrate holder of a vacuum deposition apparatus, and the deposition tank was depressurized to 1 × 10 ⁻⁵ Pa. Thereafter, the following compound (A) filled in the resistance heating boat was heated and evaporated by energizing the resistance heating boat. The vapor deposition rate was 3 は / sec, and a vapor deposition film (thin film) was formed to a thickness of 100 nm.
When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 1.152 g / cm ³ .

Production Example 3
Preparation of thin film In Production Example 2, instead of using Compound (A), except that Compound (B) was used, the operation described in Production Example 2 was followed.
A vapor deposition film (thin film) was formed. The deposition rate was 3 liters / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectance method, the density of the deposited film was 0.952 g / cm ³ .

Production Example 4
Preparation of thin film For the purpose of changing the density of the deposited film, the deposition rate of Production Example 3 was changed to prepare a thin film. That is,
As described in Production Example 2, except that Compound (A) was used in Production Example 2 and the deposition rate was 3 Å / sec instead of Compound (B) and the deposition rate was 0.5 Å / sec. A vapor deposition film (thin film) was prepared according to the operation. When the ITO glass substrate having this deposited film was measured by the X-ray reflectometry, the density of the deposited film was 0.972 g / cm ³ .

Production Example 5
Preparation of thin film In Preparation Example 2, a vapor deposition film (thin film) was prepared according to the procedure described in Preparation Example 2 except that Compound (C) was used instead of using Compound (A). When the ITO glass substrate having this deposited film was measured by the X-ray reflectometry, the density of the deposited film was 1.082 g / cm ³ .

Production Example 6
Thin Film Production In Production Example 5, the deposition rate was changed from 3 Å / sec to 10 Å / sec.
That is, in Production Example 2, the compound (A) is used, and the deposition rate is 3 Å / sec. Instead of using the compound (C) and the deposition rate is 10 Å / sec, the production method 2 is described in Production Example 2. A vapor deposition film (thin film) was prepared according to the operation. When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity measurement method, the density of the deposited film was 0.935 g / cm ³ .

Production Example 7
Formation of Thin Film A glass substrate having an ITO transparent electrode (anode) having a thickness of 150 nm was subjected to ultrasonic cleaning using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. The substrate was dried using nitrogen gas, further washed with UV / ozone, fixed to a substrate holder of a vacuum deposition apparatus, and the deposition tank was depressurized to 1 × 10 ⁻⁵ Pa. Then, the following compound (D) with which the resistance heating boat was filled was heated and evaporated by energizing the resistance heating boat. The vapor deposition rate is 3 Å / sec. At this time, the following compound (E) is co-deposited at a vapor deposition rate of 0.2 Å / sec from another resistance heating boat at the same time to form a deposited film (thin film) to a thickness of 100 nm. ) Was formed.
When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 1.192 g / cm ³ .

Production Example 8
Preparation of thin film In production example 7, instead of using compound (D) and compound (E), according to the procedure described in production example 7, except that compound (F) and compound (E) were used. A deposited film (thin film) was prepared. The deposition rates were 3 Å / sec and 0.2 Å / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 0.982 g / cm ³ .

Production Example 9
Preparation of thin film In Production Example 7, instead of using Compound (D) and Compound (E), a vapor-deposited film (in accordance with the procedure described in Production Example 7) was used except that Compound (G) and Compound (H) were used. Thin film). The deposition rates were 3 Å / sec and 0.2 Å / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 1.189 g / cm ³ .

Production Example 10
Preparation of thin film In Preparation Example 7, instead of using Compound (D) and Compound (E), the following compound (G) and Compound (H) were used. (Thin film) was prepared. The deposition rates were 3 Å / sec and 0.2 Å / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectance method, the density of the deposited film was 1.033 g / cm ³ .

Production Example 11
Preparation of thin film In Production Example 2, instead of using Compound (A), except that the following Compound (J) was used, the operation described in Production Example 2 was followed.
A deposited film (thin film) was prepared. The deposition rate was 3 liters / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectance method, the density of the deposited film was 1.040 g / cm ³ .

