KR20090030884A - Light-emitting fluorene-based copolymer and el device using the polymer - Google Patents

Abstract

A light-emitting fluorene-based polymer is provided to ensure excellent thermal and electrical stability, excellent luminous efficiency and luminous efficiency by introducing a phenothiazine having polarity and DCM derivative to the skeleton of a fluorene group derivative. A light-emitting fluorene-based polymer has a structure represented by the chemical formula 1. In the chemical formula 1, R1 and R2 are independently hydrogen, silyl group or C1~C22 linear or branched alkyl group; R3 and R4 are independently hydrogen, or C1~C22 linear or branched alkyl group; n and m are independently an integer of 1-100,000.

Description

Fluorine-based light emitting polymer and electroluminescent device using the same {LIGHT-EMITTING FLUORENE-BASED COPOLYMER AND EL DEVICE USING THE POLYMER}

The present invention relates to a fluorene-based light emitting polymer and an electroluminescent device comprising the same as a light emitting material, and more specifically, a fluorene-based compound as a main chain and a polar phenocyazine and DCM derivative is introduced therein solubility, The present invention relates to a fluorene-based light emitting polymer having excellent luminous efficiency and color purity as well as an electroluminescent device using the same.

Since poly (9,9'-dihexylfluorene) is reported as a blue light emitting polymer as a light emitting polymer for electroluminescent devices, polyfluorene-based conjugated polymers have high photoluminescence quantum efficiency, thermal, chemical and electrochemical stability, and Due to the excellent solubility characteristics in various organic solvents, many studies are being conducted as potential blue light emitting polymers. However, polyfluorene homopolymers have difficulty in equally injecting holes and electrons due to high ionization energy and low electron affinity, which leads to low efficiency of the polymer electroluminescent device and low electrical stability, resulting in undesired blue-green light emission. There is a problem falling.

In order to obtain the luminescence efficiency and high purity color coordinate in fluorene conjugated polymer, the pursuit of high purity color coordinate according to the morphology change by introducing bulky comonomer showed the disadvantage of low luminous efficiency. An experiment was also introduced to complement the luminous efficiency by introducing a transport material, but the color purity was lowered at a voltage of 5 V or higher. On the other hand, the method of introducing beta-phase by morphological effect showed high purity color coordinates and high efficiency, but to form beta-phase, cooling and cooling were performed after spin coating the polymer solution. There was a disadvantage of having to go through a complicated manner of reheating to room temperature or introducing other solvent vapors.

Therefore, the inventors of the present invention deviated from such a complicated manner and simply introduced a monomer having a polarity in the polyfluorene conjugated polymer to secure electrical stability through the morphology effect using beta-phase formation, as well as the existing fluorene-based An object of the present invention is to provide a light emitting polymer having higher efficiency and higher purity than a conjugated polymer.

The present invention introduces a polar comonomer to the fluorene-based conjugated polymer, which is being studied as a blue polymer, thereby providing high efficiency and high purity as well as solubility, thermal and electrical stability through a morphology effect using beta-phase formation. An object of the present invention is to provide a fluorene-based light emitting polymer that can exhibit characteristics.

In addition, an object of the present invention is to provide an electroluminescent device capable of emitting light with high efficiency and high purity and having excellent luminescent properties by including the fluorene-based light emitting polymer in the light emitting layer.

The present invention provides a fluorene-based light emitting polymer characterized in that represented by the following formula (1):

[Formula 1]

In Formula 1, R1, R2 are each independently hydrogen, a silyl group or a linear or branched alkyl group of C ₁ ~ C ₂₂ ,

R 3 and R 4 are each independently hydrogen or a C ₁ to C ₂₂ linear or branched alkyl group,

n and m are each independently an integer of 1 to 100000.

The present invention also provides an electroluminescent device comprising a light emitting layer containing the fluorene-based light emitting polymer.

The present invention also provides a method of preparing the fluorene-based light emitting polymer of Formula 1 by copolymerizing a monomer represented by Formula 2, a monomer represented by Formula 3 and a monomer represented by Formula 4 in the presence of a palladium catalyst.

[Formula 2]

[Formula 3]

[Formula 4]

In the above formula, R1, R2 are each independently hydrogen, silyl group or C ₁ ~ C ₂₂ linear or branched alkyl group,

R 3 and R 4 are each independently hydrogen or a C ₁ to C ₂₂ linear or branched alkyl group,

Each X is independently a halogen atom,

Y is a boron compound or a derivative thereof.

