JP2002324669A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element which can be easily formed and enjoys stable characteristics. SOLUTION: The organic electroluminescent element, structured with one or more organic layers pinched by a positive electrode 11 and a negative electrode 16 on a substrate 10, can emit light at least from one side. The organic layer is provided with a luminous layer 14 formed by depositing an organic phosphor material with a host material and a guest material in mixing ratio of 500 to 1 in weight on the substrate at a speed of several nm/sec by resistive heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an organic electroluminescent device (OLED).

[0002]

2. Description of the Related Art OL having a light emitting layer composed of an organic compound
EDs have been attracting attention for realizing DC low-voltage driving. For example, Japanese Patent Publication No. 6-32307 discloses that an indium tin oxide (ITO) semi-transparent film is formed on the upper surface of a substrate made of a translucent glass. An anode is formed, and a hole injection layer, a light emitting layer, and a cathode made of an aluminum (Al) film are sequentially formed thereon, and a power source is connected between the anode and the cathode to form an anode. The disclosed structure discloses that the generated holes are transmitted to the interface between the hole injection layer and the light emitting layer, where the holes are combined with the electrons transmitted from the cathode to emit visible light.

In order to promote hole injection, an OLED having a structure in which a hole transport layer is interposed between the hole injection layer and the light emitting layer, or an OLED having the hole injection layer and the hole transport layer OLE with a hole injection / transport layer integrated with a layer
D is also known, and similarly to the above configuration, holes generated at the anode are transmitted to the interface between the hole injection layer and the light emitting layer, where the holes are combined with electrons transmitted from the cathode. ,
Emits visible light, which is emitted through the substrate
The light is emitted to the outside of the LED.

[Problems to be solved by the invention]

The light-emitting layer is formed by doping a host material with a small amount of a guest material. When forming the light-emitting layer, the host material and the guest material are put into individual crucibles and heated individually. A so-called co-evaporation method has been used (see, for example, JP-A-11-204261).

In such a co-evaporation method, the mixing ratio of the host material and the guest material is large, for example, a weight ratio of 10%.
When the ratio is 0: 1 or more, it is difficult to stably control the deposition of the guest material, and the reproducibility of characteristics such as light emission characteristics and temperature characteristics is deteriorated.

[0006] Also, "Monthly Display April 1998"
Among the "organic EL devices using a mixed single-layer deposited film" described on pages 55 to 58, page 56 includes a hole transporting material TPD, an electron transporting luminescent material Alq3, and a luminescent material DCM. A mixed single-layer type OLED in which powder previously mixed at a target mixing ratio is filled in a vapor deposition board (corresponding to the crucible) and evaporated in a vacuum is disclosed.

In such a mixed single-layer type, the mixing ratio after film formation can substantially match the filling ratio to the vapor deposition board, and although the problem of co-deposition can be improved, It is necessary to raise the board to about 400 degrees Celsius within 10 seconds and perform it at a deposition rate of about 20 nm / second, and it is difficult to ensure uniformity of the film due to the high deposition rate. There was a problem that it was not suitable for the creation of.

An object of the present invention is to provide an OLED which can be easily formed and has stable characteristics.

[0009]

According to a first aspect of the present invention, there is provided an OLED comprising at least one organic layer sandwiched between an anode and a cathode on a substrate. An organic electroluminescent device capable of extracting light from at least one side, wherein the organic layer is formed by vapor-depositing an organic phosphor material in which a host material and a guest material are in a minor dopant relationship on the substrate. It has a layer.

According to a second aspect of the present invention, there is provided an organic electroluminescent device capable of extracting light from at least one side comprising at least one organic layer sandwiched between an anode and a cathode on a substrate. The organic layer has a light emitting layer formed by vapor-depositing an organic phosphor material having a relationship between a host material, a guest material and a trace dopant on the substrate by a resistance heating method.

According to a third aspect of the present invention, there is provided an organic electroluminescent device capable of extracting light from at least one side composed of at least one organic layer sandwiched between an anode and a cathode on a substrate. The organic layer has a light emitting layer formed by depositing an organic phosphor material having a relationship of a trace amount of dopant with a host material, a guest material, on the substrate by a vacuum deposition method.

