Patent Publication Number: US-6993214-B2

Title: Light emitting device and display unit using it

Description:
RELATED APPLICATION DATA 
     The present application claims priority to Japanese Application(s) No(s). P2002-342831 filed Nov. 26, 2003, which application(s) is/are incorporated herein by reference to the extent permitted by law. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light emitting device and a display unit using it, and more particularly such a self-luminous type light emitting device such as an organic light emitting device and a display unit using it. 
     2. Description of the Related Art 
     In these years, as a display unit instead of a liquid crystal display, an organic electroluminescence display which uses organic light emitting devices has been noted. The organic electroluminescence display has characteristics that its visual field angle is wide and its power consumption is low since it is a self-luminous type display. The organic electric field light emitting display is also thought of as a display having sufficient response to high-definition high-speed video signals, and is under development toward the practical use. 
       FIG. 1  shows a construction of a conventional organic light emitting device. This organic light emitting device has, for example, a structure wherein a transparent electrode  112  and an organic layer  113  are layered in this order on a substrate  111  made of an insulating material such as glass from the substrate  111  side. In the organic layer  113 , an electron hole transport layer  113 A and a light emitting layer  113 B are layered in this order from the substrate  111  side. Lights generated in the light emitting layer  113 B are extracted from the substrate  111  side. 
     However, in such a conventional organic light emitting device, a peak width of a spectrum of the extracted light is wide, and particularly, peak wavelengths of green and blue lights are considerably shifted. Therefore, there is a problem that a color reproduction range sufficient to display television picture cannot be obtained. 
     Therefore, trials to control lights generated in a light emitting layer, for example, a trial to improve color purity of light emitting colors and light emitting efficiency by introducing a resonator structure to the organic light emitting device have been made (for example, refer to International Publication No. 01/39554). In the organic light emitting device wherein such a resonator structure is introduced, a width of a spectrum of the extracted light can be narrowed, and peak luminance can be raised, so that a color reproduction range can be expanded. 
     There are two kinds of this organic light emitting device: one is made of a low molecular weight material, and the other is made of a high molecular weight material. As a manufacturing method for the device made of a high molecular weight material, ink jet printing method is generally known. 
     However, when the organic layer is formed by the ink jet printing method, there is a problem that variation of film thickness is high. Therefore, since it is necessary to precisely control film thickness particularly when the foregoing resonator structure is introduced, there is a problem that irregular color occurs with the ink jet printing method, so that it is difficult to obtain a color reproduction range sufficient to display, for example, television picture. This problem is significant when a high molecular weight material is used for the light emitting layer. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, it is an object of the invention to provide a light emitting device which can prevent irregular color by reducing film thickness distribution and a display unit using it. 
     A light emitting device according to the invention comprises a layer including a light emitting layer between a first electrode and a second electrode, wherein at least part of the layer including the light emitting layer is formed by transferring a raw solution and then removing a solvent. 
     A display unit according to the invention comprises a light emitting device comprising a layer including a light emitting layer between a first electrode and a second electrode, wherein at least part of the layer including the light emitting layer is formed by transferring a raw solution and then removing the solvent. 
     In the light emitting device according to the invention, at least part of the layer including the light emitting layer is formed by transferring a raw solution and then removing the solvent. Therefore, its film thickness distribution is reduced, and irregular color is prevented. 
     In the display unit according to the invention, the light emitting device according to the invention is provided. Therefore, its film thickness distribution is reduced, and irregular color is prevented. 
     Other and further objects, features and advantages of the invention will appear more fully from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view showing a construction of a conventional organic light emitting device; 
         FIG. 2  is a cross sectional view showing a construction of a display unit using organic light emitting devices which are light emitting devices according to an embodiment of the invention; 
         FIG. 3  is a cross sectional view showing a manufacturing method for the display unit illustrated in  FIG. 2  in order of process; 
         FIGS. 4A and 4B  are cross sectional views showing a process following the process illustrated in  FIG. 3 ; 
         FIGS. 5A ,  5 B, and  5 C are cross sectional views showing a process following the process illustrated in  FIG. 4B ; 
         FIGS. 6A and 6B  are cross sectional views showing a process following the process illustrated in  FIG. 5C ; 
         FIGS. 7A ,  7 B, and  7 C are cross sectional views showing a process following the process illustrated in  FIG. 6B ; 
         FIGS. 8A and 8B  are cross sectional views showing a process following the process illustrated in  FIG. 7C ; 
         FIGS. 9A ,  9 B, and  9 C are cross sectional views showing a process following the process illustrated in  FIG. 8B ; 
         FIGS. 10A and 10B  are cross sectional views showing a process following the process illustrated in  FIG. 9C ; 
         FIGS. 11A ,  11 B, and  11 C are cross sectional views showing a process following the process illustrated in  FIG. 10B ; 
         FIGS. 12A ,  12 B, and  12 C are cross sectional views showing a process following the process illustrated in  FIG. 11C ; 
         FIGS. 13A ,  13 B, and  13 C are figures showing other manufacturing method for the display unit illustrated in  FIG. 2  in order of process; 
         FIG. 14  is a cross sectional view showing a process following the process illustrated in  FIG. 13C ; 
         FIG. 15  is a figure showing light emitting spectrums of an organic light emitting device of Example 1 of the invention with light emitting spectrums of an organic light emitting device of Comparative example 2; 
         FIG. 16  is a chromaticity diagram showing chromaticity coordinates of three primary colors of the organic light emitting device of Example 1 of the invention with chromaticity coordinates of three primary colors of the organic light emitting device of Comparative example 2, and 
         FIG. 17  is a cross sectional view showing a modification of the display unit illustrated in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the invention will be described in detail hereinbelow with reference to the drawings. 