The fluorene-based light emitting polymer of the present invention exhibits excellent thermal and electrical stability, excellent luminous efficiency and high purity by introducing phenoxyazine and DCM derivatives having polarity into the skeleton of the fluorene-based derivative, and thus, as a light emitting material of the electroluminescent device. It can be usefully used.

The fluorene-based light emitting polymer of the present invention is characterized by represented by the formula (1). The fluorene-based light emitting polymer of the present invention forms a beta-phase by introducing the monomer represented by Formula 4 into the fluorene skeleton, thereby improving the morphology of the polymer film as well as the electron donor phenocyazine and electrons. Because of its polarity because it is formed as a supportive DCM derivative, it improves luminous efficiency and prevents packing of polymer chains, thereby preventing photoluminescence or electroluminescence in the long wavelength region. Can exert.

In Formula 1, n / m is preferably in the range of 99999/1 to 9980/20. More preferably, it is 99990/10-9985/15. When in the above range, it is possible to implement a blue light-emitting fluorene-based polymer having more efficient, high purity electroluminescence. Also preferably, the fluorene-based light emitting polymer of the present invention preferably has a number average molecular weight (Mn) of 5,000 to 150,000 and a weight average molecular weight (Mw) of 10,000 to 300,000.

Specific examples of the comonomer of Formula 4 for preparing the fluorene-based light emitting polymer of the present invention include a monomer of Formula 5 wherein R3 and R4 are hexyl groups and X is Br. These are selected as necessary to explain the content of the present invention, but the content of the present invention is not limited to the following compounds.

[Formula 5]

As a specific example of the comonomer of formula (4), the method for producing a monomer represented by formula (5) having a hexyl group is as follows.

First, as shown in Scheme 1, 10-hexylphenosazine is introduced into an aldehyde group through a Vilsmeyer reaction to obtain 10-phenoxyazine-3-carbaaldehyde, a phenoxyazinealdehyde monomer substituted with an alkyl group. After obtaining, 7-bromo-10-hexylphenosazine-3-carbaaldehyde can be prepared by introducing a bromine atom through a bromination reaction using N-bromosuccinimide (NBS).

Scheme 1

Next, as in Scheme 2 below, 7-bromo-10-hexylphenocyazine-3-carbaaldehyde prepared in Scheme 1 and (2,6-dimethyl-4H-pyran-4-ylidene) malono Nitrile is reacted with piperidine to give the desired 2-2,6-bis- [2- (7-bromo-10-hexyl-10H-phenoxyazin-3-yl) -vinyl]- Pyran-4-ylidene-malononitrile (hereinafter bis-PTZDCM) can be obtained.

Scheme 2

As a specific example of the fluorene monomer of the formula (2), 2,7-dibromo-9,9-dioctylfluorene, in which R1 and R2 are octyl groups and X is bromine, is a tetraphase transfer catalyst (PTC). It can be prepared by reacting 2,7-dibromofluorene and octylbromide at 80 ° C. in the presence of butylammonium bromide.

The fluorene-based light emitting polymer of the present invention can be prepared as in Scheme 3 by copolymerizing a monomer represented by Formula 2, a monomer represented by Formula 3, and a monomer represented by Formula 4 in the presence of a palladium catalyst.

Scheme 3

In the above scheme, R1, R2, R3, R4, X, Y, m and n are as defined above.

The copolymerization reaction may be performed at a temperature of 60 to 100 ° C. for 12 to 90 hours, and the amount of the monomer of Formula 2, the monomer of Formula 3, and the monomer of Formula 4 is determined to the desired n and m values of the polymer product to be polymerized. Can be adjusted accordingly.

As a specific example, as shown in Scheme 4 below, 2,7-dibromo-9,9-dioctylfluorene and 2,7-bis (4,4,5,5-tetramethyl-, wherein R1 and R2 are octyl groups 1,3,2-dioxalbororan-2-yl) -9,9-dioctylfluorene and the monomer of formula 5 wherein R3 and R4 are hexyl groups are copolymerized in the presence of a palladium catalyst to fluorene A light emitting polymer can be obtained.

Scheme 4

The light emitting polymer of the present invention prepared through the above process can be seen to have a structure in which the monomer of the formula (4) consisting of a fluorene unit and a polar phenoxyazine and a DCM derivative is distributed irregularly.