Production Example 12
Preparation of Thin Film A vapor deposition film (thin film) was prepared according to the procedure described in Preparation Example 2, except that the following compound (K) was used instead of using the compound (A) in Production Example 2. The deposition rate was 3 liters / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 1.160 g / cm ³ .

Production Example 13
In Production Example 2, a vapor deposition film (thin film) was formed according to the procedure described in Production Example 2 except that the following compound (L) was used instead of using the compound (A). The deposition rate was 3 liters / sec. When the ITO glass substrate having this deposited film was measured by the X-ray reflectivity method, the density of the deposited film was 0.989 g / cm ³ .

The average distance between the centers of gravity of the molecules was calculated by molecular dynamics simulation of the compounds (A) to (D), (F), (G), and (I) to (L).
That is, in order to obtain the amorphous state structure of the molecule necessary for calculating the distance between the average center of gravity of the molecule, the calculation was performed in two parts. First, an initial structure was obtained as a preliminary step for obtaining the amorphous structure, and then the amorphous structure was obtained using the initial structure, and the average distance between the centers of gravity of the molecules was calculated. Construction of the amorphous initial structure was performed as follows. The pcff force field was used as the force field, and 15 molecules were placed in a unit cell with periodic boundary conditions. At this time, the initial position and orientation of each molecule are randomly generated. The density of the system is set at 0.8 g / cm ³ , which is slightly smaller than the actual system in order to find a preferable arrangement more efficiently. Corrected by calculation). This trial calculation was performed while confirming that the molecules having a ring structure were in a state where they were avoided so that the rings were not combined between molecules. Then, all possible conformational structures are generated, and the energy increase due to the non-bonded interaction energy of the pcff force field is calculated. Based on the magnitude of these energy increments, a conformation structure that satisfies the probability according to the Boltzmann distribution law is adopted. Here, the set temperature was 300K. The entire structure (arrangement) in the unit cell obtained in this way was used as the initial structure candidate. By repeating this series of operations, ten initial structure candidates were prepared. For each configuration, the structure was optimized by minimizing the potential energy of the entire system by the steepest descent method. In this calculation, van der Waals interaction energy and Coulomb interaction energy, which are non-bonded interaction energy components, were calculated by the Cell multipole method. By comparing the potential energy of the obtained configurations, the configuration with the lowest energy was selected as the amorphous initial structure.

  Next, the amorphous state was determined by molecular dynamics (MD) using NVT and NPT ensembles. The calculation used a highly reliable compass force field with a time step of 1.0 femtoseconds. The atom based method was used to calculate van der Waals interaction energy, and the cut-off length was 12 mm, the spline width was 2 mm, and the buffer width was 2 mm. The Ewald method was used to calculate the Coulomb interaction energy. First, the structure was optimized by minimizing potential energy for the amorphous initial structure. Next, an MD calculation of 10,000 steps was performed at a temperature of 600K using an NVT ensemble, and the temperature was shifted to a high temperature state. And the whole system was efficiently balanced by changing temperature and pressure by MD calculation using NPT ensemble. That is, it started from the state of temperature 600K and pressure 1.0MPa, and it was made to transfer to a high temperature (600K) and high pressure (0.1GPa) state. At this time, MD was performed under each pressure while changing the pressure in parameters so that the density change of the system increased smoothly. Thereafter, the pressure and temperature were lowered and finally the temperature and the normal pressure were transferred to and equilibrated to obtain an amorphous state. Specifically, 100,000 steps at 600K / 1.0MPa, 100,000 steps at 600K / 1.5MPa, 250,000 steps at 600K / 0.1GPa, 100,000 steps at 600K / 1.0MPa, 600K / atm After performing MD calculation in the order of 100,000 steps, 100,000 steps at 450K · 1 atm, and 500,000 steps at 298K · 1 atm, finally execute MD calculation of 1 million steps at 298K · 1 atm to equilibrate The structure of the final step was taken out and made into an amorphous structure. However, when changing the temperature and pressure during the calculation process, before entering each MD stage, the time step of 0.1 femtosecond is performed under the same temperature and pressure conditions as the immediately following MD in order to avoid sudden changes in structure. Inserted a short MD calculation of 5,000 steps.

