KR20080107840A - Novel white light-emitting polymer, preparation thereof and el device using the polymer - Google Patents

Abstract

A white light-emitting polymer is provided to realize white light through the energy transfer by introducing a monomer showing an orange-red color to a blue light emitting polymer as a main chain. A white light-emitting polymer is represented by the chemical formula 1. In the chemical formula 1, R1 and R2, are independently, hydrogen, silyl or C1 ~ C22 linear or branched alkyl group; Ar is a fluorene derivative, thiophene derivative or phenylene derivative; n and m are an integer of 1 - 10000, wherein n and m are satisfied with the n / m ratio of 9995/5 ~ 90/10; and Ar is 2,7- dibromo - 9,9 '- dioctylfluorene, and 2,7- dibromo -9,9' - dihexylfluorene, 2,7- dibromo - 9,9 '- dihexylfluorene task -1,2,3,4- tetrahydroquinoline, and 5,5' - dibromo -2,2'- di thiophene or 1,4- dibromo phenylene.

Description

Novel white light emitting polymer, manufacturing method and electroluminescent device using same {NOVEL WHITE LIGHT-EMITTING POLYMER, PREPARATION THEREOF AND EL DEVICE USING THE POLYMER}

1 is a cross-sectional view of an electroluminescent device according to one embodiment of the invention,

2 is a graph showing the UV absorption spectrum of the light emitting polymers prepared in Example 4 of the present invention,

3 is a graph showing a PL emission spectrum of the light emitting polymers prepared in Example 4 of the present invention,

4 is a graph showing the EL emission spectrum of the light emitting device using the light emitting polymers prepared in Example 4 of the present invention,

FIG. 5 is a graph illustrating voltage-current density characteristics of light emitting devices using light emitting polymers prepared in Example 4 of the present invention.

6 is a graph showing the voltage-emitting intensity characteristic of the light emitting device using the light emitting polymers prepared in Example 4 of the present invention,

7 is a graph illustrating EL emission spectra according to voltages of light emitting devices using light emitting polymers prepared in Example 4 of the present invention.

[Description of Symbols for Main Parts of Drawing]

1: Substrate 2: Translucent Electrode 3: Hole Transport Layer

4: polymer light emitting layer 5: electron transport layer 6: metal electrode

The present invention relates to a novel white light emitting polymer, a method of manufacturing the same, and an electroluminescent device using the same. More specifically, a fluorene-based blue light emitting polymer is used as a single-chain white light emitting polymer composed of monomers for implementing blue and orange. Novel white luminescent polymer which has white as a main chain and has a structural characteristic by introducing a small amount of orange monomer therein to realize white color by partial energy transfer from blue luminescence to orange luminescent comonomer present in the polymer, and a method of manufacturing the same; It relates to an electroluminescent device using the same.

Currently, white organic electroluminescent devices have been widely applied to backlight units (BLUs) of LCDs and various lighting fixtures. White is a two-color system that generally implements blue and orange, or blue, green, and red. It can be implemented through a three primary color system. In the case of a white organic electroluminescent device using an organic single molecule, a method of implementing white light through energy transition by stacking materials implementing blue, green, and red, respectively, is commonly used. In the case of an electroluminescent device, a method of implementing white light by injecting a small amount of organic materials (monomers and polymers) that implement green, red, or orange into a blue polymer is mixed.

The organic monomolecular device method that realizes white light through lamination has the advantage of greatly improving the efficiency of the device, but has the disadvantage of requiring a great deal of trial and error and time and cost in the fabrication of the device and the thickness of each light emitting layer. In addition, the method of realizing the white light through the mixing method has the advantage that the device fabrication is convenient, but has the disadvantage that the device performance changes in time and space, the phase transition occurs, and the color purity of the device depending on the voltage.

Accordingly, the present inventors prepared a plurality of comonomers to implement orange, instead of implementing the conventional white light, and introduced them as a single chain through copolymerization of blue and orange as a single chain, making a simple device and time-spatially stable and phase-transition through a solution process. The present invention aims to provide a new type of white light emitting polymer that solves the problems raised in the conventional method of changing the color purity of the device according to the and voltage.