The monomer of Chemical Formula 4 has a function of reducing pollution in the long wavelength region by preventing polarization of the long wavelength region by preventing packing and improving the morphology of the polymer film by reducing the polarity.

In another aspect, the present invention provides an electroluminescent device comprising a light emitting layer containing a fluorene-based light emitting polymer represented by the formula (1).

The electroluminescent device of the present invention can be applied to a well-known functional layer and a manufacturing process that can be commonly applied to the electroluminescent device, except that the light emitting layer contains the fluorene-based light emitting polymer represented by Formula 1 above. .

A typical organic light emitting device is an organic thin film layer such as a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL) between the anode (anode) and the cathode (cathod) It may include one or more.

First, an anode is formed by depositing a material for an anode electrode having a high work function on the substrate. In this case, the substrate may be a substrate used in a conventional organic light emitting device, it is particularly preferable to use a glass substrate or a transparent plastic substrate excellent in mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproof. In addition, as the anode electrode material, transparent and excellent indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like may be used. The anode electrode material may be deposited by a conventional anode forming method, and specifically, may be deposited by a deposition method or a sputtering method.

Thereafter, a hole injection layer (HIL) material may be formed on the anode by vacuum deposition, spin coating, casting, or Langmuir-Blodgett (LB), but it is easy to obtain a uniform film quality. In addition, it is preferable to form by the vacuum evaporation method from the point which pinholes hardly generate | occur | produce. When the hole injection layer is formed by the vacuum deposition method, the deposition conditions vary depending on the compound used as the material of the hole injection layer, the structure and thermal properties of the desired hole injection layer, and generally, a deposition temperature of 50 to 500 ° C., to 10 ^-8 ~ 10 ^-3 torr vacuum, suitably selected in a film thickness range of 0.01 ~ 100 Å / sec deposition rate of, 10 Å ~ 5 ㎛ are preferred.

The hole injection layer material is not particularly limited, and TCTA, m-MTDATA, m-MTDAPB (Advanced Material, 6, p677 (1994), which are phthalocyanine compounds or starburst amine derivatives such as copper phthalocyanine disclosed in US Patent No. 4,356,429 )) And the like can be used as the hole injection layer material.

Next, a hole transport layer (HTL) material may be formed on the hole injection layer by a vacuum deposition method, a spin coating method, a cast method, an LB method, etc., but it is easy to obtain a uniform film quality and difficult to generate pin holes. It is preferable to form by the vacuum deposition method at the point. In the case of forming the hole transport layer by the vacuum deposition method, the deposition conditions vary depending on the compound used, but in general, the hole transport layer is preferably selected in the same condition range as the formation of the hole injection layer.

In addition, the hole transport layer material is not particularly limited, and may be arbitrarily selected and used from conventionally known materials used in the hole transport layer. Specifically, the hole transport layer material is carbazole derivatives such as N-phenylcarbazole, polyvinylcarbazole, N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-ratio Ordinary amines having aromatic condensed rings such as phenyl] -4,4'-diamine (TPD), N.N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD) Derivatives and the like can be used.

Thereafter, the light emitting layer (EML) material may be formed on the hole transport layer by a method such as vacuum deposition, spin coating, cast, LB, etc., but it is easy to obtain a uniform film quality and hard to generate pin holes. It is preferable to form by the vacuum deposition method. In the case of forming the light emitting layer by the vacuum deposition method, the deposition conditions vary depending on the compound used, but in general, it is preferable to select within the same condition range as the formation of the hole injection layer. In addition, the light emitting layer material may be formed using a fluorene-based light emitting polymer represented by the formula (1) of the present invention alone, or formed by blending a polymer that is easy to transport electrons or holes, such as PVK (polyvinylcarbazole) You may. The ratio of the blending is not particularly limited, but is preferably blended at 0.01 to 15 parts by weight based on 100 parts by weight of the fluorene-based light emitting polymer. If the content is less than 0.01 parts by weight, there is a problem that the color is not properly formed due to the insufficient amount, when the content is more than 15 parts by weight there is a problem that the efficiency is sharply reduced due to the concentration quenching phenomenon.

 An electron transport layer (ETL) material is formed on the light emitting layer formed as above, wherein the electron transport layer is formed by a vacuum deposition method, a spin coating method, a casting method, or the like, and is preferably formed by a vacuum deposition method.

