JP2010222551A - Luminescent material and method for producing light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic luminescent material the luminescent color of which can be adjusted easily and from which a polarized-light emitting element can be produced easily. <P>SOLUTION: The organic luminescent material consists of a supramolecule obtained by bonding a hydrogen-bondable luminescent molecule having a hydrogen-bondable substituent to a hydrogen-bondable compound having the hydrogen-bondable substituent by an intermolecular hydrogen bonding method. The organic luminescent material, from which the polarized-light emitting element can be produced, is obtained by forming a hydrogen-bondable luminescent molecule layer on the uniaxially-oriented hydrogen-bondable compound and heating the luminescent molecule layer-formed hydrogen-bondable compound. The wavelength of the light emitted from the organic luminescent material is varied according to the kind of the hydrogen-bondable compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel organic light-emitting material capable of easily adjusting the emission wavelength and capable of easily producing a polarized light-emitting element, and a polarized light-emitting element produced using these materials It is about.

Conventional technology

  As one of the light emitting elements, an organic electroluminescence (hereinafter referred to as EL) element has attracted attention. An organic EL element is a light emitting element that emits light by excitons generated by recombination of electrons and holes injected into an organic material. Of course, it is a next-generation flat panel display next to liquid crystal displays and plasma displays. It is also attracting attention as a surface emitting light source and is being actively developed.

  General white light includes light of three primary colors of red (R), green (G), and blue (B). On the other hand, white LED lamps and white organic EL lamps obtain white light by blue light and yellow phosphor, or blue and yellow light. When such a white lamp is used, there is a problem that the color rendering property is low because red light is not included. As a method for improving color rendering, there is a method of using three light emitting materials of RGB, which are the three primary colors of light, in combination, and material development is progressing. However, the emission wavelength greatly depends on the molecular structure of the material, and it is very difficult to freely select a light emitting material for each color, which is a big problem particularly in the development of organic EL materials. When an organic EL element is used as a surface emitting light source of a liquid crystal display, when light passes through the polarizing plate on the light source side, most of light in the absorption axis direction of the polarizer is absorbed, so that the amount of light is at least 50%. There was a problem that there was a loss and the light utilization efficiency deteriorated.

Thus, attempts have been made to obtain polarized light emission by controlling the molecular orientation of the organic light emitting material. As a method for controlling the molecular orientation, a water surface development method, an LB method, a friction transfer method, a rubbing method using an alignment film, and the like have been developed. In a polarized light emitting device composed of a light emitting layer in which the molecular orientation of an organic light emitting material is controlled, linearly polarized light can be directly supplied to the liquid crystal panel, or the polarization direction of the polarized light emitting device and the absorption axis of the polarizing plate on the light source side By making the directions orthogonal, the optical loss due to the polarizing plate can be greatly improved.
As an example of polarized light emission, Patent Document 1 discloses a method in which a polyamic acid is mixed with a uniaxial organic light-emitting material and is prepared by a water surface development method or an LB method. Patent Document 2 discloses a method in which polysilane is rubbed and pressed in one direction on the surface of a transparent body. Non-Patent Document 1 describes that an element using a light-emitting layer containing an organic light-emitting material formed on a rubbing-treated alignment film emits polarized light.
However, in these organic light emitting materials, the light emission wavelength peculiar to the organic light emitting material is determined, and it is difficult to adjust the emission color. In addition, the water surface development method and the LB method are not productive, and are rubbed. In the alignment film, there is a problem that static electricity and dust are generated by rubbing treatment, rubbing spots are generated, the organic light emitting material needs to have liquid crystal properties, and selection of the organic light emitting material is limited.

JP-A-4-040413

JP-A-7-292135

Advanced Materials (Adv. Mater.) Volume 4, Item 36 (1992)

  The present invention has been made in view of the above matters, and the object thereof is to easily adjust the emission wavelength of the luminescent material and to improve the productivity of the polarized light-emitting device. An organic light emitting material is provided.

  The inventors of the present invention have studied the above-described problems. As a result, a hydrogen-bonding luminescent molecule having at least one hydrogen-bonding substituent and a hydrogen-bonding compound having at least one hydrogen-bonding substituent An organic light-emitting material characterized in that the hydrogen-bonding light-emitting molecule and the hydrogen-bonding compound are composed of supramolecules that are self-assembled by intermolecular hydrogen bonding; and Prepared by a manufacturing method characterized by forming a layer of hydrogen-bonding light-emitting molecules on the film and then heat-treating it after irradiating the film with linearly polarized light or after heat treatment after irradiating with linearly polarized light The present inventors have found that the above-mentioned problems can be solved by the polarized light emitting element, and have completed the present invention.

