JP5141007B2 - Polymer light emitting device - Google Patents

Description

  The present invention relates to a polymer light emitter composition and a polymer light emitting device (polymer LED) using the composition.

  A light-emitting polymer light-emitting material (high-molecular-weight light-emitting material) that is soluble in a solvent can form a light-emitting layer in a light-emitting element by a coating method, and meets the demand for a large area of the element. For this reason, various polymer light emitters have been proposed in recent years (for example, Non-Patent Document 1).

Advanced Materials Vol.12 1737-1750 (2000)

By the way, it is desired that the light emitting element has a long lifetime, that is, the degree of decrease in luminance over time due to driving is small.
However, when a polymer light emitter is used, the lifetime of the device has not been sufficient.
An object of the present invention is to provide a polymer light-emitting composition that can provide a light-emitting element having a longer lifetime when used in a light-emitting layer of the light-emitting element.

  As a result of studies to solve the above problems, the present inventors have found that when a composition containing a metal alkoxide in a polymer light emitter is used as a material of a light emitting layer of a light emitting device, light emitting with significantly improved device lifetime is achieved. The inventors have found that an element is provided, and have reached the present invention.

  That is, the present invention provides a polymer light emitter composition containing a polymer light emitter and a metal alkoxide.

  By incorporating the light emitting polymer composition of the present invention in the light emitting layer of the light emitting device, the lifetime of the device can be extended. Therefore, the polymer LED using the polymer light emitter composition of the present invention is a curved or flat light source for backlight or illumination of a liquid crystal display, a segment type display element, a dot matrix flat panel display, etc. It can be preferably used in the apparatus.

  The alkyloxy group contained in the metal alkoxide used in the polymer light-emitting composition of the present invention may be linear, branched or cyclic, may have a substituent, and usually has about 1 to 20 carbon atoms. Specific examples thereof include methoxy group, ethoxy group, propyloxy group, i-propyloxy group, butoxy group, i-butoxy group, t-butoxy group, pentyloxy group, hexyloxy group, cyclohexyloxy group, heptyl Oxy group, octyloxy group, 2-ethylhexyloxy group, nonyloxy group, decyloxy group, 3,7-dimethyloctyloxy group, lauryloxy group, trifluoromethoxy group, pentafluoroethoxy group, perfluorobutoxy group, perfluorohexyl Group, perfluorooctyl group, methoxymethyloxy group, 2-meth Such Shiechiruokishi groups.

  The metal of the metal alkoxide used in the polymer light-emitting composition of the present invention is not particularly limited, and examples thereof include zirconium, niobium, tin, zinc, titanium, tungsten, silicon, vanadium, and aluminum.

Specific examples of the metal alkoxide include Al (OiC ₃ H ₇ ) ₃ , Ba (OC ₂ H ₅ ) ₂ , B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , Bi (OtC ₅ H ₁₁ ) ₃ , Ca (OC ₂ H ₅ ) ₂ , Fe (OiC ₃ H ₇ ) ₃ , Ga (OiC ₃ H ₇ ) ₃ , Ge (OC ₂ H ₅ ) ₄ , Hf (OiC ₃ H ₇ ) ₄ , In (OiC _{3 H 7) 3, KOC 2 H} 5, La (OiC 3 H 7) 3, LiOCH 3, Mg (OC 2 H 5) 2, Mo (OC 2 H 5) 5, NaOC 2 H 5, Nb (OC 2 H ₅ ) ₅ (niobium ethoxide), Pb (OiC ₃ H ₇ ) ₂ , PO (OCH ₃ ) ₃ , PO (OC ₂ H ₅ ) ₃ , P (OCH ₃ ) ₃ , Sb (OC ₂ H ₅ ) ₃ , Si (OC ₂ H ₅ ) ₄ , Sn (OiC ₃ H ₇ ) ₄ , Sr (OiC ₃ H ₇ ) ₂ , Ta (OC ₂ H ₅ ) ₅ , Ti (OiC ₃ H ₇ ) ₄ (titanium isopropoxide) , VO (C ₂ H ₅ ) ₃ , W (OC ₂ H ₅ ) ₅ , Y (OiC ₃ H ₇ ) ₃ , Zn (OC ₂ H ₅ ) ₂ , Zr (OiC ₃ H ₇ ) ₄ , Zr (OtC ₄ H ₉ ) ₄ , Zr (OnC ₄ H ₉ ) ₄ , and the like.