The electron transport layer material has a function of stably transporting electrons injected from an electron injection electrode (Cathode) is not particularly limited in kind, for example, quinoline derivatives, especially tris (8-quinolinorate) aluminum ( Alq3) can be used. In addition, an electron injection layer (EIL), which is a material having a function of facilitating injection of electrons from the cathode, may be stacked on the electron transport layer, and the electron injection layer material may be LiF, NaCl, CsF, Li ₂ O, BaO, or the like. The substance of can be used.

In addition, although the deposition conditions of the electron transport layer (ETL) are different depending on the compound used, it is generally preferable to select within the same condition range as the formation of the hole injection layer.

Thereafter, an electron injection layer (EIL) material may be formed on the electron transport layer, wherein the electron transport layer is formed of a conventional electron injection layer material by a vacuum deposition method, a spin coating method, a casting method, and the like. It is preferable to form by the vacuum deposition method.

Finally, the cathode forming metal is formed on the electron injection layer by a method such as vacuum deposition or sputtering and used as a cathode. The cathode forming metal may be a metal having low work function, an alloy, an electrically conductive compound, and a mixture thereof. Specific examples include lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and the like. There is this. In addition, a transmissive cathode using ITO and IZO may be used to obtain a top emitting device.

The organic light emitting device of the present invention has an organic structure of an anode, a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), a cathode (cathode) structure Not only the light emitting device, but also the structure of the organic light emitting device of various structures is possible, it is also possible to further form one or two intermediate layers as needed.

As a specific example, the structure of the electroluminescent device of the present invention includes a translucent electrode 2, a hole transport layer 3, a polymer light emitting layer 4, an electron transport layer 5, and a metal electrode 6 on a predetermined substrate 1. It may be formed by stacking sequentially, and may also be formed as a single layer electroluminescent device which is simply composed of a semi-transparent electrode 2, a polymer light emitting layer 4 and a metal electrode 6 on the substrate (1).

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention in more detail, and do not limit the scope of the present invention.

Preparation Example 1 Preparation of 10-hexylphenocyazine-3-carbaaldehyde

22.3 mL of POCl ₃ was added dropwise to a flask containing 65 mL of DMF at 0 ° C. for 30 minutes, and then 10-hexylphenocyazine (20 g, 69.3 mmol) was added to the vessel with 1,1,2-trichloroethane. The solution dissolved in 60 mL was added and then reacted at 90 ° C. for 2 hours. After cooling to room temperature, the solution was poured into iced water, and sodium hydroxide solution was added to neutralize the solution to pH 6-7. The organic layer was extracted with ethylene acetate, followed by removal of a small amount of water with MgSO ₄ , followed by solvent removal. Nosyazine-3-carbaaldehyde (15.1 g) was obtained (yield: 70%).

^One H-NMR (DMSO, ppm): d 9.77 (s, 1H), 7.70 (d, 1H), 7.54 (s, 1H), 7.20 (t, 1H), 7.12 (m, 2H), 7.03 (m, 2H ), 3.89 (t, 2H), 1.79 (q, 2H), 1.43 (m, 2H), 1.28 (m, 4H) 0.85 (m, 3H).

¹³ C-NMR (DMSO, ppm): d 190.9, 149.9, 143.0, 131.2, 130.7, 128.6, 128.4, 128.0, 124.0, 123.3, 121.1, 116.5, 115.5, 48.5, 31.2, 26.6, 26.3, 22.5, 13.9.

Elemental Analysis. C ₁₉ H ₂₁ Theoretical for NOS: C, 73.27; H, 6.80; N, 4.50; S, 10.30. Found: C, 73.15; H, 6.87; N, 4.40; S, 10.25.

Preparation Example 2 Preparation of 7-Bromo-10-hexylphenocyazine-3-carbaaldehyde

A solution of 10-hexylphenocyazine-3-carbaaldehyde (5.7 g, 18.3 mmol) and N-bromosuccinimide (3.3 g, 18.3 mmol) synthesized in Example 1 was dissolved in 40 mL of acetic acid and 10 mL of toluene. Was reacted for 3 hours. After distilled water was added to the solution, the organic layer was extracted using ethylene acetate, and then a small amount of water was removed using MgSO ₄ , and then the solvent was removed. The resulting material was subjected to column chromatography using hexane as a developing solvent. -10-hexylphenocyazine-3-carbaaldehyde (5.07 g) was obtained (yield: 71%).