As the calculation software used, Amorphous_Cell module in Accelrys Insight II (R) 4.0.0P + is used for amorphous initial structure calculation, and Accelrys Discover (R) ver. 2002.1 was used.
The structure of the molecules in the unit cell was analyzed for the obtained amorphous state, the distances between the centroids of all adjacent molecule pairs were calculated, the average value was calculated, and defined as the average distance between the centroids of the molecules. Here, a close molecule pair is a molecule-molecule pair in which the van der Waals spheres overlap, or the van der Waals spheres come into contact with each other when the vandi van der Waals radius is considered. It is. The center of gravity of each molecule was calculated as the center of gravity considering the mass of the constituent atoms. For the calculation of the distance between the centers of gravity, a self-made program was used.
The results are shown in Table-1.

The reorientation energy of the above compounds (A) to (D), (F), (G), and (I) to (L) was calculated by a molecular orbital method program.
That is,
The reorientation energy value λ _{el in the} case of becoming an anion radical and the reorientation energy value λ _{h in the} case of becoming a cation radical are represented by the following equations, respectively.
λ _el = (E _neut [anion] _{-E neut} [neutral]) + (E _ani [neutral] _{-E ani} [anion]) (1)
λ _h = (E _cat [neutral] _{-E neut} [neutral]) + (E _neut [cation] _{-E cat} [cation]) (2)
Here, when the subscript of E is cat, neut or ani, it represents the total energy of the molecule in the cation state, neutral state and anion state, respectively. In addition, [] shows the stable structure in the charged state. [Neutral], [Cation], and [Anion] indicate the stable structure in the neutral state, cation state, and anion state, respectively. I mean. Thus, for example, E _cat [neutral] is the total energy of the cation molecule in the neutral state stable structure.

The molecular orbital method program Gaussian03 rev.C.02 was used to calculate the reorientation energy value according to the above formula. The density functional method was used to calculate the stable structure of the molecule and its total energy. Specifically, for neutral molecules, it was calculated by B3LYP / 6-31G ^* , and for molecules in the cationic and anionic state, it was calculated by UB3LYP / 6-31G ^* .

For the stable structure calculation by structure optimization, if the molecules other than C ₁ symmetry, was confirmed to be possible in a stable structure perform vibration analysis. Further, regarding the calculation of the total energy of the charged state of the cation or anion, all the <S ² > values were 0.75 to 0.78, and it was confirmed that the other spin states were hardly mixed.
Based on these, the reorientation energy value was calculated by the above two formulas.
The results are shown in Table-1.