       FIG. 2  shows a cross sectional structure of a display unit using organic light emitting devices which are light emitting devices according to an embodiment of the invention. This display unit is used as an ultrathin organic electroluminescence color display unit or the like, and, for example, a driving panel  10  and a sealing panel  20  are placed opposite, and their whole faces are bonded together by an adhesive layer  30 . The driving panel  10  is provided with a plurality of organic light emitting devices  12  in a matrix state as a whole on a driving substrate  11  made of an insulating material such as glass. 
     In the organic light emitting device  12 , for example, a first electrode  13  as an anode, an organic layer  14 , and a second electrode  15  as a cathode are layered in this order from the driving substrate  11  side. The first electrode  13  is a common electrode for the plurality of organic light emitting devices  12  located, for example, in column direction, and the second electrode  15  is a common electrode for the plurality of organic light emitting devices  12  located, for example, in row direction. 
     The first electrode  13  also has a function as a reflection layer, so that it is desirable that the first electrode  13  has reflectance as high as possible in order to improve light emitting efficiency. For example, as a material to make the first electrode  13 , a simple substance or an alloy of metal elements with high work function such as platinum (Pt), gold (Au), silver (Ag), chrome (Cr), tungsten (W) and the like can be cited. It is preferable that a thickness of the first electrode  13  in layer direction (hereinafter simply referred to as “thickness”) is set to 100 nm to 300 nm. As an alloy material, for example, AgPdCu alloy whose main base is silver, including palladium (Pd) of 0.3 wt % to 1 wt % and copper (Cu) of 0.3 wt % to 1 wt % can be cited. 
     The organic layer  14  has a structure wherein an electron hole transport layer  14 A and a light emitting layer  14 B are layered in this order from the first electrode  13  side. Lights generated in the light emitting layer  14 B are extracted from the second electrode  15  side. A function of the electron hole transport layer  14 A is to improve efficiency to inject electron holes into the light emitting layer  14 B. A function of the light emitting layer  14 B is to produce lights by current injection. The light emitting layer  14 B also functions as an electron transport layer. The electron hole transport layer  14 A and the light emitting layer  14 B are formed by transferring a raw solution and then removing a solvent as described later. A total thickness of the electron hole transport layer  14 A and the light emitting layer  14 B is preferably, for example, from 15 nm to 100 nm. 
     The electron hole transport layer  14 A is made of a conductive polymeric material such as poly(3,4)-ethylene dioxythiophene (PEDOT), or polyaniline. 
     The light emitting layer  14 B has a red light emitting layer  14 BR which generates red lights, a green light emitting layer  14 BG which generates green lights, and a blue light emitting layer  14 BB which generates blue lights. The red light emitting layer  14 BR, the green light emitting layer  14 BG, and the blue light emitting layer  14 BB are arranged in parallel with each other between the first electrode  13  and the second electrode  15 . 
     The red light emitting layer  14 BR is made of a polymeric organic light emitting material such as poly [{9,9-dihexyl-2,7-bis(1-cyanovinylene) fluorenylene}-alt-co-{2,5-bis(N, N′-diphenylamino)-1,4-phenylene}] shown in Chemical formula 1. The polymeric material means what has a molecular mass of 10,000 or more.                  
 
     The green light emitting layer  14 BG is made of a polymeric organic light emitting material such as poly [{9,9-dioctylfluorenyl-2,7-dityl}-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethyl hexyloxy}-benzene)] shown in Chemical formula 2.                  
 
     The blue light emitting layer  14 BB is made of a polymeric organic light emitting material such as poly [{9,9-dioctyl fluorenyl-2,7-dityl}-co-{1,4-(2,5-dimethoxy)benzene}] shown in Chemical formula 3.                  
 
     The second electrode  15  has a structure wherein a semi-transparent electrode  15 A having semi-transparency for the lights generated in the light emitting layer  14 B, and a transparent electrode  15 B having transparency for the lights generated in the light emitting layer  14 B are layered in this order from the organic layer  14  side. The semi-transparent electrode  15 A has, for example, a thickness of 5 nm to 50 nm, and is made of a simple substance or an alloy of metal elements with a low work function such as aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na) and the like. Specially, an alloy of magnesium and silver (hereinafter referred to as “MgAg alloy”) is preferable, and a volume ratio of magnesium and silver is preferably Mg:Ag=5:1 to 30:1. In addition, a laminated structure of a calcium layer and an MgAg alloy layer is possible. 
