JP2016096097A - Organic electroluminescent device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL device that is manufactured by a conventional manufacturing method, and can reduce power consumption by using a conventional spacer.SOLUTION: There is provided an organic electroluminescent device including: an organic electroluminescent element including an anode and cathode that are arranged opposite to each other, and an organic light emitting layer that is arranged between the anode and cathode and is liquid crystal or liquid at a predetermined temperature to emit light; two substrates that are arranged to sandwich the organic electroluminescent element and opposite to each other; and a spacer that is arranged between the two substrates and supports both substrates, where the thickness of the cathode is made larger than the thickness of the organic light emitting layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic electroluminescence device.

  One type of organic device using an organic material is an organic electroluminescence device (hereinafter sometimes referred to as “organic EL device”), which is expected to be used in a wide range of applications.

  In an organic EL device, for example, as disclosed in Patent Documents 1 and 2, a transparent anode, an organic light emitting layer, and a cathode are sequentially laminated on a substrate made of glass or plastic, and further sealed on it. It has the structure which laminated | stacked the board | substrate for a stop.

International Publication No. 2011/010656 International Publication No. 2012/014976

  Here, in the case of using an organic light emitting layer of a type that emits liquid crystal or liquid at a predetermined temperature as the organic light emitting layer, a spacer for supporting the substrate is used in addition to the above structure.

  FIG. 6 is a schematic cross-sectional view of an organic EL device using a conventional spacer.

  In manufacturing the organic EL device 50 as shown in FIG. 6, a lower substrate 52 provided with an anode 51 and an upper substrate 54 provided with a cathode 53 are prepared, and these are prepared as anodes. In general, the light emitting diode is manufactured by pouring the organic light emitting layer 56 into a space formed between the anode 51 and the cathode 52 by supporting the substrate 51 with the spacer 55 so that the cathode 51 and the cathode 52 face each other.

  When such a manufacturing method is adopted, the thickness of the entire organic EL device 50 is largely caused by the height of the spacer 55. At present, considering the production accuracy of the spacer 55 itself and the processing technology of the organic EL device 50, the height of the spacer 55 is generally about 4 μm. That is, when a spacer with a certain height is used, the distance between the upper substrate and the lower substrate, the so-called cell gap, is equal to the height of the spacer used, but this cell gap can be produced stably. The standard is about 2 μm to 4 μm, and no matter how small it is, the limit is about 1 μm, and it is difficult to produce a cell gap with a high yield by using a spacer 55 smaller than this.

  Under such circumstances, for example, when a spacer having a height of 1 μm is used, the interval between the lower substrate 52 and the upper substrate 54 is naturally 1 μm, and the interval of 1 μm is divided into the anode 51, the cathode 53, and the organic light emission. Although the thickness of the anode 51 and the cathode 53 is generally 100 nm to 200 nm, the thickness of the organic light emitting layer 56 is inevitably 600 nm to 800 nm. Become.

  The inventors of the present application have found a problem in the present situation that seems to be extremely natural. That is, when the thickness of the organic light emitting layer 56 is 600 nm to 800 nm, the voltage for causing the organic light emitting layer 56 to emit light increases in proportion to the thickness, and only by that amount. The problem is that power consumption is required. The problem becomes more prominent as the height of the spacer 55 increases.

  The present invention is an invention made based on such an idea, and it is a main object to provide an organic EL device capable of reducing power consumption by using a conventional spacer by a conventional manufacturing method. And

  An organic electroluminescence device for solving the above-mentioned problems is an organic including an anode and a cathode facing each other, and an organic light-emitting layer disposed between the anode and the cathode and emitting liquid crystal or liquid at a predetermined temperature. An electroluminescent element; and two substrates disposed so as to sandwich the organic electroluminescent element and opposed to each other; a spacer disposed between the two substrates and supporting each other substrate; and the cathode Is thicker than the organic light emitting layer.

  In this invention, the thickness of the organic light emitting layer may be less than 100 nm.

  According to the organic electroluminescence device of the present invention, the power consumption can be reduced by using the conventional spacers while using the conventional spacers.

It is a schematic sectional drawing of the organic device concerning embodiment of this invention. It is a schematic front view of the organic device shown in FIG. It is a schematic front view of the organic device concerning another embodiment of this invention. It is a schematic sectional drawing of the organic device concerning another embodiment of this invention. It is a schematic sectional drawing of the organic device concerning another embodiment of this invention. It is a schematic sectional drawing of the organic EL device using the conventional spacer.

  Below, the organic EL device concerning the embodiment of the present invention is explained in detail using a drawing.

Organic EL Device FIG. 1 is a schematic cross-sectional view of an organic EL device according to an embodiment of the present invention.

  As shown in FIG. 1, an organic EL device 10 according to this embodiment is disposed between an anode 11 and a cathode 12 facing each other, and between the anode 11 and the cathode 12, and emits liquid crystal or liquid at a predetermined temperature. An organic light-emitting layer 13 including the organic light-emitting layer 13, the organic electroluminescence element 14 disposed between the two substrates 15 and 16 facing each other, and the two substrates 15 and 16. And a spacer 17 that supports the substrates 15 and 16. The cathode 12 is thicker than the organic light emitting layer 13.

