JP2008235011A - Method of manufacturing display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of using a material having proper light-emitting characteristics as the material of a light-emitting layer and enabling micronization of the light-emitting layer and enlargement of a substrate, in a method for pattern-forming the light-emitting layer made of a plurality of light-emitting materials on a device substrate. <P>SOLUTION: On a substrate, a first transfer layer containing a first organic material and a second transfer layer containing a second organic material are pattern-formed by a printing method, at least via a photothermal conversion layer. Meanwhile, the lower electrode or the like are formed on the device substrate, and then the substrate to be transferred is formed. Successively, by irradiating radiation rays on the substrate equipped with the first transfer layer and the second transfer layer, the transfer layer is transferred in a lump on the substrate to be transferred. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a manufacturing method of a display device, and more particularly to a manufacturing method using a coating film forming method and a thermal transfer method for forming a light emitting layer in manufacturing a display device using an organic electroluminescent element.

  An organic electroluminescent element using electroluminescence of an organic material has an organic layer in which a hole transport layer and a light emitting layer are laminated between a lower electrode and an upper electrode, and is driven by a low voltage direct current drive. It attracts attention as a light emitting element capable of emitting light with high luminance.

  A full-color display device using such organic electroluminescent elements is formed by arranging organic electroluminescent elements of each color of R (red), G (green), and B (blue) on a substrate. In manufacturing such a display device, it is necessary to pattern-form a light emitting layer made of an organic light emitting material that emits light of each color for each light emitting element. And the pattern formation of a light emitting layer is performed by the shadow masking method which vapor-deposits a light emitting material through a mask, for example, and the inkjet method.

  However, in pattern formation by the shadow masking method, it is difficult to finely process the opening pattern formed in the mask, and it is difficult to form a pattern with high positional accuracy due to bending and extension of the mask. And it is difficult to increase the size of the substrate.

  Also, pattern formation by the ink jet method has a limit in patterning accuracy, and it is difficult to miniaturize the light emitting element and increase the size of the substrate. In general, an organic light-emitting material made of a polymer is used in the ink jet method, but the polymer light-emitting material has a problem that the light-emitting characteristics are inferior to that of a low-molecular light-emitting material. Furthermore, when the ink jet method is used, there is a restriction that it must be devised so that the layer serving as the base of the light emitting layer does not dissolve.

  On the other hand, a transfer method using an energy source (heat source) (that is, a thermal transfer method) has been proposed as another pattern forming method. The display device using the thermal transfer method is manufactured as follows, for example. First, a lower electrode or the like is formed on a substrate of a display device (hereinafter referred to as a device substrate). On the other hand, a light emitting layer is formed on the entire surface of another substrate (hereinafter referred to as a transfer substrate) via a photothermal conversion layer or the like. Then, the device substrate and the transfer substrate are arranged in a state where the light emitting layer and the lower electrode face each other, and the light emitting layer is transferred onto the device substrate by irradiating the transfer substrate with laser light. At this time, the light emitting layer can be selectively transferred only to a predetermined region on the lower electrode by scanning with laser light (see Patent Document 1 below).

  However, in such a thermal transfer method, it is necessary to repeat the transfer process from the transfer substrate to the apparatus substrate by the number of colors of the light emitting layer to be patterned. Then, it is necessary to prepare as many transfer substrates as the number of colors of the light emitting layer to be patterned for one device substrate. For this reason, there are problems that the number of steps is large and the manufacturing apparatus is increased in size, and is not particularly suitable as a mass production process.

  Here, as a method for reducing the transfer process from the transfer substrate to the device substrate, Patent Document 2 below thermally transfers a light emitting layer made of a plurality of light emitting materials patterned on the transfer substrate onto the device substrate. This method is proposed. However, it has been proposed to use a vapor deposition method or an ink jet method as a means for forming a pattern on the transfer substrate, and the above-mentioned problems have not been solved.

JP 2002-110350 A JP 2004-87143 A

  Therefore, the present invention can use a material having good light emission characteristics as the material of the light emitting layer in the method of patterning the light emitting layer made of a plurality of light emitting materials on the device substrate, miniaturizing the light emitting element and increasing the size of the substrate. It is an object of the present invention to provide a technique suitable for mass production processes.