Preparation of organic electroluminescent device A glass substrate having a 150 nm thick ITO transparent electrode (anode) was ultrasonically cleaned using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. The substrate was dried using nitrogen gas, further subjected to UV / ozone battlefield, and then fixed to a substrate holder of a vacuum deposition apparatus. The vapor deposition tank was depressurized to 1 × 10 ⁻⁵ Pa, and first, copper phthalocyanine was deposited on the ITO transparent substrate to a thickness of 30 nm at a deposition rate of 2 Å / sec to form a hole injection layer. Next, 4,4′-bis (N-phenyl-N-1 ″ -naphthylamino) -1,1′-biphenyl was deposited at a deposition rate of 3 nm / sec to a thickness of 20 nm to form a hole transport layer. Next, the compound (A) was vapor-deposited to a thickness of 30 nm at a vapor deposition rate of 3 mm / sec under the same conditions as in Production Example 2. Further, Tris (8- Quinolinolato) aluminum was deposited at a deposition rate of 2.5 Å / sec to a thickness of 20 nm to form an electron transport layer, on which lithium fluoride was deposited at a deposition rate of 0.5 Å / sec to a thickness of 0.5 nm. Vapor deposition was performed, and finally, aluminum was deposited as a cathode at a deposition rate of 10 Å / sec to a thickness of 120 nm to prepare an organic electroluminescent device, where each vapor deposition step was performed under consistent vacuum conditions. Electroluminescent device Move to an argon-substituted glove box with a dew point of -95 ° C and an oxygen concentration of 0.5 ppm or less, and seal with a sealing glass with a desiccant (made by SAES Getter Co., Ltd.). By the above operation, the density of the film was 1.152 g / cm ³ , the distance between the molecular centroids calculated by molecular dynamics simulation was 9.780 mm, and the reorientation energy in the case of an anion radical was 32. An organic electroluminescent element having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 31.66 KJ / mol to be .51 KJ / mol and a cation radical was prepared.
Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current voltage was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.2 V, and blue light emission with a luminance of 1400 cd / m ² was confirmed. This element had a luminance attenuation rate of 74% after being driven at 50 mA / cm 2 for 200 hours.

Comparative Example 1
Preparation of organic electroluminescent element In Example 4, instead of depositing the compound (A) by the same operation as in Production Example 2, the compound (B) was deposited by the same operation as in Production Example 3 in forming the light emitting layer. Except that the density of the membrane was 0.952 g / cm ³ , the distance between the molecular centroids calculated by the molecular dynamics simulation was 10.703Å, and the reorientation energy in the case of an anion radical was 41 according to the procedure described in Example 4. An organic electroluminescent device having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 29.576 KJ / mol when it becomes a .412 KJ / mol and cation radical was prepared. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current voltage was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 6.3 V, and blue light emission with a luminance of 920 cd / m 2 was confirmed. This device had half the brightness after 55 hours.

Preparation of organic electroluminescent element In Example 4, instead of depositing the compound (A) by the same operation as in Production Example 2, the compound (C) was deposited by the same operation as in Production Example 5 in forming the light emitting layer. Except for the above, according to the operation described in Example 4, the film density is 1.082 g / cm ³ , the distance between the molecular centroids calculated by molecular dynamics simulation is 12.473Å, and the reorientation energy when it becomes an anion radical is 38 An organic electroluminescent element having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 27.402 KJ / mol in the case of .358 KJ / mol and a cation radical was prepared. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.1 V, and blue light emission of 1640 cd / m ² was confirmed. This element had a residual ratio of luminance of 76% after being driven at 50 mA / cm ² for 200 hours.

Comparative Example 2
Preparation of organic electroluminescent device In Example 4, in forming the light-emitting layer, instead of depositing compound (A) at a deposition rate of 3 Å / sec by the same operation as in Production Example 2, the compound was produced by the same operation as in Production Example 6. Except that (C) was deposited at a deposition rate of 10 速度 / sec, the film density was 0.935 g / cm ³ and the distance between molecular centroids calculated by molecular dynamics simulation was 12.473 に 従 い according to the procedure described in Example 4. An organic electroluminescence device having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 38.358 KJ / mol when becoming an anion radical and a reorientation energy of 27.402 KJ / mol when becoming a cation radical is prepared. did. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.4 V, and blue light emission of 1430 cd / m ² was confirmed. This element had a residual luminance ratio of 53% after being driven at 50 mA / cm ² for 100 hours.

Comparative Example 3
Preparation of organic electroluminescence device In Example 4, in forming the light emitting layer, instead of depositing the compound (A) at a deposition rate of 3 Å / sec in the same manner as in Production Example 2, the compound was produced in the same manner as in Production Example 11. Except that (J) was deposited at a deposition rate of 3 Å / sec, the film density was 1.040 g / cm ³ and the distance between molecular centroids calculated by molecular dynamics simulation was 11.800 に 従 い according to the operation described in Example 4. An organic electroluminescent device having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 47.977 kJ / mol when it becomes an anion radical and 29.018 kJ / mol when it becomes a cation radical did. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.1 V, and blue light emission of 870 cd / m ² was confirmed. This device had half the brightness after being driven at 50 mA / cm ² for 78 hours.