  In the organic EL device 10 according to the present embodiment, the thickness of the cathode 12 is designed to be larger than the thickness of the organic light emitting layer 13, so the distance between the upper substrate 15 and the lower substrate 16, so-called cell. Even when the gap is large, since the cell gap can be filled with the cathode, the thickness of the organic light emitting layer 13 can be reduced by that much, and the number of consumption electrodes can be reduced. In other words, the design philosophy of the conventional organic EL device was to reduce the power consumption by reducing the cell gap by reducing the height of the spacer and reducing the thickness of the entire organic EL element. The organic EL device 10 according to the present embodiment changes the way of thinking and pays attention to the proportion of the cathode 12 and the organic light emitting layer 13 in the cell gap generated by the spacer 17 and dares to make the cathode 12 easy to thin. By designing it thick, the cell gap is filled with the cathode 12, and the organic light-emitting layer 13 is made thin by that much, thereby reducing the number of consumption electrodes.

  Hereinafter, each configuration of the organic EL device 10 according to the present embodiment will be described.

Organic EL Device Element The organic EL device element 14 includes an anode 11, a cathode 12, and an organic light emitting layer 13 disposed between the two electrodes 11 and 12.

-Anode The anode 11 constituting the organic EL device element 14 is not particularly limited, and the conventionally used anode 11 can be appropriately selected and used.

  As a material of the anode 11, a conventionally known transparent electrode material such as ITO (indium tin oxide) or IZO (indium zinc oxide) may be used. Further, the thickness of the anode 11 can be appropriately designed in relation to the height of the spacer 17 described later. For example, when the height of the spacer 17 is about 1 μm, the thickness of the anode 11 is about 30 nm to 500 nm. Also good. In particular, 50 nm to 200 nm is preferable in consideration of the influence of transmittance.

  The method for producing the anode 11 is not particularly limited, and the anode 11 may be produced on a lower substrate 15 to be described later by using a dry process such as a sputtering method or a vacuum deposition method. You may produce using a process.

-Cathode The cathode 12 which comprises the organic EL device element 14 is one of the characteristic parts of the organic EL device 10 concerning this embodiment, and is provided thicker than the organic light emitting layer 13 mentioned later. Therefore, the material for producing the cathode 12 can be appropriately selected from conventionally known materials, but it is necessary to select a material that can be thickened in consideration of the thickness of the organic light emitting layer 13 and the like. For example, metal electrode materials such as gold, platinum, silver, copper, and aluminum, and various alloy materials may be used, and aluminum is preferable in consideration of cost. Further, it is preferable to use a metal material having a melting point lower than that of the upper substrate 16. This is because, by using such a material, the cathode 12 can be manufactured regardless of the evaporation method, and thus the thickness can be increased.

  The metal material having a melting point lower than that of the upper substrate 16 is, for example, a Ga-based alloy that is in a paste state at a temperature equal to or higher than the melting point, and includes a Ga-based liquid metal that is liquid at room temperature and an alkali metal or an alkaline earth metal. Examples thereof include at least an electron injection function.

  In general, “metal paste” means a paste obtained by using a resin as a binder and dispersing metal powder in this resin to form a paste. Means a resin that contains no metal and is in a paste state. Thus, since the cathode comprised from this paste-like metal does not contain resin or the like, it has an excellent electron injection function. The “electron injection function” in the present specification means a function capable of injecting electrons from the cathode or the electron injection layer when an electric field is applied.

  The Ga-based liquid metal means a liquid that is in a liquid state at room temperature (as a guideline, 5 to 45 ° C.) and exhibits sufficient fluidity at a relatively low temperature up to a metal temperature of about 50 ° C. even at room temperature or when heated. The melting point is preferably 50 ° C. or lower. As the Ga-based liquid metal, Ga or an alloy of Ga and one or more metals selected from In, Sn, and Zn can be preferably used.

  Ga-based alloys are preferably used because of their low fluidity and toxicity at room temperature. In the present embodiment, an alloy is an apparently uniform metal composed of two or more kinds of metals, and it is not always necessary that a metal bond be formed between different kinds of metals. In the present embodiment, the Ga-based alloy contains Ga as a main component, preferably 40% by mass, more preferably 50% by mass of the metal constituting the Ga-based alloy.

  Ga alone is a liquid in a wide temperature range from room temperature to high temperature, with a melting point of 30 ° C. and a boiling point of 2400 ° C. As a metal capable of maintaining a liquid state at a lower temperature, a Ga-based liquid metal containing Ga and at least one other metal of In, Sn, and Zn as an essential component can be used. Table 1 shows an example of the composition ratio and melting point of Ga and Ga-based liquid metal that can be used in this embodiment.

  In addition, the composition of each component constituting the Ga-based alloy means a charged mass of each metal component weighed in advance, or a composition measured by an X-ray diffraction method, an XPS method, or other appropriate methods.

  The alkali metal or alkaline earth metal constituting the Ga-based alloy is preferably one or more metals selected from Ca, Li, Na, K, Mg, Rb, Cs, Ba, Be, and Sr.

  Alkaline metals and alkaline earth metals have low melting points such as Li (180 ° C.), Na (98 ° C.), K (64 ° C.), Rb (39 ° C.), Cs (29 ° C.) and high melting points. Ca (839 ° C.), Mg (650 ° C.), Ba (725 ° C.), Be (1284 ° C.), Sr (770 ° C.). Since alkali metals or alkaline earth metals are highly dangerous due to their strong oxidative combustion properties in the atmosphere, they are usually preferably handled in a glove box substituted with an inert gas.

