JP5049613B2 - Organic light emitting device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an organic light emitting device having an organic light emitting element (organic electroluminescence element) used for a flat panel display and the like, and a method for manufacturing the same.

  In recent years, organic light-emitting elements, which are self-luminous devices, have attracted attention as flat panel displays. The organic light-emitting element is liable to deteriorate characteristics due to moisture and oxygen, and a slight amount of moisture causes the organic compound layer and the electrode layer to peel off, causing dark spots. Therefore, cover the organic light-emitting device with an etching glass cover, attach the periphery with a sealant, attach a moisture absorbent inside, and absorb moisture from the seal surface with the moisture absorbent to ensure the life of the organic light-emitting device is doing. However, in order to realize a space-saving flat panel display using a thin organic light emitting device, it is necessary to eliminate the space of the hygroscopic agent around the light emitting area and to make it thinner, and a large amount of hygroscopic agent is required. There is a need for a method of sealing an organic light emitting device that does not. Therefore, solid sealing with a highly functional passivation layer for preventing intrusion of moisture and oxygen into the organic compound layer is required.

  In order to solve these problems, in recent years, as a moisture-proof layer of an organic light-emitting element, a solid material such as a silicon nitride film using a CVD method or a sputtering method, an inorganic film such as a silicon oxynitride film, or a moisture-proof layer formed by laminating them is used. Sealing has been proposed.

  The moisture-proof film formed by the sputtering method has insufficient step coverage, and at the same time, since the film is hard, cracks are likely to occur.

  Further, a semiconductor moisture-proof layer formed by a plasma CVD method is generally formed at a high temperature of 350 ° C. or more and 500 ° C. or less. However, an organic material forming an organic compound layer such as a hole injection layer, a hole transport layer, an electron injection layer, or a light emitting layer of an organic light emitting device has a glass transition point of a low temperature of about 100 ° C. to 100 tens of degrees C. Depending on the temperature, the characteristics of the organic light emitting device deteriorate. Therefore, when forming the upper electrode and further the moisture-proof layer on the upper layer on at least the substrate on which the organic compound layer is formed, it is necessary to form the organic compound layer at a very low temperature such that the temperature is lower than 100 ° C.

  Patent Document 1 proposes a method of forming a moisture-proof layer on an organic compound layer using only monosilane gas and nitrogen gas by plasma CVD.

  Further, according to Patent Document 2, a method for producing an organic electroluminescence element in which a moisture-proof layer is coated at a temperature range of 30 ° C. to 100 ° C. by an ECR plasma CVD method is proposed.

JP 2002-1000046 A Japanese Patent No. 3577117

  However, the moisture-proof layer formed at such a low temperature becomes a film with innumerable dangling bonds (unbonded hands of hydrogen atoms), and the film deteriorates due to adhesion of moisture, and the moisture-proof layer easily penetrates moisture. There is a problem.

  Therefore, the present invention provides an organic light-emitting device that has a moisture-proof layer that is free from defects and has a water-repellent effect, can prevent moisture and oxygen from entering, and can have a long lifetime, and a method for manufacturing the same. Objective.

That is, the organic light-emitting device of the present invention includes a substrate, an organic light-emitting element formed on the substrate, and a moisture-proof layer formed on the organic light-emitting element and covering the organic light-emitting element. The organic light emitting device includes an organic light emitting device having a lower electrode, an organic compound layer, and an upper electrode in order from the substrate side, wherein the moisture-proof layer includes deuterium, silicon nitride, silicon oxide, acid It is characterized by being made of any one of silicon nitride .

The organic light-emitting device manufacturing method of the present invention covers a substrate, an organic light-emitting element having a lower electrode, an organic compound layer, and an upper electrode that are sequentially disposed on the substrate, and the organic light-emitting element. In a method for manufacturing an organic light emitting device having a moisture barrier layer, a step of forming the organic light emitting element on the substrate , a plasma CVD method using a source gas containing deuterium gas, a Cat-CVD method, a heat Forming a moisture-proof layer made of silicon nitride, silicon oxide, or silicon oxynitride containing deuterium on the organic light-emitting element and in the vicinity of the organic light-emitting element by a CVD method or a photo-CVD method. It is characterized by having.

  Since the organic light emitting device of the present invention has a water repellency and a moisture proof layer having a high moisture proof performance, it can prevent deterioration of elements and generation of dark spots.

