JP2009043576A - Color organic el display and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: if a non-luminous layer is inserted in order to make a carrier stay, a manufacturing process becomes complicated, and since a carrier blocking layer which blocks the flow of a current is inserted in a region where the current flows, a driving voltage rises, and luminous efficiency of an organic EL element with respect to drive power is not necessarily improved. <P>SOLUTION: A red light-emitting layer 215 is held between a blue light-emitting layer 216 and a green light-emitting layer 214. If the driving voltage is impressed under this condition, electrons e<SP>-</SP>are accumulated on the interface between the blue light-emitting layer 216 and the red light-emitting layer 215, and holes h<SP>+</SP>are accumulated on the interface between the green light-emitting layer 214 and the red light-emitting layer 215. Since the electrons e<SP>-</SP>are accumulated on the interface between the blue light-emitting layer 216 and the red light-emitting layer 215, the hole h<SP>+</SP>injected from the blue light-emitting layer 216 side is recombined on the interface between the blue light-emitting layer 216 and the red light-emitting layer 215 to emit light. Therefore, the EL display can be made to emit light with blue luminous intensity and red luminous intensity well balanced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a color organic EL display and an electronic apparatus.

As a color organic EL display, white light including three primary colors of R, G, B (R (red), G (green), B (blue)) is emitted, and full color display is performed using color filters of the R, G, B primary colors. A structure for performing is known. Here, as a technique for emitting white light, a structure in which a plurality of light emitting layers corresponding to the three primary colors R, G, and B are stacked and white light is obtained by superimposing light from the respective light emitting layers is known. ing.
A display having a good color balance can be obtained by emitting light from the plurality of light emitting layers in a well-balanced manner. For this reason, technical development has been carried out so that the light intensity of the organic EL elements constituting the color organic EL display can emit light in a balanced manner for each color. For example, as shown in Patent Document 1 and Patent Document 2, a technique is known in which a carrier block layer for generating carrier retention is inserted to improve the luminous efficiency with respect to the amount of injected carriers, that is, current intensity. ing.

Japanese Patent Laid-Open No. 11-204259 JP 2007-12946 A

  When the techniques used in Patent Document 1 and Patent Document 2 are used, a non-light-emitting layer is inserted to retain the carrier, so that the manufacturing process becomes complicated. In addition, since a carrier block layer that inhibits the flow of current is inserted in a region where current flows, the drive voltage rises, and there is a problem that the light emission efficiency of the organic EL element with respect to drive power does not necessarily improve.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A color organic EL display according to this application example is sandwiched between a first light emitting layer, a second light emitting layer, the first light emitting layer, and the second light emitting layer. And a third light emitting layer having a high energy level of HOMO (highest occupied molecular orbital) and a low energy level of LUMO (lowest unoccupied molecular orbital) as compared with the second light emitting layer. To do.

  According to this configuration, when a current is passed through the organic EL element constituting the color organic EL display, electrons are accumulated at the interface between the first light emitting layer and the third light emitting layer, and the second light emitting layer and the third light emitting layer are emitted. Holes accumulate at the interface with the layer. Therefore, the injected carriers are prevented from flowing out and accumulated at both interfaces. Therefore, light emission caused by carrier recombination can be performed with higher efficiency than in the case where the carrier outflow of the conventional technique is not suppressed. In addition, since it is not necessary to insert a non-light emitting carrier block layer, an increase in power consumption accompanying an increase in driving voltage can be suppressed as compared with the prior art.

  Application Example 2 In the color organic EL display according to the application example described above, the energy level of the third light emitting layer is higher than the energy level of the first light emitting layer and the second light emitting layer. The potential difference is 0.5 eV or less, and the energy level difference in LUMO is 0.5 eV or less.

  According to this configuration, an increase in voltage due to electrons exceeding the second light emitting layer from the third light emitting layer and holes exceeding the first light emitting layer from the third light emitting layer can be suppressed. Therefore, it is possible to suppress an increase in drive voltage applied to the organic EL elements constituting the color organic EL display.

  Application Example 3 An electronic device according to this application example includes the above-described color organic EL display.

  According to this configuration, it is possible to obtain an electronic device that can reduce power consumption as compared with the related art.

(Configuration of color organic EL display)
Hereinafter, the color organic EL display according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a wiring structure of the color organic EL display of this embodiment. The color organic EL display 1 uses a thin film transistor (hereinafter referred to as TFT) as a switching element. For example, in an active matrix system using TFTs 122 and 123, a plurality of scanning lines 101, a plurality of signal lines 102 extending in a direction intersecting with each scanning line 101, and a plurality of signal lines 102 extending in parallel with each signal line 102 are used. A sub-pixel 40 is provided in the vicinity of each intersection of the scanning line 101 and the signal line 102 while having a wiring configuration including the power supply line 103. The sub-pixel 40 includes a color filter 200 (R, G, B) (R (red), G (green), B (blue)) described later.