Preparation of organic electroluminescent device A glass substrate having a 150 nm thick ITO transparent electrode (anode) was ultrasonically cleaned using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. This substrate was dried using nitrogen gas, further UV / ozone cleaned, and then fixed to a substrate holder of a vacuum deposition apparatus. The vapor deposition tank was depressurized to 1 × 10 ⁻⁵ Pa, and first, copper phthalocyanine was deposited on the ITO transparent substrate to a thickness of 30 nm at a deposition rate of 2 Å / sec to form a hole injection layer. Next, 4,4′-bis (N-phenyl-N-1 ″ -naphthylamino) -1,1′-biphenyl was deposited at a deposition rate of 3 nm / sec to a thickness of 20 nm to form a hole transport layer. Next, the compound (D) and the compound (E) were co-deposited to a thickness of 30 nm at a deposition rate of 3 Å / sec and a deposition rate of 0.2 Å / sec under the same conditions as in Production Example 7. Further, tris (8-quinolinolato) aluminum was deposited on the light emitting layer at a deposition rate of 2.5 蒸 着 / sec to a thickness of 20 nm to form an electron transporting layer. Fluoride was vapor-deposited at a rate of 0.5 nm / sec to a thickness of 0.5 nm, and finally aluminum was deposited as a cathode at a rate of 10 nm / sec to a thickness of 120 nm to produce an organic electroluminescent device. , Each deposition After that, the organic electroluminescence device was moved to an argon-substituted glove box with a dew point of −95 ° C. and an oxygen concentration of 0.5 ppm or less, and a desiccant (manufactured by SAES Getter) was applied. The organic electroluminescence device was prevented from coming into contact with moisture / oxygen by the attached sealing glass, whereby the film density was 1.192 g / cm ³ and the molecular centroid calculated by molecular dynamics simulation was obtained. Organic having a light-emitting layer made of a low molecular weight organic material having a distance of 10.8 angstroms, a reorientation energy for an anion radical of 42.028 KJ / mol and a reorientation energy for a cation radical of 24.198 KJ / mol An electroluminescent element was prepared.
Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current voltage was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 4.8 V, and blue light emission with a luminance of 3300 cd / m ² was confirmed. This element had a residual luminance rate of 79% after being driven at 50 mA / cm ² for 200 hours.

Comparative Example 4
Preparation of organic electroluminescent element In Example 6, in forming the light emitting layer, the compound (D) and the compound (E) were deposited from different vapor deposition sources under the same conditions as in Production Example 7, and the vapor deposition rate was 0.3 mm / sec. Instead of co-evaporation at a thickness of 30 nm at 2 mm / sec, under the same conditions as in Production Example 8, compound (F) and compound (E) were vapor-deposited at a rate of 3 mm / sec and a vapor deposition rate of 0.2 mm / sec from different vapor deposition sources. Except for co-evaporation to a thickness of 30 nm in sec, according to the procedure described in Example 6, the density of the film was 0.982 g / cm ³ , the distance between the molecular centroids calculated by molecular dynamics simulation was 12.890 angstroms, The reorientation energy to become an anion radical is 36.296 KJ / mol and the reorientation energy to become a cation radical is 32.251 KJ / mol. It created the organic electroluminescent device having a light-emitting layer composed of a molecular organic material.
Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current voltage was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.1 V, and blue light emission with a luminance of 2100 cd / m ² was confirmed. Note that the luminance of this element was reduced by half after 29 hours at 50 mA / cm ² .