^One H-NMR (DMSO, ppm): d 9.78 (s, 1H), 7.64 (d, 1H), 7.54 (s, 1H), 7.23 (m, 2H), 6.87 (d, 1H), 6.68 (d, 1H ), 3.82 (t, 2H), 1.78 (m, 2H), 1.41 (m, 2H), 1.27 (m, 4H) 0.86 (t, 3H).

¹³ C-NMR (DMSO, ppm): d 190.5, 149.6, 142.4, 131.0, 130.4, 130.2, 129.1, 127.9, 125.2, 122.9, 118.1, 115.8, 114.9, 47.0, 30.7, 25.9, 25.6, 22.0, 13.8.

Elemental Analysis. C ₁₉ H ₂ Theoretical for 0 BrNOS: C, 58.46; H, 5.16; N, 3.59; S, 8.21. Found: C, 58.41; H, 5.26; N, 3.50; S, 8.09.

Preparation Example 3 2-2,6-Bis- [2- (7-Bromo-10-hexyl-10H-phenoxyazin-3-yl) -vinyl] -pyran-4-ylidene-malononitrile Manufacture

7-Bromo-10-hexylphenocyazine-3-carbaaldehyde (4.68 g, 12 mmol) synthesized in Example 2, (2,6-dimethyl-4H-pyran-4-ylidine) malononitrile (0.94 g, 5.5 mmol), piperidine (0.6 mL) and a solution consisting of 30 mL of n-butanol were reacted at 90 ° C. for 24 hours. After the reaction was completed, the solution was cooled to room temperature and excess methanol was added to give a red solid. After filtration, it was dried, dissolved in methylene chloride and recrystallized with methanol to give red 2-2,6-bis- [2- (7-bromo-10-hexyl-10H-phenoxyazin-3-yl) -vinyl] -Pyran-4-ylidene-malononitrile solid material (3.43 g) was obtained (yield: 68%).

^One H-NMR (DMSO, ppm): d 7.65 (m, 6H), 7.37 (m, 4H), 7.24 (d, 2H), 7.09 (d, 2H), 6.98 (d, 2H), 6.79 (s, 2H ), 3.89 (t, 4H), 1.66 (q, 4H), 1.38 (m, 4H), 1.25 (m, 8H) 0.83 (t, 6H).

¹³ C-NMR (DMSO, ppm): d 159.3, 156.0, 149.4, 149.2, 141.9, 134.7, 130.9, 130.3, 130.0, 129.3, 127.9, 125.1, 123.3, 118.1, 116.4, 115.5, 114.3, 56.1, 47.0, 30.9, 25.9, 25.6, 21.9, 13.8.

Elemental Analysis. C ₄₈ H ₄₄ Br ₂ N ₄ OS ₂ Theorem for: C, 62.88; H, 4.84; N, 6.11; S, 6.99. Found: C, 63.05; H, 4.86; N, 6.29; S, 6.81.

Examples 1 to 3 and Comparative Examples: Preparation of Light-Emitting Polymers

To 50 mol% of monomer 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxalborolan-2-yl) -9,9-dioctyl fluorene, 2,7-Dibromo-9,9-dioctylfluorene and 2-2,6-bis- [2- (7-bromo-10-hexyl-10H-phenoxyazine-3 obtained in Example 3 -Yl) -vinyl] -pyran-4-ylidene-malononitrile was added to a total of 50 mol% to vary the addition ratio. These monomers and tetrakis (triphenylphosphine) palladium (1 mol%) were dissolved in toluene and reacted at 90 ° C. for 60 hours by adding Aliquat 336, which is a phase transfer catalyst, and K ₂ CO ₃ . A small amount of bromobenzene was dissolved in toluene and injected into it for endcapping, and after 12 hours, phenylboronic acid was injected into toluene. After the reaction, the solution was slowly dropped into a mixed solution composed of hydrochloric acid and methanol to obtain a polymer, which was then reprecipitated and purified by Soxhlet extractor for 3 days to synthesize pure polymer. The reaction scheme is the same as in Scheme 4.

The light emitting polymers prepared through the above examples can be easily dissolved in various organic solvents, and the number average molecular weight (Mn) measured by gel permeation chromatography was 63,000 to 123,000, and the dispersion degree (Mn / Mw) was 1.9. To 2.3. Such polymerization results are shown in Table 1 below.