Next, the polymer light emitter used in the present invention will be described. The polymer light emitter used in the present invention is not particularly limited, and the polystyrene-equivalent number average molecular weight is usually from 10 ³ to 10 ⁸ .
The polymer light emitters contained in the polymer light emitter composition of the present invention may be one kind alone or two or more kinds.
The polymer light-emitting material used in the present invention may be a homopolymer or a copolymer, and may be a conjugated polymer or a non-conjugated polymer.
Among the polymer light emitters used in the present invention, those that are conjugated polymers are preferred.

  The conjugated polymer is (1) a polymer consisting essentially of a structure in which double bonds and single bonds are arranged alternately, (2) a structure in which double bonds and single bonds are arranged via nitrogen atoms. (3) a polymer consisting essentially of a structure in which double bonds and single bonds are arranged alternately and a structure consisting essentially of a structure in which double bonds and single bonds are arranged via nitrogen atoms, etc. In the present specification, specifically, an unsubstituted or substituted fluorenediyl group, an unsubstituted or substituted benzofluorenediyl group, a dibenzofurandiyl group, an unsubstituted or substituted dibenzothiophenediyl group, an unsubstituted Or a substituted carbazolediyl group, an unsubstituted or substituted thiophenediyl group, an unsubstituted or substituted furandyl group, an unsubstituted or substituted pyrroldiyl group, an unsubstituted or substituted benzothiadiazolediyl group, an unsubstituted or substituted phenylenebi group One or two or more types selected from the group consisting of a rangenyl group, an unsubstituted or substituted thienylenevinylenediyl group, and an unsubstituted or substituted triphenylaminediyl group are used as a repeating unit, and the repeating units are directly or linking groups It is a polymer bonded via

  In the conjugated polymer, when the repeating units are bonded via a linking group, examples of the linking group include phenylene, biphenylene, naphthalenediyl, anthracenediyl, and the like.

The conjugated polymer, film forming ability, from the viewpoint of solubility in solvents, it is preferred that the number average molecular weight of 10 ³ to 10 approximately ⁸ in terms of polystyrene, among others, 10 ³ number-average molecular weight in terms of polystyrene More preferably, it is about -10 < ⁶ >. It is preferable that the weight average molecular weight in terms of polystyrene is 10 ³ ~1 × 10 ^8, more preferably ^{1 × 10 3 ~1 × 10 6} .

  The conjugated polymer is prepared by synthesizing a monomer having a functional group suitable for the polymerization reaction to be used, and then dissolved in an organic solvent as necessary. For example, an alkali, an appropriate catalyst, or a ligand is used. It can be synthesized by polymerization by a known polymerization method such as aryl coupling.