  Since the low melting point group can be heated and melted in the glove box relatively safely, it can be weighed and mixed with the Ga-based liquid metal. On the other hand, even in the glove box, it is very dangerous for the high melting point group to be heated and melted and directly mixed with the Ga-based liquid metal because of the large amount of heat. For this reason, it is preferable to prepare an alloy with another metal in advance in a vacuum melting furnace that can prevent combustion, and to handle it after it is in a stable state.

  Alkali metals or alkaline earth metals are all preferable because they have a low work function and can exhibit a high electron injection function, and Ca (work function 2.87 eV), Li (work function 2.4 eV), Na (work function) 2.36 eV), K (work function 2.28 eV), Mg (work function 3.66 eV), Rb (work function 2.16 eV), Cs (work function 2.14 eV), Ba (work function 2.52 eV), Be (work function 2.45 eV) and Sr (work function 2.59 eV) can be preferably used. In this embodiment, the value of “work function” of each element is “J. Appl. Phys. 48 "(1977), page 4729, and the actual measurement data of the ionization potential measuring device.

Among these, Ca is particularly preferable because it can be easily mixed in a large amount with a Ga-based liquid metal. Ca has a much larger molar volume than other metals, and it is considered that Ca can be dissolved in a large amount in the Ga-based liquid metal. In addition, a cathode having high power conversion efficiency and a long element life can be easily obtained. An example of the molar volume of each metal is shown below.
Ca 26.2 × 10 ³ (m ³ / mol)
Li 13.0 × 10 ⁻⁶ (m ³ / mol)
Na 23.8 × 10 ⁻³ (m ³ / mol)
K 45.9 × 10 ⁻³ (m ³ / mol)
Mg 14.0 × 10 ⁻³ (m ³ / mol)
Rb 55.8 × 10 ⁻⁶ (m ³ / mol)
Cs 70.9 × 10 ⁻³ (m ³ / mol)
Ba 38.2 × 10 ⁻³ (m ³ / mol)
Be 4.9 × 10 ⁻³ (m ³ / mol)
Sr 33.9 × 10 ⁻³ (m ³ / mol)

  By containing 5 to 30% by mass of Ca, an appropriate paste property can be obtained as described below, and an electron injection function can be exhibited. Further, a higher electron injection function can be imparted by mixing a small amount of other alkali metal or alkaline earth metal.

  As other metals forming an alloy with an alkali metal or alkaline earth metal, In or Sn is preferable. An alloy of an alkali metal or alkaline earth metal and In or Sn melts into a Ga-based liquid metal in the atmosphere at room temperature, so that it can be easily weighed and mixed. In addition, since In or Sn is easily melted in Ga, even if the above alloy is dissolved in Ga-based liquid metal, In or Sn is not separated as a solid phase, and a Ga-type alloy in a uniform paste state is manufactured. it can.

  Needless to say, even a high melting point group alkali metal or alkaline earth metal can be directly alloyed with a Ga-based liquid metal in a vacuum melting furnace. It is easier to change conditions such as concentration adjustment by preparing an alloy with In or Sn and mixing this alloy with Ga-based liquid metal.

  Since the Ga-based alloy obtained by such a method is in a liquid state at a lower temperature than Ga simple substance (melting point is lowered), it is easy to handle.

  In order to make the Ga-based liquid metal into a highly viscous paste, it is particularly preferable to contain 5 to 30% by mass of Ca. By setting the Ca concentration within this range, it is possible to obtain a viscosity of 5 to 100 Pa · s suitable for various printing methods, and to exhibit a sufficient electron injection function necessary for an organic EL element as an electrode. Viscosity varies somewhat with the Ca concentration, depending on the type of Ga-based liquid alloy.

  The Ga-based alloy further contains a metal having a melting point of 300 ° C. or lower, and is preferably solid at normal temperature and in a paste state at a temperature higher than the melting point. Thus, by further containing a metal having a melting point of 300 ° C. or lower in the Ga-based alloy, a Ga-based alloy that is solid at normal temperature and is in a paste state at a temperature equal to or higher than the melting point can be obtained. By using such a Ga-based alloy for electrode formation, it is not necessary to form an adhesive layer.

  The Ga-based alloy according to the preferred embodiment is solid at room temperature. When heated, it begins to soften at a certain temperature, and when heated further, it transitions to a liquid state through a viscous paste state. In the present specification, the “melting point” means not a temperature at which a metal transitions to a liquid state but a temperature at which softening starts (softening temperature).

  To add a metal having a melting point of 300 ° C. or lower, an alloy of an alkali metal or an alkaline earth metal and In or Sn is dissolved in a liquid Ga-based liquid metal at room temperature to form a paste-like Ga-based alloy. Then, the metal is heated to a temperature at which a metal having a melting point of 300 ° C. or lower is melted, and the metal having a melting point of 300 ° C. or lower is mixed in the paste alloy.

  Examples of the metal having a melting point of 300 ° C. or lower include In, Sn, Bi, and alloys containing these as main components. Among these, InSn can be preferably used. An “alloy” is an apparently uniform metal composed of two or more kinds of metals, and does not necessarily require a metal bond to be formed between different metals.

  Table 2 shows an example of a metal having a melting point of 300 ° C. or lower that can be used for the Ga-based alloy.