  In order to achieve such an object, in the method for manufacturing a display device of the present invention, first, a first transfer layer and a second organic material containing a first organic material on a substrate at least via a photothermal conversion layer. A second transfer layer containing is patterned by a printing method. On the other hand, a lower electrode or the like is formed on the device substrate to form a transfer substrate. Subsequently, the substrate having the first transfer layer and the second transfer layer is irradiated with radiation, whereby the transfer layer is collectively transferred onto the transfer substrate.

  A low molecular material can be used as the organic material to be patterned by a printing method.

  According to the present invention, since the organic layer made of a plurality of organic materials is patterned in advance on the transfer substrate, the transfer layer can be collectively transferred from the transfer substrate to the transfer substrate. That is, the transfer process is performed once and there is no need to scan the laser. In addition, since the transfer layer is patterned by a printing method, a light emitting material made of a low molecule with good light emission characteristics can be used, and the organic layer can be patterned with high positional accuracy. Therefore, it can respond to the enlargement of a board | substrate.

  Hereinafter, an embodiment in which the present invention is applied to the manufacture of a full-color display device including organic electroluminescent elements that emit light of red (R), green (G), and blue (B) will be described with reference to FIG. Embodiment) and the flowchart of FIG. 2 (second embodiment).

  The transfer substrate is prepared as follows. First, the substrate 31 is prepared. The substrate 31 may be any material that is sufficiently smooth and has light transmission properties, and is made of a glass substrate, a quartz substrate, a light-transmitting ceramic substrate, or the like.

  Subsequently, the photothermal conversion layer 33 and the oxidation protection film 34 are formed on the substrate 31.

  The material of the photothermal conversion layer 33 is preferably a material having a low reflectance with respect to the wavelength range of laser light used as a heat source in the thermal transfer process. For example, when laser light having a wavelength of about 800 nm from a solid laser light source is used, chromium (Cr), molybdenum (Mo), and the like are preferable, but not limited thereto. For example, Mo is deposited to a thickness of 200 nm by sputtering.

Examples of the material of the oxidation protection layer 34 include SiN _x and SiO ₂ . The oxidation protection layer 34 is formed using, for example, a CVD (chemical vapor deposition) method.

  Subsequently, a red transfer layer 35r for forming a red light emitting layer, a green transfer layer 35g for forming a green light emitting layer, and a green light emitting layer on the substrate 31 via the photothermal conversion layer 33 and the oxidation protection layer 34, and The blue transfer layer 35b for forming the blue light emitting layer is patterned by a printing method.

Pattern formation by a printing method refers to applying ink containing a light emitting material of each color to a predetermined region. Each ink is preferably prepared only with a light emitting material and an organic solvent. As the light emitting material, a low molecular light emitting material is used. The viscosity of such an ink is 0.5 mPa · s to 20 mPa · s, and more preferably 1.0 mPa · s to 10 mPa · s.
When the viscosity is higher than this range, it has been found that performance degradation considered to be caused by thermal decomposition of the thickening component is observed, and contamination inside the transfer device is observed.

  Further, the solid content concentration of the light emitting material is preferably 0.5 wt% or more and 15 wt% or less, more preferably 0.8 wt% or less and 7 wt% or less. If the solid content concentration is less than this range, the amount of coating is large and printing unevenness is likely to occur. Also, since the amount of solvent to be dried increases, uneven drying tends to occur. If the solid content concentration is higher than this range, the coating amount is too small, and printing unevenness is likely to occur. Further, the content of the solid component is preferably 80% or less, more preferably 70% or less of the saturated dissolution amount of each component at room temperature.

  As the solvent, polar solvents such as N-methyl-2-pyrrolidone (NMP), butyl cellosolve, and γ-butyrolactone are preferable. Nonpolar solvents such as toluene and xylene have a high affinity with the material used for the printing plate and are likely to cause damage such as swelling to the printing plate. Furthermore, in order to make it easy to apply ink, a material that increases the viscosity of the ink may be included as part of the solvent. An example of such a material is polyhydric alcohol. As the polyhydric alcohol, those having a relatively low ratio of carbon atoms such as 1,5-pentanediol, 1,3-butanediol, triethylene glycol monobutyl ether are preferable. Those having a relatively high carbon atom ratio have a high affinity with the material used for the printing plate, and thus are liable to cause damage such as swelling to the printing plate.

  The boiling point of the solvent is preferably about 150 to 250 ° C. When the boiling point is lower than 150 ° C., the volatility of the solvent is high, so that the ink is dried or concentrated on the printing plate. When the boiling point is higher than 250 ° C., it is necessary to increase the drying temperature or lengthen the drying time.