     The semi-transparent electrode  15 A also has a function as a semi-transparent reflection layer. That is, this organic light emitting device  12  has a resonator structure wherein lights generated in the light emitting layer  14 B are resonated and extracted from a second end P 2  side, by setting an end face of the first electrode  13  on the light emitting layer  14 B side to a first end P 1 , setting an end face of the second electrode  15  on the light emitting layer  14 B side to the second end P 2 , and setting the organic layer  14  to a resonance part. It is preferable that the organic light emitting device  12  has such a resonator structure, since the lights generated in the light emitting layer  14 B generate multiple interference, and act as a kind of narrow band filter, so that a half value width of spectrums of the lights to be extracted is reduced and color purity can be improved. Further, it is preferable that the organic light emitting device  12  has such a resonator structure, since outside lights which enter from the sealing panel  20  can be also attenuated by the multiple interference, and reflectance of outside lights in the organic light emitting device  12  can be extremely lowered in combination with a color filter  22  described later. 
     To that end, it is preferable that an optical distance L between the first end P 1  and the second end P 2  of the resonator satisfies mathematical formula 1, and a resonance wavelength of the resonator (peak wavelength of a spectrum of an extracted light) corresponds to a peak wavelength of a spectrum of a light desired to be extracted. Actually, it is preferable that the optical distance L is selected to be a positive minimum value which satisfies the mathematical formula 1.
 
(2 L )/λ+Φ/(2π)= m   [Mathematical formula 1]
 
     (In the formula, L represents an optical distance between the first end P 1  and the second end P 2 , Φ represents a sum (Φ=Φ 1 +Φ 2 ) (rad) of phase shift Φ 1  of a reflected light generated in the first end P 1  and phase shift Φ 2  of a reflected light generated in the second end P 2 , λ represents a peak wavelength of a spectrum of a light desired to be extracted from the second end P 2  side, and m represents an integer to make L positive, respectively. In the mathematical formula 1, units for L and λ should be common, for example, nm is used as a common unit.) 
     As a concrete construction of the organic light emitting device  12  which satisfies the mathematical formula 1, for example, where peak wavelength λ of a spectrum of a light desired to be extracted is 635 nm for red light, 535 nm for green light, and 450 nm for blue light, a laminated structure wherein the first electrode  13  made of chrome, the electron hole transport layer  14 A having a thickness of 20 nm made of poly(3,4)-ethylene dioxythiophene or polyaniline, the red light emitting layer  14 BR having a thickness of 75 nm made of the polymeric organic light emitting material shown in Chemical formula 1, the green light emitting layer  14 BG having a thickness of 65 nm made of the polymeric organic light emitting material shown in Chemical formula 2, the blue light emitting layer  14 BB having a thickness of 45 nm made of the polymeric organic light emitting material shown in Chemical formula 3, and the semi-transparent electrode  15 A having a laminated structure of a calcium layer having a thickness of 10 nm and an MgAg alloy layer having a thickness of 12 nm are sequentially layered can be cited. 
     A function of the transparent electrode  15 B is to lower electric resistance of the semi-transparent electrode  15 A, and the transparent electrode  15 B is made of a conductive material having translucency sufficient for the lights generated in the light emitting layer  14 B. As a material making the transparent electrode  15 B, for example, indium tin oxide (ITO), a compound containing indium, zinc (Zn), and oxygen, and the like are preferable, since with such materials, good conductivity can be obtained even when deposition is made under room temperature. A thickness of the transparent electrode  15 B is preferably, for example, from 30 nm to 1,000 nm. 
     The sealing panel  20  is located on the second electrode  15  side of the driving panel  10 , and comprises a sealing substrate  21  to seal the organic light emitting devices  12  with the adhesive layer  30 . The sealing substrate  21  is made of a material such as glass which is transparent to lights generated in the organic light emitting device  12 . In the sealing substrate  21 , for example, the color filter  22  is provided, so that lights generated in the organic light emitting device  12  are extracted, outside lights reflected in the organic light emitting device  12  and wiring between each organic light emitting device  12  are absorbed, and contrast is improved. 
     The color filter  22  can be provided on either side of the sealing substrate  21 . However, it is preferable to provide the color filter  22  on the driving panel  10  side, since the color filter  22  is not exposed on the surface, and can be protected by the adhesive layer  30 . The color filter  22  comprises a red filter  22 R, a green filter  22 G, and a blue filter  22 B, which are orderly arranged corresponding to the red light emitting layer  14 BR, the green light emitting layer  14 BG, and the blue light emitting layer  14 BB. 
     The red filter  22 R, the green filter  22 G, and the blue filter  22 B are respectively, for example, formed in the shape of rectangle with no space between them. The red filter  22 R, the green filter  22 G, and the blue filter  22 B are respectively made of a resin mixed with a pigment. The red filter  22 R, the green filter  22 G, and the blue filter  22 B are adjusted so that light transmittance in the targeted red, green, or blue wavelength band becomes high and light transmittance in other wavelength bands becomes low by selecting a pigment. 
     Further, a wavelength range with high transmittance in the color filter  22  corresponds to a peak wavelength λ of a spectrum of a light desired to be extracted from the resonator structure. Therefore, among the outside lights which enter from the sealing panel  20 , only the lights having a wavelength equal to a peak wavelength λ of a spectrum of an extracted light pass through the color filter  22 , and other outside lights having other wavelengths are prevented from intruding into the organic light emitting device  12 . 