  According to the present invention, the emission color of the organic light-emitting material can be easily adjusted. The polarized light-emitting device manufactured by the method can be manufactured more easily than the water surface development method and the LB method, and can be improved in productivity by eliminating problems such as generation of static electricity and dust and rubbing spots due to rubbing treatment. Thereby, the problems of the prior art can be solved.

Details of the present invention will be described below.
The organic light-emitting material of the present invention comprises a hydrogen-bonding light-emitting molecule having at least one hydrogen-bonding substituent and a hydrogen-bonding compound having at least one hydrogen-bonding substituent, and the hydrogen bond An organic light-emitting material, wherein the light-emitting molecule and the hydrogen bonding compound are composed of supramolecules self-assembled by intermolecular hydrogen bonding.

A hydrogen-bonding light-emitting molecule is a molecule having a luminescent core of fluorene, polyacetylene, anthracene, etc., and a molecular structure having a hydrogen-bonding substituent on the core. It is a compound having a group.
The light emitting core only needs to have molecular anisotropy, and is not particularly limited to the compounds exemplified here. Further, the hydrogen-bonding light-emitting molecule may or may not have liquid crystallinity.

Examples of the hydrogen bonding substituent include a carboxyl group, a hydroxyl group, a sulfonic acid group, and an amino group, but the substituent is not particularly limited as long as the substituent forms a hydrogen bond.
When a hydrogen-bonding light-emitting molecule and a hydrogen-bonding molecule are mixed, a hydrogen bond is formed between the molecules by the mutual hydrogen-bonding substituents, and a supramolecular structure can be formed.

  A hydrogen-bonding light-emitting molecule can emit light alone, but the hydrogen-bonding light-emitting molecule and the hydrogen-bonding compound form a supramolecule, so that the emission wavelength is longer than that of a hydrogen-bonding light-emitting molecule alone It was found that it has a changing property, and it became possible to adjust the emission wavelength by adjusting the kind and acidity of the hydrogen bonding compound to be mixed.

When a high molecular weight hydrogen bonding compound is used as the hydrogen bonding compound, a film of the hydrogen bonding compound is formed on a glass substrate, and the film is irradiated with linearly polarized light or irradiated with linearly polarized light. After the heat treatment, a polarized light-emitting element can be easily manufactured by forming a layer of hydrogen-bonding light-emitting molecules on the film and performing heat treatment.
In particular, in the case of a hydrogen bonding compound having a hydrogen bonding substituent such as a carboxyl group at the end of the side chain of the photoreactive polymer, the side chain is pseudo-crosslinked by intermolecular hydrogen bonding of the carboxyl group to form a liquid crystalline mesogenic core. . When this hydrogen bonding compound is irradiated with linearly polarized light and heated, the liquid crystalline mesogen side chain that is pseudo-crosslinked by hydrogen bonding has a characteristic that it is aligned in a uniaxial direction. At this time, the direction of uniaxial orientation differs depending on the material used, and the orientation is parallel or perpendicular to the electric field vector direction of linearly polarized light.
When a hydrogen-bonded luminescent molecule layer is formed on a uniaxially oriented hydrogen-bonded compound film, the hydrogen-bonded luminescent molecules are not oriented after the formation, and the emission color is the same as when the hydrogen-bonded luminescent molecules are alone. Same as the emission wavelength. However, by heating the uniaxially oriented hydrogen bonding compound film and the hydrogen bonding luminescent molecule layer in contact with each other, the hydrogen bonding luminescent molecules are taken in between the hydrogen bonding groups of the uniaxially oriented hydrogen bonding compound. In addition, a supramolecule due to hydrogen bonding is formed between the hydrogen-bonding light-emitting molecule and the hydrogen-bonding compound, the emission wavelength is changed, and the hydrogen-bonding light-emitting molecule can be uniaxially oriented. It became possible to produce it easily.
In general alignment films, the light-emitting molecules must have liquid crystallinity. However, in the present invention, the light-emitting molecules may have liquid crystallinity or may be aligned even without liquid crystallinity. It is.

A synthesis method relating to the compound used in the examples of the present invention is shown below.
(Luminescent molecule 1)
9,9-dihexyl-fluorene was synthesized by heating 9H-fluorene and 1-bromohexane under alkaline conditions. 2,7-bis (bromomethyl) -9,9-dihexyl-fluorene was synthesized by heating 9,9-dihexyl-fluorene, paraformaldehyde and hydrogen bromide in acetic acid. 2,7-bis (bromomethyl) -9,9-dihexyl-fluorene, trimethylsilylcyanide and tetrabutylammonium fluoride were reacted in acetonitrile under a nitrogen atmosphere to obtain 2,2 ′-(9,9-dihexylfluorene- 2,7-Diyl) diacetonitrile was synthesized. 2,2 ′-(9,9-dihexylfluorene-2,7-diyl) diacetonitrile was reacted with 4-pyridinecarboxaldehyde and potassium t-butoxide in tetrahydrofuran to synthesize luminescent molecule 1.