The Ga-based alloy is in a completely liquid state at a high temperature that further exceeds its melting point. Therefore, the “paste state” is considered to be a state in a viscous region between the liquid state and the solid state. In the present embodiment, the temperature range in the paste state is preferably 5 ° C. or higher. By having such a temperature range, the organic EL device element can be stably manufactured.

  The Ga-based alloy preferably has a melting point of 50 ° C. or higher. When the melting point is lower than 50 ° C., the electrode of the manufactured organic device element may be melted and peeled due to environmental change or the like. In order to be solid at normal temperature and to be in a paste state at a temperature equal to or higher than the melting point, and to have the temperature characteristics as described above, it is preferable that 5-30% by mass of Ca is contained in the Ga-based alloy. Note that the viscosity of the paste varies depending not only on the Ca content but also on the type of metal having a melting point of 300 ° C. or lower.

  A Ga-based alloy is obtained by melting and mixing a Ga-based liquid metal as shown in Table 1 above, a metal having a melting point of 300 ° C. or lower as shown in Table 2 above, and an alkali metal or alkaline earth metal such as Ca. Although obtained, when Ca is used, in order to prevent combustion and explosion of Ca, it is preferable to melt and mix in a vacuum melting furnace or an inert gas melting furnace.

  Specifically, it is safe to prepare an alloy of In, Sn, and Ca, which is a metal that is easily melted into Ga metal, in a vacuum melting furnace in advance, and to melt these CaIn or CaSn alloy into Ga-based liquid metal. From the viewpoint of surface and handleability, it is preferable.

  When a CaIn or CaSn alloy is immersed in a Ga-based liquid metal, a Ga-based alloy in a paste state at room temperature can be obtained by dissolution. Since this Ga-based alloy has a good electron injection function, it exhibits good emission characteristics when used as a cathode of an organic EL device. That is, in an organic EL element, in order to be able to control a larger current, it is preferable that the electrode has a good charge injection efficiency (hole injection efficiency at the anode and electron injection efficiency at the cathode). Uses a metal having a low work function from the viewpoint of easily emitting electrons. In a conventional cathode, Al having a work function of 4.2 eV is preferably used as a typical metal. However, in Ga-based alloys, the work function of Ga is 4.3 eV, which is close to Al. In addition to this advantage, when a Ga-based alloy is used as the cathode, there is also an advantage that electron injection from the cathode to the organic light emitting layer becomes good.

  Moreover, since the work functions of each metal such as In, Sn, Bi, and Ga constituting the Ga-based alloy are close to the work functions of 4.1 eV, 4.4 eV, 4.3 eV, 4.3 eV, and Al, respectively, The Ga-based alloy in the present embodiment is advantageous not only from the manufacturing aspect of electrode formation as described above but also from the aspect of the electron injection function.

  In the Ga-based alloy, other metals may be contained as necessary. For example, in order to improve the electron injection efficiency of the cathode, as a substance having a low work function, alkali metals and alkalis other than Ca are used. At least one selected from earth metals can be mixed with the cathode. Among these, one or more metals selected from Li, Na, K, Mg, Rb, Cs, Ba, Be, and Sr are preferable. Moreover, 1 mass% or less is preferable and 0.05-2 mass% is more preferable. If the addition amount is within this range, the paste properties of the Ga-based alloy are not affected. The method for adding these metals is as described above.

  On the other hand, examples of the metal material having a melting point lower than that of the upper substrate 16 include a Bi alloy in which Al is dispersed in a Bi alloy composed of Bi and at least one of In and Sn. .

  In the alloy, since Al is dispersed in the Bi alloy, the work function can be lowered as compared with the case where only the Bi alloy is used. Therefore, in the organic EL device according to the present embodiment using such a Bi alloy as a cathode, the electron injection barrier can be reduced at the interface between the Bi alloy electrode and the layer in contact with the Bi alloy electrode. It is possible to improve. In addition, since the Bi alloy is composed of Bi and at least one of In and Sn, it can be an organic device that does not contain Pb or Cd and is environmentally friendly. Further, the Bi alloy is composed of Bi and at least one of In and Sn. Usually, since the melting point of the Bi alloy is within a predetermined range, the electrode can be formed by a wet process, and the organic device can be enlarged. The manufacturing cost can be reduced, and damage to the organic layer during electrode formation can be prevented. Moreover, the reliability with respect to an environmental change can be improved.

  The present Bi alloy is not particularly limited as long as it is composed of Bi and at least one of In and Sn, and may be composed of Bi, In and Sn. It may be composed of Bi or Sn. In the present specification, “Bi alloy” refers to an alloy containing Bi, and includes not only a Bi-containing alloy having the highest Bi content but also a Bi-containing alloy having the highest In content and Sn content.

  The melting point of the Bi alloy may be any temperature that can form the cathode of the Bi alloy by a wet process without damaging the organic light emitting layer 13, and is preferably in the range of 60 ° C to 180 ° C. Is in the range of 70 ° C to 160 ° C, more preferably in the range of 72 ° C to 138 ° C. This is because if the melting point of the Bi alloy is too high, the organic light emitting layer 13 may be seriously damaged during the formation of the cathode. Moreover, in order to use an organic EL device stably also in a high temperature environment, it is practically preferable that the melting point of the Bi alloy is in the above range, and if the melting point of the Bi alloy is too low, This is because the Bi alloy cathode may melt during use. In particular, since the organic EL element generates heat during driving, if the melting point of the Bi alloy is lower than the above range, the Bi alloy cathode may be melted by heat. Even if Al is added to the Bi alloy, the melting point of the Bi alloy does not change.