     The display unit having these organic light emitting devices  12 , for example, can be manufactured as below. 
       FIG. 3  to  FIGS. 12A ,  12 B, and  12 C show a manufacturing method for this display unit in order of process. First, as shown in  FIG. 3 , on the driving substrate  11  made of the foregoing material, the first electrode  13  made of the foregoing material is formed by, for example, DC spattering. 
     Next, as shown in  FIG. 4A , as an ink to form the electron hole transport layer  14 A by transfer, a raw solution for electron hole transport layer  41  containing the foregoing material for the electron hole transport layer  14 A and a solvent is prepared. When poly(3,4)-ethylene dioxythiophene is used as a material for the electron hole transport layer  14 A, water is used as a solvent. When polyaniline is used as a material for the electron hole transport layer  14 A, an organic solvent is used as a solvent. Subsequently, this raw solution for electron hole transport layer  41  is applied to an application face for electron hole transport layer  51 . The application face for electron hole transport layer  51  is, for example, made of a sheet member arranged so that the sheet member is wound around a roller for electron hole transport layer  52 . The raw solution for electron hole transport layer  41  is applied to the application face for electron hole transport layer  51 , accompanied by rotation of the roller for electron hole transport layer  52 . As a material for the application face for electron hole transport layer  51 , for example, a silicone resin which is easily processed and has a high resistance to the organic solvent is preferable, and an urethane material and the like are preferable when water is used as a solvent. 
     After that, as shown in  FIG. 4B , a relief printing plate for electron hole transport layer  53  wherein concave portions  54  are formed corresponding to a pattern of the electron hole transport layer  14 A of the organic light emitting device  12  on the driving substrate  11  is prepared. By rotating or rolling the roller for electron hole transport layer  52  on the relief printing plate for electron hole transport layer  53 , the raw solution for electron hole transport layer  41  on the application face for electron hole transport layer  51  is selectively removed. Then, it is possible either to rotate and move the roller for electron hole transport layer  52 , or to move the relief printing plate for electron hole transport layer  53 . It is also possible to move both the roller for electron hole transport layer  52  and the relief printing plate for electron hole transport layer  53 . Consequently, as shown in  FIG. 5A , the raw solution for electron hole transport layer  41  remains on the application face for electron hole transport layer  51 , corresponding to the pattern of the electron hole transport layer  14 A. 
     Next, as shown in  FIG. 5B , by rotating or rolling the roller for electron hole transport layer  52  on the driving substrate  11  on which the first electrode  13  is formed, raw solution for electron hole transport layer  41  remaining on the application face for electron hole transport layer  51  is transferred. Then, it is possible either to rotate and move the roller for electron hole transport layer  52 , or to move the driving substrate  11  in the direction of arrow A. It is also possible to move both the roller for electron hole transport layer  52  and the driving substrate  11 . After that, the solvent is removed, and as shown in  FIG. 5C , the electron hole transport layer  14 A is formed on the first electrode  13 . As above, since the electron hole transport layer  14 A is formed by transferring the raw solution for electron hole transport layer  41 , and then removing the solvent, film thickness distribution of the electron hole transport layer  14 A is reduced compared to in a conventional case wherein the electron hole transport layer is formed by spin coat method. 
     After forming the electron hole transport layer  14 A, for example, as shown in  FIG. 6A , as an ink to form the red light emitting layer  14 BR, a red raw solution  61 R containing the polymeric organic light emitting material shown in Chemical formula 1 and xylene as the solvent is prepared. The red raw solution  61 R is applied to a red application face  71 R which is wound around a red roller  72 R, as in the case of the electron hole transport layer  14 A. The red application face  71 R is constructed as in the application face for electron hole transport layer  51 . That is, since an organic solvent is used for a solvent here, it is preferable that the red application face  71 R is made of a silicone resin. 
     Next, as shown in  FIG. 6B , a red relief printing plate  73 R wherein concave portions  74 R are formed corresponding to a pattern of the red light emitting layer  14 BR of the organic light emitting device  12  on the driving substrate  11  is prepared. By rotating or rolling the red roller  72 R on the red relief printing plate  73 R as in the case of the electron hole transport layer  14 A, the red raw solution  61 R is selectively removed. Consequently, as shown in  FIG. 7A , the red raw solution  61 R remains on the red application face  71 R, corresponding to the pattern of the red light emitting layer  14 BR. 
     Next, as shown in  FIG. 7B , by rotating or rolling the red roller  72 R on the driving substrate  11  on which the first electrode  13  and the electron hole transport layer  14 A are formed as in the case of the electron hole transport layer  14 A, the red raw solution  61 R is transferred. After that, the solvent is removed, and as shown in  FIG. 7C , the red light emitting layer  14 BR is formed. 
     After forming the red light emitting layer  14 BR, for example, as shown in  FIG. 8A , as an ink to form the green light emitting layer  14 BG, a green raw solution  61 G containing the polymeric organic light emitting material shown in Chemical formula 2 and xylene as the solvent is prepared. This green raw solution  61 G is applied to a green application face  71 G which is wound around a green roller  72 G, as in the case of the electron hole transport layer  14 A. The green application face  71 G is also constructed as in the application face for electron hole transport layer  51 . 
