JP2005100897A - Method of manufacturing organic el device, organic el device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device capable of having a long life by forming a functional layer composed of crystalline thin film without heat-treatment, and improving flexibility of display by enabling dot display, an organic EL device and an electronic apparatus. <P>SOLUTION: A method of manufacturing an organic EL device 10 comprising a step of dissolving formation material consisting of low-molecular material having recrystallization property as formation material of functional layer 110 in a solvent to form a liquefied object and disposing the liquefied object on a first electrode 111; a step of producing crystal nucleus in the liquefied object by controlling partial pressure of gas consisting of the solvent near the liquefied object to be a first partial pressure in which the solvent forming the liquefied object becomes in a supersaturation condition; and a step of forming a crystalline thin film consisting of the formation material by reducing the partial pressure near the liquefied object to a second partial pressure by which the crystal nucleus has a possibility of crystal growth after producing the crystal nucleus; and a step of forming a layer constructing a functional layer 110 from the crystalline thin film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an organic EL element, an organic EL element, and an electronic device that enable thickening of a functional layer such as a light emitting layer and thereby improve characteristics such as a long life.

  2. Description of the Related Art In recent years, organic electroluminescent elements (hereinafter referred to as organic EL elements) using an organic substance in a light emitting layer have been developed as spontaneous emission type displays. In such an organic EL element, a functional material for forming a light emitting layer or a carrier injection / transport layer, that is, a functional layer such as a hole injection / transport layer or an electron injection / transport layer, is obtained. This is one of the important factors in determining characteristics.

As such an organic EL element, in particular, when the light emitting layer is formed of a polymer material, the functional layer including the light emitting layer is generally composed of a light emitting layer and a hole injection / transport layer. In that case, in particular, in forming this functional layer, a method using an ink jet method which is a kind of droplet discharge method is known (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Reference 4).
In low molecular weight materials, it has been reported that a phenylamine derivative is formed by vapor deposition as a hole injection / transport layer.

By the way, in the conventional organic EL element, not only when a high molecular weight material is used as a functional layer forming material but also when a low molecular weight material is used, the functional layer to be formed usually has an amorphous structure. Have. This is because an incomplete crystal deteriorates the element due to a leak current or the like generated at the incomplete portion.
However, if an organic crystal thin film with low incompleteness and high integrity can be formed, for example, there is no grain boundary, the mobility of electrons, holes, etc. is increased, and it is useful to have anisotropy. Therefore, it is possible to achieve long life and high brightness.
Against this background, as an example of an organic EL element that uses a crystalline thin film as a functional layer, a light emitting layer made of an organic crystal is obtained by melting and solidifying a material for forming a light emitting layer and then solidifying it. There is known a method of forming (see, for example, Patent Document 5).
Japanese Patent Laid-Open No. 10-12377 JP-A-10-153967 Japanese Patent Laid-Open No. 11-40358 Japanese Patent Laid-Open No. 11-54270 JP-A-5-182863

  However, in the method of forming the light emitting layer with an organic crystal, a method of filling a gap between the electrodes with a melt of the light emitting layer forming material using a capillary phenomenon and then crystallizing the melt is adopted. However, since such a method basically performs crystallization by heating, thermal influence on other components is inevitable. In addition, it is difficult to divide the obtained light emitting layer into predetermined regions to enable dot display, and thus the organic EL element has a problem that the degree of freedom of display is remarkably limited.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to form a functional layer made of a crystalline thin film without heat treatment, thereby extending the service life, etc. It is in providing the manufacturing method of the organic EL element which can raise the freedom degree of a display, and the organic EL element obtained by this, and an electronic device.

In order to achieve the above object, the present invention comprises a first electrode, a second electrode, and a functional layer having at least a light emitting layer provided between the first electrode and the second electrode. In the method for manufacturing an organic EL element, the step of forming the layer constituting the functional layer is formed of a low molecular material having recrystallization as a material for forming at least one layer constituting the functional layer. Preparing a material, dissolving the forming material in a solvent to prepare a liquid, and arranging the obtained liquid at a predetermined position on the first electrode; from the liquid, from the forming material And a step of forming a crystalline thin film.
Further, in this method of manufacturing an organic EL element, the step of forming the crystalline thin film is a solution that forms a partial pressure of a gas composed of the same component as the solvent in the vicinity of the liquid after the arrangement. Controlling the first partial pressure at which the liquid is supersaturated to generate crystal nuclei in the liquid, and after generating the crystal nuclei, the partial pressure of the gas in the vicinity of the liquid is changed to the crystal. And a step of forming a crystalline thin film made of the forming material by reducing the nucleus to a second partial pressure at which crystal growth is possible.

According to this method for manufacturing an organic EL element, first, immediately after being arranged on the first electrode by controlling to a first partial pressure (for example, a partial pressure equal to or substantially the same as the saturated vapor pressure). When the solution forming the liquid is supersaturated, crystal nuclei necessary for crystallization are generated in the solution (liquid).
Next, the partial pressure of the gas (a gas composed of the same component as the solvent) in the vicinity of the liquid is changed from the first partial pressure (a high partial pressure at which the solvent hardly evaporates from the solution forming the liquid). Until the partial pressure of 2 (the crystal growth of the crystal nucleus that has already occurred is a low partial pressure that occurs preferentially over the formation of further crystal nuclei, for example, 1/10 to 1/100 of the saturated vapor pressure) Crystal growth starts by lowering. Thus, a crystalline thin film made of the forming material is formed, and a layer constituting the functional layer is formed from the crystalline thin film.
Therefore, it is possible to form a functional layer made of a crystalline thin film by a comparatively simple operation (method) without requiring any heat treatment, thereby extending the lifetime of the element. .

In the method of manufacturing the organic EL element, it is preferable that the liquid material is arranged at a predetermined position on the first electrode by a droplet discharge method.
In this way, a crystalline thin film having a dot pattern, for example, can be easily formed. Therefore, by enabling dot display, the degree of freedom of display of an organic EL device having a large number of such organic EL elements. Can be increased.