  The film thickness of each transfer layer is set to about 10 to 100 nm after drying. For example, if the solid content and the solvent density are equal, when the solid content concentration of the light emitting material is 1%, the film thickness after drying is 1% before drying. That is, when it is desired to set the thickness of the transfer layer to 45 nm, the thickness of the ink is set to 4.5 μm.

<Formation of red transfer layer: Step S11>
A red ink containing a red light emitting material is prepared, and this ink is patterned on the substrate 31 by a printing method. Thereafter, the ink is dried to remove the solvent, thereby forming the red transfer layer 35r.

  The red light emitting material is mainly composed of a host material having hole transportability and a red light emitting guest material. Of these, the guest material may be fluorescent or phosphorescent, but is preferably fluorescent because of easy control of the light emission characteristics.

<Formation of green transfer layer: Step S12>
A green ink containing a green light emitting material is prepared, and this ink is patterned on the substrate 31 by a printing method. Thereafter, the ink is dried to remove the solvent, thereby forming the green transfer layer 35g.

  The green light emitting material is mainly composed of a host material having an electron transporting property and a green light emitting guest material. The host material only needs to have a higher electron transporting property than the material constituting the hole transport layer. Specifically, the host material used for the green material layer has a lower level of HOMO than the energy level of the highest occupied orbital of α-NPD constituting the hole transport layer (hereinafter abbreviated as HOMO). Specifically, the difference between the two may be 0.2 eV or more. The guest material may be fluorescent or phosphorescent, but is preferably fluorescent because of easy control of light emission characteristics.

<Formation of blue transfer layer: Step S13>
A blue ink containing a blue light emitting material is prepared, and this ink is patterned on the substrate 31 by a printing method. Thereafter, the ink is dried to remove the solvent, thereby forming the blue transfer layer 35b.

  The blue light emitting material is mainly composed of a host material having an electron transporting property and a blue light emitting guest material. Similar to the green light emitting material, the host material only needs to have a higher electron transporting property than the material constituting the hole transport layer. The guest material may be fluorescent or phosphorescent, but is preferably fluorescent because of easy control of light emission characteristics.

  In addition, when it is not necessary to pattern-form a blue light emitting layer, ie, when forming a blue light emitting layer collectively as a common layer, process S13 can be abbreviate | omitted (corresponding to 2nd Embodiment of FIG. 2).

  Examples of the drying method for removing the ink solvent include hot plate drying, infrared heat drying, and hot air drying. The drying step is preferably performed in an inert gas such as nitrogen, argon or helium. The drying temperature can be appropriately selected in consideration of the drying speed of the solvent and the heat resistance of the light-emitting material, but is preferably 40 ° to 150 °, more preferably 50 ° to 80 °. Below this range, the drying rate is slow and productivity is poor. If it is higher than this range, drying unevenness is liable to occur, and the device characteristics deteriorate.

  The steps S11, S12, and S13 may be performed in any order.

<Process S1>
In step S1, the lower electrode 3 and the like are formed on the device substrate 1.

  The device substrate 1 is made of glass, silicon, a plastic substrate, a TFT substrate on which a TFT (thin film transistor) is formed, or the like.

  Next, a lower electrode 3 for supplying a first charge is formed on each pixel on the device substrate 1. Here, when the first charge is a positive charge, the lower electrode 3 is formed as an anode. On the other hand, when the first charge is a negative charge, the lower electrode 3 is formed as a cathode.

  The lower electrode 3 is patterned into a suitable shape depending on the driving method of the display device to be manufactured. For example, when the driving method of the display device is a simple matrix method, the lower electrode 3 is formed in a continuous stripe shape with a plurality of pixels. When the driving method of the display device is an active matrix method, the lower electrode 3 is formed in a pattern corresponding to each of a plurality of arranged pixels. Similarly, the lower electrode 3 thus formed is connected to a TFT formed in each pixel through a contact hole (not shown) formed in an interlayer insulating film covering the TFT.

  For the lower electrode 3, a suitable material is selected depending on the light extraction method of the display device to be manufactured. That is, when the display device is a top emission type in which emitted light is extracted from the side opposite to the substrate 1, the lower electrode 3 is made of a highly reflective material. On the other hand, when the display device is a transmissive type or a double-sided light emitting type that extracts emitted light from the substrate 1 side, the lower electrode 3 is made of a light transparent material.