The polymerization method by aryl coupling is not particularly limited. Examples of the functional group suitable for the polymerization reaction include a monomer having a boric acid group or a boric acid ester group, a halogen atom such as a bromine atom, an iodine atom, or a chlorine atom as a functional group, or a trifluoromethanesulfonate group, p- Monomers having a sulfonate group such as toluene sulfonate group and inorganic bases such as sodium carbonate, potassium carbonate, cesium carbonate, tripotassium phosphate, potassium fluoride, tetrabutylammonium fluoride, tetrabutylammonium chloride, tetrabutylammonium bromide In the presence of an organic base such as tetraethylammonium hydroxide, palladium [tetrakis (triphenylphosphine)], [tris (dibenzylideneacetone)] dipalladium, palladium acetate, bis (triphenylphosphine) palladium dichloride, bis Pd or Ni complexes such as cyclooctadiene) nickel and, if necessary, further triphenylphosphine, tri (2-methylphenyl) phosphine, tri (2-methoxyphenyl) phosphine, diphenylphosphinopropane, tri (cyclohexyl) phosphine , A method of polymerizing by a Suzuki coupling reaction using a catalyst comprising a ligand such as tri (tert-butyl) phosphine; monomers having a sulfonate group such as a halogen atom or a trifluoromethanesulfonate group are bis (cyclooctadiene) ) Using a catalyst comprising a nickel zero-valent complex such as nickel and a ligand such as bipyridyl, or [bis (diphenylphosphino) ethane] nickel dichloride, [bis (diphenylphosphino) propane] nickel dichlori A catalyst comprising a Ni complex such as triphenylphosphine, diphenylphosphinopropane, tri (cyclohexyl) phosphine, tri (tert-butyl) phosphine and a reducing agent such as zinc or magnesium, if necessary And a method of polymerizing by a Yamamoto coupling reaction, if necessary, under a dehydrating condition; a compound having a magnesium halide group and a compound having a halogen atom are [bis (diphenylphosphino) ethane] nickel dichloride, [ Bis (diphenylphosphino) propane] Nickel catalyst such as nickel dichloride, reaction under dehydration conditions, polymerization by aryl coupling reaction, polymerization by Kumada-Tamao coupling reaction, FeC as a functional group A method of polymerization with an oxidizer ₃ or the like, a method in which electrochemical oxidation polymerization.

  The reaction solvent should be selected in consideration of the polymerization reaction used, the solubility of the monomer and polymer, and the like. Specifically, organic solvents such as tetrahydrofuran, toluene, 1,4-dioxane, dimethoxyethane, N, N-dimethylacetamide, N, N-dimethylformamide, a mixed solvent of two or more thereof, or water and The two-phase system is exemplified.

  In the Suzuki coupling reaction, an organic solvent such as tetrahydrofuran, toluene, 1,4-dioxane, dimethoxyethane, N, N-dimethylacetamide, N, N-dimethylformamide, a mixed solvent of two or more thereof, or with them A two-phase system with water is preferred. In general, the reaction solvent is preferably subjected to deoxygenation treatment in order to suppress side reactions.

  In the Yamamoto coupling reaction, organic solvents such as tetrahydrofuran, toluene, 1,4-dioxane, dimethoxyethane, N, N-dimethylacetamide, N, N-dimethylformamide, and a mixed solvent of two or more thereof are preferable. In general, the reaction solvent is preferably subjected to deoxygenation treatment in order to suppress side reactions.

  Among the aryl coupling reactions, the Suzuki coupling reaction and the Yamamoto coupling reaction are preferable from the viewpoint of reactivity, and the Suzuki coupling reaction and the Yamamoto coupling reaction using a nickel zero-valent complex are more preferable. More specifically, with respect to polymerization by Suzuki coupling, see, for example, Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 39, 1533-1556 (2001) can be referred to. With respect to polymerization by Yamamoto coupling, for example, known methods described in Macromolecules 1992, 25, 1214-1223 can be referred to.

  The reaction temperature in these reactions is not particularly limited as long as the reaction solution is kept in a liquid state, but the lower limit is preferably −100 ° C., more preferably −20 from the viewpoint of reactivity. The upper limit is preferably 200 ° C., more preferably 150 ° C., particularly preferably from the viewpoint of the stability of the conjugated polymer and the compound represented by the formula (1). Is 120 ° C.

  The conjugated polymer can be taken out according to a known method. For example, the conjugated polymer can be obtained by adding a reaction solution to a lower alcohol such as methanol and filtering and drying the deposited precipitate. When the purity of the obtained conjugated polymer is low, it can be purified by usual methods such as recrystallization, continuous extraction with a Soxhlet extractor, column chromatography and the like.

  The polymer light emitter composition of the present invention may be a composition (solution state) containing the polymer light emitter, a metal alkoxide, and a solvent.

  As the solvent, a stable solvent capable of uniformly dissolving or dispersing the polymer light emitter and the metal alkoxide can be appropriately selected from known solvents. Examples of such solvents include alcohols (methanol, ethanol, isopropyl alcohol, etc.), ketones (acetone, methyl ethyl ketone, etc.), organic chlorines (chloroform, 1,2-dichloroethane, etc.), and aromatic hydrocarbons (benzene, Toluene, xylene, etc.), aliphatic hydrocarbons (normal hexane, cyclohexane, etc.), amides (dimethylformamide, etc.), sulfoxides (dimethyl sulfoxide, etc.) and the like. These solvents may be used alone or in combination of two or more.