  Moreover, the manufacturing method of the organic light-emitting device of the present invention can form a moisture-proof layer having water repellency and high moisture-proof performance.

  The organic light emitting device of the present invention is an organic light emitting device having a substrate, an organic light emitting element formed on the substrate, and a moisture-proof layer covering the organic light emitting element. The organic light emitting device includes a lower electrode, an organic compound layer, and an upper electrode in order from the substrate side. The moisture-proof layer includes deuterium.

  Moisture immediately adheres to the surface of the organic light emitting device left in the atmosphere, and the attached moisture reaches the moisture-proof layer surface. It is considered that this moisture reacts with dangling bonds in the moisture-proof layer and promotes deterioration due to oxidation of the moisture-proof layer.

  As a result of repeated experiments to reduce the dangling bonds in the moisture-proof layer and improve the moisture-proof property, the present inventor has performed deuterium treatment to produce deuterium as compared to the moisture-proof layer subjected to hydrogen treatment. It has been found that when it is contained, the surface layer portion is terminated with deuterium and exhibits a water repellent effect. This is presumably because not only dangling bonds were terminated with deuterium, but also hydrogen on the surface layer was replaced with deuterium, surface energy was reduced, and water repellency was increased.

  Furthermore, by using deuterium gas as a source gas and reacting with other source gases to form a moisture-proof layer, it is possible to obtain a moisture-proof layer having a higher water-repellent effect than when the formed moisture-proof layer is subjected to deuterium treatment Can do. When the formed moisture barrier layer is subjected to deuterium treatment, it is difficult to sufficiently terminate dangling bonds inside the moisture barrier layer, whereas the moisture barrier layer is formed by using deuterium gas as a raw material. Internal dangling bonds can be terminated. Furthermore, hydrogen contained in the moisture-proof layer can be replaced with deuterium, and moisture permeation from microscopic void defects connected from the surface of the moisture-proof layer to the inside is prevented.

  The moisture-proof layer covers the organic light emitting element and extends to the substrate surface around the organic light emitting element. Furthermore, it is preferable that the moisture-proof layer is formed so as to extend to the side edge of the substrate except for the extraction electrode portion, which is effective in enhancing the moisture-proof effect around the moisture-proof layer.

  The present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram showing a part of a cross section of an example of the organic light emitting device of the present invention.

  In FIG. 1, a TFT layer 2 (thin film transistor), an insulating film, and an organic flattening film are laminated in this order on a glass substrate 1, and a Cr electrode that is a lower electrode 4 for each pixel is formed thereon. The element isolation film 3 made of polyimide covers the periphery of each pixel. An organic compound layer 5 made of, for example, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, or the like is formed on this substrate, and a transparent electrode is formed as an upper electrode 6 on the organic compound layer 5. An organic light emitting element is formed by the lower electrode 4, the organic compound layer 5, and the upper electrode 6, and the organic compound layer 5 emits light by passing a current between the electrodes. A plurality of organic light emitting elements are formed on the substrate 1. The organic compound layer 5 only needs to have at least a light emitting layer. In addition, the organic compound layer 5 has a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, etc. involved in carrier transport and carrier injection. Also good.

  Further, except for the extraction electrode, the upper electrode 6, the organic compound layer 5, the element isolation film 3, and further the organic planarization layer of the TFT layer 2 are covered almost entirely to form a moisture-proof layer 10. A circularly polarizing plate 9 is provided on the moisture-proof layer 10.

  The moisture-proof layer 10 of FIG. 1 includes an inner sub-moisture-proof layer 7 and an outer sub-moisture-proof layer 8 containing deuterium on the outermost surface on the opposite side of the substrate 1.

  In general, the surface of the upper electrode 6 of the organic light emitting device has unevenness of several tens of nm of the upper electrode 6 and unevenness reaching 1 μm due to the influence of the lower layer. Therefore, the moisture-proof layer 10 is preferably laminated with an internal sub-moisture-proof layer 7 for flattening them and an external sub-moisture-proof layer 8 for blocking moisture as shown in FIG.

  And it is preferable that the external sub moisture-proof layer 8 contains 0.01 atomic% or more of deuterium. As a result, it is possible to realize a moisture-proof layer with excellent water repellency and high moisture resistance that does not cause film deterioration.