  Here, the display device is a top emission type, and the lower electrode 3 is an anode. In this case, the lower electrode 10 includes silver (Ag), aluminum (Al), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), tantalum (Ta), tungsten ( W), platinum (Pt), and gold (Au), such as a highly reflective conductive material and alloys thereof.

  When the display device is a top emission type and the lower electrode 3 is a cathode, a conductive material having a small work function is used as the lower electrode 3. As such a conductive material, for example, an alloy of an active metal such as Li, Mg, or Ca and a metal such as Ag, Al, or In can be used. In addition, a layer made of a compound of an active metal such as Li, Mg, or Ca and a halogen such as fluorine or bromine, oxygen, or the like may be formed on the lower electrode 3.

  When the display device is a transmissive type or a double-sided light emitting type and the lower electrode 3 is used as an anode, the conductivity is high such as ITO (Indium-Tin-Oxide) or IZO (Indium-Zinc-Oxide). The lower electrode 3 is made of a material.

  When the active matrix method is adopted as the driving method of the display device, it is desirable that the display device is a top emission type in order to ensure the aperture ratio of the organic electroluminescence element.

  Next, the insulating film 5 is formed in a pattern so as to cover the periphery of the lower electrode 3. The insulating film 5 is formed with a portion (window) that exposes the lower electrode 3, and the window serves as a pixel region in which the organic electroluminescent element is provided. The insulating film 5 is formed using an organic insulating material such as polyimide or photoresist, or an inorganic insulating material such as silicon oxide.

  Thereafter, a first charge injection layer (here, a hole injection layer) 7 is formed as a common layer covering the lower electrode 3 and the insulating film 5. As the hole injection layer 7, a general hole injection material is used. For example, m-MTDATA [4,4,4-tris (3-methylphenylphenylamino) triphenylamine] is formed to a thickness of 10 nm by a vapor deposition method.

  Next, a first charge transport layer (here, a hole transport layer) 9 is formed as a common layer covering the hole injection layer 7. As the hole transport layer 9, a general hole transport material is used. For example, α-NPD [4,4-bis (N-1-naphthyl-N-phenylamino) biphenyl] is formed to a thickness of 35 nm by a vapor deposition method. Examples of other hole transport materials include benzidine derivatives, styrylamine derivatives, triphenylmethane derivatives, hydrazone derivatives, and the like.

  The hole injection layer 7 and the hole transport layer 9 may each be formed as a laminated structure including a plurality of layers.

<Process S2>
In step S2, the transfer layer 35 formed in steps S11 to S13 or steps S11 to S12 is collectively transferred above the lower electrode 3 by a thermal transfer method.

  First, the transfer substrate 30 provided with the transfer layer 35 is disposed opposite to the apparatus substrate 1. At this time, the transfer layer 35 and the hole transport layer 9 are disposed so as to face each other, and the device substrate 1 and the transfer substrate 30 are in contact with each other. Even in this case, the transfer layer 35 is supported on the insulating film 5 on the device substrate 1 side, and the transfer substrate 30 is in contact with the hole transport layer 9 on the lower electrode 3. There is no.

  In this state, a laser hr having a wavelength of, for example, 800 nm is irradiated from the transfer substrate 30 side facing the device substrate 1.

  The laser beam hr is absorbed by the photothermal conversion layer 33, and the transfer layer 35 is sublimated and transferred to the substrate 1 side by the heat. Then, a transfer layer 35 is formed on the hole transport layer 9 on the substrate 1.

  The thermal transfer process can be performed under atmospheric pressure, but is preferably performed in a vacuum. By performing thermal transfer in a vacuum, transfer using a lower energy laser becomes possible, and the thermal adverse effect on the transfer layer can be reduced. Furthermore, by performing the thermal transfer process in a vacuum, the adhesion between the substrates is increased, and the pattern accuracy of the transfer is improved.

<Process S3>
Step S3 is performed only when the blue light emitting layer is collectively formed as a common layer (corresponding to the second embodiment in FIG. 2).

<Step S4>
In step S4, an upper layer is further formed on the device substrate 1.

  First, as shown in FIG. 5A, the second charge transport layer (here, electron transport layer) 13 is formed in a state of covering the entire surface of the device substrate 1 on which the respective color light emitting layers 11r, 11g, and 11b are formed. Form a film. As the electron transport layer 13, a general electron transport material is used. For example, 8≡hydroxyquinoline aluminum (Alq3) is formed by vapor deposition with a film thickness of about 20 nm.