  The composition and melting point of the Bi alloy are exemplified in Table 3.

  In the present specification, the composition of Bi, In, and Sn constituting the Bi alloy is the charged mass of each component weighed in advance, or X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) Or the composition measured by the other suitable method is meant.

  The content of Al in the Bi alloy electrode is not particularly limited as long as the electron injection characteristics can be improved, and can be within a range of 0.0001 mass% or more and less than 100 mass%, preferably 0. It is within the range of 0.0001% by mass to 50% by mass, and more preferably within the range of 0.0006% by mass to 10% by mass. This is because if the Al content is too small, the effect of improving the electron injection characteristics may not be sufficiently obtained, and even if the Al content is increased, the effect of improving the electron injection characteristics does not change.

  It is preferable that the concentration of Al in the Bi alloy electrode increases from the side opposite to the organic layer side toward the organic layer side. With such a configuration, the work function can be lowered from the opposite side of the organic light emitting layer side to the organic light emitting layer side in the Bi alloy cathode, and at the interface between the Bi alloy cathode and the layer in contact therewith. This is because the electron injection barrier can be further reduced. In the Bi alloy, Al is an impurity solute element. The solubility of solute elements is lower in the solid phase than in the liquid. Therefore, solute elements are segregated and concentrated in the liquid as the solidification progresses. That is, the movement of Al during the solidification process occurs because Al as an impurity is segregated during alloy solidification. By using this principle and solidifying from the opposite side of the organic light emitting layer, it is possible to increase the concentration of Al from the opposite side of the organic light emitting layer toward the organic light emitting layer side. Note that the Al concentration in the cathode of the Bi alloy increases from the side opposite to the organic light emitting layer side toward the organic light emitting layer side. It can be confirmed by measuring the depth direction by angle resolution with respect to the analyzer or by measuring the depth direction using ion beam sputtering.

  The work function of the Bi alloy cathode is not particularly limited as long as it is lower than the work function of the Bi alloy alone. Further, the lower limit of the work function of the Bi alloy electrode may be about the same as that of Al. Specifically, the work function of the Bi alloy electrode is preferably in the range of 3.9 eV to 4.6 eV, more preferably in the range of 3.9 eV to 4.3 eV, and still more preferably 3.9 eV to 4 eV. Within the range of 1 eV. In addition, the value of the work function measured using the photoelectron spectrometer AC-3 by Riken Keiki Co., Ltd. was applied to the work function. The measurement was performed based on the energy value at which photoelectrons were emitted from the photoelectron spectrometer AC-3 by forming a layer formed of the material to be measured on the substrate as a single layer. As measurement conditions, it was performed in increments of 0.05 eV with a light amount of 50 nW.

  As a method of adding Al to the Bi alloy, a method of mixing Al with a Bi alloy in a molten state can be used. Specifically, Al can be added to the Bi alloy by immersing Al in an arbitrary shape such as a wire, a rod, a sheet, or a lump in the molten Bi alloy. Even if Al is mixed with the Bi alloy in the molten state, the Al does not melt as long as the melting point of the Bi alloy is reached, so it does not become an alloy but is dispersed in the Bi alloy.

  The method for forming the cathode of the Bi alloy is not particularly limited as long as it is a method capable of forming an electrode in which Al is dispersed in the Bi alloy, but an electrode material composed of a molten Bi alloy and Al is used. A coating method is preferably used. A wet process such as a coating method can prevent damage to the organic light emitting layer during Bi alloy electrode formation. In addition, all layers of the organic EL device can be formed by a wet process such as a coating method without using a dry process such as a vapor deposition method, thereby realizing an increase in the size of the organic EL device and a reduction in manufacturing cost. be able to. Further, the method of applying an electrode material composed of a molten Bi alloy and Al has an advantage that the thickness of the Bi alloy electrode can be easily controlled.

  The method of applying an electrode material composed of a molten Bi alloy and Al is not particularly limited as long as it is a method using a coating apparatus having a heating mechanism in a discharge portion such as a nozzle. For example, a method using a dispenser, a spray coating method, a blade coating method, a casting method, a bar coating method, a die coating method, and an ink jet method can be used. In the coating apparatus, it is preferable that the heating mechanism of the discharge unit such as a nozzle is processed with an alloy having excellent stability such as SUS. Furthermore, it is also possible to apply the substrate by immersing the substrate in a molten metal bath. After applying an electrode material made of a molten Bi alloy and Al, it is cooled to form a Bi alloy cathode.

  Examples of the atmosphere at the time of forming the cathode of the Bi alloy include inert gases such as nitrogen and argon.

  Further, in a state where the lower substrate 15 and the upper substrate 16 are supported by the spacers 17 to be described later, an electrode material composed of the molten Bi alloy and Al is injected using a capillary phenomenon, and then cooled. By doing so, a Bi alloy cathode may be formed.

  In the organic EL device 10 of the present embodiment, the lower substrate 15 and the upper substrate 16 that are installed so as to sandwich the organic EL device element 14 are supported by the spacers 17, so that the organic device element The space for forming 10 can be designed freely. Therefore, particularly when the cathode 12 is formed, the formation method can be freely selected.

