JP3865807B2 - Organic electroluminescence device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescent device (hereinafter, "organic EL device") about the.
[0002]
[Prior art]
Conventionally, as an organic EL element, as shown in FIG. 5, a hole transport layer 3 and an organic fluorescent dye (light emitting layer) 4 are laminated between a transparent anode 2 and a metal cathode 5 provided on a substrate 1. Is known. In addition, as shown in FIG. 6, a structure in which three layers including a hole transport layer 3, a light emitting layer 4, and an electron transport layer 6 are laminated between a transparent anode 2 and a metal cathode 5 provided on a substrate 1. Are also known.
[0003]
The organic EL element is usually produced by sequentially forming a hole transport layer 3, a light emitting layer 4, an electron transport layer 6 and a metal cathode 5 on a patterned transparent anode 2 through a vapor deposition mask.
[0004]
[Problems to be solved by the invention]
The thickness of the organic EL element is usually 100 to 200 nm for the transparent anode 2, 100 to 300 nm for the organic layer composed of the hole transport layer 3, the light emitting layer 4 and the electron transport layer 6 as a whole, and 100 to 300 nm for the cathode 5. is there. In an organic EL element, since a high electric field of 50 to 100 MV / m is applied between the transparent anode 2 and the metal cathode 5, the electric field tends to concentrate mainly on the end face (edge portion) of the electrode. The loss becomes Joule heat, causing a problem that the organic thin film and the metal cathode are separated from each other and a non-light emitting region (dark spot) is generated.
[0005]
Since the organic layer is produced by a vapor deposition method, it is difficult for the film to grow on the side of the transparent anode. Therefore, there is a problem that the thickness of the organic layer 7 in the portion surrounded by a circle in FIG. 7 is thinner than other portions, and the electric field tends to concentrate here. In FIG. 7, 1, 2 and 5 indicate the same as those in FIGS.
[0006]
Moreover, since the metal cathode 5 is formed through a vapor deposition mask, it is difficult to obtain a light emitting surface with a fine pattern, which is a problem in producing a display.
[0007]
The present invention eliminates the influence of the end face of the transparent anode, a short circuit of the device to solve the problem of increase in the non-emitting region, and its object is to provide an organic EL device having a stable emission surface.
[0008]
[Means for Solving the Problems]
The present invention relates to an organic electroluminescence device comprising an anode, an organic layer and a cathode provided on a substrate, an insulating layer is provided on the anode or between the anodes by patterning, and the organic layer and the cathode are formed thereon. In the luminescence element, the insulating layer is formed by vapor deposition polymerization of urea and an ultraviolet exposure and heat development of a polyurea film containing an oligomer state obtained by the vapor deposition polymerization, and the insulating layer is further subjected to oxygen plasma treatment. And
[0009]
In the organic EL device of the present invention, for example, as shown in FIG. 1, an insulating layer 8 obtained by patterning an insulating film is provided on a transparent anode 2 provided on a substrate 1, and hole transport is provided thereon. A layer 3, a light emitting layer 4, an electron transport layer (not shown), and a metal cathode 5 are formed. As shown in FIG. 2, when the transparent electrode 2 is patterned on the substrate 1, the insulating layer 8 is embedded between the transparent electrodes.
[0010]
As the insulating layer, after UV exposure of the polyurea film occupies clothed evaporation, patterned film by heat development is employed. In this development step, after UV exposure, the light non-irradiated portion is removed by decomposition by pressurized heat.
[0011]
The organic EL element of the present invention, for example, an insulating layer is formed by patterning the inter-anode on or anode provided on a substrate, the organic layer was formed thereon, and then a mask vapor deposition of an electrode pattern thereon Without forming the cathode, the light emitting surface is formed in the pattern surrounded by the insulating layer.
[0012]
In the present invention, as described above, since the insulating layer patterned on the transparent anode or between the anodes is provided, light emission occurs at a portion where the insulating layer is removed. For this reason, the metal cathode 5 does not need to use a particularly patterned film. Therefore, the patterning process of the metal cathode can be omitted in the manufacturing process of the organic EL element.