  A data line driving circuit 100 including a shift register, a level shifter, a video line, and an analog switch is connected to the signal line 102. Further, a scanning line driving circuit 80 including a shift register and a level shifter is connected to the scanning line 101.

  Each of the sub-pixels 40 includes a switching TFT 122 in which a scanning signal is supplied to the gate electrode via the scanning line 101, and a storage capacitor that holds a pixel signal shared with the signal line 102 via the switching TFT 122. 113. When a pixel signal held by the holding capacitor 113 is electrically connected to the power supply line 103 via the TFT 123 for driving supplied to the gate electrode and the TFT 123, a drive current is given from the power supply line 103. An organic EL element 17 (R, G, B) sandwiched between the pixel electrode 23 and the counter electrode 50 facing the pixel electrode 23 is provided.

  Next, a specific aspect of the color organic EL display 1 of the present embodiment will be described with reference to FIG. Here, FIG. 2 is a plan view schematically showing the configuration of the color organic EL display 1.

As shown in FIG. 2, in the actual display area 4 on the substrate 20A, subpixels 40 provided corresponding to R, G, and B are regularly arranged in a matrix.
Here, the substrate 20A includes a substrate body 20 and a cover layer 21 (see FIG. 4 to be described later) provided on the substrate body 20 on which an interlayer insulating layer or the like is disposed.
The sub-pixels 40 (R, G, B) of R, G, and B colors constitute a display unit pixel 41 as one basic unit. In addition, each of the sub-pixels 40 (R, G, B) has an organic EL element 17 (R, G, B) corresponding to the light emission of each of R, G, B in accordance with the operation of the TFT 122, TFT 123 (see FIG. 1). B) (see FIG. 1).

  Although details will be described later, in the present embodiment, the color filter 200 (corresponding to each organic EL element 17 (R, G, B) is caused to emit light from the organic EL element 17 (R, G, B) (see FIG. 1). R, G, B) (see FIG. 3 to be described later) is transmitted, so that R, G, B light emission can be obtained from each sub-pixel 40 (R, G, B). As a result, the display unit pixel 41 performs a full-color display by mixing R, G, and B emission colors.

  In the present embodiment, the pixel unit 3 (within the alternate long and short dash line in the figure) includes an actual display area 4 (within the alternate long and two short dashes line in the figure) and a dummy area 5 (one point around the actual display area 4). And a region between a chain line and a two-dot chain line). A scanning line driving circuit 80 is arranged so as to sandwich the actual display area 4.

  In addition, an inspection circuit 90 is disposed above the actual display area 4. The inspection circuit 90 is a circuit for inspecting the operating state of the color organic EL display 1, and includes, for example, inspection information output means (not shown) for outputting the inspection result to the outside, and is in the middle of manufacturing or shipping. It is configured so that the quality and defect inspection of the organic EL display can be performed.

(Organic EL device)
Next, a cross-sectional structure of the color organic EL display 1 will be described with reference to FIGS. FIG. 3 is a schematic cross-sectional view of the organic EL elements 17 (R, G, B) constituting the color organic EL display 1 (see FIG. 1). Corresponding color filters 200 (R, G, B) are given to the organic EL elements 17 (R, G, B), respectively. For convenience of explanation, the upper side of the drawing is defined as “upper” and will be described below.

  FIG. 4 is a schematic cross-sectional view showing a laminated structure constituting the organic EL element 17 corresponding to one color. The organic EL element 17 described below is formed on a substrate 20A including a cover layer 21 including, for example, a color filter 200 (R, G, B) and a substrate body 20 capable of transmitting light. It has a so-called bottom emission configuration that emits light to the side.

  An optically transparent anode 219 made of ITO is disposed on the substrate 20A. As the layer thickness of the anode 219, for example, a value of about 100 nm is used. On the anode 219, a hole injection layer 218 made of copper phthalocyanine (CuPc) is disposed. The layer thickness of the hole injection layer 218 is, for example, about 10 nm. On the hole injection layer 218, a hole transport layer 217 using 4,4′-bis [N- (1-naphthyl)]-N-phenylamino] biphenyl (α-NPD) is disposed. The The layer thickness of the hole transport layer 217 is, for example, about 40 nm.

  On the hole transport layer 217, BH215 + BD102 (both manufactured by Idemitsu Kosan Co., Ltd.) is arranged as a blue light emitting layer 216 as a first light emitting layer. The layer thickness of the blue light emitting layer 216 is, for example, about 10 nm. Then, on the blue light emitting layer 216, red as a third light emitting layer using an aluminum quinolinol complex (Alq3) + rubrene (5,6,11,12-tetraphenyltetracene) + dicyanomethylenepyran derivative (DCM2). A light emitting layer 215 is disposed. The layer thickness of the red light emitting layer 215 is, for example, about 5 nm. On the red light emitting layer 215, BH215 + GD206 (both manufactured by Idemitsu Kosan Co., Ltd.) is arranged as a green light emitting layer 214 as a second light emitting layer. The thickness of the green light emitting layer 214 is, for example, about 10 nm.