  The hole injection layer 7, the hole transport layer 9, the light emitting layers 11r, 11g, and 11b and the electron transport layer 13 constitute an organic layer 15.

  Next, a first charge injection layer (here, an electron injection layer) 17 is formed on the electron transport layer 13. As the electron injection layer 17, a general electron injection material is used. For example, LiF is formed by a vapor deposition method with a film thickness of about 0.3 nm (vapor deposition rate to 0.01 nm / sec).

  Next, the upper electrode 19 is formed on the electron injection layer 17. When the display device to be manufactured is a simple matrix system, the upper electrode 19 is formed in a stripe shape intersecting with the stripe of the lower electrode 3. On the other hand, when the display device is an active matrix system, the upper electrode 19 is formed so as to cover one surface of the substrate 1 and is used as an electrode common to each pixel. In this case, an auxiliary electrode (not shown) may be formed in the same layer as the lower electrode 3. By connecting the upper electrode 19 to the auxiliary electrode, the voltage drop of the upper electrode 19 can be prevented.

  Then, a red light emitting element 21r, a green light emitting element 21g, and a blue light emitting element 21b including the respective color light emitting layers 11r, 11g, and 11b are formed at intersections of the lower electrode 3 and the upper electrode 19.

  The upper electrode 19 is made of a material suitable for each light extraction method of the display device to be manufactured. When the display device is a top emission type or a dual emission type, a light transmissive material or a semi-transmissive material is used. When the display device is a bottom emission type, a highly reflective material is used.

  Here, the display device is a top emission type, and the upper electrode 19 is used as a cathode electrode. Therefore, the upper electrode 19 is formed using a material having a good light transmittance among the materials having a small work function described above so that electrons can be efficiently injected into the organic layer 15.

  For example, as the upper electrode 19, MgAg is formed with a film thickness of 10 nm. At this time, a film forming method in which the energy of the film forming particles is small enough not to affect the base is used. Examples of such a method include a vapor deposition method and a CVD (chemical vapor deposition) method.

  Further, when the display device is a top emission type, the upper electrode 19 is made semi-transmissive, and a resonator structure is formed between the upper electrode 19 and the lower electrode 3 so that the intensity of extracted light can be increased. It is preferable to do.

  When the display device is a transmissive type and the upper electrode 19 is used as a cathode electrode, the upper electrode 19 is formed of a conductive material having a low work function and high reflectivity. Further, when the display device is a transmissive type and the upper electrode 19 is used as an anode electrode, the upper electrode 19 is formed of a conductive material having a high reflectance.

<Step S5>
In step S5, the organic electroluminescent elements 21r, 21g, and 21b are sealed. For example, a protective film (not shown) is formed so as to cover the upper electrode 19. In order to prevent moisture from reaching the organic layer 15, the protective film is formed with a sufficient film thickness using a material having low permeability and water absorption. Further, when the display device is a top emission type, the protective film is made of a material that transmits light generated in each color light emitting layer 11r, 11g, 11b. For example, a transmittance of about 80% may be ensured.

  As the protective film, an insulating material can be used. For example, an inorganic amorphous insulating material is preferable because it does not form grains and has low water permeability. Examples include amorphous silicon (α-Si), amorphous silicon carbide (α-SiC), amorphous silicon nitride (α-Si1-xNx), amorphous carbon (α-C), and the like.

  For example, when a protective film made of amorphous silicon nitride is formed, it is formed to a thickness of 2 to 3 μm by the CVD method. At this time, in order to prevent a decrease in luminance due to deterioration of the organic layer 15, it is preferable to set the film formation temperature to room temperature. Furthermore, in order to prevent the protective film from peeling off, it is desirable to form the film under conditions that minimize the stress of the film.

  When the display device is an active matrix system and the upper electrode 19 is provided as a common electrode, the protective film may be made of a conductive material. In this case, a material such as ITO or IZO is used.

  Here, the steps up to step S5 described above, more preferably the steps up to step S6, are preferably performed in an inert atmosphere including a vacuum state without being exposed to the atmosphere.

  Then, the protective substrate is bonded to the device substrate 1 on which the protective film is formed via an adhesive resin material. For example, an ultraviolet curable resin is used as the resin material for bonding. For example, a glass substrate is used as the protective substrate. In the case where the display device is a top emission type, the adhesive resin material and the protective substrate are made of a light-transmitting material.

  As described above, the full-color display device 23 including the light emitting elements 21r, 21g, and 21b on the substrate 1 is completed.