     Next, as shown in  FIG. 8B , a green relief printing plate  73 G wherein concave portions  74 G are formed corresponding to a pattern of the green light emitting layer  14 BG of the organic light emitting device  12  on the driving substrate  11  is prepared. By rotating or rolling the green roller  72 G on the green relief printing plate  73 G as in the case of the electron hole transport layer  14 A, the green raw solution  61 G is selectively removed. Consequently, as shown in  FIG. 9A , the green raw solution  61 G remains on the green application face  71 G, corresponding to the pattern of the green light emitting layer  14 BG. 
     Next, as shown in  FIG. 9B , by rotating or rolling the green roller  72 G on the driving substrate  11  on which the first electrode  13 , the electron hole transport layer  14 A, and the red light emitting layer  14 BR are formed as in the case of the electron hole transport layer  14 A, the green raw solution  61 G is transferred. After that, the solvent is removed, and as shown in  FIG. 9C , the green light emitting layer  14 BG is formed. 
     After forming the green light emitting layer  14 BG, for example, as shown in  FIG. 10A , as an ink to form the blue light emitting layer  14 BB, a blue raw solution  61 B containing the polymeric organic light emitting material shown in Chemical formula 3 and xylene as the solvent is prepared. This blue raw solution  61 B is applied to a blue application face  71 B which is wound around a blue roller  72 B, as in the case of the electron hole transport layer  14 A. The blue application face  71 B is also constructed as in the application face for electron hole transport layer  51 . 
     Next, as shown in  FIG. 10B , a blue relief printing plate  73 B wherein concave portions  74 B are formed corresponding to a pattern of the blue light emitting layer  14 BB of the organic light emitting device  12  on the driving substrate  11  is prepared. By rotating or rolling the blue roller  72 B on the blue relief printing plate  73 B as in the case of the electron hole transport layer  14 A, the blue raw solution  61 B is selectively removed. Consequently, as shown in  FIG. 11A , the blue raw solution  61 B remains on the blue application face  71 B, corresponding to the pattern of the blue light emitting layer  14 BB. 
     Next, as shown in  FIG. 11B , by rotating or rolling the blue roller  72 B on the driving substrate  11  on which the first electrode  13 , the electron hole transport layer  14 A, the red light emitting layer  14 BR, and the green light emitting layer  14 BG are formed as in the case of the electron hole transport layer  14 A, the blue raw solution  61 B is transferred. After that, the solvent is removed, and as shown in  FIG. 1C , the blue light emitting layer  14 BB is formed. Consequently, the light emitting layer  14 B having the red light emitting layer  14 BR, the green light emitting layer  14 BG, and the blue light emitting layer  14 BB is formed. As above, the light emitting layer  14 B is formed by transferring the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B which contain the solvent, and then removing the solvent. Therefore, film thickness distribution of the light emitting layer  14 B is reduced, compared to in the conventional case wherein the light emitting layer is formed by ink jet printing method. 
     After forming the light emitting layer  14 B, as shown in  FIG. 12A , for example, by deposition method, the second electrode  15  which has the foregoing thickness and is made of the foregoing material is deposited to form the organic light emitting devices  12  as shown in  FIG. 2 . Consequently, the driving panel  10  is formed. After that, as shown in  FIG. 12A  as well, the adhesive layer  30  is formed on the organic light emitting devices  12 . 
     Further, as shown in  FIG. 12B , for example, by applying a material of the red filter  22 R by spin coat and the like onto the sealing substrate  21  made of the foregoing material, patterning with photolithography technique and firing, the red filter  22 R is formed. Subsequently, as shown in  FIG. 12B  as well, as in the red filter  22 R, the blue filter  22 B and the green filter  22 G are subsequently formed. Consequently, the sealing panel  20  is formed. 
     After forming the driving panel  10  and the sealing panel  20 , as shown in  12 C, the driving panel  10  and the sealing panel  20  are bonded with the adhesive layer  30  in between. Then, it is preferable that a face of the sealing panel  20  on which the color filter  22  is formed is placed opposite to the driving panel  10 . Consequently, the driving panel  10  and the sealing panel  20  are bonded, and the display unit shown in  FIG. 2  is completed. 
     This display unit, for example, can be also manufactured as follows. 
     First, as shown in  FIG. 3  to  FIG. 5C , the first electrode  13  and the electron hole transport layer  14 A are formed on the driving substrate  11  in a manner similar to the foregoing method. 
     Next, as shown in  FIG. 13A , the red raw solution  61 R is applied onto an application face for light emitting layer  71  which is wound around a roller for light emitting layer  72 , and the red raw solution  61 R is selectively removed by using the red relief printing plate  73 R as in the case of the electron transport layer  14 A. The application face for light emitting layer  71  is also constructed as in the application face for electron transport layer  51 . 