[0013]
In addition, since there is no influence of the edge (edge part) of the transparent anode, there is no portion where the electric field concentrates when a voltage is applied, and the electric field is uniformly applied to the entire film, so that stable light emission can be obtained. Can do.
[0014]
Since the insulating film can be finely processed, the area per pixel can be reduced. In conventional mask deposition of metal cathodes, the area of 0.5 mm × 0.5 mm is the limit, and microfabrication is difficult at smaller areas.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0016]
First, the structure of the organic EL element will be described.
[0017]
As the structure of the organic EL element, when the organic compound film such as anode / insulating layer / light emitting layer / cathode has a single layer structure consisting only of a light emitting layer (consisting of a polymer film or an oligomer film), the anode / insulating layer / When the organic compound film such as hole transport layer / light emitting layer / cathode or anode / insulating layer / light emitting layer / electron transport layer / cathode has a two-layer structure of a hole transport layer and a light emitting layer or a light emitting layer and an electron transport layer The organic compound film such as anode / insulating layer / hole transporting layer / light emitting layer / electron transporting layer / cathode may have a three-layer structure.
[0018]
Here, as described above, the polyurea film exposed to ultraviolet rays is patterned by heat development as the insulating layer .
[0019]
The hole transport layer of the organic compound film may be, for example, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (hereinafter referred to as “N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine”). Vapor deposition polymerization of thin films formed by vapor deposition of low molecular weight dyes with hole transport ability typified by TPD) and polymer films (polyamide, polyimide, polyazomethine, etc.) having a hole transport molecular structure A thin film formed by the above method may be used, and a low molecular dye having a hole transporting property may be deposited and dispersed in a polymer thin film.
[0020]
In addition, the light emitting layer has, for example, a thin film in which a light emitting dye typified by 8-oxyquinolino aluminum complex (hereinafter referred to as Alq ₃ ) is formed by a vapor deposition method, or a conjugated structure such as stilbene or oxadiazole. A thin film in which a polymer film is formed by vapor deposition polymerization is used, and a luminescent dye may be deposited and dispersed in the polymer thin film.
[0021]
Furthermore, as the electron transport layer, for example, a vapor-deposited thin film of Alq ₃ or an oxadiazole derivative is used, and a thin film of an anthraquinodimethane derivative or a diphenylquinone derivative can also be used.
[0022]
An example of the deposition apparatus of the insulating layer used in the present invention include the following as described, the evaporation source for evaporating the raw material monomer of the photosensitive synthetic resin in vacuum, absolute polyurea film vapor deposition polymerization of the raw material monomer Enmaku exposure but that the vapor deposition polymerization chamber which is disposed to face each other substrates formed was placed an ultraviolet source for irradiating ultraviolet rays to the insulating film on the substrate, a photomask used for forming a pattern on the insulating film and the chamber, and a developing chamber arranged a heating device for applying heat treatment to the insulating film after the irradiation exposure of the ultraviolet rays.
[0023]
First, FIG. 3 shows one example of a pattern forming apparatus of the insulating layer serving polyurea layer, vapor deposition polymerization chamber 11 to form a polyurea film, the exposure chamber 12 for irradiating ultraviolet rays to the polyurea membrane, The developing chamber 13 is configured to heat-treat the polyurea film irradiated with ultraviolet rays, and the vapor deposition polymerization chamber 11, the exposure chamber 12, and the developing chamber 13 are communicated with each other in this order by valves 14b and 14c.
[0024]
Further, a vacuum chamber 16 connected to an external vacuum pump or other evacuation system 15a is disposed on the upstream side of the vapor deposition polymerization chamber 11 via a valve 14a, and on the downstream side of the developing chamber 13 via a valve 14d. A vacuum chamber 17 connected to an external vacuum pump or other vacuum exhaust system 15b is disposed, and either one of the vacuum exhaust systems 15a and 15b or both of the vacuum exhaust systems are operated to operate in the vapor deposition polymerization chamber 11 and the exposure chamber 12. The inside of the developing chamber 13 can be set to a predetermined pressure.