Accordingly, the present invention provides a novel polymer having a fluorene-based blue light emitting polymer as a main chain and introducing a small amount of an orange monomer therein to realize white light through partial energy transfer from blue light emission to orange light emission, and It aims at providing the manufacturing method.

In addition, an object of the present invention is to provide an electroluminescent device capable of emitting pure white light by including the white light emitting polymer in the light emitting layer.

In order to achieve the above object, the present invention provides a white light emitting polymer represented by the following formula (1):

     [Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are each independently hydrogen, a silyl group, or a C ₁ to C ₂₂ linear or branched alkyl group;

Ar is a fluorene derivative, a thiophene derivative or a phenylene derivative;

n and m are each independently It is an integer of 1-10000.

The present invention also provides a method of preparing the light emitting polymer, comprising copolymerizing a monomer of Formula 2, a monomer of Formula 3, and a monomer of Formula 4 in the presence of a palladium (0) catalyst in an organic solvent:

      [Formula 2]

[Formula 3]

[Formula 4]

In Chemical Formulas 2, 3, and 4,

R ₁ , R ₂ and Ar are as defined above;

X is a halogen atom;

Y represents a boron compound derivative.

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

Hereinafter, the present invention will be described in more detail.

The white light emitting polymer of the present invention has a structure in which a fluorene-based blue light emitting polymer is used as a main chain and a small amount of orange monomer is introduced therein, and the fluorene unit and the monomer having a low band gap are irregularly repeated. do.

In Chemical Formula 1, preferably, n / m is 9995/5 to 90/10, but is not limited thereto, and Ar is 2,7-dibromo-9,9'-dioctylfluorene, 2,7 -Dibromo-9,9'-dihexylfluorene, 2,7-dibromo-9,9'-dihexylfluorenyl-1,2,3,4-tetrahydroquinoline, 5,5 ' -Dibromo-2,2'-dithiophene or 1,4-dibromo phenylene.

The light emitting polymer of the present invention has a conjugated structure consisting of monomers 1, 2, and 3. In this case, the fluorene skeleton can exhibit excellent luminous efficiency. When the polymer skeleton of Formula 1 receives energy transferred from the fluorene skeleton, the addition ratio of comonomer 3 increases from blue to white according to the addition ratio of comonomer 3 It will emit red. The luminescence process is carried out through partial energy transfer from the high fluorene backbone to the backbone of orange comonomer 3 having a relatively low band gap present in the polymer. Therefore, in the present invention, the desired white light emitting fluorene polymer can be realized by controlling the addition ratio of comonomer 3 to the existing blue light emitting polymer.

The light emitting polymer of the present invention may have a number average molecular weight (Mn) of 5,000 to 50,000 and a weight average molecular weight (Mw) of 10,000 to 100,000.

In addition, the light emitting polymer of Formula 1 may be prepared by copolymerizing the monomer of Formula 2, the monomer of Formula 3 and the monomer of Formula 4 in the presence of a palladium (0) catalyst in an organic solvent such as toluene, as shown in Scheme 1 below. Can be.

In Scheme 1,

R ₁ , R ₂ , Ar, n, m, X and Y 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 in Scheme 2 below, R ₁ And R ₂ 2,7-dibromo-9,9-dihexylfluorene, 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxalborolane- substituted with a hexyl group 2-yl) -9,9-dihexylfluorene, and Monomer 2- (2,6-bis- {2- [1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3 substituted with fluorene derivative , 4-tetrahydroquinolin-6-yl] -vinyl} -paran-4-ylidene) -malononitrile was copolymerized in an organic solvent using a palladium (0) catalyst to form luminescent polymers (F6DCMs) of the present invention. You can get it.

Specifically, the example portion also illustrates a monomer represented by the following Formula 5 in which the fluorene derivative is substituted, which is selected as necessary to explain the contents of the present invention, and the content of the present invention is not limited to the compound.

[Formula 5]

The fluorene derivative of Chemical Formula 5 may be prepared by the following method.