TABLE 1

Copolymer Example 1 (F8R5) Example 2 (F8R8) Example 3 (F8R10) Comparative example Number average molecular weight (Mn) 100,000 63,000 123,000 60,000 Mass average molecular weight (Mw) 190,000 138,000 271,000 120,000 Dispersion (Mn / Mw) 1.9 2.2 2.3 2.0 Yield (%) 75  65 68 74 m ratio (%) 0.13 0.15 0.20 0 * m ratio is calculated based on nitrogen through elemental analysis. Comparative Example: Fluorene Homopolymer

Example 4 Absorption (UV) and Photoluminescence (PL) Properties of Polymers

The light emitting polymers prepared in Example 1 were dissolved in chloroform to prepare a film using a known spin coating method on a quartz plate. UV maximum absorption wavelength in the film state appears at 395 nm and it can be seen that the shift to a longer wavelength than the fluorene homopolymer (Fig. 2). In addition, the absorption wavelength at 435 nm is seen as the monomer represented by Formula 4 enters, which is the same as the result obtained when the beta-phase was formed by using a conventional solvent. It can be seen that.

When the photoluminescence spectra of the prepared polymers were measured in a film state, the maximum absorption wavelength was shifted slightly longer than that of the fluorene homopolymer because the monomer having the low energy band gap (Formula 4) enters. In general, the photoluminescence spectra of polyfluorenes without beta-phase have peaks at 423 nm (strong peak, 0-0 bands), 447 nm (shoulder, 0-1 bands), and 470 nm (weak shoulder, 0-2 bands). Although the form appears, but the beta-phase is formed because the conjugate length is long, it shows a phenomenon of moving to a longer wavelength. As the monomer (Formula 4) enters, the maximum wavelength appears at 440 nm (strong peak, 0-0 bands) and peaks at 423 nm due to the amorphous portion. It was found that energy transfer to the beta-phase acting as a self-dopant on the force. In addition, in the case of the polymer (F8R10) of Example 3 containing 10% of the monomer (Formula 4), it was confirmed from FIG. 3 that the spectrum appeared in the red region of 606 nm together with the spectrum of the short wavelength, that is, the blue region.

The spectral results are shown in Table 2 below, and the photoluminescent quantum efficiency is expressed as a relative value when the quantum efficiency of the comparative example is set to 1. The quantum efficiencies of the polymers prepared in Examples 1 to 3 were much higher than those of the comparative example. This is because the luminescent efficiencies are increased by the morphology effect of the beta-phase by introducing a monomer having a polarity into the fluorene main chain. Shows that it increases. Detailed results are shown in Table 2 below.

TABLE 2

Copolymer Wavelength (λmax) Photoluminescent Quantum Efficiency (Film) UV absorption Photoluminescence Electroluminescence Example 1 (F8R5) 395 424,440,465 434,458,488 1.92 Example 2 (F8R8) 395 424,440,465 434,458,490 1.58 Example 3 (F8R10) 395 424,439,606 434,458,617 1.01 Comparative example 384 422,446,476 430,456,490 1.00 Comparative Example: Fluorene Homopolymer

Example 5: Electroluminescence (EL) Properties of Polymers

A light emitting device was manufactured in which the polymers prepared in Examples 1 to 3 were used as light emitting layers. That is, by using a commercial product laminated 100 nm of ITO on an organic substrate, first spin-coated PODOT (PSDOT: PSS) on the ITO layer, and then forming a light emitting layer having a thickness of 100 nm by dissolving the prepared polymer in chloroform. After laminating calcium (Ca), 500 nm of aluminum (Al), which is used as a cathode, was stacked thereon to manufacture a single layer light emitting device. The electroluminescence spectrum of the manufactured light emitting device is shown in FIG. 4, and it can be seen that a phenomenon similar to the photoluminescence spectrum also appears in the electroluminescence spectrum. In particular, in Example 1 (F8R5) and Example 2 (F8R8), the maximum wavelength of the electroluminescence spectrum is shifted toward longer wavelength than the comparative example (fluorene homopolymer), and on the long wavelength side, polyfluorene homopolymer The intensity of the spectrum is lowered. In the case of F8R10 prepared in Example 3, it can be seen that the spectrum appears at 617 nm, which is due to partial energy transfer from the polyfluorene to the monomer having the low energy bandgap, thereby emitting light from the monomer having the low energy bandgap. This shows that this is done. This shows that when the monomer having a low energy bandgap is less than 0.15%, only the blue portion appears, but when more than that, the red portion appears to reduce the purity of blue. In addition, when controlling the ratio of monomers composed of phenocazine and DCM derivatives having a polarity, it is possible to realize white light by simultaneously implementing red as well as blue. The color coordinates of the manufactured light emitting device are shown in FIG. 5. As shown in FIG. 5, F8R5 and F8R8 showed better performance in color purity than polyfluorene homopolymers.