[0025]
The vapor deposition polymerization chamber 11, with placing the substrate holder 18 for holding the substrate 1 for forming the vapor deposition polymerization film of polyurea membrane, is opposed to the substrate 1 below the the vapor deposition polymerization chamber 11 Poly Glass evaporation sources 19a and 19b for evaporating diamine as one raw material monomer (a) and diisocyanate as the other raw material monomer (b) are provided, respectively, and the respective evaporation sources 19a and 19b are Crystal evaporation evaporation monitors 20a and 20b and heaters 21a and 21b provided in the vicinity can control the evaporation amounts of the raw materials monomers (a) and (b) to a predetermined temperature that always keeps constant.
[0026]
In addition, a shutter 22 is disposed between the substrate 1 and the evaporation sources 19a and 19b, and a partition plate 23 is provided between the evaporation sources 19a and 19b.
[0027]
An ultraviolet ray source 24 is provided below the exposure chamber 12 so as to face the substrate 1 held by the substrate holder 18, a photomask 25 having a predetermined pattern is provided in front of the substrate 1, and the vapor deposition polymerization chamber 11. The polyurea film formed on the surface of the substrate 1 was irradiated with ultraviolet rays from the ultraviolet light source 24 to be exposed in a pattern.
[0028]
A heating device 26 made of a halogen lamp is provided in the developing chamber 13 on the back side of the substrate 1 held by the substrate holder 18, and the polyurea film crosslinked by being irradiated with ultraviolet rays in the exposure chamber 12 has a predetermined temperature. To remove the polyurea film in the non-exposed portion by depolymerization.
[0029]
First, the substrate 1 on which ITO (Indium-Tin-Oxide), for example, is formed as a transparent electrode is charged into the vacuum chamber 16 and transported to the vapor deposition polymerization chamber 11 using the insulating layer deposition apparatus as shown in FIG. forming a insulation Enmaku polyurea film on the arranged substrate 1 on the substrate holder 18 and. Next, the substrate 1 is carried out to the vacuum chamber 12 and exposed through the photomask 25 by the ultraviolet ray source 24. After that, it is transferred to the vacuum chamber 13 and the ultraviolet light unirradiated portion is decomposed and removed by the heating device 26 to complete the patterning of the insulating film.
[0030]
FIG. 4 shows an example of an apparatus used for manufacturing the organic EL element of the present invention, but the anode forming apparatus and the insulating layer forming apparatus are not shown here. In the figure, 27 is an oxygen plasma treatment chamber, 28 is a deposition chamber for organic compound films such as a hole transport layer, a light emitting layer, and an electron transport layer, 29 is a cathode formation chamber, 30 is a protective film formation chamber, and 31 is an ultraviolet treatment. Indicates a room. The oxygen plasma processing chamber 27, film forming chamber 28, cathode forming chamber 29, protective film forming chamber 30, and ultraviolet processing chamber 31 are partitioned by gate valves 32a, 32b, 32c, and 32d that can be opened and closed. At the same time, a tray type transfer system 33 for transferring the substrate 1 is disposed in each chamber.
[0031]
The oxygen plasma processing chamber 27 was connected to a vacuum exhaust system 34 such as a vacuum pump, and a copper RF electrode 35 for performing plasma processing on an anode such as an ITO film was disposed in the oxygen plasma processing chamber 27.
[0032]
The inside of the film forming chamber 28 is connected to an evacuation system 36 such as a vacuum pump, and predetermined ones are provided by heaters 37a and 37b in which a dye material T such as TPD or Alq ₃ is wound around one side below the film forming chamber 28. Two dye evaporation sources 38a and 38b made of alumina or glass that are heated to a temperature and evaporated are arranged side by side, and the raw material monomers U and V of the vapor-deposited polymer film are placed on the other lower side in the film forming chamber 28 by infrared rays. Glass or metal organic matter evaporation sources 40a and 40b that are heated to a predetermined temperature by the lamps 39a and 39b and evaporated are disposed. A substrate 1 on which an organic compound film is to be formed is disposed above the deposition chamber 28 so as to face the dye evaporation sources 38a and 38b and the organic substance evaporation sources 40a and 40b. A sheath heater 41 for heating the formed polymer film was provided.