In the method for manufacturing the organic EL element, a partition wall is formed in advance so as to place the liquid material at a predetermined position on the first electrode so as to surround the predetermined position. It is preferable to carry out by arranging. In that case, it is preferable that the shape of the opening part enclosed by the said partition is a substantially rectangular shape, and the length of each side is 5 micrometers or more and 30 micrometers or less.
In this way, the size and shape of the crystalline thin film formed from the liquid can be defined by the partition walls, and thus it is possible to form a crystalline thin film having a desired size and shape. Become.
Further, if the shape of the opening surrounded by the partition wall is substantially rectangular and the length of each side is 5 μm or more and 30 μm or less, crystallization of the liquid material disposed in the opening is more likely to occur. Therefore, it becomes possible to form a crystalline thin film with good crystallinity.

In the method of manufacturing the organic EL element, in the step of generating crystal nuclei in the liquid material, the control for making the partial pressure of the gas the first partial pressure is performed by discharging the solvent onto the partition wall. It is preferable to do so.
In this way, by discharging the solvent onto the partition wall where the liquid material is not directly disposed and in the vicinity of the liquid material disposed portion, the partial pressure of the gas in the vicinity of the disposed liquid material is reduced. The first partial pressure can be controlled more easily.

Further, in the method for manufacturing the organic EL element, the forming material may be a forming material of a light emitting layer in a functional layer, or may be a forming material of a hole injection / transport layer, Further, it may be a material for forming an electron injection / transport layer.
In this way, the light emitting layer, the hole injection / transport layer, or the electron injection / transport layer of the functional layer can be a crystalline thin film, and therefore the carrier ( By increasing the mobility of electrons, holes, or excitons in which electrons and holes are combined, characteristics such as a longer life can be improved.

The organic EL device of the present invention is obtained by the above-described manufacturing method.
According to this organic EL element, a functional layer made of a crystalline thin film is formed by a comparatively simple operation (method) without requiring any heat treatment, and the functional layer is made of a crystalline thin film. As a result, the lifetime of the element is increased.

Another organic EL device of the present invention includes a first electrode, a second electrode, and a functional layer having at least a light emitting layer and a hole injection / transport layer provided between the electrodes. In the organic EL device provided, the hole injection / transport layer is formed of a crystalline thin film made of a low molecular material having recrystallization.
According to this organic EL element, characteristics are improved by increasing the mobility of holes in the hole injection / transport layer made of a crystalline thin film.

Another organic EL device of the present invention includes a first electrode, a second electrode, and a functional layer having at least a light emitting layer and an electron injection / transport layer provided between the electrodes. The organic EL element is characterized in that the electron injection / transport layer is formed of a crystalline thin film made of a low molecular material having recrystallization.
According to this organic EL element, the characteristics are improved by increasing the electron mobility of the electron injection / transport layer made of a crystalline thin film.

The electronic device of the present invention is characterized by including the organic EL element obtained by the manufacturing method or the organic EL element.
According to this electronic device, by providing the organic EL element with a long lifetime, the electronic device itself can improve the characteristics of the display unit made of, for example, the organic EL element.

The present invention will be described in detail below.
First, prior to describing the method for manufacturing an organic EL element of the present invention, an example of an organic EL device including a large number of organic EL elements to which the manufacturing method is applied will be described with reference to FIG. FIG. 1 is an enlarged view of a cross-sectional structure of a display region in an organic EL device. In FIG. 1, reference numeral 1 denotes an organic EL device, and 10 denotes an organic EL element. In FIG. 1, three organic EL elements 10 are shown, and each of these organic EL elements 10 forms a single dot.

The organic EL device 1 is configured by sequentially laminating a circuit element unit 14 in which a circuit such as a TFT is formed on a substrate 2 and an EL element unit 11 in which a functional layer 110 is formed.
In the organic EL device 1, light emitted from the functional layer 110 to the substrate 2 side is transmitted through the circuit element unit 14 and the substrate 2 and emitted to the lower side (observer side) of the substrate 2. Light emitted from 110 to the opposite side of the substrate 2 is reflected by the counter electrode (cathode) 12, passes through the circuit element unit 14 and the substrate 2, and is emitted to the lower side (observer side) of the substrate 2. It has become.
In addition, by using a transparent material for the counter electrode (cathode) 12, light can be emitted from the counter electrode (cathode) 12 side.

In the circuit element portion 14, a base protective film 2c made of a silicon oxide film is formed on the substrate 2, and an island-shaped semiconductor film 141 made of polycrystalline silicon is formed on the base protective film 2c. Note that a source region 141a and a drain region 141b are formed in the semiconductor film 141 by high-concentration P ion implantation, and a portion where P is not introduced is a channel region 141c.
Further, a transparent gate insulating film 142 that covers the base protective film 2c and the semiconductor film 141 is formed in the circuit element portion 14, and a gate electrode made of Al, Mo, Ta, Ti, W, or the like is formed on the gate insulating film 142. 143 (scanning line 101) is formed, and a transparent first interlayer insulating film 144a and a second interlayer insulating film 144b are formed on the gate electrode 143 and the gate insulating film 142. The gate electrode 143 is provided at a position corresponding to the channel region 141c of the semiconductor film 141.

Further, contact holes 145 and 146 connected to the source / drain regions 141a and 141b of the semiconductor film 141 are formed in the first and second interlayer insulating films 144a and 144b, and the contact holes 145 and 146 are formed in the contact holes 145 and 146, respectively. Each is embedded with a conductive material.
A transparent pixel electrode (first electrode, anode) 111 made of ITO or the like is patterned and formed in a predetermined shape on the second interlayer insulating film 144b, and one contact hole 145 is formed in the pixel electrode 111. It is connected to the.
The other contact hole 146 is connected to the power supply line 103.
In this manner, the thin film transistor 123 connected to each pixel electrode 111 is formed in the circuit element unit 14.
The circuit element unit 14 is also formed with a storage capacitor (not shown) and other thin film transistors (not shown).