     Further, as in the case of the electron transport layer  14 A, the green raw solution  61 G is applied onto the application face for light emitting layer  71  on which the red raw solution  61 R remains as shown in  FIG. 13A . At this time, the green raw solution  61 G is applied onto the red raw solution  61 R. Subsequently, the green raw solution  61 G is selectively removed by using the green relief printing plate  73 G. Then, the green raw solution  61 G applied on the red raw solution  61 R is removed. Consequently, as shown in  FIG. 13B , the red raw solution  61 R and the green raw solution  61 G are applied onto the application face for light emitting layer  71 . 
     After that, as in the case of the electron hole transport layer  14 A, the blue raw solution  61 B is applied to the application face for light emitting layer  71  on which the red raw solution  61 R and the green raw solution  61 G are applied. At this time, the blue raw solution  61 B is applied onto the red raw solution  61 R and the green raw solution  61 G. Subsequently, the blue raw solution  61 B is selectively removed by using the blue relief printing plate  73 B. Then, the blue raw solution  61 B which is applied on the red raw solution  61 R and the green raw solution  61 G is removed. Consequently, as shown in  FIG. 13C , the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B are applied on the application face for light emitting layer  71 . 
     Next, as shown in  FIG. 14 , as in the case of the electron transport layer  14 A, by rotating or rolling a roller for light emitting layer  72  on the driving substrate  11  on which the first electrode  13  and the electron hole transport layer  14 A are formed, the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B are transferred at once. After that, the solvent is removed, and the light emitting layer  14 B which has the red light emitting layer  14 BR, the green light emitting layer  14 BG, and the blue light emitting layer  14 BB is formed. 
     After that, the driving panel  10  and the sealing panel  20  are formed by a process shown in  FIGS. 12A ,  12 B, and  12 C, and then the driving panel  10  and the sealing panel  20  are bonded with the adhesive layer  30  in between. Consequently, the display unit shown in  FIG. 2  is completed. 
     Though not shown in the figure, it is possible that the raw solution for electron hole transport layer  41 , the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B are layered and applied on the same application face. 
     In the foregoing method, the raw solution for electron hole transport layer  41 , the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B, which contain the material for the electron hole transport layer  14 A or the polymeric organic light emitting material are used. However, instead of them, a raw solution containing a precursor material which becomes a material for them by polymerization can be used. In this case, it is possible that polymerization is made after transferring a solution containing the precursor material, and then the solvent is removed, or it is also possible that after making transfer and removing the solvent, polymerization is made. 
     In this display unit, when a certain voltage is applied between the first electrode  13  and the second electrode  15 , current is applied to the light emitting layer  14 B, and electron holes and electrons recombine, so that light emitting occurs. This light multiple-reflects between the first electrode  13  and the second electrode  15 , and is extracted through the second electrode  15 , the color filter  22 , and the sealing substrate  21 . Then, since the electron hole transport layer  14 A and the light emitting layer  14 B are formed by transferring the raw solution for electron hole transport layer  41 , the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B, the film thickness distribution is reduced. Therefore, occurrence of irregular color is prevented, and images with high-definition and excellent color reproducibility can be obtained. 
     As above, according to the embodiment, since the electron hole transport layer  14 A and the light emitting layer  14 B are formed by transferring the raw solution for electron hole transport layer  41 , the red raw solution  61 R, the green raw solution  61 G, and the blue raw solution  61 B, film thickness distribution can be reduced. Therefore, occurrence of irregular color can be prevented, and images with high-definition and excellent color reproducibility can be obtained. 
     EXAMPLES 
     Further, concrete examples of the invention will be described in detail with reference to  FIG. 2  by using the same symbols. 
     Example 1 
     As in the foregoing embodiment, on the driving substrate  11  made of glass, the first electrode  13  having a thickness of 230 nm made of chrome, the electron hole transport layer  14 A having a thickness of 20 nm made of poly(3,4)-ethylene dioxythiophene, the red light emitting layer  14 BR having a thickness of 75 nm made of the polymeric organic light emitting material shown in Chemical formula 1, the green light emitting layer  14 BG having a thickness of 65 nm made of the polymeric organic light emitting material shown in Chemical formula 2, the blue light emitting layer  14 BB having a thickness of 45 nm made of the polymeric organic light emitting material shown in Chemical formula 3, the semi-transparent electrode  15 A having a laminated structure of a calcium layer having a thickness of 10 nm and an MgAg alloy layer having a thickness of 12 nm, and the transparent electrode  15 B having a thickness of 300 nm made of ITO were sequentially layered to fabricate the driving panel  10  having the organic light emitting devices  12  on the driving substrate  11 . When measuring film thickness distribution of the electron hole transport layer  14 A and the light emitting layer  14 B, the resulting value was 3% or less, which was within a tolerance for film thickness distribution to introduce the resonator structure. 
     Further, on the sealing substrate  21  made of glass, the color filters  22  having the red filter  22 R, the green filter  22 G, and the blue filter  22 B were formed to fabricate the sealing panel  20 . Subsequently, the driving panel  10  and the sealing panel  20  were bonded with the adhesive layer  30  in between, and the display unit shown in  FIG. 2  was obtained. 