  The moisture-proof layer 10 is preferably made of silicon nitride, silicon oxide, or silicon oxynitride, and more preferably made of hydrogenated silicon nitride, hydrogenated silicon oxide, or hydrogenated silicon oxynitride. Thereby, transparency is secured and application to a top emission type becomes possible.

  The source gas for forming the moisture-proof layer 10 is preferably monosilane, nitrogen, ammonia, hydrogen, oxygen, or all or part of nitrous oxide. For example, monosilane, nitrogen, or hydrogen may be used as a source gas for forming silicon nitride, or nitrogen may be changed to ammonia or mixed. Further, it is not necessary to use hydrogen, but deuterium is used when forming the outer sub moisture-proof layer 8. Further, the outer sub moisture-proof layer 8 may be formed using deuterium only in the vicinity of the surface layer.

  Examples of the method for forming the moisture-proof layer 10 include a plasma CVD method, a Cat-CVD method, a thermal CVD method, a photo-CVD method, and the like. Good. In the case of the plasma CVD method, it is preferable to use a VHF band of 27 MHz to 100 MHz as the excitation frequency of plasma CVD. As a result, the ion bombardment of plasma is weakened to suppress the thermal damage of the element, and the content rate of deuterium in the film is increased, so that a moisture-proof layer having high water repellency can be realized. Further, after forming the moisture-proof layer 10, deuterium treatment may be performed using a plasma CVD method.

  FIG. 2 is a conceptual diagram showing a part of a cross section of another example of the organic light emitting device of the present invention.

  The element shown in FIG. 2 has the same structure as that of the element shown in FIG. 1 except that the inner sub moisture-proof layer has a two-layer structure of an inner sub moisture-proof layer 7 having high adhesion performance with the base layer and an inner sub moisture-proof layer 7 ′ having high planarization performance. It is the same.

  In addition, the layer structure of the moisture-proof layer 10 is not limited to these, A single layer may be sufficient and an external sub moisture-proof layer may be formed in a multilayer.

  The organic light emitting device according to the embodiment described above is a so-called top emission type light emitting device in which the upper electrode 6 is a transparent electrode and light emitted from the organic compound layer 5 is extracted through the upper electrode 6. The present invention is not limited to such a top emission type light emitting device, and may be a so-called bottom emission type light emitting device in which light emitted from the organic compound layer 5 is extracted from the lower electrode 4 side.

  The organic light emitting device according to the embodiment described above is a so-called active matrix organic light emitting device in which a TFT for controlling light emission of each organic light emitting element on the substrate is formed. The present invention is not limited to such an active matrix organic light-emitting device, and may be a so-called passive matrix organic light-emitting device in which organic light-emitting elements are formed at portions where stripe-shaped electrodes intersect.

  Moreover, although the organic light-emitting device of the embodiment described above has a plurality of organic light-emitting elements formed on the substrate, it may be a single organic light-emitting element. When a plurality of organic light emitting elements are formed, it can be used as a display device. As the display device, a television receiver, a display unit of a PC, a display unit of a mobile phone, a rear display unit of a digital camera, and the like can be considered. In the case of one organic light emitting element, it can be used for a backlight of a liquid crystal display device.

  Examples of the present invention will be described below.

<Example 1>
The organic light emitting device shown in FIG. 1 is formed.

  First, a chrome electrode is formed as a lower electrode 4 on a glass substrate 1 having a TFT layer 2, and the periphery thereof is insulated by a polyimide element isolation film 3.

  Next, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are deposited in this order on the lower electrode 4 of the substrate as an organic compound layer 5 to form a stacked layer. On the upper layer, a transparent electrode made of ITO is formed as an upper electrode 6 by sputtering to a thickness of 200 nm.

  Further, the moisture-proof layer 10 is formed by VHF plasma CVD so as to cover the organic compound layer 5, the upper electrode 6, and the substrate 1 exposed around the upper electrode 6.

That is, the substrate formed up to the upper electrode 6 is set in the substrate holder of the discharge furnace of the moisture-proof layer forming apparatus, the pressure of the discharge furnace is evacuated to the 10 ⁻³ Pa level, and then monosilane gas, nitrogen gas, and hydrogen gas are flowed Then, the reaction space pressure is controlled to 100 Pa. Then, 60 MHz high frequency power is supplied to the high frequency electrode, and the internal sub moisture-proof layer 7 made of silicon nitride is formed to 3 μm. Furthermore, monosilane gas, nitrogen gas, and deuterium gas are continuously flowed to control the reaction space pressure to 100 Pa. Then, 60 MHz high frequency power is supplied to the high frequency electrode to form 0.1 μm of the external sub moisture-proof layer 8 made of silicon nitride containing deuterium.