The EL element unit 11 includes a functional layer 110 stacked on each of the plurality of pixel electrodes 111..., A partition 112 provided between each pixel electrode 111 and the functional layer 110 to partition each functional layer 110, and a function The counter electrode (second electrode, cathode) 12 formed on the layer 110 is mainly used.
Here, the pixel electrode 111 is formed of a transparent conductive material, for example, ITO, and is patterned into a substantially rectangular shape in plan view. A partition 112 is provided between the pixel electrodes 111.

The partition 112 is composed of an inorganic bank 112a made of SiO ₂ or the like on the substrate 2 side, and an organic bank 112b formed on the inorganic bank 112a.
The inorganic bank 112a is formed so as to ride on the peripheral edge of the pixel electrode 111, and has a structure in which the periphery of the pixel electrode 111 and the inorganic bank 112a are planarly overlapped in a plan view. It has become. The organic bank 112b is also arranged so as to overlap with a part of the pixel electrode 111 in a plan view. The organic bank 112b is formed of a heat resistant and solvent resistant material such as an acrylic resin or a polyimide resin.

  Further, the organic bank 112b has an opening 112c surrounded by the organic bank 112b, and a functional layer forming material is disposed and formed in the opening 112c as will be described later. The functional layer 110 is formed. Here, the opening 112c is an opening surrounded by a partition wall in the present invention, and the shape thereof, that is, the shape in a plan view, is substantially rectangular, and the length of each side thereof is It is preferably 5 μm or more and 30 μm or less. In addition, the substantially rectangular shape mentioned here includes, for example, those whose corners (corners) are rounded to have a shape close to an ellipse or an ellipse. Moreover, the length of each side means the long side and the short side, and these sides are preferably in the range of 5 μm or more and 30 μm or less as described above. If the opening 112c has such a shape and size, crystallization of the liquid material disposed in the opening 112c can be made easier to occur as will be described later. It becomes possible to form a conductive thin film more easily.

  The functional layer 110 is constituted by the functional layer according to the present invention as described above, and is disposed between the pixel electrode (anode, first electrode) 111 and the counter electrode (cathode, second electrode) 12. As a result, the pixel electrode 111 and the counter electrode 12 constitute an organic EL element. Here, in this example, in order to achieve full color display, the organic EL element 10 is a dot that emits red light, a dot that emits green light, and a dot that emits blue light. Each is composed of things.

  These organic EL elements 10 have the electron injection shown in any one of the layers constituting the functional layer 110, that is, the light emitting layer 150, the hole injection / transport layer 151, and only one of the three organic EL elements 10. / At least one of the transport layers 152 is formed of a crystalline thin film. This crystalline thin film is made of a low molecular material having recrystallization property. Note that the recrystallization property means a property in which after a crystalline substance is dissolved in a solvent, it is precipitated again as a crystal by an appropriate method and crystallized.

  Here, the hole injection / transport layer 151 has a function of injecting holes of the pixel electrode (anode) 111 into the light-emitting layer 150, or a function of transporting holes therein. On the other hand, the electron injection / transport layer 152 has a function of injecting electrons of the counter electrode (cathode) 12 into the light emitting layer 150, or has a function of transporting electrons therein. By providing such a hole injection / transport layer between the pixel electrode 111 and the light emitting layer 150 and further providing an electron injection / transport layer between the counter electrode 12 and the light emitting layer 150, Characteristics such as luminous efficiency and lifetime can be improved. Further, in the light emitting layer 150, holes injected from the pixel electrode 111 side and electrons injected from the counter electrode (cathode) 12 side are recombined to generate exciton, which emits light. It has become.

On each functional layer 110 in the organic EL element 10, a counter electrode (cathode) 12 is formed on the entire surface of the EL element portion 11. The counter electrode (cathode) 12 functions as a pair with the pixel electrode 111 so that a current flows through the functional layer 110, and is formed of a laminated film (Ca / Al) of Ca and Al. Here, Ca is formed to a thickness of about 20 nm, for example, and Al is formed to a thickness of about 200 nm.
Further, an anti-oxidation protective layer (not shown) made of SiO, SiO ₂ , SiN or the like may be provided on the counter electrode (cathode) 12.
And the sealing substrate (not shown) is arrange | positioned on the organic EL element 10 formed in this way, and also the organic EL device 1 is bonded by sealing resin (not shown). It is configured.

Next, based on the manufacturing method of the organic EL device 1 having such a configuration, the manufacturing method of the organic EL element of the present invention will be described.
(First embodiment)
First, a case where the hole injection / transport layer 151 is formed of a crystalline thin film will be described as a first embodiment of the manufacturing method of the present invention.
In order to manufacture the organic EL device 1 having the above-described configuration, first, as shown in FIG. 2, a thin film transistor 123 and various wirings are formed on the substrate 2 as shown in FIG. 2, and an interlayer insulating film and a planarizing film are further formed. To do.
Next, an ITO film is formed on the substrate 2 by vapor deposition or the like, and further patterned to form the pixel electrode 111.

Subsequently, an inorganic bank 112 a made of SiO ₂ is formed on the substrate 2 so as to surround the pixel electrode 111. Further, as shown in FIG. 3, an organic bank 112b made of resin is formed on the inorganic bank 112a, thereby forming an opening 112c on the pixel electrode 111. Here, the opening 112c is substantially rectangular in a plan view as described above, and is formed so that the length of each side thereof is 5 μm or more and 30 μm or less. Examples of the material used for the organic bank 112b include polyimide and acrylic resin. As these materials, a material containing a fluorine element in advance may be used.
Next, the wettability on the substrate 2 is controlled by performing continuous treatment with oxygen plasma-CF ₄ plasma on the opening 112c surrounded by the inorganic bank 112a and the organic bank 112b. In addition, as a method for controlling the wettability on the substrate 2, for example, a method of forming a self-assembled film can be employed.

  Next, triphenylamine (for example, T8160-4 manufactured by aldrich can be used) is used as a material for forming the hole injection / transport layer, in this embodiment, a low molecular weight material having recrystallization, and the concentration thereof is For example, it is dissolved in a solvent (for example, dodecylbenzene) so as to be 0.1% by weight to obtain a liquid. The liquid is not particularly limited, but the concentration of the forming material (low molecular weight material) is such that the forming material contains an amount that is 1/10 or more of the saturation concentration. Preferably there is.