Preparation of organic electroluminescent device In Example 6, in forming the light emitting layer, under the same conditions as in Production Example 7, the compound (D) and the compound (E) were deposited from different vapor deposition sources at a vapor deposition rate of 3 mm and a vapor deposition rate of 0.2 mm / Instead of co-evaporation to a thickness of 30 nm at / sec, the compound (G) and the compound (H) are vapor-deposited at a rate of 3 L / sec and a rate of 0.2 L / sec from different evaporation sources by the same operation as in Production Example 9. The film density was 1.189 g / cm ³ and the distance between the molecular centroids calculated by molecular dynamics simulation was 10.369 Å anion radical, except that the film was co-evaporated to a thickness of 30 nm. A low molecular organic material having a reorientation energy of 21.477 KJ / mol and a reorientation energy of 19.613 KJ / mol when becoming a cation radical. An organic electroluminescent element having a light emitting layer was prepared. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.2 V, and blue light emission of 4720 cd / m ² was confirmed. This element had a luminance residual ratio of 86% after being driven at 50 mA / cm ² for 200 hours.

Comparative Example 5
Preparation of organic electroluminescent device In Example 6, the compound (D) and the compound (E) were subjected to the same operation as in Production Example 7, but the deposition rate was 3 nm / sec and the deposition rate was 0.2 nm / sec. Instead of co-evaporation, compound (I) and compound (H) were co-deposited from different deposition sources to a thickness of 30 nm at a deposition rate of 3 Å / sec and a deposition rate of 0.2 Å / sec. Except for vapor deposition, following the procedure described in Example 6, the reorientation energy when the film density is 1.033 g / cm ³ and the distance between the molecular centroids calculated by molecular dynamics simulation is 11.43Å anion radical. 42.878 KJ / mol, having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 40.289 KJ / mol when becoming a cation radical It created the electromechanical field light-emitting element. Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 5.6 V, and blue light emission of 4400 cd / m ² was confirmed. When this device was driven at 50 mA / cm ² for 32 hours, the luminance was reduced by half.

Preparation of organic electroluminescent device A glass substrate having a 150 nm thick ITO transparent electrode (anode) was ultrasonically cleaned using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. This substrate was dried using nitrogen gas, further UV / ozone cleaned, and then fixed to a substrate holder of a vacuum deposition apparatus. The vapor deposition tank was depressurized to 1 × 10 ⁻⁵ Pa, and first, copper phthalocyanine was deposited on the ITO transparent substrate to a thickness of 30 nm at a deposition rate of 2 Å / sec to form a hole injection layer. Next, by the same operation as in Production Example 12, that is, the compound (K) was deposited to a thickness of 20 nm at a deposition rate of 3 Å / sec to form a hole transport layer. Next, tris (8-quinolinolato) aluminum was vapor-deposited to a thickness of 60 nm at a vapor deposition rate of 2.5 Å / sec to form a light emitting layer / electron transport layer. On top of this, lithium fluoride is deposited to a thickness of 0.5 nm at a deposition rate of 0.5 Å / sec, and finally aluminum is deposited as a cathode to a thickness of 120 nm at a deposition rate of 10 Å / sec. It was created. In addition, each vapor deposition process was implemented on the vacuum consistent conditions. Then, the created organic electroluminescence device was moved to an argon-substituted glove box having a dew point of −95 ° C. and an oxygen concentration of 0.5 ppm or less, and sealed with a sealing glass to which a desiccant (manufactured by SAES Getter) was attached. The organic electroluminescence device was prevented from coming into contact with moisture / oxygen. By the above operation, the film density is 1.160 g / cm ³ , the distance between the molecular centroids calculated by molecular dynamics simulation is 10.52 Å, the reorientation energy in the case of an anion radical is 28.340 KJ / mol, and the cation An organic electroluminescent element having a hole transport layer made of a low molecular weight organic material having a realignment energy of radicals of 22.350 KJ / mol was prepared.
Thereafter, the organic electroluminescent element was taken out of the glove box, applied with a DC voltage, and continuously driven at a constant current density of 30 mA / cm ² . Initially, the voltage value was 5.8 V, and green light emission with a luminance of 1430 cd / m ² was confirmed. The device had a luminance remaining rate of 61% after being driven at 30 mA / cm ² for 100 hours.