  Further, as described above, the organic EL device 10 according to the present embodiment is characterized by the thickness of the cathode 12 constituting the organic EL device element 14. Is not particularly limited, and may be designed to be thicker than the organic light emitting layer 13 described later. In other words, the distance between the lower substrate 15 and the upper substrate 16, the size of the so-called cell gap, the thickness of the anode 11, the thickness of the organic light emitting layer 13, and the like should be considered. For example, by setting the cathode 12 to a thickness that is more than half the size of the cell gap, the thickness of the cathode 12 can inevitably be made larger than the thickness of the organic light emitting layer 13. The effect can be demonstrated.

  Moreover, it is preferable to design the cathode 12 to be thick so that the thickness of the organic light emitting layer 13 is less than 100 nm. By setting the thickness of the organic light emitting layer 13 to less than 100 nm, power consumption can be sufficiently reduced. For example, when the distance between the lower substrate 15 and the upper substrate 16, the so-called cell gap, is 1 μm and the thickness of the anode 11 is 150 nm, by making the thickness of the cathode thicker than 750 nm, As a result, the thickness of the organic light emitting layer 13 can be less than 100 nm.

  From such a viewpoint, it can be said that the cathode 12 in the organic EL device 10 according to the present embodiment has a thickness adjusting function for designing the thickness of the organic light emitting layer to a desired thickness. Therefore, the cathode 12 does not necessarily have to exist as a single layer, and may have a laminated structure in which a plurality of layers are laminated.

Organic Light-Emitting Layer The organic light-emitting layer 13 constituting the organic EL device element 14 is an organic light-emitting layer that emits light as a liquid crystal or a liquid at a predetermined temperature, and is not particularly limited as long as it satisfies this condition.

As a material for such an organic light emitting layer 13, a material that exhibits a liquid crystal or a liquid at a predetermined temperature may be used as it is, and specifically, for example, Tables 1 to 52 in JP-A-09-316442. And the general formulas (I) to (I) disclosed in JP-A-10-231260.
I) and the materials disclosed in Table 1 or the materials disclosed in JP-A-2006-248948 (Chemical Formula 1) to (Chemical Formula 9) and Tables 1-2 may be used as appropriate. Good.

  In addition, a dopant may be separately added to these liquid crystal or liquid-expressing materials for the purpose of improving the light emission efficiency or changing the light emission wavelength. In the case of a polymer material, these may be included as a light emitting group in the molecular structure. As such a dopant, for example, those disclosed in JP 2009-290204 A can be used, and specific examples include perylene derivatives, coumarin derivatives, rubrene derivatives, carbazole derivatives, and fluorene derivatives. it can. Moreover, the compound which introduce | transduced the spiro group into these can also be used. These materials may be used alone or in combination of two or more.

  Further, the organic light emitting layer 13 may be a single layer or a laminated structure in which a plurality of layers are laminated. Examples of the organic light emitting layer 13 as a laminated structure include a laminated structure in which a hole injection / transport layer, an organic liquid crystal layer, and an electron injection / transport layer are sequentially laminated.

  The details of each layer constituting the organic light-emitting layer 13 described above, that is, the material, the thickness of the layer, and the manufacturing method thereof are not particularly limited, and each conventionally known layer is appropriately selected. can do. Therefore, the organic layer 13 may be composed of a high molecular compound having a molecular weight of 1000 or more, or may be composed of a low molecular compound having a molecular weight of less than 1000. Further, the organic layer 13 may be produced by vapor deposition or coating.

  Moreover, when the organic light emitting layer 13 in this embodiment is a laminated structure which laminated | stacked several layers, the layer which consists of an inorganic substance and a metal complex may be contained in the said several layers. That is, for example, when the organic light emitting layer 13 is a laminated structure in which a hole injection transport layer, an organic liquid crystal layer, and an electron injection transport layer are sequentially stacked, the hole injection transport layer and the electron injection transport layer are inorganic or metal It may be a layer made of a complex. Furthermore, a charge generation layer may be added as necessary.

-Substrate The organic EL device 10 according to the present embodiment has two opposing substrates, that is, a lower substrate 15 and an upper substrate 16. These substrates 15 and 16 play a role of supporting or sealing the organic EL device element 14 described above.

  Such substrates 15 and 16 may be flexible substrates or rigid substrates.

  The substrates 15 and 16 may or may not have optical transparency, and are appropriately selected according to the use of the organic EL device 10 according to the present embodiment.

  The materials of the substrates 15 and 16 are appropriately selected according to the use of the organic EL device 10 and the like, for example, glass such as quartz, alkali glass and non-alkali glass, thin glass, polyethylene, polypropylene, Examples thereof include resins such as polyethylene terephthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, polycarbonate, polyethersulfone, polyetheretherketone, polyvinyl fluoride, polyolefin, and fluorine resin, and SUS substrates. The substrates 15 and 16 may be not only a single layer but also a laminated structure in which a plurality of the above-described materials are laminated. In particular, when a resin is used as a material, a structure in which a barrier layer for preventing intrusion of water or oxygen is preferably laminated.

  Although the thickness of the board | substrates 15 and 16 is not specifically limited, Usually, it is about 0.5 mm-2.0 mm.

Spacer The organic EL device 10 according to the present embodiment includes a spacer 17 that is disposed between the two substrates 15 and 16 described above and supports them.