(Compound 1)
4-Dodecyloxy-benzoic acid was synthesized by heating 4-hydroxy-benzoic acid and 1-bromododecane under alkaline conditions.

(Polymer 1)
4- (6-Hydroxyhexyloxy) cinnamic acid was synthesized by heating p-coumaric acid and 6-chloro-1-hexanol under alkaline conditions. A large excess of methacrylic acid was added to this product for esterification to synthesize 4-methacryloyloxyhexyloxycinnamic acid. This product was dissolved in tetrahydrofuran, polymerized by adding azobisisobutyronitrile as a reaction initiator, and polymerized.
Hereinafter, the present invention will be specifically described with reference to examples.

Example 1
A light-emitting molecule 1 as a hydrogen-bonding light-emitting molecule, a compound 1 and polymethyl methacrylate as a hydrogen-bonding compound were dissolved in tetrahydrofuran, and then spin-coated on a glass substrate to produce a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 491 nm.

(Example 2)
A light-emitting molecule 1 as a hydrogen-bonding light-emitting molecule and succinic acid and polymethyl methacrylate as hydrogen-bonding compounds were dissolved in tetrahydrofuran, and then spin-coated on a glass substrate to produce a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 508 nm.

Example 3
A luminescent molecule 1 as a hydrogen-bonding luminescent molecule and terephthalic acid and polymethyl methacrylate as hydrogen-bonding compounds were dissolved in tetrahydrofuran, and then spin-coated on a glass substrate to produce a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 510 nm.

Example 4
A light-emitting molecule 1 as a hydrogen-bonding light-emitting molecule and phthalic acid and polymethyl methacrylate as hydrogen-bonding compounds were dissolved in tetrahydrofuran, and then spin-coated on a glass substrate to produce a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 540 nm.

(Example 5)
Luminescent molecule 1 as a hydrogen bonding luminescent molecule and malonic acid and polymethyl methacrylate as hydrogen bonding compounds were dissolved in tetrahydrofuran and spin coated on a glass substrate to prepare a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 543 nm.

(Example 6)
A light-emitting molecule 1 as a hydrogen-bonding light-emitting molecule and oxalic acid and polymethyl methacrylate as hydrogen-bonding compounds were dissolved in tetrahydrofuran, and then spin-coated on a glass substrate to produce a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 557 nm.

(Example 7)
A light-emitting molecule 1 as a hydrogen-bonding light-emitting molecule and camphorsulfonic acid and polymethyl methacrylate as hydrogen-bonding compounds were dissolved in tetrahydrofuran and spin-coated on a glass substrate to prepare a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 555 nm.

(Example 8)
Polymer 1 was dissolved in tetrahydrofuran and applied to a glass substrate with a thickness of 0.3 μm using a spin coater. The coated surface was irradiated with light from a high-pressure mercury lamp converted to linear polarization by a Grand Taylor prism. Next, the luminescent molecule 1 was dissolved in chloroform and coated on the substrate using a spin coater. The substrate was heated to 165 ° C. and cooled to room temperature. When the film thus produced was irradiated with 365 nm light, the maximum wavelength λmax of the fluorescence spectrum was 508 nm, and the light had polarization.

(Comparative Example 1)
A luminescent molecule 1 and polymethyl methacrylate were dissolved in tetrahydrofuran as hydrogen-bonding luminescent molecules and then spin-coated on a glass substrate to prepare a thin film. The maximum wavelength λmax of the fluorescence spectrum when the produced film was irradiated with 365 nm light was 460 nm.

(Comparative Example 2)
A material exhibiting birefringence is dissolved in tetrahydrofuran by linearly polarized light having no hydrogen bonding substituent described in Patent 3945790 and heat treatment, and applied to a glass substrate with a thickness of 0.3 μm using a spin coater. did. The coated surface was irradiated with light from a high-pressure mercury lamp converted to linear polarization by a Grand Taylor prism. Next, the luminescent molecule 1 was dissolved in chloroform and coated on the substrate using a spin coater. The substrate was heated to 120 ° C. and cooled to room temperature. When the film produced in this manner was irradiated with 365 nm light, the maximum wavelength λmax of the fluorescence spectrum was 460 nm, and the light had no polarization.