Comparative Example 6
Preparation of organic electroluminescence device In Example 8, the formation of the hole transport layer was carried out in the same manner as in Production Example 12, but instead of vapor deposition of compound (K) at a deposition rate of 3 Å / sec, the same operation as in Production Example 13 According to the procedure described in Example 8, except that the compound (L) was deposited at a deposition rate of 3 Å / sec, the film density was 0.989 g / cm ³ and the distance between the molecular centroids calculated by molecular dynamics simulation was Organic electroluminescence having a hole transporting layer made of a low molecular weight organic material having a reorientation energy of 42.650 KJ / mol when becoming an anion radical and 21.340 KJ / mol when becoming a cation radical A device was created.
Thereafter, the organic electroluminescent element was taken out of the glove box, applied with a DC voltage, and continuously driven at a constant current density of 30 mA / cm 2. Initially, the voltage value was 5.6 V, and green light emission with a luminance of 960 cd / m ² was confirmed. Note that the luminance of this element was reduced by half after being driven at 30 mA / cm ² for 26 hours.

Preparation of organic electroluminescent device A glass substrate having a 150 nm thick ITO transparent electrode (anode) was ultrasonically cleaned using a neutral detergent, Semicoclean (manufactured by Furuuchi Chemical), ultrapure water, acetone, and isopropanol. The substrate was dried using nitrogen gas, further subjected to UV / ozone battlefield, and then fixed to a substrate holder of a vacuum deposition apparatus. The vapor deposition tank was depressurized to 1 × 10 ⁻⁵ Pa, and first, copper phthalocyanine was deposited on the ITO transparent substrate to a thickness of 30 nm at a deposition rate of 2 Å / sec to form a hole injection layer. Next, the compound (K) was vapor-deposited to a thickness of 20 nm at a vapor deposition rate of 3 Å / sec by the same operation as in Production Example 13 to form a hole transport layer. Next, the compound (D) and the compound (E) were vapor-deposited from different vapor deposition sources to a thickness of 30 nm at a vapor deposition rate of 3 mm / sec and a vapor deposition rate of 0.2 mm / sec under the same conditions as in Production Example 7. Formed. Further, tris (8-quinolinolato) aluminum was vapor-deposited to a thickness of 20 nm on the light-emitting layer at a vapor deposition rate of 2.5 Å / sec to form an electron transport layer. On top of this, lithium fluoride is deposited to a thickness of 0.5 nm at a deposition rate of 0.5 Å / sec, and finally aluminum is deposited as a cathode to a thickness of 120 nm at a deposition rate of 10 Å / sec. It was created. In addition, each vapor deposition process was implemented on the vacuum consistent conditions. Then, the created organic electroluminescent element was dew point -95 ° C,
Move to an argon-substituted glove box with an oxygen concentration of 0.5 ppm or less, and seal with a sealing glass with a desiccant (made by SAES Getter Co., Ltd.) so that the organic electroluminescent device does not come into contact with moisture or oxygen. did. By the above operation, the density of the film is 1.160 g / cm ³ , the distance between the molecular centroids calculated by molecular dynamics simulation is 10.52 Å, the reorientation energy in the case of an anion radical is 28.34.kJ / mol, A hole transport layer made of a low molecular weight organic material having a reorientation energy of 22.350 kJ / mol when it becomes a cation radical, a film density of 1.192 g / cm ³ , and a distance between molecular centroids calculated by molecular dynamics simulation Electroluminescent device having a light emitting layer made of a low molecular weight organic material having a reorientation energy of 42.028 KJ / mol when it becomes an anion radical and 24.198 KJ / mol when it becomes an anion radical It was created.
Thereafter, the organic electroluminescence device was taken out of the glove box, a direct current voltage was applied, and the organic electroluminescence device was continuously driven at a constant current density of 50 mA / cm ² . Initially, the voltage value was 4.4 V, and blue light emission with a luminance of 3850 cd / m ² was confirmed. This element had a luminance residual rate of 89% after being driven at 50 mA / cm ² for 200 hours.