     As Comparative example 1 in relation to this example, the display unit was fabricated in a manner similar to this example, except that the electron hole transport layer  14 A and the light emitting layer  14 B were formed by ink jet printing method. When measuring film thickness distribution of the electron hole transport layer  14 A and the light emitting layer  14 B for the obtained display unit, the resulting value was high, i.e. about 10%. 
     As Comparative example 2 in relation to this example, a display unit having an organic light emitting device shown in  FIG. 1  was fabricated. This display unit was fabricated in a manner similar to this example, except that an electron hole transport layer  113 A and a light emitting layer  113 B were formed by ink jet printing method, a transparent electrode  112  was made of ITO, and a metal electrode  114  had a laminated structure of a calcium layer and an aluminum layer. 
     Images of the obtained display units of Example 1 and Comparative example 1 were visually checked. In this Example 1, images with sufficient high definition and excellent color reproducibility were obtained. However, in Comparative example 1, irregular color occurred and sufficient images could not be obtained. 
     Further, light emitting spectrums of the organic light emitting devices were measured regarding display units of Example 1 and Comparative example 2. The results are shown in  FIG. 15 . As evidenced by  FIG. 15 , in Example 1, lights in wavelengths around wavelength λ of lights which were desired to be extracted were extracted by multiple reflection in the resonator structure, half-value widths of spectrums of respective colors became narrow, and color purity was improved. Meanwhile, in Comparative example 2, spectrum widths were wide, and peak wavelengths were shifted. 
     Regarding the obtained display units of Example 1 and Comparative example 2, chromaticity coordinates (x, y) of three primary colors (red, green and blue) of the organic light emitting devices were measured. As shown in  FIG. 16 , in Example 1, a coordinate of red was (0.633, 0.333), a coordinate of green was (0.330, 0.630), and a coordinate of blue was (0.157, 0.110). In Comparative example 2, a coordinate of red was (0.681, 0.317), a coordinate of green was (0.400, 0.575), and a coordinate of blue was (0.157, 0.208). In  FIG. 16 , chromaticity coordinates of three primary colors in NTSC (National Television System Committee) (red: (0.67, 0.33), green: (0.21, 0.71), and blue: (0.14, 0.08)) are also shown. As evidenced by  FIG. 16 , the chromaticity coordinates in Example 1 were closer to the chromaticity coordinates of three primary colors in NTSC than the coordinates in Comparative example 2 were, and chromaticity of green and blue was particularly improved in Example 1. 
     That is, it was found that when the electron hole transport layer  14 A and the light emitting layer  14 B were formed by transfer, film thickness distribution could be reduced; and when construction was made to have the resonator structure, image definition and color reproducibility could be improved. 
     Example 2 
     A display unit was fabricated in a manner similar to Example 1, except that the electron hole transport layer  14 A was made of polyaniline. When light emitting spectrums and chromaticity coordinates of three primary colors were measured, results similar to those in Example 1 were obtained. 
     While the invention has been described with reference to the embodiment and examples, the invention is not limited to the foregoing embodiment and examples, and various modifications may be made. For example, materials, thicknesses, deposition methods, and deposition conditions for each layer are not limited to those described in the foregoing embodiment and the foregoing examples, and other materials, thicknesses, deposition methods, and deposition conditions can be applied. For example, though in the foregoing embodiment and the foregoing examples, the case wherein the organic layer  14  is made of a high molecular weight material has been described, the invention can be applied to a case using an oligomer material having a molecular mass of 1,000 to 10,000, or a case using a low molecular weight material having a molecular mass of 1,000 or less. However, when the material having a high molecular mass is used, more significant effect can be obtained. 
     Further, for example, in the foregoing embodiment and the foregoing examples, the case wherein the organic layer  14  has a two-layer structure of the electron hole transport layer  14 A and the light emitting layer  14 B has been described. However, the organic layer  14  can have other structure such as a single layer structure of the light emitting layer only, a two-layer structure of the light emitting layer and the electron transport layer, and a three-layer structure of the electron transport layer, the light emitting layer, and the electron transport layer. 
     Further, in the foregoing embodiment and the foregoing examples, the case wherein both the electron hole transport layer  14 A and the light emitting layer  14 B are formed by transfer has been described. However, when at least part of the organic layer  14  is manufactured by this method, effects can be obtained. The same is equally true of the case wherein only the light emitting layer is provided, or the case wherein a layer other than the electron hole transport layer  14 A and the light emitting layer  14 B is provided as mentioned above. 
     In addition, in the foregoing embodiment and the foregoing examples, though the case wherein the resonator structure which resonates the lights generated in the light emitting layer  14 B between the first end P 1  and the second end P 2  is provided has been described, it is possible that the resonator structure is not provided. However, since control of the film thickness becomes particularly important when the foregoing resonator structure is provided, significant effect can be obtained by the invention. 
     Further, in the foregoing embodiment and the foregoing examples, the case wherein the organic layer  14  including the light emitting layer  14 B between the first electrode  13  and the second electrode  15  is provided has been described. However, the invention can be applied to the case wherein construction is made of other material. 
     Further, for example, in the foregoing embodiment and the foregoing examples, the case wherein the first electrode  13  is set to an anode and the second electrode  15  is set to a cathode has been described. However, the anode and the cathode can be reversed, that is, the first electrode  13  can be set to a cathode and the second electrode  15  can be set to an anode. 