Then, the liquid material is selectively disposed in the opening 112c by a droplet discharge method such as an ink jet method. In addition to the operation of disposing the liquid material in the opening 112c, the solvent in the liquid material in an atmosphere immediately before, immediately after, or in parallel with the operation in the vicinity of the opening 112c. The partial pressure of the gas composed of the same component is controlled to the first partial pressure at which the solution forming the liquid becomes supersaturated. Here, the first partial pressure is specifically the same or substantially the same partial pressure as the saturated vapor pressure. By making such a partial pressure, the solvent is removed from the solution forming the liquid material. It becomes difficult to evaporate.
In addition, although control in order to make the partial pressure of the said gas into the 1st partial pressure of the atmosphere in the vicinity in the said opening part 112c is not specifically limited, For example, the said solvent is the said partition 112 ( This is preferably done by discharging onto the organic bank 112b). Alternatively, the solvent may be applied on the substrate 2 in advance by a spin coating method, and the solvent may be disposed in advance in a sealed container. However, these solvents are arranged for adjusting the atmosphere in the vicinity of the opening 112c, and even when applied by a spin coating method, the solvent remains basically in a liquid state and does not remain on the substrate 2. It is used for evaporating to increase the solvent vapor concentration in the atmosphere.

  Here, as a droplet discharge device that performs droplet discharge by the droplet discharge method, a device that includes a droplet discharge head 310 as shown in FIG. 4A is preferably used. The droplet discharge head 310 includes, for example, a stainless steel nozzle plate 312 and a vibration plate 313, which are joined via a partition member (reservoir plate) 314. A plurality of spaces 315 and a liquid pool 316 are formed by the partition member 314 between the nozzle plate 312 and the vibration plate 313. Each space 315 and the liquid reservoir 316 are filled with a liquid material, and each space 315 and the liquid reservoir 316 communicate with each other via a supply port 317. The nozzle plate 312 is formed with a plurality of nozzle holes 318 for ejecting the liquid material from the space 315 in a line. On the other hand, a hole 319 for supplying a liquid material to the liquid reservoir 316 is formed in the vibration plate 313.

Also, a piezoelectric element (piezo element) 320 is joined to the surface of the diaphragm 313 opposite to the surface facing the space 315 as shown in FIG. The piezoelectric element 320 is positioned between a pair of electrodes 321 and is configured to bend so that when it is energized, it projects outward. The diaphragm 313 to which the piezoelectric element 320 is bonded in such a configuration is integrated with the piezoelectric element 320 and bends outward at the same time, so that the volume of the space 315 is increased. It is going to increase. Therefore, the liquid corresponding to the increased volume in the space 315 flows from the liquid reservoir 316 through the supply port 317. Further, when the energization to the piezoelectric element 320 is released from such a state, both the piezoelectric element 320 and the diaphragm 313 return to the original shape. Therefore, since the space 315 also returns to its original volume, the pressure of the liquid material inside the space 315 increases, and the liquid droplet 322 is discharged from the nozzle hole 318 toward the substrate.
As the structure of the droplet discharge head 310, a known type other than the piezo jet type using the piezoelectric element 320 may be adopted.

In addition, such a droplet discharge head 310 is disposed in, for example, a sealed space with a decompression pump, and the substrate 2 is placed in the sealed space to place (discharge) the liquid material.
That is, with such a droplet discharge head 310, the liquid material for the hole injection / transport layer is discharged at, for example, 20 picoliters per droplet, and a predetermined amount of the liquid material is disposed in the opening 112c. . Further, as described above, separately from the discharge of the liquid material, a solution that forms the liquid material by dividing the partial pressure of the gas composed of the same component as the solvent in the liquid material in the atmosphere in the vicinity of the opening 112c. Is controlled to the first partial pressure at which becomes supersaturated. Then, crystal nuclei are generated in the liquid disposed in the opening 112c.

  Here, if the partial pressure of the gas in the vicinity of the liquid (gas consisting of the same component as the solvent of the solution forming the liquid) is low, the solvent easily evaporates from the liquid, so the concentration of the solution forming the liquid is The temperature rapidly rises and the supersaturation degree of the solution also increases rapidly, and a large number of crystal nuclei are formed, so that the solute is easily powdered. On the other hand, by adjusting the discharge and the atmosphere as described above, the liquid solution is stabilized in a supersaturated state having a relatively low supersaturation level (that is, the degree of increase in the supersaturation degree of the solution forming the liquid material). Only a few (ideally one) nuclei are generated. In order to form a single-crystal thin film, it is necessary to grow only one nucleus after one nucleus is generated and not to cause another nucleus formation. However, if the partial pressure of the gas in the vicinity of the liquid just after the liquid is arranged remains high, further nuclei are generated.

Therefore, in the present invention, after the formation of the crystal nuclei, the partial pressure of the gas in the vicinity of the liquid is made to allow the crystal nuclei that have already been generated to grow, so that the crystal growth is higher than the formation of further crystal nuclei. Is reduced to a second partial pressure that occurs preferentially, for example, 1/10 to 1/100 of the saturated vapor pressure of the solvent. Such partial pressure reduction processing from the first partial pressure to the second partial pressure is performed immediately after a small number (ideally one) crystal nucleus is generated in the liquid. For example, at the same time as the arrangement of the liquid material is finished, the pressure reducing pump is operated, and the sealed space is moved from the first partial pressure (same or substantially the same partial pressure as the saturated vapor pressure) to the second partial pressure, for example, The pressure is reduced to 1.3 Pa (10 ⁻² torr) in 1 to 10 seconds, and this state is maintained for 6 hours, for example. Then, crystal growth starts, thereby forming a crystalline thin film made of the forming material, and a hole injection / transport layer 151 is formed from the crystalline thin film as shown in FIG.
In addition to the above triphenylamine, examples of the low molecular weight material having recrystallization properties used as a material for forming the hole injection / transport layer include CuPc (copper phthalocyanine) and the following compounds 1 to 14. Etc. can be used.