In addition, the electroluminescence spectrum according to the voltage is shown in FIG. As the voltage increased, the electroluminescence spectrum with voltage was more stable with F8R5 than with the fluorene homopolymer having the spectrum at the longer wavelength.

In addition, the voltage-current characteristic is shown in FIG. 7, and the voltage-emitting intensity characteristic is shown in FIG. 8. As shown in FIG. 7 and FIG. 8, F8R5 and F8R10 of the present invention were confirmed to exhibit excellent electrical properties.

1 is a cross-sectional view of an organic light emitting device according to an embodiment of the present invention,

2 is a graph showing the UV emission spectrum of the light emitting polymers prepared in Examples 1 to 3 of the present invention,

3 is a graph showing the PL emission spectrum of the light emitting polymers prepared in Examples 1 to 3 of the present invention,

4 is a graph showing the EL emission spectrum of the light emitting polymers prepared in Examples 1 to 3 of the present invention,

5 is a graph illustrating color coordinates of a light emitting device using light emitting polymers prepared in Examples 1 to 3 of the present invention;

6 is a graph illustrating EL emission spectra according to voltages of light emitting polymers prepared in Examples 1 to 3 of the present invention;

7 is a graph illustrating voltage-current density characteristics of light emitting devices using light emitting polymers prepared in Examples 1 to 3 of the present invention.

8 is a graph illustrating voltage-emitting intensity characteristics of light emitting devices using light emitting polymers prepared in Examples 1 to 3 of the present invention.

[Description of Symbols for Main Parts of Drawing]

1: substrate 2: anode 3: hole transport layer

4: polymer light emitting layer 5: electron transport layer 6: cathode

Claims (10)

Fluorene-based light emitting polymer, characterized in that represented by the formula (1): [Formula 1]

In Formula 1, R1, R2 are each independently hydrogen, a silyl group or a linear or branched alkyl group of C ₁ ~ C ₂₂ , R 3 and R 4 are each independently hydrogen or a C ₁ to C ₂₂ linear or branched alkyl group, n and m are each independently an integer of 1 to 100000. The method of claim 1, Fluorine-based light emitting polymer, characterized in that n and m of the formula (1) satisfies n / m in the range of 99999/1 to 9980/20. The method of claim 1, The fluorene-based light emitting polymer, characterized in that n and m in the general formula (1) satisfies n / m in the range of 99990/10 to 9985/15, the polymer emits blue. The method of claim 1, Fluorine-based light emitting polymer, characterized in that the fluorene-based light emitting polymer has a weight average molecular weight (Mw) of 10,000 to 300,000. Comonomers represented by the following formula (4): [Formula 4]

In the above formula, R 3 and R 4 are each independently hydrogen or a C ₁ to C ₂₂ linear or branched alkyl group, X is each independently a halogen atom. A method for preparing a fluorene-based light emitting polymer of Formula 1, comprising copolymerizing a monomer represented by Formula 2, a monomer represented by Formula 3, and a comonomer represented by Formula 4 in the presence of a palladium catalyst: [Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

R 1 and R 2 in the formula are each independently hydrogen, a silyl group or a C ₁ to C ₂₂ linear or branched alkyl group, R 3 and R 4 are each independently hydrogen or a C ₁ to C ₂₂ linear or branched alkyl group, n and m are each independently an integer of 1 to 100000, Each X is independently a halogen atom, Y is a boron compound or a derivative thereof. The method of claim 6, The n and m of the formula (1) is a method for producing a fluorene-based light emitting polymer, characterized in that it satisfies n / m in the range 99999/1 to 9980/20. An electroluminescent device comprising a light emitting layer containing the light emitting polymer of claim 1. The method of claim 8, The electroluminescent device has a multi-layered thin film structure comprising an anode, a hole transporting layer, a polymer light emitting layer containing the light emitting polymer of claim 1, an electron transporting layer and a cathode sequentially on the substrate. Electroluminescent device. The method of claim 8, Electroluminescent device, characterized in that the light emitting layer further contains an electron transport polymer or a hole transport polymer.

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