[0033]
Further, shutters 42a and 42b are disposed between the substrate 1 and the dye evaporation sources 38a and 38b, and a shutter 43 is disposed between the substrate 1 and the organic substance evaporation sources 40a and 40b. Further, thermocouples 44a and 44b are disposed in the organic matter evaporation sources 40a and 40b, respectively.
[0034]
The inside of the cathode forming chamber 29 is connected to an evacuation system 45 such as a vacuum pump, and one of the cathode raw materials W (the raw material W is Mg, for example) is wound around one of the lower portions of the cathode forming chamber 29. A cathode material evaporation source 47 made of alumina, which is heated to a predetermined temperature by a heater 46 and evaporated, is disposed, and the other raw material X of the negative electrode (the raw material X is, for example, Ag) on the lower side in the cathode forming chamber 29. A cathode material evaporation source 48 composed of a boat made of tungsten or molybdenum that is heated to a predetermined temperature and evaporated is disposed.
[0035]
A shutter 49 is disposed between the substrate 1 and the cathode material evaporation source 47, and a shutter 50 is disposed between the substrate 1 and the cathode material evaporation source 48.
[0036]
The inside of the protective film forming chamber 30 is connected to an evacuation system 51 such as a vacuum pump, and a raw material monomer Y, Z of a protective film such as a polyurea film is disposed below the protective film forming chamber 30 (for example, the raw material Y is a diamine monomer). The raw material monomer Z is a diisocyanate monomer) heated to a predetermined temperature by infrared heaters 52a and 52b, and glass or metal protective film evaporation sources 53a and 53b for evaporation are disposed.
[0037]
In addition, a shutter 54 is disposed between the substrate 1 and the protective film evaporation sources 53a and 53b, and a quartz vibration type film thickness monitor 55 for the protective film is disposed in the vicinity of the substrate 1. Further, thermocouples 56a and 56b are disposed in the protective film evaporation sources 53a and 53b, respectively.
[0038]
In order to connect the inside of the ultraviolet treatment chamber 31 to a vacuum exhaust system 57 such as a vacuum pump, and to irradiate the inside of the ultraviolet treatment chamber 31 with ultraviolet rays to crosslink and polymerize low molecular polyurea to form a polyurea protective film. UV lamp 58 was provided.
[0039]
In FIG. 4, 59 denotes a partition plate provided between the organic material evaporation sources 40a and 40b, and 60 denotes a partition plate provided between the protective film evaporation sources 53a and 53b.
[0040]
Using an organic EL device manufacturing apparatus as shown in FIG. 4, the substrate obtained by patterning the insulation Enmaku polyurea film was charged into the vacuum chamber 27 in FIG. 4, performs the oxygen plasma treatment. The treatment in this case serves as both removal of the insulating film remaining on the transparent anode and flattening on the transparent anode. Next, an organic layer 7 composed of the hole transport layer 3, the light emitting layer 4, the electron transport layer 6 and the like is formed in the film forming chamber 28. Thereafter, a cathode is formed in the cathode forming chamber 29 and a protective film is formed in the protective film forming chamber 30 to complete the EL element.
[0041]
The apparatus shown in FIG. 3 and FIG. 4 also includes an oxygen plasma processing chamber and an organic layer deposition chamber shown in FIG. 4 from the preparation chamber through the integrated insulating film formation chamber. It may be configured to be transported to the cathode forming chamber, the protective film forming chamber, and then to the take-out chamber.
[0042]
In the case of an organic EL element having a structure in which an insulating layer 8 is embedded between a patterned anode (ITO) 2 and planarized as shown in FIG. the ITO was formed by patterning, an insulating film thereon, then (1) ultraviolet irradiation (the ITO), (2) by heat development, removing the insulating film on the I tO, The remaining insulating film is embedded between the ITO so as to be flattened, and then, as described above, an organic layer composed of the hole transport layer 3, the light emitting layer 4, the electron transport layer (not shown) and the like is formed. The EL element may be manufactured by forming a film, then forming the cathode 5 and forming a protective film (not shown).
[0043]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0044]
Example 1
The production of the organic EL element having the structure shown in FIG. 1 will be described.