Claims (7)

A hydrogen-bonding luminescent molecule having at least one hydrogen-bonding substituent; and
A hydrogen bonding compound having at least one hydrogen bonding substituent,
An organic light-emitting material characterized in that the hydrogen-bonding light-emitting molecule and the hydrogen-bonding compound are composed of supramolecules self-assembled by intermolecular hydrogen bonding. The organic light-emitting material according to claim 1, wherein the emission wavelength varies depending on the type of the hydrogen bonding compound. A supramolecule in which the hydrogen-bonding luminescent molecule and the hydrogen-bonding compound are self-assembled by intermolecular hydrogen bonding, and the hydrogen-bonding luminescent molecule and two or more types of hydrogen-bonding compounds having different chemical structures The organic light-emitting material according to claim 1, wherein the organic light-emitting material is a supramolecule. The organic light-emitting material according to claim 1, wherein the hydrogen-bonding light-emitting molecule is a compound represented by Chemical Formulas 1 to 6.

In the formula, k and l are positive integers of 0 and 1, X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
R ₁ and R ₂ are an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a phenylalkyl group having 7 to 26 carbon atoms, a phenylalkoxy group having 7 to 26 carbon atoms, a phenyl group, and a phenoxy group. , One selected from the group consisting of alkyl group-substituted phenyl groups,
R ₃ , R ₄ , R ₅ , and R ₆ are each independently one selected from the group consisting of a hydrogen atom or a cyano group,
R _{7 to} R ₂₈ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom.

Where k and l are positive integers of 0 and 1,
R ₁ and R ₂ are an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a phenylalkyl group having 7 to 26 carbon atoms, a phenylalkoxy group having 7 to 26 carbon atoms, a phenyl group, and a phenoxy group. , One selected from the group consisting of alkyl group-substituted phenyl groups,
R ₃ , R ₄ , R ₅ , R ₆ are each independently one type from a group consisting of a hydrogen atom or a cyano group,
R _{7 to} R ₂₈ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom.

Where k and l are positive integers of 0 and 1,
X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
R _{1 to} R ₁₆ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom.

Where k and l are positive integers of 0 and 1,
R _{1 to} R ₁₆ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom.

Where k and l are positive integers of 0 and 1,
X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
R _{1 to} R ₈ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom.

Where k and l are positive integers of 0 and 1,
R _{1 to} R ₁₆ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkyloxy group, and a halogen atom. The organic light-emitting material according to claim 1, wherein the hydrogen bonding compound is a compound represented by Chemical Formulas 7 to 9.

In the formula, X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
R is one selected from the group consisting of an alkyl group, an alkoxyl group, a methacryloylalkyloxy group, an acryloylalkoxyl group, a methacryloylalkyl group, and an acryloylalkyl group.

In the formula, X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
Y is one selected from the group consisting of an alkyl group, an alkoxyl group, a methacryloylalkyloxy group, an acryloylalkyloxy group, a methacryloylalkyl group, and an acryloylalkyl group,
l = 0, 1, k = 0-3,
z = none, O, CH ₂ , N = N, C = C, C≡C, COO, OCO,
R _{1 to} R ₈ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, and a halogen atom,
R _{9 and} R ₁₀ are each independently one selected from the group consisting of a hydrogen atom or a cyano group.

Where k = 0-2.
z = none, O, CH ₂ , N = N, C = C, C≡C, COO, OCO,
Y is one selected from the group consisting of an alkyl group, an alkoxyl group, a methacryloylalkoxyl group, and an acryloylalkoxyl group,
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, and a halogen atom. is there. The organic light-emitting material according to claim 1, wherein the hydrogen bonding compound is a homopolymer or a copolymer containing one or more repeating units represented by Chemical Formulas 10 and 11.

In the formula, X is a hydrogen bonding substituent such as a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group,
n = 0-20, m = 0,1, k = 0-3, c = 0,1,
Y = none, O, CH ₂ , N = N, C = C, C≡C, COO, OCO,
R ₁ is a hydrogen atom or a methyl group,
R _{2 to} R ₉ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, and a halogen atom, and R _{10 and} R ₁₁ are each independently a hydrogen atom or cyano. It is a kind selected from the county consisting of groups.

Where n = 0 to 20, m = 0,1, k = 0,1,
Y = none, O, CH ₂ , N = N, C = C, C≡C, COO, OCO,
R ₁ is a methyl group or a hydrogen atom,
R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ are each independently one selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, and a halogen atom. is there. 7. A step of irradiating the hydrogen bonding compound according to claim 6 with linearly polarized light, or a step of applying a hydrogen bonding luminescent molecule to a film formed in the step of heating after irradiation with linearly polarized light, or hydrogen bonding luminescence A polarized light-emitting element manufactured by a process including a process of applying molecules and a process of heating.