[0012] In particular, as set forth in claim 1 to claim 3, in the trace dopant, the mixing ratio of the host material and the guest material is 100: 100 by weight.
It is one or more.

[0013] In particular, as set forth in claim 5 in any one of claims 1 to 3, the rate of the deposition is 0.01 to 2.
nm / sec.

According to a sixth aspect of the present invention, there is provided an organic electroluminescent device capable of extracting light from at least one side composed of at least one organic layer sandwiched between an anode and a cathode on a substrate. The organic layer is formed by depositing an organic phosphor material having a mixing ratio of a host material and a guest material in a weight ratio of 500: 1 or more on the substrate by a resistance heating method at a speed of several nm / sec. It has a light emitting layer.

[0015] Thus, an OL which can obtain stable characteristics.
The ED can be easily formed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments shown in the accompanying drawings.

In this embodiment, as shown in FIG. 1, an anode 11 having a thickness of 100 [nm] made of a translucent ITO film is formed on an upper surface of a substrate 10 made of a transparent glass. A 20 [nm] -thick hole injection layer 12 made of copper phthalocyanine (CuPc), N, N'-bis (3-methylphenyl) -N,
A hole transport layer 13 having a thickness of 70 [nm] made of N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (TPD), and a light emitting layer 14 having a thickness of 70 [nm] to be described later. , And a film thickness of 150 [n
m] are successively formed, and a DC power supply 16 of several volts to several tens of volts is connected between the anode 11 and the cathode 15.

The light emitting layer 14 is composed of a host material and a guest material. A suitable amount of a suitable material is used to obtain desired characteristics such as light emission characteristics and temperature characteristics. The present invention is suitable for the case where the mixing ratio is large, for example, 100: 1 or more, and a method for manufacturing an OLED having such a configuration will be described below.

The manufacturing apparatus of the present embodiment is constituted by a vapor deposition apparatus as shown in FIG. 2. Numeral 20 denotes a vacuum chamber, in which a plurality of crucibles 21 for vapor deposition and a quartz crystal for film thickness monitoring are provided. Substrate 10 having vibrator 22 and serving as OLED base
Is set above the crucible 21 in the vacuum chamber 20. After the anode 11 is formed by coating or the like, the substrate 10 is subjected to ultrasonic cleaning with a surfactant, washed with deionized water, degreased with toluene vapor, surface-treated with a strong oxidizing agent, and It is set in the vacuum chamber 20 so as to face the crucible 21.

Then, the crucible 2 is formed by the aluminum board 23 for electrodes.
1 is heated to form a stack of the organic layer and the cathode 15 on the upper surface of the anode 11 (below the drawing in FIG. 2), so that the mask 2 positioned between the crucible 21 and the substrate 10 is formed.
4 and a shutter 25 are controlled by a microcomputer (microcomputer) 26.

That is, the microcomputer 26 calculates the film thickness data from the crystal oscillator 22 via the film thickness meter 27 and the temperature from the thermocouple (not shown) set in the crucible 21 via the 8-channel A / D converter 28. After obtaining the data, switching of the crucible 21 and control of the mask 24 and the shutter 25 via the 8-bit 3-port PPI control circuit 29 are performed, and
The aluminum board 23 is controlled via the channel D / A converter 30.

Thus, under high vacuum in the vacuum chamber 20 (~
(2 × 10 ↑ −5 [Torr]), all the organic layers and the cathode 15 can be continuously deposited.

Further, by forming the substrate 10 as a light-transmitting substrate such as glass, an OLED that emits light emitted from the light emitting layer 14 to the outside through the substrate 10, that is, an OLED that can extract light from at least one side, On the other hand, by making the cathode 15 translucent, these buffer layers 15
The OLED emits light emitted from the light emitting layer 14 to the outside through the cathode 16 or the cathode 16, that is, an OLED capable of extracting light from at least one side, and may be used in combination. Further, the substrate 10 is a non-translucent substrate such as silicon or the like, and a cathode 15, a light emitting layer 14, and an anode 11 are formed thereon.
(If necessary, a hole transport layer 13 and / or a hole injection layer 12 or a layer obtained by integrating them may be interposed between the light emitting layer 14 and the anode 11). The anode 1 on the opposite side of the substrate 10 is formed by lamination.
1 emits light from the light emitting layer 14 to the outside, that is, O which can take out light from at least one side.
It becomes an LED.