[0045]
An ITO (In ₂ O ₃ -10% SnO ₂ ) film 2 having a thickness of 1000 mm was formed on a glass substrate 1 boiled and washed in isopropanol by sputtering. Charged the substrate into the vacuum chamber 16 of the patterning device polyurea film shown in FIG. 3, after reaching the 1.0 × 10 ^-3 Pa, and transported by opening the valve 14a to the vapor deposition polymerization chamber 11. Under pressure of 5.3 × 10 ⁻³ Pa, 4,4′-diaminodiphenylmethane (MDA) a and 4,4′-diphenylmethane diisocyanate (MDI) b were evaporated from the evaporation sources 19a and 19b, respectively. Then, 6000 kg of oligomeric polyurea was deposited on the substrate 1 with the ITO film 2. The valve 14b was opened, the substrate was conveyed to the vacuum chamber 12, and light having a central wavelength of 254 nm was irradiated from the ultraviolet source 24 through the photomask 25 for 30 minutes. Next, the valve 14c is opened, the substrate is transported to the vacuum chamber 13, and the substrate is heated within the range of 200 ° C. to 300 ° C. by the heating device 26 under a pressure of 1.33 × 10 ⁻³ Pa, and unexposed. Part of the film was removed by decomposition and evaporation. Thus, the polyurea film 8 patterned on the ITO film 2 was completed. At this time, the film thickness of the exposed portion was 2000 mm. The substrate was taken out through the vacuum chamber 17 and charged into the vacuum chamber (oxygen plasma processing chamber) 27 of the organic EL element manufacturing apparatus shown in FIG. After the processing chamber was evacuated to 1.33 × 10 ⁻³ Pa, oxygen was introduced, and a plasma treatment was performed for 5 minutes at a pressure of 6.65 Pa and an RF power supply of 50 W. The gate valve 32a is opened, the substrate is transferred to the film forming chamber 28, and N, N'-diphenyl-N, N'-bis (3-methylphenyl)-is used at a vacuum degree of 6.65 × 10 ^-4 Pa. 1,1′-diphenyl-4,4′-diamine (TPD) was evaporated from the evaporation source 38 a, and 500 μm of the hole transport layer 3 was deposited on the substrate 1. Next, the 8-oxyquinolino aluminum complex (Alq ₃ ) was evaporated from the evaporation source 38b, and the light emitting layer 4 was formed in a thickness of 500 mm. Thereafter, the gate valve 32b is opened, the substrate is transferred to the cathode forming chamber 29, and magnesium and silver are evaporated at an atomic ratio of 10: 1 from the evaporation sources 47 and 48 at a vacuum degree of 1.33 × 10 ⁻⁴ Pa. As a result, 2000 mg of MgAg negative electrode 5 was formed to complete an organic EL device.
[0046]
When a luminance and a current value were measured by applying a DC voltage to the element using the insulating pattern thus obtained, a luminance of 10500 cd / m ² (130 mA / cm ² ) was obtained at 11V. The light emission starting voltage was 3V. On the other hand, when no insulating pattern was used, the current density at 10000 cd / m ² was 500 mA / cm ² . Therefore, it can be seen that the current density at the same luminance is reduced by using the insulating pattern.
[0047]
(Example 2)
The organic EL device produced in Example 1, by opening the gate valve 32 c, and conveyed to the protective film forming chamber 30, and the polyurea protective film is 1μm deposited onto the element. That is, after the protective film forming chamber 30 is evacuated to 1.33 × 10 ⁻³ Pa by the vacuum exhaust system 51, the temperature of the raw material monomer Y (4,4′-diaminodiphenylmethane: MDA ) in the evaporation source 53a is adjusted to a thermocouple. While the temperature is measured at 56a, the heater 52a is heated to 100 ° C., and the temperature of the raw material monomer Z (4,4′-diphenylmethane diisocyanate: MDI ) in the evaporation source 53b is measured by the thermocouple 56b while the temperature is measured by the heater 52b. After heating to 0 ° C. and setting the respective evaporation rates so that the monomer composition ratio of MDA: MDI is 1: 1, MDA and MDI are evaporated by opening / closing the shutter 54, and the film thickness monitor 55 is used on the cathode. The film was deposited to a thickness of 1 μm and polymerized on the cathode to form a polyurea film.