  Next, as shown in FIG. 6, a light emitting layer 150 is formed on the hole injection / transport layer 151 made of a crystalline thin film in the opening 112c. For the formation of the light emitting layer 150, for example, a precursor of PPV (poly (paraphenylene vinylene)) or a derivative thereof is preferably used as a forming material thereof. As a solvent for dissolving the precursor of this PPV or its derivative, a polar solvent such as water, methanol, ethanol or the like is preferably used as a solvent or dispersion medium that does not re-dissolve the hole injection / transport layer 151. It is done.

  In forming the light emitting layer 150, the droplet discharge method is preferably used. That is, the light emitting layer forming material is discharged and disposed on the hole injection / transport layer 151 in the opening 112c using the droplet discharge head 310, and then dried and further baked. Thus, the light emitting layer 150 is formed. When the organic EL device 1 performs full color display, each organic EL element 10 is a dot that emits light of any one of red, green, and blue, and these are regularly arranged. There is a need. Therefore, in that case, three types of materials for each color are prepared in advance as the light emitting layer forming material, and each light emitting layer is formed by selectively disposing these at predetermined positions.

When the functional layer 110 is formed in this manner, a Ca (calcium) film is formed to a thickness of about 20 nm so as to cover the functional layer 110 and the organic bank 112b by vapor deposition or the like in the same manner as in the past, and further on this By forming a film of Al (aluminum) to a thickness of about 200 nm, a counter electrode (cathode) 12 having a Ca / Al laminated structure is formed as shown in FIG. Thus, an organic EL element comprising a pixel electrode (anode) 111, a functional layer 110, and a counter electrode (cathode) 12, and in particular, a hole injection / transport layer 151 constituting the functional layer 110 is formed of a crystalline thin film. Get 10.
Then, the organic EL device 1 is obtained by forming a protective layer and a sealing resin on the counter electrode 12 and further attaching a sealing substrate.

  In the organic EL device 1 thus obtained, in the organic EL element 10 constituting each dot, the hole injection / transport layer 151 constituting the functional layer 110 is made of a crystalline thin film. The hole mobility in the hole injection / transport layer 151 made of this crystalline thin film is increased. Therefore, for example, even if the film thickness of the hole injection / transport layer 151 is made thicker than before, the hole mobility is increased and reaches the light emitting layer 150 by being injected and transported. The time until will not change. On the other hand, impurity ions from the anode (pixel electrode 111) side become movable ions and move through the hole injection / transport layer 151 to the light emitting layer 151 side. By increasing the thickness, the time until the impurity ions reach the light emitting layer 150 can be delayed, and the concentration of the impurity ions in the hole injection / transport layer 151 can be lowered. Therefore, functional deterioration of the light emitting layer 150 and the hole injection / transport layer 151 due to the impurity ions can be prevented, thereby improving the characteristics such as extending the life. In addition, since the hole mobility is increased, a decrease in electrical efficiency due to Joule heat or the like can be suppressed, and thereby, display brightness and resolution can be increased.

Furthermore, since the hole injection / transport layer 151 made of a crystalline thin film can be formed by a comparatively simple operation (method) without particularly requiring heat treatment, for example, the grain boundary It is possible to form an organic crystal thin film having high completeness such as the absence of a thin film, thereby extending the life of the device.
Further, by selectively forming each functional layer 110 by the droplet discharge method, dot display becomes possible, and thus the obtained organic EL device 1 has a high degree of display freedom.

(Second Embodiment)
Next, as a second embodiment of the manufacturing method of the present invention, a case where the electron injection / transport layer 152 is formed of a crystalline thin film will be described.
In order to manufacture the organic EL device 1 having the above-described configuration, first, as in the first embodiment, a thin film transistor 123 and various wirings are formed on the substrate 2, and ITO is further formed and patterned. Thus, the pixel electrode 111 is formed. Subsequently, as shown in FIG. 3, an inorganic bank 112 a is formed, and an organic bank 112 b made of resin is formed on the inorganic bank 112 a, thereby forming a substantially rectangular opening 112 c on the pixel electrode 111. The wettability on the substrate 2 is obtained by performing a continuous treatment of oxygen plasma-CF ₄ plasma on the opening 112c surrounded by the inorganic bank 112a and the organic bank 112b, or by forming a self-assembled film. To control.

  Next, as a material for forming the hole injection / transport layer, for example, a mixture of 3,4-polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) is the main component, and this is dispersed in a dispersion medium such as water. Prepare a liquid material. Then, the hole injection / transport layer forming material is ejected and disposed on the pixel electrode 111 in the opening 112c using the droplet ejection head 310, and then dried and further baked. Then, the hole injection / transport layer 151 is formed.

  Next, in the same manner as in the first embodiment, the light emitting layer forming material is discharged and disposed on the hole injection / transport layer 151 by the droplet discharge method, and further dried and baked, as shown in FIG. As described above, the light emitting layer 151 is formed. In addition, as a light emitting layer forming material, it can replace with the precursor of said PPV or its derivative (s), and can use a polyfluorene type polymer material. Also in this embodiment, when the organic EL device 1 performs full color display, red, green, and blue colors are prepared as the light emitting layer forming materials, and these are selectively sorted. To do.

  After forming the light emitting layer 151 in this way, in the present embodiment, unlike the first embodiment, the electron injection / transport layer 152 is formed. First, as a material for forming an electron injection / transport layer, in this embodiment, calcium acetylacetonate is used as a low molecular weight material having recrystallization, and its concentration is set to 0.2% by weight, for example. For example, it is dissolved in 2-butoxyethanol) to obtain a liquid. The liquid is not particularly limited, but the concentration of the forming material (low molecular weight material) is such that the forming material contains an amount that is 1/10 or more of the saturation concentration. Preferably there is.