Next, a method for forming the light emitting layer 14 will be described. The light emitting layer 14 is composed of a host material and a guest material. An organic phosphor material was prepared by weighing a guest material consisting of Idemitsu Kosan's trade name "IDE103" to a host material consisting of IDE120 "at a mixing ratio of 500: 1, and mixing it in a mortar so as to be uniform. Thereafter, this is set in the crucible 21 and vapor-deposited on the substrate 10 by the resistance heating method at a vapor deposition rate of several nm / sec.

At this time, in order to confirm the uniformity of the organic phosphor material, it is desirable to irradiate the mixed organic phosphor material with black light to determine whether uniform light emission is obtained.

As described above, by mixing the host material and the guest material before the vapor deposition to obtain the organic phosphor material and then performing the vapor deposition, the amount of the guest material, which is smaller than the host material, can be reduced. The light emitting layer 14 can be formed by simultaneously depositing the host material and the guest material by a single operation using the same crucible 21 because the material is deposited together with the host material in a form dragged by the material. .

Thus, the light emitting layer 14 containing a predetermined amount of dopant according to the mixing ratio of the host material and the guest material at the time of preparing the organic phosphor material.
Can be obtained with good reproducibility, especially when the mixing ratio is 1 by weight.
Emitting layer 14 by controlling a trace amount of 000: 1 or more dopant
This has a great effect on the formation of the structure, and further simplifies the working process.

The light emitting layer 14 can be formed by a vacuum evaporation method or the like in addition to the resistance heating method.

In the formation of the light emitting layer 14 by the above method, it is difficult to simultaneously deposit the host material and the guest material unless the mixing ratio is about 100: 1 or more. .

The rate of vapor deposition of the light emitting layer 14 is desirably as low (slow) as possible, for example, 0.01 to 2 nm.
/ Sec is optimal.

[0031]

According to the present invention, an OLED which can be easily formed and has stable characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a configuration of an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating the manufacturing apparatus of the above.

[Explanation of symbols]

 Reference Signs List 10 substrate 11 anode 12 hole injection layer (organic layer) 13 hole transport layer (organic layer) 14 light emitting layer (organic layer) 15 cathode 16 power supply

Claims (6)

[Claims] 1. An organic electroluminescent device comprising at least one organic layer sandwiched between an anode and a cathode on a substrate and capable of extracting light from at least one side, wherein the organic layer comprises a host material. An organic electroluminescent device, comprising: a light emitting layer formed by depositing an organic phosphor material having a relation of a trace dopant with a guest material on the substrate. 2. An organic electroluminescent device capable of extracting light from at least one side composed of at least one organic layer sandwiched between an anode and a cathode on a substrate, wherein the organic layer comprises a host material and An organic electroluminescent device comprising a light emitting layer formed by depositing an organic phosphor material having a relationship between a guest material and a trace dopant on the substrate by a resistance heating method. 3. An organic electroluminescent device capable of extracting light from at least one side composed of at least one organic layer sandwiched between an anode and a cathode on a substrate, wherein the organic layer is formed of a host material. An organic electroluminescent device comprising a light emitting layer formed by depositing an organic phosphor material having a relationship with a guest material and a trace amount of dopant on the substrate by a vacuum deposition method. 4. The organic electric field according to claim 1, wherein the mixing ratio of the host material and the guest material in the trace dopant is 100: 1 or more by weight. Light emitting element. 5. The organic electroluminescent device according to claim 1, wherein the deposition rate is 0.01 to 2 nm / sec. 6. An organic electroluminescent device capable of extracting light from at least one side composed of at least one organic layer sandwiched between an anode and a cathode on a substrate, wherein the organic layer comprises a host material. A light emitting layer formed by depositing an organic phosphor material having a mixing ratio of 500: 1 or more with a guest material on the substrate by a resistance heating method at a speed of several nm / sec. Organic electroluminescent device.