[0048]
When the device thus obtained was continuously driven in the atmosphere at a current density of 10 mA / cm ² (initial luminance 500 cd / m ² ), the luminance half time was 730 hours. The non-light emitting region appeared after about 300 hours, but its diameter did not become larger than 100 μm.
[0049]
(Example 3)
Organic having structure such as ITO / polyurea pattern / TPD (hole transport layer) 500 Å / Alq ₃ (light emitting layer) 100 Å / polyazomethine (electron transport layer) 300 Å / MgAg (cathode) 2000 Å / polyurea protective film 10000 Å An EL element was produced.
[0050]
The same process as in Example 1 was repeated until the Alq ₃ film was formed. In the film formation chamber 28 of FIG. 4, terephthalaldehyde was filled into the organic matter evaporation source 40a and paraphenylenediamine was filled into the organic matter evaporation source 40b, respectively, and co-evaporation was performed to form a 300-nm polyazomethine film. The manufacturing process after the MgAg electrode was the same as described in Examples 1 and 2.
[0051]
When the organic EL device thus obtained was continuously driven in the air at a current density of 10 mA / cm ² and 700 cd / m ² , the luminance half time was 1000 hours. The non-light emitting region appeared after about 300 hours, but its diameter did not become larger than 100 μm.
[ 0052 ]
In the case of an organic EL element having a structure in which the insulating layer 8 is provided between the patterned anodes (ITO) 2 as shown in FIG. 2, the same results as in the above-described embodiment can be obtained.
[00 53 ]
【The invention's effect】
According to the organic EL device of the present invention, since the pattern of the insulating layer is formed on the flat transparent anode or between the anodes, the influence of the edge of the anode is eliminated, so that the device is short-circuited and the non-light emitting portion is increased. The problem disappears.
[00 54 ]
Further, since the insulating layer can be finely patterned and the cathode may be solid, a light emitting surface with a small area can be obtained. Therefore, it is advantageous in manufacturing a display.
[00 55 ]
Furthermore, the insulating layer pattern because it is formed using a polyurea, the withstand voltage is 1000 mV / m or more. Therefore, it can reduce the thickness of the insulating layer, because the Ru possible Dare to about 1000 Å, may flatten the entire device.
[Brief description of the drawings]
FIG. 1 is a schematic partial cross-sectional view showing the structure of one embodiment of an organic EL device of the present invention.
FIG. 2 is a schematic partial cross-sectional view showing the structure of another example of the organic EL element of the present invention.
FIG. 3 is an explanatory diagram of an example of an insulating layer film forming apparatus according to the present invention.
FIG. 4 is an explanatory diagram of an example of an organic EL element manufacturing apparatus of the present invention.
FIG. 5 is a schematic partial cross-sectional view showing an example of the structure of a conventional organic EL element.
FIG. 6 is a schematic partial cross-sectional view showing a structure of an example of a conventional three-layer organic EL element.
FIG. 7 is a schematic partial sectional view showing an example of the structure of an organic EL device according to the prior art in order to explain problems.
[ Explanation of symbols ]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Transparent anode 3 Hole transport layer 4 Light emitting layer 5 Metal cathode 6 Electron transport layer 7 Organic layer 8 Insulating layer 11 Deposition polymerization chamber 12 Exposure chamber 13 Development chamber 24 Ultraviolet source 26 Heating device 27 Oxygen plasma processing chamber a, b Raw material monomer

Claims (1)

In an organic electroluminescence device comprising an anode, an organic layer and a cathode provided on a substrate, an insulating layer is provided by patterning on or between the anode, and the organic layer and the cathode are formed thereon. ,
The organic electro Ruminessa, wherein the insulating layer was formed by the UV exposure of the polyurea film comprising oligomeric state obtained by vapor deposition polymerization and the vapor deposition polymerization of urea heating and development were oxygen plasma treatment the insulating layer further Element.

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