  In the above embodiment, the case where the first charge is a positive charge and the second charge is a negative charge, the lower electrode 3 is an anode, and the upper electrode 19 is a cathode has been described. However, the present invention can also be applied to the case where the first charge is a negative charge, the second charge is a positive charge, the lower electrode 3 is a cathode, and the upper electrode 19 is an anode. In that case, the layers 7 to 17 between the lower electrode 3 and the upper electrode 19 are in the reverse stacking order.

≪Schematic configuration of display device≫
6A and 6B are diagrams illustrating an example of the entire configuration of the display device 23. FIG. 6A is a schematic configuration diagram, and FIG. 6B is a configuration diagram of a pixel circuit. Here, an embodiment in which the present invention is applied to an active matrix display device will be described.

  As shown in FIG. 6A, the display device 23 includes a display area 1a and a peripheral area 1b. In the display area 1a, a plurality of scanning lines 41 and a plurality of signal lines 43 are wired vertically and horizontally, and one pixel a is provided at each intersection. Each pixel a is provided with any one of the organic electroluminescent elements 21r, 21g, and 21b shown in FIG. A scanning line driving circuit b that scans and drives the scanning lines 41 and a signal line driving circuit c that supplies a video signal (that is, an input signal) corresponding to luminance information to the signal lines 43 are disposed in the peripheral region 1b. .

  FIG. 6B shows an example of a pixel circuit provided in each pixel a. The video signal written from the signal line 43 via the writing transistor Tr2 is held in the holding capacitor Cs by driving by the scanning line driving circuit b, and a current corresponding to the held signal amount is sent from the driving transistor Tr1 to each organic electroluminescence. The organic electroluminescent elements 21r, 21g, and 21b emit light with luminance corresponding to the current value supplied to the elements 21r, 21g, and 21b.

  The configuration in FIG. 6B is an example, and a capacitor element may be provided in the pixel circuit or a plurality of transistors may be provided as necessary. Further, a necessary drive circuit is added to the peripheral region 1b according to the change of the pixel circuit.

  The display device according to the present invention includes a module shape as shown in FIG. For example, a sealing module 51 is provided so as to surround the display area 1a, and a display module formed by being attached to an opposing part (sealing substrate 52) such as transparent glass using the sealing part 51 as an adhesive corresponds. . The sealing substrate 52 may be provided with a color filter, a protective film, a light shielding film, and the like. The device substrate 1 may be provided with a flexible printed circuit board 53 for inputting and outputting signals and the like from the outside to the display area 1a.

≪Application example≫
The display device according to the present invention can be applied to electronic devices as shown in FIGS. For example, any video signal input to an electronic device such as a digital camera, a notebook personal computer, a portable terminal device such as a mobile phone, a video camera, or a video signal generated in the electronic device is displayed as an image or video. Used as a display device for electronic devices in the field. An example of an electronic device to which the present invention is applied will be described below.

  FIG. 8 is a perspective view showing a television to which the present invention is applied. The television according to this application example includes a video display screen unit 101 including a front panel 102, a filter glass 103, and the like, and the display device according to the present invention is used as the video display screen unit 101.

  9A and 9B are diagrams showing a digital camera to which the present invention is applied. FIG. 9A is a perspective view seen from the front side, and FIG. 9B is a perspective view seen from the back side. The digital camera according to this application example includes a light emitting unit 111 for flash, a display unit 112, a menu switch 113, a shutter button 114, and the like, and the display device according to the present invention is used as the display unit 112.

  FIG. 10 is a perspective view showing a notebook personal computer to which the present invention is applied. The notebook personal computer according to this application example includes a main body 121 including a keyboard 122 that is operated when inputting characters and the like, a display unit 123 that displays an image, and the like, and the display device according to the present invention is used as the display unit 123. It is done.

  FIG. 11 is a perspective view showing a video camera to which the present invention is applied. The video camera according to this application example includes a main body 131, a subject shooting lens 132 on a side facing forward, a start / stop switch 133 at the time of shooting, a display unit 134, and the like, and the display unit 134 according to the present invention. A display device is used.

  12A and 12B are diagrams showing a mobile terminal device to which the present invention is applied, for example, a mobile phone. FIG. 12A is a front view in an opened state, FIG. 12B is a side view thereof, and FIG. (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view. The mobile phone according to this application example includes an upper housing 141, a lower housing 142, a connecting portion (here, a hinge portion) 143, a display 144, a sub-display 145, a picture light 146, a camera 147, and the like. The display device according to the present invention is used as the sub display 145.