Then, the liquid is selectively disposed on the light emitting layer 150 in the opening 112c by the droplet discharge method to form the electron injection / transport layer 152. In addition to the operation of disposing the liquid material in the opening 112c, just as in the formation of the hole injection / transport layer 151 in the first embodiment, just before or immediately after this, or this operation. In parallel, the partial pressure of the gas composed of the same component as the solvent in the liquid material in the atmosphere in the vicinity of the opening 112c is the first partial pressure at which the solution forming the liquid material becomes supersaturated. To control. Here, the first partial pressure is specifically the same or substantially the same partial pressure as the saturated vapor pressure. By making such a partial pressure, the solvent is removed from the solution forming the liquid material. It becomes difficult to evaporate.
In addition, as control for making the partial pressure of the gas the first partial pressure of the atmosphere in the vicinity of the opening 112c, for example, the solvent is used for the partition 112 (organic) as in the first embodiment. This is preferably done by discharging onto the bank 112b). Alternatively, the solvent may be applied on the substrate 2 in advance by a spin coating method, and the solvent may be disposed in advance in a sealed container.

Also, in the arrangement by discharging the liquid material, similarly to the first embodiment, the droplet discharge head 310 is arranged in, for example, a sealed space with a decompression pump, and the above-described liquid space is filled with the above-described liquid space. The substrate 2 is put in and the liquid material is arranged (discharged).
That is, with such a droplet discharge head 310, the liquid material for the electron injection / transport layer is discharged at, for example, 20 picoliters per droplet, and a predetermined amount of the liquid material is disposed in the opening 112c. Further, as described above, separately from the discharge of the liquid material, a solution that forms the liquid material by dividing the partial pressure of the gas composed of the same component as the solvent in the liquid material in the atmosphere in the vicinity of the opening 112c. Is controlled to the first partial pressure at which becomes supersaturated. Then, crystal nuclei are generated in the liquid disposed in the opening 112c.

  Here, if the partial pressure of the gas in the vicinity of the liquid (a gas composed of the same components as the solvent of the solution forming the liquid) is low, the solvent easily evaporates from the liquid as described above. As the concentration of the solution rises rapidly, the degree of supersaturation of the solution also rises rapidly, and a large number of crystal nuclei are formed, so that the solute is easily powdered. On the other hand, by adjusting the discharge and the atmosphere as described above, the liquid solution is stabilized in a supersaturated state having a relatively low supersaturation level (that is, the degree of increase in the supersaturation degree of the solution forming the liquid material). Only a few (ideally one) nuclei are generated. In order to form a single-crystal thin film, it is necessary to grow only one nucleus after one nucleus is generated and not to cause another nucleus formation. However, if the partial pressure of the gas in the vicinity of the liquid just after the liquid is arranged remains high, further nuclei are generated.

Therefore, also in the present embodiment, after the generation of the crystal nuclei, the partial pressure of the gas in the vicinity of the liquid is made to allow the crystal nuclei that have already been generated to grow crystals, and thus more than the generation of further crystal nuclei. The second partial pressure at which crystal growth occurs preferentially, for example, 1/10 to 1/100 of the saturated vapor pressure of the solvent is reduced. Such partial pressure reduction processing from the first partial pressure to the second partial pressure is performed immediately after a small number (ideally one) crystal nucleus is generated in the liquid. For example, at the same time as the arrangement of the liquid material is finished, the pressure reducing pump is operated, and the sealed space is moved from the first partial pressure (same or substantially the same partial pressure as the saturated vapor pressure) to the second partial pressure, for example, The pressure is reduced to 1.3 Pa (10 ⁻² torr) in 1 to 10 seconds, and this state is maintained for 6 hours, for example. Then, crystal growth starts, thereby forming a crystalline thin film made of the forming material, and an electron injection / transport layer 152 is formed from the crystalline thin film as shown in FIG.
In addition to the above-mentioned calcium acetylacetonate, for example, Li quinololol or the following compounds 15 to 18 can be used as a low molecular weight material having recrystallization properties as a material for forming an electron injection / transport layer. is there.

After the electron injection / transport layer 152 is formed in this way, and the functional layer 110 is formed by this, the functional layer 110 and the organic bank 112b are covered by a vapor deposition method or the like in the same manner as in the first embodiment. A counter electrode (cathode) 12 having a laminated structure of Ca / Al is formed as shown in FIG. 9 by forming a film of calcium and further forming a film of Al (aluminum) thereon. Thus, the organic EL element 10 is composed of the pixel electrode (anode) 111, the functional layer 110, and the counter electrode (cathode) 12, and in particular, the electron injection / transport layer 152 constituting the functional layer 110 is formed of a crystalline thin film. Get.
Then, the organic EL device 1 is obtained by forming a protective layer and a sealing resin on the counter electrode 12 and further attaching a sealing substrate.

  In the organic EL device 1 thus obtained, in particular, in the organic EL element 10 in which the electron injection / transport layer 152 constituting the functional layer 110 is formed of a crystalline thin film, the electrons formed of the crystalline thin film The hole mobility in the injection / transport layer 152 is increased. Therefore, for example, even when the thickness of the electron injection / transport layer 152 is made thicker than before, the time required to reach the light-emitting layer 150 due to the injection and transport of electrons due to the higher electron mobility. Will not change. On the other hand, impurity ions from the cathode (counter electrode 12) side become movable ions and move through the electron injection / transport layer 152 to the light emitting layer 150 side, but the electron injection / transport layer 152 is made thicker than before. Thus, the time until the impurity ions reach the light emitting layer 150 can be delayed, and the concentration of the impurity ions in the electron injection / transport layer 152 can be lowered. Therefore, it is possible to prevent functional deterioration of the light emitting layer 150 and the electron injection / transport layer 152 due to the impurity ions, thereby improving characteristics such as extending the life. In addition, since the electron mobility is increased, a reduction in electrical efficiency due to Joule heat or the like can be suppressed, and thereby, display brightness and resolution can be increased.

Further, regarding the formation of the electron injection / transport layer 152 made of a crystalline thin film, it can be formed by a comparatively simple operation (method) without particularly requiring heat treatment. It is possible to form an organic crystal thin film having high completeness such as the absence of an element, thereby extending the life of the element.
Further, by selectively forming each functional layer 110 by the droplet discharge method, dot display becomes possible, and thus the obtained organic EL device 1 has a high degree of display freedom.

(Third embodiment)
Next, a case where the light emitting layer 150 is formed of a crystalline thin film will be described as a third embodiment of the manufacturing method of the present invention.
In order to manufacture the organic EL device 1 having the above configuration, first, up to the hole injection / transport layer 151 is formed on the substrate 2 in the same manner as in the second embodiment.