First, as shown in Scheme 3 below, 2,7-dibromo-9,9-dihexylfluorene and 1,2,3,4-tetrahydroquinoline are reacted in the presence of a palladium (0) catalyst to fluorene To obtain a quinoline monomer.

Next, as in Scheme 4 below, 1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1 prepared in Scheme 3 through a Vilsmeyer reaction An aldehyde group is introduced into 2,3,4-tetrahydroquinoline to obtain a quinoline-carbaaldehyde monomer substituted with a fluorene derivative.

Next, as in Scheme 5 below, 1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3,4-tetra prepared in Scheme 4 above. Hydroquinoline-6-carbaaldehyde and (2,6-dimethyl-4H-paran-4-yridine) propanedinitrile with piperidine were reacted with 2- (2,6- via Knoevenagel reaction. Bis- {2- [1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3,4-tetrahydroquinolin-6-yl] -vinyl} -Paran-4-ylidine) -malononitrile (hereinafter DCMF) can be obtained.

In addition, the present invention provides an electroluminescent device comprising a light emitting layer containing the light emitting polymer, and as an example, the electroluminescent device according to one embodiment of the present invention is shown in FIG.

In the electroluminescent device of the present invention, a semi-transparent electrode 2, a hole transport layer 3, a polymer light emitting layer 4, an electron transport layer 5 and a metal electrode 6 are sequentially stacked on a predetermined substrate 1, More simply, the translucent electrode 2, the polymer light emitting layer 4, and the metal electrode 6 may be sequentially stacked on the substrate 1. In this case, the polymer light emitting layer 4 includes the light emitting polymer of the present invention, and may further include a polymer that facilitates electron or hole transport, such as PVK (polyvinylcarbazole).

As described above, the light emitting polymer of the present invention has a characteristic structure in which a fluorene-based blue light emitting polymer is used as a main chain and a small amount of a monomer representing orange is introduced therein, thereby stably realizing pure white. It can be usefully used as a white light emitting material of the electroluminescent device.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

Example  1: 1-7- Bromo -9,9- Dihexyl -9H- Fluorene -2-yl) -1,2,3,4- Tetrahydroquinoline  Produce

Tetra (dibenzylideneacetone) dipalladium (0) (0.103 g, 0.112 mol), 1,1'-bis (diphenylphosphino) ferrocene (0.096 g, 0.173 mmol) and 2,7-dibromo-9 , 9-dihexylfluorene (5.42 g, 11 mmol) was dissolved in toluene and stirred for 15 minutes, followed by sodium t-butoxide (1.08 g, 11.2 mmol) and 1,2,3,4-tetrahydroquinoline ( 1.0 g, 7.5 mmol) was added and reacted at 100 ° C for 24 hours. The reaction solution was extracted with ethylene acetate, and the obtained organic layer was dried over MgSO ₄ and the solvent was removed. The obtained material was column chromatographed with hexane / ethylene acetate (10: 1) developing solvent to give the result (2.04 g, 50%).

¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 7.70 (d, 1H), 7.68 (s, 1H), 7.55 (d, 1H), 7.45 (d, 1H), 7.44 (s, 1H) , 7.33 (d, 1H), 7.19 (m, 1H), 7.18 (d, 1H), 6.53 (q, 1H), 6.50 (d, 1H), 3.74 (t, 2H), 2.91 (t, 2H), 2.12 (m, 2H), 1.89 (m, 4H), 1.10 (m, 8H), 1.03 (m, 4H), 0.78 (m, 6H), 0.64 (m, 4H).

¹³ C-NMR (100 MHz, CDCl ₃ ) δ (ppm): 153, 152.3, 150.5, 145.6, 139.3, 138.2, 131.2, 130.1, 126.3, 126.1, 125.4, 122.4, 121.2, 121.1, 121, 120, 118.1, 113.1 , 55.5, 51.8, 40.1, 31.4, 29.5, 27.7, 23.7, 22.5, 21.9, 13.9.