  Next, as a specific example of the present invention and a comparative example to the example, a manufacturing procedure of each color light emitting organic electroluminescent element constituting the full color display device will be described.

Example 1
Each color light emitting element 21r, 21g, 21b constituting the display device was manufactured as follows based on the present invention.

On the substrate 31 made of glass, a photothermal conversion layer 33 made of molybdenum was formed with a film thickness of 200 nm by a sputtering method. Next, an oxidation protection layer 34 made of silicon nitride SiN _x was formed on the photothermal conversion layer 33 by a CVD method with a film thickness of 100 nm.

<Step S11>
In order to form the red transfer layer 35r, red ink was adjusted. As a red light emitting material, α-NPD (α-naphtyl phenil diamine) as a hole transporting material is used as a host material, and 2,6≡bis [(4′≡methoxydiphenylamino) styryl] ≡1,5 as a guest material ≡Dicyanonaphthalene (BSN) mixed at 30% by weight was used. This luminescent material was dissolved at a concentration of 0.9% by weight in a solvent in which NMP and butyl cellosolve were mixed at a ratio of 4: 1 to obtain a red ink.

  The adjusted red ink was patterned on the substrate 31 by flexographic printing. Thereafter, the substrate was dried on a hot plate (80 ° C., 30 seconds), and the solvent was removed to form a red transfer layer 35r. The film thickness of the red transfer layer 35r was set to 45 nm. That is, the solid content concentration of the red ink is 0.9%, and the density of the ink and the density of the light emitting material are approximately 1. Therefore, the ink was formed to a thickness of 5 μm (45 / 0.009 [nm]).

<Step S12>
Green ink was adjusted to form a green transfer layer 35g. As the green light emitting material, an electron transporting ADN (anthracene dinaphtyl) was used as a host material, and a guest material mixed with 5% by weight of coumarin 6 was used. This luminescent material was dissolved at a concentration of 0.6% by weight in a solvent in which NMP and butyl cellosolve were mixed at a ratio of 4: 1 to obtain a green ink.

  The adjusted green ink was patterned on the substrate 31 by flexographic printing. Thereafter, the substrate was dried on a hot plate (80 ° C., 30 seconds), and the solvent was removed to form a green transfer layer 35 g. The film thickness of the green transfer layer 35g was set to 30 nm. That is, since the solid content concentration of the green ink is 0.6%, and the density of the ink and the density of the light emitting material are approximately 1, the ink was deposited to 5 μm (30 / 0.006 [nm]).

<Step S13>
Blue ink was prepared to form the blue transfer layer 35b. As a blue light emitting material, an electron transporting ADN (anthracene dinaphtyl) is used as a host material, and 4,4′≡bis [2≡ {4≡ (N, N≡diphenylamino) phenyl} vinyl] biphenyl (DPAVBi) as a guest material. ) Was mixed at 2.5% by weight. This luminescent material was dissolved at a concentration of 0.6% by weight in a solvent in which NMP and butyl cellosolve were mixed at a ratio of 4: 1 to obtain a blue ink.

  The adjusted blue ink was patterned on the substrate 31 by flexographic printing. Thereafter, the substrate was dried on a hot plate (80 ° C., 30 seconds), and the solvent was removed to form a blue transfer layer 35b. The film thickness of the blue transfer layer 35b was set to 30 nm. That is, since the solid content concentration of the blue ink is 0.6% and the density of the ink and the density of the light emitting material are approximately 1, the ink was formed into a film of 5 μm (30 / 0.006 [nm]).

(Process S1)
On the device substrate 1 made of glass, an APC (Ag—Pd—Cu) layer (film thickness 120 nm), which is a silver alloy layer, and a transparent conductive layer (film thickness 10 nm) made of ITO are formed in this order. The lower electrode 3 was formed as an anode. Next, an insulating film 5 made of silicon oxide was formed to a thickness of about 2 μm by sputtering so as to cover the periphery of the lower electrode 3. Next, the lower electrode 3 was exposed from the insulating film 5 by lithography to form a pixel region. On the surface, m-MTDATA was deposited as a hole injection layer 7 with a film thickness of 10 nm. Next, α-NPD was deposited as a hole transport layer 9 to a thickness of 35 nm.