  Table 2 summarizes the initial driving voltage, luminance, and driving life of the organic electroluminescent elements prepared in Examples 4 to 9 and Comparative Examples 1 to 6. From comparison between Examples 4 and 5 and Comparative Examples 1 to 3, it can be seen that the drive life of the organic electroluminescent element containing the thin film made of the low molecular weight organic material of the present invention as the light emitting layer is remarkably long. Further, from comparison between Examples 6 and 7 and Comparative Examples 4 and 5, it can be seen that the driving life of the organic electroluminescent element containing a thin film made of the low molecular weight organic material of the present invention as a light emitting layer is remarkably long. . Furthermore, it can be seen from a comparison between Example 8 and Comparative Example 6 that an organic electroluminescent element containing a thin film made of the organic material of the present invention as a hole transporting material also has a long driving life. From Example 9 and Example 6, it can be seen that the drive life can be further extended by containing a thin film made of the low molecular weight organic material of the present invention as a light emitting layer and a hole transport material.

  To provide an organic electroluminescence device having a long emission life, excellent durability, and high emission luminance, and an organic electroluminescence device having a long emission lifetime, excellent durability, and high emission luminance. And a low-molecular organic material for forming the thin film can be provided.

It is a cross-sectional schematic diagram of an example of an organic electroluminescent element. It is a cross-sectional schematic diagram of an example of an organic electroluminescent element. It is a cross-sectional schematic diagram of an example of an organic electroluminescent element. It is a cross-sectional schematic diagram of an example of an organic electroluminescent element. It is a cross-sectional schematic diagram of an example of an organic electroluminescent element.

Explanation of symbols

1: Substrate 2: Anode 3: Hole injection / transport layer 3a: Hole injection / transport component 4: Light emitting layer 4a: Light emitting component 5: Electron injection / transport layer 5 ": Electron injection / transport layer 5a: Electron injection / transport component 6: Cathode 7: Power supply

Claims (8)

A method for producing an organic electroluminescent device comprising, between a pair of electrodes, at least one thin film made of a low molecular organic material that is a hole injection layer, a hole transport layer or a light emitting layer,
Wherein Ri Der density of the thin film is 1.05 g / cm ³ or more,
The manufacturing method of an organic electroluminescent element including the process of forming into a film on the pressure conditions of 1 * 10 < ^-5 > Pa or less by the vacuum evaporation method . The method of manufacturing an organic electroluminescent device of claim 1, wherein the measured value density of the thin film by X-ray reflectance method. The method of manufacturing an organic electroluminescent device according to claim 1 or 2, wherein the density of the thin film is 1.10 g / cm ³ or more. The organic electroluminescent element according to any one of claims 1 to 3 , wherein the low-molecular organic material comprises a condensed hydrocarbon compound, an aromatic amine compound, a heterocyclic compound, and / or an organometallic complex compound. Manufacturing method . The manufacturing method of the organic electroluminescent element as described in any one of Claims 1-4 with which the said low molecular organic material satisfy | fills the conditions of following (2) or (3) .
(2) A low molecular weight organic material having an average center-to-center distance of molecules calculated by molecular dynamics simulation of 11.0 mm or less.
(3) A low molecular weight organic material having a reorientation energy value of 1 kJ / mol to 40 kJ / mol in the case of an anion radical and a cation radical calculated using a molecular orbital method program. The manufacturing method of the organic electroluminescent element as described in any one of Claims 1-5 which comprises the said thin film as a positive hole injection layer or a positive hole transport layer. The manufacturing method of the organic electroluminescent element as described in any one of Claims 1-5 which comprises the said thin film as a light emitting layer. The method for manufacturing an organic electroluminescent element according to claim 7, wherein the light emitting layer is formed of a host material and a dopant material.

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