  Next, the light emitting layer 150 is formed. In this embodiment, a quinolinol-aluminum complex (Alq3) is used as a material for forming the light emitting layer as a low molecular material having recrystallization, and its concentration is, for example, 0.2. It is dissolved in a solvent (for example, 2,3-dihydrobenzofurane) so as to be in weight% to obtain a liquid. The liquid is not particularly limited, but the concentration of the forming material (low molecular weight material) is such that the forming material contains an amount that is 1/10 or more of the saturation concentration. Preferably there is.

Then, the liquid material is selectively disposed on the hole injection / transport layer 151 in the opening 112c by the droplet discharge method to form the light emitting layer 150. In addition to the operation of disposing the liquid material in the opening 112c, just as in the formation of the hole injection / transport layer 151 in the first embodiment, just before or immediately after this, or this operation. In parallel, the partial pressure of the gas composed of the same component as the solvent in the liquid material in the atmosphere in the vicinity of the opening 112c is the first partial pressure at which the solution forming the liquid material becomes supersaturated. To control. Here, the first partial pressure is specifically the same or substantially the same partial pressure as the saturated vapor pressure. By making such a partial pressure, the solvent is removed from the solution forming the liquid material. It becomes difficult to evaporate.
In addition, as control for making the partial pressure of the gas the first partial pressure of the atmosphere in the vicinity of the opening 112c, for example, the solvent is used for the partition 112 (organic) as in the first embodiment. This is preferably done by discharging onto the bank 112b). Alternatively, the solvent may be applied on the substrate 2 in advance by a spin coating method, and the solvent may be disposed in advance in a sealed container.

Also, in the arrangement by discharging the liquid material, similarly to the first embodiment, the droplet discharge head 310 is arranged in, for example, a sealed space with a decompression pump, and the above-described liquid space is filled with the above-described liquid space. The substrate 2 is put in and the liquid material is arranged (discharged).
That is, with such a droplet discharge head 310, the liquid material for the light emitting layer is discharged at, for example, 20 picoliters per droplet, and a predetermined amount of the liquid material is disposed in the opening 112c. Further, as described above, separately from the discharge of the liquid material, a solution that forms the liquid material by dividing the partial pressure of the gas composed of the same component as the solvent in the liquid material in the atmosphere in the vicinity of the opening 112c. Is controlled to the first partial pressure at which becomes supersaturated. Then, crystal nuclei are generated in the liquid disposed in the opening 112c.

  Here, if the partial pressure of the gas in the vicinity of the liquid (a gas composed of the same components as the solvent of the solution forming the liquid) is low, the solvent easily evaporates from the liquid as described above. As the concentration of the solution rises rapidly, the degree of supersaturation of the solution also rises rapidly, and a large number of crystal nuclei are formed, so that the solute is easily powdered. On the other hand, by adjusting the discharge and the atmosphere as described above, the liquid solution is stabilized in a supersaturated state having a relatively low supersaturation level (that is, the degree of increase in the supersaturation degree of the solution forming the liquid material). Only a few (ideally one) nuclei are generated. In order to form a single-crystal thin film, it is necessary to grow only one nucleus after one nucleus is generated and not to cause another nucleus formation. However, if the partial pressure of the gas in the vicinity of the liquid just after the liquid is arranged remains high, further nuclei are generated.

Therefore, also in the present embodiment, after the generation of the crystal nuclei, the partial pressure of the gas in the vicinity of the liquid is made to allow the crystal nuclei that have already been generated to grow crystals, and thus more than the generation of further crystal nuclei. The second partial pressure at which crystal growth occurs preferentially, for example, 1/10 to 1/100 of the saturated vapor pressure of the solvent is reduced. Such partial pressure reduction processing from the first partial pressure to the second partial pressure is performed immediately after a small number (ideally one) crystal nucleus is generated in the liquid. For example, at the same time as the arrangement of the liquid material is finished, the pressure reducing pump is operated, and the sealed space is moved from the first partial pressure (same or substantially the same partial pressure as the saturated vapor pressure) to the second partial pressure, for example, The pressure is reduced to 1.3 Pa (10 ⁻² torr) in 1 to 10 seconds, and this state is maintained for 6 hours, for example. Then, crystal growth starts, thereby forming a crystalline thin film made of the forming material, and a light emitting layer 150 is formed from the crystalline thin film as shown in FIG.
In addition to the quinolinol-aluminum complex, p-terphenyl, for example, can be used as the low molecular weight material having recrystallizing properties for forming the light emitting layer.

After forming the light emitting layer 150 in this manner, a Ca (calcium) film is formed in a state of covering the light emitting layer 150 and the organic bank 112b by vapor deposition or the like in the same manner as in the first embodiment. By forming a film of Al (aluminum), a counter electrode (cathode) 12 having a Ca / Al laminated structure is formed as shown in FIG. As a result, the organic EL element 10 including the pixel electrode (anode) 111, the functional layer 110, and the counter electrode (cathode) 12 and in particular the light emitting layer 150 constituting the functional layer 110 is formed of a crystalline thin film is obtained.
Then, the organic EL device 1 is obtained by forming a protective layer and a sealing resin on the counter electrode 12 and further attaching a sealing substrate.

  In the organic EL device 1 thus obtained, particularly in the organic EL element 10 in which the light emitting layer 152 constituting the functional layer 110 is formed of a crystalline thin film, the light emitting layer 150 made of this crystalline thin film is used. Therefore, even if the thickness of the light-emitting layer 150 is larger than that of the conventional case, the generation of excitons due to recombination of electrons and holes does not decrease. If the thickness of the light emitting layer 150 is made thicker than before, collision between excitons caused by local concentration of excitons is less likely to occur when the light emitting layer 150 is widened. As a result, the phenomenon that the light emission action by excitons is canceled is reduced, and the light emission efficiency is increased.