     Further, for example, in the foregoing embodiment and the foregoing examples, the case wherein the first electrode  13 , the organic layer  14 , and the second electrode  15  are sequentially layered on the driving substrate  11  from the driving substrate  11  side, and lights are extracted from the sealing panel  20  side has been described. However, the lamination order can be reversed, that is, the second electrode  15 , the organic layer  14 , the first electrode  13  are sequentially layered on the driving substrate  11  from the driving substrate  11  side, and lights can be extracted from the driving substrate  11  side. Further, it is possible that the first electrode  13  is set to a cathode and the second electrode  15  is set to an anode, and the second electrode  15 , the organic layer  14 , and the first electrode  13  are sequentially layered on the driving substrate  11  from the driving substrate  11  side, and lights are extracted from the driving substrate  11  side. However, it is preferable that the first electrode  13 , the organic layer  14 , and the second electrode  15  are sequentially layered from the driving substrate  11  side and lights are extracted from the second electrode  15  side, rather than that lights are extracted from the driving substrate  11  side wherein a structure part such as TFT (thin film transistor) or the like is formed, since opening ratio can be raised and high luminance and high resolution can be obtained. Further, extracting lights from the second electrode  15  side as mentioned above is preferable since excellent color purity can be also realized by introducing the resonator structure. 
     Further, in the foregoing embodiment and the foregoing examples, descriptions have been made with reference to the concrete construction of the organic light emitting device  12 . However, it is not necessary to provide all layers, and other layer can be provided additionally. For example, it is possible that a thin film layer for injecting electron holes made of chromic oxide (III) (Cr 2 O 3 ), ITO and the like can be provided between the first electrode  13  and the organic layer  14 . It is also possible that the organic light emitting device  12  is covered with a protective film composed of a transparent dielectric, and the adhesive layer  30  is formed on the protective film. This protective film has, for example, a thickness of 500 nm to 1,000 nm, and can be made of silicon oxide (SiO 2 ), silicon nitride (SiN) and the like. Further, for example, it is possible that the first electrode  13  has a two-layer structure wherein a transparent conductive film is layered on a reflective film such as a dielectric multilayer film or aluminum. In this case, an end face of the reflective film on the light emitting layer side constructs an end of a resonance part, and the transparent conductive film constructs part of a resonance part. 
     Further, in the foregoing embodiment and the foregoing examples, the case having a structure wherein the semi-transparent electrode  15 A and the transparent electrode  15 B of the second electrode  15  are layered from the first electrode  13  side has been described. However, the second electrode  15  can be comprised of only the semi-transparent electrode. 
     Further, in the foregoing embodiment and the foregoing examples, it is possible that a resonator structure wherein the semi-transparent electrode  15 A is used as one end, the other end is located on the transparent electrode  15 B on the side opposite to the semi-transparent electrode  15 A, and the transparent electrode  15 B is used as a resonance part is formed. Further, under the condition of providing such a resonator structure, it is preferable that the organic light emitting device  12  is covered with a protective film, and this protective film is made of a material having refractive index nearly equal to that of the material for the transparent electrode  15 B, since the protective film can be part of the resonance part. 
     Further, the invention can be applied to the case wherein the second electrode  15  is composed of only the transparent electrode  15 B, reflectance of an end face of this transparent electrode  15 B on the opposite side of the organic layer  13  is set to large, and a resonator structure in which an end face of the first electrode  13  on the light emitting layer  14 B side is the first end and an end face of the transparent electrode  15 B on the opposite side of the organic layer  14  is the second end is constructed. For example, it is possible that the transparent electrode  15 B is contacted to atmospheric layer, reflectance of an interface between the transparent electrode  15 B and the atmospheric layer is raised, and this interface is set to the second end. Further, it is possible that reflectance of an interface between the transparent electrode  15 B and the adhesive layer  30  is raised and this interface is set to the second end. Further, it is possible that the organic light emitting device  12  is covered with a protective film, reflectance of the interface between the transparent electrode  15 B and this protective film is raised, and this interface is set to the second end. 
     Further, in the foregoing embodiment and the foregoing examples, the case wherein one organic light emitting device  12  has the red light emitting layer  14 BR, the green light emitting layer  14 BG, and the blue light emitting layer  14 BB has been described. However, in the invention, as shown in  FIG. 17 , it is possible that an organic light emitting device  80 R having a red light emitting layer  81 R, an organic light emitting device  80 G having a green light emitting layer  81 G, and an organic light emitting device  80 B having a blue light emitting layer  81 B are separately arranged on the driving substrate  11 . 
     Further, in the foregoing embodiment and the foregoing examples, the case of the full color display unit has been described. However, the invention can be applied to a unicolor display unit. 
     As described above, according to the light emitting device of the invention and the display unit of the invention, at least part of the layer including the light emitting layer is formed by transferring the raw solution, and then removing the solvent. Therefore, film thickness distribution can be reduced. Consequently, occurrence of irregular color can be prevented, and images with high definition and excellent color reproducibility can be obtained. 
     Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.