Elemental Analysis. Theoretical for C ₃₄ H ₄₂ BrN: C, 74.98; H, 7.77; N, 2.57. Found: C, 74.36; H, 7.59; N, 2.51.

Example 2 Preparation of 1- (7-Bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3,4-tetrahydroquinoline-6-carbaaldehyde

1 mL (10.7 mmol) of POCl ₃ was added dropwise to a flask containing 15 mL of DMF at 0 ° C., followed by (1-7-bromo-9,9-dihexyl-9H-fluoren-2-yl)- 1,2,3,4-tetrahydroquinoline (4.8 g, 8.8 mmol) was added and reacted at 90 ° C. for 3 hours. After the reaction solution was cooled to room temperature, it was immersed in iced water, added with sodium hydroxide solution, neutralized to pH 6-7, extracted with ethylene acetate, and the obtained organic layer was dried over MgSO ₄ and the solvent was removed. The obtained material was column chromatographed with hexane / ethylene acetate (30: 1) developing solvent to give the result (3.93 g, 78%).

¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 9.67 (s, 1H), 7.70 (d, 1H), 7.68 (s, 1H), 7.55 (d, 1H), 7.45 (d, 1H) , 7.44 (s, 1H), 7.33 (d, 1H), 7.19 (s, 1H), 7.18 (d, 1H), 6.50 (d, 1H), 3.74 (t, 2H), 2.91 (t, 2H), 2.12 (m, 2H), 1.89 (m, 4H), 1.10 (m, 8H), 1.03 (m, 4H), 0.78 (m, 6H), 0.64 (m, 4H).

¹³ C-NMR (100 MHz, CDCl ₃ ) δ (ppm): 190.2, 153, 152.3, 150.5, 145.6, 139.3, 138.2, 131.2, 130.1, 126.3, 126.1, 125.4, 122.4, 121.2, 121.1, 121, 120, 113.1 , 55.5, 51.8, 40.1, 31.4, 29.5, 27.7, 23.7, 22.5, 21.9, 13.9.

Elemental Analysis. Theoretical for C ₃₅ H ₄₂ BrNO: C, 73.41; H, 7.39; N, 2.45. Found: C, 73.14; H, 7.53; N, 2.41.

Example 3: 2- (2,6-bis- {2- [1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3,4- Preparation of Tetrahydroquinolin-6-yl] -vinyl} -paran-4-ylidine) -malononitrile

1- (7-bromo-9,9-dihexyl-9H-fluoren-2-yl) -1,2,3,4-tetrahydroquinoline-6-carbaaldehyde synthesized in Example 2 (6.87 g , 12 mmol), (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 120 The reaction was carried out at ℃ for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and an excess of methanol was added to obtain a red solid. The red solid obtained was filtered and dried, and then dissolved in methylene chloride and dropped into methanol to recrystallize to obtain a red solid substance (5.73 g, 77%).

¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 7.67 (d, 2H), 7.51 (d, 2H), 7.45 (m, 4H), 7.38 (s, 2H), 7.34 (s, 2H) , 7.26 (m, 4H), 7.19 (d, 2H), 6.60 (d, 2H), 6.53 (s, 2H), 6.48 (d, 2H), 3.71 (t, 4H), 2.91 (t, 4H), 2.14 (q, 4H), 1.89 (m, 8H), 1.08 (m, 16H), 1.05 (m, 8H), 0.78 (t, 12H), 0.66 (m, 8H).

¹³ C-NMR (100 MHz, CDCl ₃ ) δ (ppm): 159.2, 156, 153, 152.2, 147.2, 146.2, 139.5, 137.9, 137.5, 130, 129.2, 127.1, 126.1, 124.7, 124, 123.6, 121, 120.88 , 120.85, 120.84, 120.5, 116.1, 114.5, 113.6, 105.5, 55.5, 51.5, 40.1, 31.4, 29.5, 27.8, 23.7, 22.5, 22.2, 14.0.

Elemental Analysis. Calcd for C ₈₀ H ₈₈ Br ₂ N ₄ O: C, 74.99; H, 6.92; N, 4.37. Found: C, 75.96; H, 7.21; N, 4.74.