Further, impurity ions from the anode (pixel electrode 111) or cathode (counter electrode 12) side become movable ions and move into the light emitting layer 150. By increasing the film thickness of the light emitting layer 150 compared to the prior art, light emission is achieved. The impurity ion concentration in the layer 150 can be lowered, and therefore the deterioration of the light emitting layer 150 due to the impurity ions can be reduced.
Therefore, it is possible to improve the characteristics such as extending the life, and the mobility of holes, electrons, and excitons can be increased, so that a decrease in electrical efficiency due to Joule heat can be suppressed. Brightness and further high definition can also be achieved.

In addition, when the light emitting layer 150 is made of a crystalline thin film in this way, the organic EL element 10 obtained by having anisotropy has polarization. Therefore, for example, when a polarizing plate is inserted, the attenuation due to this can be minimized, so that the required luminance can be lowered. Therefore, it is possible to extend the life from now on.
Furthermore, since the light-emitting layer 150 made of a crystalline thin film can be formed by a comparatively simple operation (method) without particularly requiring heat treatment, it is completely free of, for example, no grain boundary. It is possible to form an organic crystal thin film with high properties, thereby extending the life of the element.
Further, by selectively forming each functional layer 110 by the droplet discharge method, dot display becomes possible, and thus the obtained organic EL device 1 has a high degree of display freedom.

  In the embodiment, among the layers constituting the functional layer 110, only the hole injection / transport layer 151 is a crystalline thin film, and only the electron injection / transport layer 152 is a crystalline thin film. Although the case where only the light emitting layer 152 is a crystalline thin film has been described, the present invention is not limited thereto, and any two of the layers constituting the functional layer 110 may be a crystalline thin film. Of course, all of the hole injection / transport layer 151, the light emitting layer 150, and the electron injection / transport layer 152 may be formed as a crystalline thin film.

Next, a specific example of an electronic device including the organic EL element 10 having the above configuration will be described.
FIG. 10 is a perspective view showing an example of a mobile phone. In FIG. 10, reference numeral 600 denotes a mobile phone body, and reference numeral 601 denotes a display unit including the organic EL element 10 as a constituent element.
In this electronic apparatus, since the organic EL element 10 whose characteristics such as the extension of life are improved is provided as a component of the display unit, the display unit is sufficiently improved in characteristics. .
The organic EL element of the present invention can be suitably used as a display unit in various electronic devices such as portable information processing devices such as word processors and personal computers, and wristwatch type electronic devices.

It is principal part side sectional drawing of an example of the organic electroluminescent apparatus which concerns on this invention. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. (A), (b) is a figure which shows the internal structure of a droplet discharge head. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. FIG. 2 is a side cross-sectional view for explaining a manufacturing method of the organic EL device shown in FIG. 1. It is a perspective view which shows the electronic device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Organic EL apparatus, 10 ... Organic EL element, 12 ... Counter electrode (cathode [2nd electrode]),
110 ... functional layer, 111 ... pixel electrode (anode [first electrode]),
112 ... partition wall, 112a ... inorganic bank, 112b ... organic bank,
150 ... light emitting layer, 151 ... hole injection / transport layer, 152 ... electron injection / transport layer,
600 ... Mobile phone body (electronic equipment)

Claims (13)

In a method of manufacturing an organic EL element comprising a first electrode, a second electrode, and a functional layer having at least a light emitting layer provided between the first electrode and the second electrode,
The step of forming a layer constituting the functional layer includes:
As a forming material of at least one layer constituting the functional layer, a forming material made of a low molecular weight material having recrystallization property is prepared, and this forming material is dissolved in a solvent to prepare a liquid. Placing the liquid material at a predetermined position on the first electrode;
And a step of forming a crystalline thin film made of the forming material from the liquid material. The step of forming the crystalline thin film includes:
By controlling the partial pressure of the gas composed of the same component as the solvent in the vicinity of the liquid after the arrangement to the first partial pressure at which the solution forming the liquid becomes supersaturated, the liquid is crystallized. Generating a nucleus; and
After the generation of the crystal nuclei, the partial pressure of the gas in the vicinity of the liquid is reduced to a second partial pressure at which the crystal nuclei can grow crystals, thereby forming a crystalline thin film made of the forming material. The method of manufacturing an organic EL element according to claim 1, further comprising:   3. The method of manufacturing an organic EL element according to claim 1, wherein the liquid material is arranged at a predetermined position on the first electrode by a droplet discharge method.   The liquid material is arranged at a predetermined position on the first electrode by previously forming a partition wall surrounding the predetermined position and disposing the liquid material in the partition wall. Item 4. A method for producing an organic EL device according to any one of Items 1 to 3.   5. The method of manufacturing an organic EL element according to claim 4, wherein the shape of the opening surrounded by the partition walls is substantially rectangular, and the length of each side is 5 μm or more and 30 μm or less.   In the step of generating crystal nuclei in the liquid, the control for setting the partial pressure of the gas to the first partial pressure is performed by discharging the solvent onto the partition wall according to claim 4. The manufacturing method of the organic EL element of Claim 2.   The method for producing an organic EL element according to claim 1, wherein the forming material is a forming material for a light emitting layer in a functional layer.   The said formation material is a formation material of the positive hole injection / transport layer in a functional layer, The manufacturing method of the organic EL element as described in any one of Claims 1-7 characterized by the above-mentioned.   The method for manufacturing an organic EL element according to claim 1, wherein the forming material is a forming material for an electron injection / transport layer in the functional layer.   An organic EL device obtained by the manufacturing method according to claim 1. In an organic EL element comprising a first electrode, a second electrode, and a functional layer having at least a light emitting layer and a hole injection / transport layer provided between the electrodes,
The organic EL device, wherein the hole injection / transport layer is formed of a crystalline thin film made of a low molecular material having recrystallization. In an organic EL element comprising a first electrode, a second electrode, and a functional layer having at least a light-emitting layer and an electron injection / transport layer provided between the electrodes,
An organic EL device, wherein the electron injection / transport layer is formed of a crystalline thin film made of a low molecular material having recrystallization. An electronic apparatus comprising the organic EL element obtained by the manufacturing method according to any one of claims 1 to 9, or the organic EL element according to any one of claims 10 to 12. .

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