  The shape of the spacer 17 is not particularly limited, and may be any design as long as it has the above-described effects, that is, a shape that can support the two substrates 15 and 16. Specifically, for example, in addition to the columnar shape as shown in FIG. 1, a spherical shape, a wall shape, or a shape in which particles are stacked can be employed. Further, even in the case of a columnar shape, a trapezoidal shape or a columnar shape may be used in addition to the rectangular shape as shown in FIG.

  Further, the height of the spacer 17 is not particularly limited, and the distance between the two substrates 15 and 16, the so-called cell gap, and the thickness of the organic light emitting layer 13 are designed. Thus, it is possible to design freely considering whether to reduce power consumption. Specifically, for example, the thickness may be about 1 μm to 3000 μm.

  The material of the spacer 30 is not particularly limited. For example, various resins that can be used in the substrates 15 and 16, that is, polyethylene, polypropylene, polyethylene terephthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, polycarbonate, polyethersulfone, polyetheretherketone, polyfluoride Resins such as vinyl, polyolefin, and fluorine-based resins may be used, while inorganic materials such as silica, alkali-free glass, quartz glass, soda-lime glass, borosilicate glass, and titanium barium-based glass may be used.

  Moreover, even if it exists in the formation method of the spacer 17, it does not specifically limit, It can select suitably from a conventionally well-known formation method. For example, the spacers 17 may be manufactured individually and installed on the substrates 15 and 16 using an adhesive, and the spacers 17 may be formed simultaneously with the formation of the substrates 15 and 16. Further, a thick substrate material may be prepared, and the spacer 17 may be formed by etching or the like. When an adhesive is used, the adhesive may be a thermosetting adhesive or a photocurable adhesive.

  The timing for forming the spacer 17 is not particularly limited. For example, the organic EL device element 14 is formed on the lower substrate 15, then the spacer 17 is formed on the lower substrate 15, and finally the upper substrate 16 is mounted, and the upper substrate 16 and the spacer 17 are placed. And the order of the formation of the organic EL device element 14 and the formation of the spacer 17 may be interchanged. Further, a spacer 17 may be provided on the upper substrate 16 and finally bonded to the lower substrate 15.

  Next, the position where the spacer is provided will be described.

  FIG. 2 is a schematic front view of the organic device shown in FIG.

  The spacers 17 need not be formed so as to completely surround the organic EL device element 14 and may be provided only at the four corners as shown in FIG. The spacer 17 forms a space in which the organic EL device element 14 is installed by supporting the substrates 15 and 16 that are provided so as to sandwich the organic EL device element 14. If possible, the installation location is not particularly limited.

  In this manner, by providing the spacers 17 with a predetermined interval, various layers constituting the organic EL device element 14 can be formed using the spaces between the spacers 17 (see arrows in FIG. 2). The desiccant can be installed by utilizing the space existing between the substrates 15 and 16.

  On the other hand, although not shown, for example, a spacer may be provided in a wall shape so as to surround the periphery of the organic EL device element 14. Thus, by providing a spacer in the shape of a wall, the airtightness of the organic EL device element 14 can be improved, and moisture or the like can be prevented from entering the organic EL device element 14.

  FIG. 3 is a schematic front view of an organic EL device according to another embodiment of the present invention. In addition, the same code | symbol is used about the same structure as FIG.

  As shown in FIG. 3, the organic EL device according to the present embodiment is a so-called “multi-sided”, that is, a plurality of organic EL device elements 14, 14. is there. In this case, the spacer 17 can be appropriately installed between the organic EL device elements 14.

  FIG. 4 is a schematic cross-sectional view of an organic device according to another embodiment of the present invention. In addition, the same code | symbol is used about the same structure as FIG.

  As shown in FIG. 4, in the organic EL device 10 according to this embodiment, the desiccant 40 is disposed in a space existing between the two substrates 15 and 16 supported by the spacer 17.

  Thus, in the organic EL device 10 according to the present embodiment, as described above, an appropriate space can be created between the substrates 15 and 16 by appropriately designing the installation positions of the spacers. Can be used effectively. By disposing the desiccant 40 in the space, the organic EL device element 14 can be prevented from being affected by moisture, and the life of the organic device element 10 can be extended.

  The desiccant 40 is not particularly limited, and can be appropriately selected from various desiccants already used in the field of organic EL devices.

  Also, the arrangement method of the desiccant 40 is not particularly limited, and may be arranged by adhering the desiccant 40 to the upper substrate 16 as shown in FIG. Although not shown, a desiccant may be installed on the lower substrate 15 or may be installed on both the substrates 15 and 16.

  FIG. 5 is a schematic cross-sectional view of an organic device according to another embodiment of the present invention. In addition, the same code | symbol is used about the same structure as FIG.

  As shown in FIG. 5, in the organic EL device 10 according to the present embodiment, the counterbore 22 is provided on the upper substrate 16 constituting the device, and the desiccant 40 is disposed on the counterbore 22. Has been. Thus, the spot 22 may be provided in a part of the substrate 16 and the desiccant 40 may be disposed in the part. By providing the counterbore part 22 and disposing the desiccant 40 on the part, it becomes difficult for the organic EL device element 14 and the desiccant to come into contact with each other, and the yield during manufacturing can be improved.