Example 4 Preparation of Light-Emitting Polymer

Monomer 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxalborolan-2-yl) -9,9-dihexyl fluorene, 2,7-dibromo -9,9-dihexylfluorene and 2- (2,6-bis- {2- [1- (7-bromo-9,9-dihexyl-9H-fluorene-2- obtained in Example 3) Il) -1,2,3,4-tetrahydroquinolin-6-yl] -vinyl} -paran-4-ylidine) -malononitrile, but satisfies the n / m ratio shown in Table 1 below The reaction was carried out while varying the amount used. These monomers and tetrakis (triphenylphosphine) palladium (1 mol%) were dissolved in toluene, and then reacted at 90 ° C. for 60 hours by adding Aliquat 336, a phase transfer catalyst, and K ₂ CO ₃ . For end capping, a small amount of bromobenzene was dissolved in toluene and injected, and after 12 hours, phenylboronic acid was dissolved in toluene. After 12 hours, after the reaction was completed, the solution was slowly dropped into a mixed solution of hydrochloric acid and methanol to obtain a polymer. Pure precipitates were synthesized by reprecipitation and Soxhlet extractor for 3 days (see Scheme 2).

The light emitting polymers prepared in Example 4 may be easily dissolved in various organic solvents, and the number average molecular weight (Mn) measured using gel permeation chromatography was 12,000 to 39,000, and the dispersion degree (Mn / Mw) was The range was 1.7 to 3.3. Such polymerization results are shown in Table 1 below.

Copolymer F6DCM005 F6DCM010 F6DCM050 F6DCM100 Number average molecular weight (Mn) 30,000 17,000 12,000 39,000 Mass average molecular weight (Mw) 72,000 29,000 40,000 74,000 Dispersion (Mn / Mw) 2.4 1.7 3.3 1.9 Yield (%) 70 73 70 78 Addition ratio (n / m) 9995/5 9990/10 9950/50 9900/100

Subsequently, the prepared polymers were dissolved in chloroform to prepare a polymer film using a known spin coating method on a quartz plate, and UV absorption and photoluminescence characteristics were measured, respectively, and are shown in FIGS. 2 and 3, respectively.

From the graph of FIG. 2, it can be seen that the UV maximum absorption wavelength of the film-like polymer is shown at 384 nm, and the absorption band in the long wavelength region increases as the addition ratio of the comonomer 3 increases.

From the graph of FIG. 3, the prepared film-like polymers exhibit photoluminescence even at an orange wavelength as the addition ratio of the comonomer (3) increases, and more of the orange region appears in the blue region spectrum as the addition ratio increases. It showed a phenomenon. For example, when 0.05 mol% of comonomer (3) is added, l _max appears at 423 nm, and photoluminescence is slowly observed at 575 nm, and when the comonomer is added at 1 mol%, the spectrum of the blue region is considerably reduced and maximum. It can be seen that the photoluminescence wavelength appeared at 600 nm.

Furthermore, a light emitting device using the light emitting polymers prepared in Example 4 as a light emitting layer was manufactured. Specifically, a commercial product having 100 nm of ITO laminated on a glass substrate is first coated with PODOT (PSD) on the ITO layer, then a light emitting layer of 100 nm is formed, and calcium is deposited and then used as a cathode. 500 nm of aluminum was laminated to manufacture a light emitting device. The electroluminescence spectrum of the manufactured light emitting device is shown in FIG. 4, the voltage-current characteristic is shown in FIG. 5, and the voltage-emitting intensity characteristic is shown in FIG. 6.

Comparing the graphs of FIG. 3 and FIG. 4, it can be seen that the electroluminescence spectrum and the photoluminescence spectrum show a considerable difference. That is, it can be seen that the orange region appears strongly in the electroluminescence spectrum when compared with the photoluminescence spectrum in the film state. Such a large difference between the blue region and the orange region in the photoluminescence spectrum and the electroluminescence spectrum is a phenomenon generally observed in a white light emitting device using a single polymer, and this phenomenon has a low energy band gap during electroluminescence driving. This is because holes and electrons are captured and accumulated in the DCM derivative.