  Thereafter, the circularly polarizing plate 9 is adhered and sealed to obtain an organic light emitting device.

  For comparison, an organic light-emitting device manufactured in the same manner except that no moisture-proof layer is formed is sealed with a getter sheet placed in a glass cap and left indoors.

  Both organic light-emitting elements are allowed to stand for 1000 hours in an environment with a temperature of 60 ° C. and a relative humidity of 90%, and then the elements are allowed to emit light and the luminance of the elements is measured with a luminance meter. In addition, the dark spot is observed and evaluated while the organic light emitting element emits light with an optical microscope.

  As a result, the organic light emitting device of the example and the organic light emitting device of the comparative example are equivalent, and no deterioration is observed in the luminance characteristics. In addition, there is no difference from the initial characteristics. Further, luminance deterioration around the pixel and dark spots of Φ1 μm or more are not generated.

<Example 2>
The organic light emitting device shown in FIG. 2 is formed in the same manner as in Example 1 except that the thickness of the upper electrode 6 is 60 nm and the moisture-proof layer is formed by VHF plasma CVD as follows.

The substrate formed up to the upper electrode 6 is set in the substrate holder of the discharge furnace of the moisture-proof layer forming apparatus, and after evacuating the discharge furnace to a pressure of 10 ⁻³ Pa, monosilane gas, nitrogen gas, and hydrogen gas are flowed. The reaction space pressure is controlled to 100 Pa. Then, 60 MHz high frequency power is supplied to the high frequency electrode, and the internal sub moisture-proof layer 7 made of silicon nitride is formed to a thickness of 0.5 μm. Thereafter, monosilane gas, nitrogen gas, nitrous oxide gas, and hydrogen gas are flowed to control the reaction space pressure to 100 Pa. Then, 60 MHz high frequency power is supplied to the high frequency electrode to form 5 μ of an internal sub moisture-proof layer 7 ′ made of silicon oxynitride. Next, monosilane gas, nitrogen gas, and deuterium gas are flowed, and the reaction space pressure is controlled to 100 Pa. Then, 60 MHz high frequency power is supplied to the high frequency electrode to form 0.5 μm of the external sub moisture-proof layer 8 made of silicon nitride containing deuterium.

  For comparison, an organic light-emitting device manufactured in the same manner except that no moisture-proof layer is formed is sealed with a getter sheet placed in a glass cap and left indoors.

  When evaluated in the same manner as in Example 1, the organic light-emitting device of the example and the organic light-emitting device of the comparative example are equivalent, and no deterioration in luminance characteristics is observed. Furthermore, luminance deterioration from the periphery of the pixel and dark spots of Φ1 μm or more have not occurred.

It is typical sectional drawing which shows an example of the organic light-emitting device of this invention. It is typical sectional drawing which shows the other example of the organic light-emitting device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 TFT layer 3 Element isolation film 4 Lower electrode 5 Organic compound layer 6 Upper electrode 7, 7 'Internal sub moisture-proof layer 8 External sub moisture-proof layer 9 Circularly polarizing plate 10 Moisture-proof layer

Claims (2)

A substrate, an organic light emitting element formed on the substrate, and a moisture-proof layer formed on the organic light emitting element and covering the organic light emitting element. In an organic light emitting device having a lower electrode, an organic compound layer, and an upper electrode in order from the substrate side, the moisture-proof layer is made of any one of silicon nitride, silicon oxide, and silicon oxynitride containing deuterium. An organic light emitting device. In a method for manufacturing an organic light-emitting device, comprising: a substrate; an organic light-emitting element having a lower electrode, an organic compound layer, and an upper electrode arranged in order on the substrate; and a moisture-proof layer covering the organic light-emitting element. ,
Forming the organic light emitting device on the substrate;
Silicon nitride containing deuterium on and around the organic light emitting device by plasma CVD, Cat-CVD, thermal CVD or photo CVD using a source gas containing deuterium gas And a step of forming a moisture-proof layer made of one of silicon oxide and silicon oxynitride .

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