(Process S2)
With the formed organic layers facing each other, the transfer substrate 30 was placed on the device substrate 1 and adhered in vacuum. Both substrates maintain a small gap of about 2 μm depending on the thickness of the insulating film 5. In this state, an area equivalent to the pixel area of the device substrate 1 was irradiated with a laser beam having a wavelength of 800 nm from the back side of the transfer substrate 30, thereby forming transfer layers of each color on the device substrate 1.

(Process S4)
On the light-emitting layer formed by thermal transfer, 8≡hydroxyquinoline aluminum (Alq3) was deposited as an electron transport layer 13 to a thickness of about 20 nm. Subsequently, LiF was vapor-deposited as the electron injection layer 17 with a film thickness of about 0.3 nm (deposition rate: 0.01 nm / sec). Subsequently, MgAg was vapor-deposited with a film thickness of 10 nm as a cathode to be the upper electrode 19.

<< Example 2 >>
Example 2 is the same as Example 1 except that the blue light emitting layer is formed in a lump by vapor deposition or the like. As described above, even when only the red transfer layer and the green transfer layer are formed on the transfer substrate and the blue light emitting layer is collectively formed by vapor deposition or the like, the same effect can be obtained.

≪Comparative example≫
In the step of patterning each color transfer layer on the transfer substrate, a printing method other than the flexographic printing method was used. Table 1 shows the results of evaluating the performance of pattern formation for each printing method.

  From the above results, by applying the method of the present invention to produce a display device, even a low-viscosity ink composed of a low-molecular light-emitting material and a solvent can be accurately formed by a printing method. It was confirmed that it was possible. Furthermore, it was confirmed that the flexographic printing method is preferable as the printing method.

It is a flowchart which shows the manufacture procedure of 1st Embodiment. It is a flowchart which shows the manufacture procedure of 2nd Embodiment. It is sectional drawing of the transfer substrate produced in embodiment. It is sectional drawing of the to-be-transferred substrate produced in embodiment. It is sectional process drawing which shows the manufacturing method of embodiment. It is a figure which shows an example of the circuit structure of the display apparatus of embodiment. It is a block diagram which shows the module-shaped display apparatus of the sealed structure to which this invention is applied. It is a perspective view which shows the television to which this invention is applied. It is a figure which shows the digital camera to which this invention is applied, (A) is the perspective view seen from the front side, (B) is the perspective view seen from the back side. 1 is a perspective view showing a notebook personal computer to which the present invention is applied. It is a perspective view which shows the video camera to which this invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the portable terminal device to which this invention is applied, for example, a mobile telephone, (A) is the front view in the open state, (B) is the side view, (C) is the front view in the closed state , (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Device substrate, 3 ... Lower electrode (anode), 11r ... Red light emitting layer, 11g ... Green light emitting layer, 11b ... Blue light emitting layer, 19 ... Upper electrode (cathode), 21r ... Red light emitting element, 21g ... Green light emitting element 21b ... Blue light emitting element, 23 ... Display device, 31 ... Substrate, 33 ... Heat conversion layer, 35r ... Red transfer layer, 35g ... Green transfer layer, 35b ... Blue transfer layer

Claims (7)

Forming at least a photothermal conversion layer on the substrate;
Patterning a first transfer layer containing a first organic material on the substrate on which at least a photothermal conversion layer is formed by a printing method;
Patterning a second transfer layer containing a second organic material on the substrate on which at least a photothermal conversion layer is formed by a printing method;
Irradiating the substrate with radiation, and transferring the first transfer layer and the second transfer layer onto the substrate to be transferred in a lump. 2. The method for manufacturing a display device according to claim 1, wherein the first organic material and the second organic material are made of a low molecule. Forming the first transfer layer comprises:
Forming a first ink obtained by dissolving the first organic material in an organic solvent on the substrate by a printing method; and drying the first transfer layer.
Forming the second transfer layer comprises:
Forming a second ink obtained by dissolving the second organic material in an organic solvent on the substrate by a printing method; and drying the second transfer layer.
The method for manufacturing a display device according to claim 2. The method for manufacturing a display device according to claim 3, wherein the organic solvent has a boiling point of 150 ° C. or higher and 250 ° C. or lower. The method for manufacturing a display device according to claim 3, wherein the ink has a content of the organic solvent of 50 wt% or more and less than 100 wt%. 2. The display device according to claim 1, further comprising a step of collectively forming a third organic material on the transfer target substrate including the first transfer layer and the second transfer layer by an evaporation method. Production method. The method for manufacturing a display device according to claim 1, wherein the printing method is a flexographic printing method.

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