The content of the metal alkoxide is usually 0.01 to 1000 parts by weight, preferably 0.1 to 500 parts by weight, and more preferably 1 to 50 parts by weight with respect to 100 parts by weight of the polymer.
When the polymer light emitter composition of the present invention contains a solvent, the total amount of the solvent is usually about 1,000 to 100,000 parts by weight with respect to 100 parts by weight of the total amount of the polymer and the metal alkoxide.

  In addition to the polymer light emitter and metal alkoxide, the polymer light emitter composition of the present invention may contain other components as long as the charge transport property and the charge injection property are not impaired.

The polymer light-emitting device of the present invention has a layer formed using the polymer light-emitting composition, and specifically includes, for example, an electrode composed of an anode and a cathode, and the composition provided between the electrodes. A layer made of a material is used as a light emitting layer. For example, the following layer structure is mentioned.
a) Anode / hole injection layer (hole transport layer) / light emitting layer / cathode b) Anode / light emitting layer / electron injection layer (electron transport layer) / cathode c) Anode / hole injection layer (hole transport layer) / Light emitting layer / electron injection layer (electron transport layer) / cathode d) anode / hole injection layer / hole transport layer / light emitting layer / cathode

  The light emitting layer formed using the polymer light emitter composition of the present invention is preferably formed by a coating method. The coating method is preferable in that the manufacturing process can be simplified and the productivity is excellent, and the casting method, spin coating method, bar coating method, blade coating method, roll coating method, gravure printing, screen printing, ink jet method, etc. Is mentioned. In the coating method, a composition (solution state) containing the polymer light emitter, metal alkoxide, and solvent is prepared as a coating solution, and the coating solution is applied onto a desired layer or electrode and dried. Layers and films can be formed.

  Examples will be shown below for illustrating the present invention in more detail, but the present invention is not limited to these examples.

-Method for measuring molecular weight-
In Examples, the number average molecular weight (Mn), the weight average molecular weight (Mw), and the peak top molecular weight (Mp) were determined in terms of polystyrene by gel permeation chromatography (GPC). Specifically, using a column in which three TSKgel SuperHM-H (manufactured by Tosoh) are connected in series by GPC (manufactured by Tosoh, product name: HLC-8220GPC), the flow rate is 0.5 mL / min using tetrahydrofuran as a developing solvent. And measured at 40 ° C. A differential refractive index detector was used as the detector.

で表される化合物Ａ 6.2171g、下記式：

で表される化合物Ｂ 0.5085g、下記式：

で表される化合物Ｃ 6.2225g、及び下記式：

で表される化合物Ｄ 0.5487gを取り、窒素置換した。トルエン100mlを加え、ジクロロビス（トリフェニルホスフィン）パラジウム（II） 7.6mg、炭酸ナトリウム水溶液24mlを加え、環流下で３時間攪拌した後、フェニルホウ酸0.40gを加え、終夜攪拌した。ナトリウムＮ，Ｎ−ジエチルジチオカルバメート水溶液を加え、さらに環流下で３時間攪拌した。得られた反応液を分液し、有機相を酢酸水溶液及び水で洗浄した後、メタノール中に滴下したところ、沈殿が生じた。得られた沈殿を、ろ過し、減圧乾燥した後、トルエンに溶解させ、シリカゲル−アルミナカラムを通し、トルエンで洗浄した。得られたトルエン溶液をメタノール中に滴下したところ、沈殿が生じた。得られた沈殿を、ろ過し、減圧乾燥した後、トルエンに溶解させ、メタノールに滴下ところ、沈殿が生じた。得られた沈殿を、ろ過し、減圧乾燥して、7.72gの高分子化合物１（共役系高分子）を得た。高分子化合物１のポリスチレン換算の数平均分子量Ｍｎは１．２×１０⁵であり、ポリスチレン換算の重量平均分子量Ｍｗは２．９×１０⁵であった。 <Synthesis Example 1> (Synthesis of Polymer Compound 1)
Triscaprylylmethylammonium chloride (trade name: Aliquat336) 1.72 g in a 500 ml four-necked flask, the following formula:

6.2171 g of the compound A represented by the following formula:

Compound B 0.5085 g represented by the following formula:

6.2225 g of the compound C represented by the formula:

The compound D represented by the formula (0.5487 g) was taken and replaced with nitrogen. Toluene (100 ml) was added, dichlorobis (triphenylphosphine) palladium (II) (7.6 mg) and sodium carbonate aqueous solution (24 ml) were added, and the mixture was stirred for 3 hours under reflux, then phenylboric acid (0.40 g) was added, and the mixture was stirred overnight. Sodium N, N-diethyldithiocarbamate aqueous solution was added, and the mixture was further stirred under reflux for 3 hours. The obtained reaction solution was separated, and the organic phase was washed with an acetic acid aqueous solution and water, and then dropped into methanol, resulting in precipitation. The obtained precipitate was filtered, dried under reduced pressure, dissolved in toluene, passed through a silica gel-alumina column, and washed with toluene. When the obtained toluene solution was dropped into methanol, precipitation occurred. The obtained precipitate was filtered, dried under reduced pressure, dissolved in toluene, and dropped into methanol, resulting in precipitation. The resulting precipitate was filtered and dried under reduced pressure to obtain 7.72 g of polymer compound 1 (conjugated polymer). The number average molecular weight Mn in terms of polystyrene of the polymer compound 1 was 1.2 × 10 ⁵ , and the weight average molecular weight Mw in terms of polystyrene was 2.9 × 10 ⁵ .

で表される化合物Ａ 234.06g、下記式：

で表される化合物Ｅ 172.06g、及び下記式：

で表される化合物Ｆ 28.5528gを取り、窒素置換した。アルゴンバブリングしたトルエン2620gを加え、攪拌しながら更に30分間バブリングした。酢酸パラジウム 99.1mg、トリス（ｏ−トリル）ホスフィン 937.0mgを加え、158gのトルエンで洗い流し、95℃に加熱した。17.5重量％炭酸ナトリウム水溶液855gを滴下後、バス温110℃に昇温し、9.5時間攪拌した後、フェニルホウ酸5.39gをトルエン96mlに溶解して加え、14時間攪拌した。200mlのトルエンを加え、反応液を分液し、有機相を３重量％酢酸水溶液850mlで２回、更に850mlの水とナトリウムＮ，Ｎ−ジエチルジチオカルバメート19.89gを加え、４時間攪拌した。分液後、シリカゲル−アルミナカラムを通し、トルエンで洗浄した。得られたトルエン溶液をメタノール50Lに滴下したところ、沈殿が生じた。得られた沈殿を、メタノールで洗浄した。減圧乾燥後、11Lのトルエンに溶解させ、得られたトルエン溶液をメタノール50Lに滴下したところ、沈殿が生じた。得られた沈殿を、ろ過し、減圧乾燥して、278.39gの高分子化合物２を得た。高分子化合物２のポリスチレン換算の数平均分子量Ｍｎは７．７×１０⁴であり、ポリスチレン換算の重量平均分子量Ｍｗは３．８×１０⁵であった。 <Synthesis Example 2> (Synthesis of Polymer Compound 2)
Triscaprylylmethylammonium chloride (trade name: Aliquat336) 40.18 g in a 5 L separable flask, the following formula:

234.06 g of the compound A represented by the following formula:

172.06 g of the compound E represented by the formula:

28.5528 g of the compound F represented by the formula (1) was taken and replaced with nitrogen. Arranged bubbling toluene (2020 g) was added and bubbling was continued for another 30 minutes. 99.1 mg of palladium acetate and 937.0 mg of tris (o-tolyl) phosphine were added, washed with 158 g of toluene, and heated to 95 ° C. After dropwise addition of 855 g of a 17.5 wt% sodium carbonate aqueous solution, the temperature was raised to a bath temperature of 110 ° C. and stirred for 9.5 hours. Then, 5.39 g of phenylboric acid was dissolved in 96 ml of toluene and stirred for 14 hours. 200 ml of toluene was added, the reaction solution was separated, and the organic phase was added twice with 850 ml of 3% by weight acetic acid aqueous solution, and further 850 ml of water and 19.89 g of sodium N, N-diethyldithiocarbamate were added and stirred for 4 hours. After separation, the solution was passed through a silica gel-alumina column and washed with toluene. When the obtained toluene solution was dropped into 50 L of methanol, precipitation occurred. The resulting precipitate was washed with methanol. After drying under reduced pressure, the product was dissolved in 11 L of toluene, and the resulting toluene solution was added dropwise to 50 L of methanol, resulting in precipitation. The resulting precipitate was filtered and dried under reduced pressure to obtain 278.39 g of polymer compound 2. The number average molecular weight Mn in terms of polystyrene of the polymer compound 2 was 7.7 × 10 ⁴ , and the weight average molecular weight Mw in terms of polystyrene was 3.8 × 10 ⁵ .

  In addition, the said compounds AF can be synthesize | combined by the method described in WO2005 / 52027, for example.

  <Examples 1 to 3, Comparative Example 1> (Production and Evaluation of Organic Electroluminescence Element)

<Creation and evaluation of organic EL element>
Spin on a glass substrate with an indium tin oxide (ITO) film having a thickness of 150 nm by sputtering using a solution of poly (ethylenedioxythiophene) / polystyrene sulfonic acid (trade name: Baytron AI4083, manufactured by Starck). A film was formed by coating, and dried at 200 ° C. for 10 minutes on a hot plate in the atmosphere to produce a hole injection layer (film thickness: 60 nm). Next, a toluene solution of polymer compound 2 (filtered through a 0.2 μm Teflon (registered trademark) filter) was applied by spin coating, and baked at 200 ° C. for 15 minutes in a nitrogen atmosphere in a glove box. A hole transport layer (film thickness: 20 nm) was prepared. Further, a toluene solution having a composition shown in Table 1 was prepared (filtered with a 0.2 μm Teflon (registered trademark) filter), and the resulting solution was applied with a light emitting layer by spin coating. The thickness of the light emitting layer was adjusted to 70 nm.
This was dried under reduced pressure at 90 ° C. for 1 hour, LiF was deposited by 4 nm, and Al was deposited by 100 nm. The degree of vacuum at the time of vapor deposition was in the range of 1 × 10 ⁻⁴ Pa to 9 × 10 ⁻³ Pa. Thereafter, the device was sealed by adhering glass with an ultraviolet curable resin in a nitrogen atmosphere. The shape of the element was a regular square of 2 mm × 2 mm. By applying a voltage stepwise to the obtained device, the current density, emission luminance, and emission spectrum were measured. The lifetime was evaluated by constant current drive according to the initial luminance of the device of 3000 cd / m ² . In that case, the time when it becomes 80% of the initial luminance was regarded as the LT 80 life. Table 1 shows the peak wavelength of EL emission and the LT80 lifetime.

As can be seen from Table 1, the light emitting layer formed using the composition containing the polymer light emitter (polymer compound 1) and titanium tetraisopropoxide or niobium pentaethoxide is composed of the polymer light emitter alone. Compared with the light emitting layer formed by using, the lifetime of LT80 when the initial luminance is the same is remarkably improved. Therefore, it was confirmed that the device using the polymer light emitter composition of the present invention was excellent in lifetime.

Claims (4)

A polymer light emitting device having an electrode composed of an anode and a cathode, and a light emitting layer formed between the electrodes and using a polymer light emitter composition,
A polymer light emitting device, wherein the polymer light emitter composition comprises a polymer light emitter and a metal alkoxide. The polymer light emitting device according to claim 1, wherein the polymer light emitter is a conjugated polymer. 3. The polymer light emitting device according to claim 1, wherein the content of the metal alkoxide is 0.001 to 1000 parts by weight when the polymer light emitter is 100 parts by weight. The polymer light-emitting device according to claim 1, wherein the alkyloxy group of the metal alkoxide has 1 to 20 carbon atoms.