  Even in this case, although not shown, a counterbore part may be provided on the lower substrate 15 and a desiccant may be provided on the counterbore part, or a counterbore part may be provided on both the substrates 15 and 16. You may install a desiccant in a part.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described using examples and comparative examples.

  The production of the organic EL device was performed in a nitrogen-substituted glove box having a moisture concentration of 1 ppm or less and an oxygen concentration of 1 ppm or less unless otherwise specified.

Example 1
-Production of substrate A A glass substrate with a thin film of ITO having a thickness of 150 nm was used as an anode. After this glass substrate was cut into a size of 25 mm × 25 mm, an ITO film on the glass substrate was patterned in a stripe shape. The glass substrate thus obtained was ultrasonically cleaned in order of neutral detergent and ultrapure water, and then subjected to UV ozone treatment.

  Next, PEDOT (AI4083), which is a hole injection material, was applied to the glass substrate by spin coating in the air, and dried in the air at 200 ° C. for 30 minutes to form a film having a thickness of 20 nm.

  Next, as a hole transport material, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butyl) which is a polymer material. Phenyl)) diphenylamine)] (TFB). A film in which the TFB was dissolved in xylene at a concentration of 0.4 wt% was applied by spin coating to form a film. After applying the TFB solution, the film was dried at 200 ° C. for 30 minutes using a hot plate in order to evaporate the solvent, thereby forming a film having a thickness of 20 nm. Substrate A was obtained through these steps.

-Production of substrate B A glass substrate having a size of 25 mm x 25 mm was subjected to UV ozone treatment by ultrasonic cleaning in the order of neutral detergent and ultrapure water. Next, Al (thickness: 3730 nm) was formed as a cathode on the glass substrate. This film formation was performed by resistance heating vapor deposition in vacuum (pressure: 1 × 10 ⁻⁴ Pa).

  Next, 3TPYMB (tris [3- (3-pyridyl) mesityl] borane): Liq (8-hydroxyquinolinolato-lithium) = 1: 1 (solid content concentration 1% by mass on the cathode as an electron injecting and transporting layer, 1-butanol solution) was applied by spin coating, and heated at 150 ° C. for 30 minutes using a hot plate. The thickness after heating was 30 nm. A substrate B was obtained through these steps. In the formation of the electron injecting and transporting layer, when it is difficult to form a coating film, an evaporation method may be used.

  The substrate A and the substrate B were bonded together using a spacer having a size of 4 μm and an adhesive. At this time, the gap between the hole transport layer of the substrate A, the substrate B, and the electron injection transport layer was 50 nm.

  The liquid crystal material used for the organic light emitting layer is 2-4-octyloxyphenyl-6-butoxybenzothiazole (phase transition temperature: Cryst 68.3 ° C SmC 100.8 ° C Nematic 123.9 ° C Iso, described below, 8O- (Abbreviated as PBT-O4). 8O-PBT-O4: C545T (10- (2-Benzothiazolyl) -2,3,6,7-tetrahydro-1,1,7,7, -tetramethyl l- 1H, 5H, 11H- [1] benzopyrano [6 , 7,8-ij] quinolizin-11-one) = 95: 5 (weight ratio) was injected at 130 ° C. on a hot plate using capillary action. After the injection, the temperature was returned to room temperature.

  If it is difficult to inject using capillary action, a powder of 8O-PBT-O4: C545T = 95: 5 (weight ratio) is provided on the substrate A, and then the substrate B is bonded to a spacer having a size of 4 μm. An adhesive may be used and then heated after pasting.

  The organic EL device concerning Example 1 was obtained by the above.

(Comparative Example 1)
An organic EL device according to Comparative Example 1 was obtained under the same conditions as in Example 1 except that the thickness of the organic light emitting layer was changed to 3680 nm by setting the thickness of Al as the cathode to 100 nm.

(Device characteristic evaluation)
The organic EL devices of Example 1 and Comparative Example 1 all emitted green light derived from C545T. About these, the light emission brightness | luminance and the spectrum were measured using the spectroradiometer SR-2 by Topcon Corporation. The measurement results are shown in Table 4 below. The current efficiency was calculated from the drive current and the luminance.

  As a result of causing the organic EL devices of Example 1 and Comparative Example 1 to emit light, light emission CIE (x, y) = (0.32, 0.58) derived from C545T could be confirmed. It was found that the characteristics of Example 1 were better than those of Comparative Example 1 for both the light emission start voltage and the maximum luminance. In Comparative Example 1, it is considered that the organic light emitting layer is too thick, resulting in a high voltage and a decrease in the recombination carrier balance in the organic light emitting layer.

DESCRIPTION OF SYMBOLS 10 ... Organic EL device 11 ... Anode 12 ... Cathode 13 ... Organic light emitting layer 14 ... Organic EL device element 15, 16 ... Substrate 17 ... Spacer

Claims (2)

An anode and a cathode facing each other;
An organic light emitting layer disposed between the anode and the cathode and emitting light at a predetermined temperature as a liquid crystal or a liquid;
An organic electroluminescence device comprising:
Two substrates disposed so as to sandwich the organic electroluminescence element and facing each other;
A spacer disposed between the two substrates and supporting each other substrate;
Have
The organic electroluminescence device, wherein the thickness of the cathode is thicker than the thickness of the organic light emitting layer.   The organic electroluminescent device according to claim 1, wherein the organic light emitting layer has a thickness of less than 100 nm.

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