Existing methods of implementing white light have difficulty in applying to displays because color coordinates change according to voltage, and color purity is poor. However, the light emitting device of the present invention manufactured through a single polymer exhibits stable color coordinates according to voltage. It can be seen that there is a significant advantage to the (see Fig. 7). These results are shown in Table 2 below, wherein light in the liquid phase (chloroform solution) of each of the polymers prepared in Example 4 using dilute quinine sulfate (1 × 10 ⁻⁵ M in sulfuric acid) as a standard material was used. The luminous efficiency was measured.

Copolymer Wavelength (l _max ) Photoluminescent Quantum Efficiency (Solution) UV absorption Photoluminescence Electroluminescence F6DCM005 382 423, 448 423, 450, 580 0.95 F6DCM010 384 423, 448, 575 426, 448, 584 0.85 F6DCM050 384 423, 448, 575 426, 448, 584 0.81 F6DCM100 384 421, 445, 602 608 0.60

Although the present invention has been illustrated and described in connection with specific embodiments as described above, it will be readily apparent to those skilled in the art that various modifications and variations are possible in accordance with the teachings of the present invention. .

As can be seen from the above experimental results, the light emitting polymer of the present invention has a characteristic structure in which a fluorene-based blue light emitting polymer is used as a main chain and a small amount of a monomer showing orange is introduced therein, thereby leaving pure white. Since it can be implemented stably, it can be usefully used as a white light emitting material of an electroluminescent element.

Claims (12)

A light emitting polymer represented by Formula 1 below: [Formula 1]

Where R ₁ and R ₂ are each independently hydrogen, a silyl group, or a C ₁ to C ₂₂ linear or branched alkyl group; Ar is a fluorene derivative, a thiophene derivative or a phenylene derivative; n and m are each independently an integer from 1 to 10000. The method of claim 1, The n and m is a light emitting polymer, characterized in that to satisfy the n / m ratio of 9995/5 ~ 90/10. The method of claim 1, Ar is 2,7-dibromo-9,9'-dioctylfluorene, 2,7-dibromo-9,9'-dihexyl fluorene, 2,7-dibromo-9,9 '-Dihexylfluorenyl-1,2,3,4-tetrahydroquinoline, 5,5'-dibromo-2,2'-dithiophene or 1,4-dibromo phenylene Light emitting polymer. The method of claim 1, The light emitting polymer, characterized in that the polymer emits white. The method of claim 1, A light emitting polymer, characterized in that the polymer has a number average molecular weight (Mn) of 5,000 to 50,000 and a weight average molecular weight (Mw) of 10,000 to 100,000. A process for preparing the light emitting polymer of claim 1, comprising copolymerizing the monomer of Formula 2, the monomer of Formula 3, and the monomer of Formula 4 in the presence of a palladium (0) catalyst in an organic solvent: [Formula 2]

[Formula 3]

[Formula 4]

Where R ₁ and R ₂ are each independently hydrogen, a silyl group, or a C ₁ to C ₂₂ linear or branched alkyl group; Ar is a fluorene derivative, a thiophene derivative or a phenylene derivative; X is a halogen atom; Y represents a boron compound derivative. The method of claim 6, Method for producing a light emitting polymer, characterized in that the copolymerization is carried out for 12 to 90 hours at a temperature of 60 to 100 ℃. The method of claim 6, Method for producing a light emitting polymer, characterized in that the monomer of Formula 4 has the structure of Formula 5 [Formula 5]

An electroluminescent device comprising a light emitting layer containing the light emitting polymer of any one of claims 1 to 5. The method of claim 9, The electroluminescent device has a structure in which a semi-transparent electrode, a hole transport layer, a light emitting layer, an electron transport layer and a metal electrode are sequentially stacked on the substrate. The method of claim 9, The electroluminescent device has a structure in which a semi-transparent electrode, a light emitting layer and a metal electrode are sequentially stacked on the substrate. The method of claim 9, Electroluminescent device, characterized in that the light emitting layer further comprises an electron or hole transport polymer.

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