  On the green light emitting layer 214, an electron transport layer 213 using Alq3 is disposed. The layer thickness of the electron transport layer 213 is, for example, about 20 nm. On the electron transport layer 213, an electron injection layer 212 using lithium fluoride LiF (LiF) is disposed. The layer thickness of the electron injection layer 212 is, for example, about 1 nm. A cathode 211 made of aluminum (Al) is formed on the electron injection layer 212, and the layer thickness is, for example, about 100 nm.

  FIG. 5 is an energy diagram of the blue light-emitting layer 216, the red light-emitting layer 215, and the green light-emitting layer 214 when no driving voltage is applied. The red light emitting layer 215 is sandwiched between the blue light emitting layer 216 and the green light emitting layer 214. The red light emitting layer 215 has a smaller energy gap between HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) than the blue light emitting layer 216 and the green light emitting layer 214.

FIG. 6 is an energy diagram showing the blue light emitting layer 216, the red light emitting layer 215, and the green light emitting layer 214 when a driving voltage is applied. When a driving voltage is applied in this state, electrons e ⁻ are accumulated at the interface between the blue light emitting layer 216 and the red light emitting layer 215, and holes h ⁺ are accumulated at the interface between the green light emitting layer 214 and the red light emitting layer 215. Is done. Electrons e ⁻ are accumulated at the interface between the blue light-emitting layer 216 and the red light-emitting layer 215, so that holes h ⁺ injected from the blue light-emitting layer 216 side are regenerated at the interface between the blue light-emitting layer 216 and the red light-emitting layer 215. Combines and emits light. Therefore, the blue light emission intensity and the red light emission intensity can be emitted with a good balance.

Similarly, holes h ⁺ are accumulated at the interface between the green light-emitting layer 214 and the red light-emitting layer 215, so that electrons e ⁻ injected from the green light-emitting layer 214 side are emitted from the green light-emitting layer 214 and the red light-emitting layer 215. Recombines at the interface and emits light. Therefore, green light emission and red light emission can be emitted with a good intensity balance. That is, all the colors of R, G, and B can be emitted with a good balance. When the balance of R, G, and B is poor, for example, when the emission intensity of G is weak, R and B are emitted strongly, and the G component included in the emission components of R and B is extracted by a color filter and corrected. Is required. Therefore, the lifetime of the blue light emitting layer 216 and the red light emitting layer 215 constituting R and B is shortened, causing early deterioration.

  According to this embodiment, R, G, and B colors can be emitted with a good balance. Therefore, it is not necessary to forcibly increase the light emission intensity of the blue light emitting layer 216, the red light emitting layer 215, and the green light emitting layer 214, and the life of each light emitting layer can be extended.

In the light emitting part in which the electrons e ⁻ are accumulated, the light emission intensity is governed by the amount of holes h ⁺ injected. In the light emitting part in which holes h ⁺ are accumulated, the light emission intensity is governed by the injection amount of electrons e ⁻ . Therefore, the light intensity has a high correlation with the drive current intensity, so that the light intensity can be easily controlled.

  Further, the position variation of the light emitting part is suppressed (limited to the interface). Therefore, even when the luminance is varied, it is possible to suppress variations in color purity and hue, and it is possible to provide the organic EL element 17 having excellent color reproducibility.

  In this embodiment, the LUMO side energy difference is suppressed to 0.1 eV, and the HOMO side energy difference is suppressed to 0.2 eV. Therefore, an electron and hole accumulation region can be formed without hindering carrier transmission. By suppressing this energy difference to 0.5 eV or less, an increase in driving voltage can be suppressed. The light intensity is substantially proportional to the drive current. That is, by suppressing the energy difference between the LUMO side and the HOMO side to 0.5 eV or less, it is possible to provide the organic EL element 17 that is excellent in terms of power consumption.

(Modification)
In the organic EL element 17 described above, the blue light emitting layer 216 is provided on the anode side, the green light emitting layer 214 is provided on the cathode side, and the red light emitting layer 215 is sandwiched. Alternatively, a structure in which the blue light emitting layer 216 is provided on the cathode side and the red light emitting layer 215 is sandwiched may be used.
In the present embodiment, an example in which ITO is used as the anode 219 has been described. However, the anode 219 can be made of a conductive transparent material, such as SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO. These oxides, Au, Pt, Ag, Cu, alloys containing these, and conductive resin materials such as polythiophene and polypyrrole can be used.

  Moreover, although the example which uses CuPc as the hole injection layer 218 was demonstrated, it replaced with CuPc and this is 4,4 ', 4' '-tris (N, N-phenyl-3-methylphenylamino) triphenyl. An amine (m-MTDATA) or the like can be used.

  In addition, an example in which 4,4′-bis [N- (1-naphthyl)]-N-phenylamino] biphenyl (α-NPD) is used as the hole transport layer 217 has been described. Examples of the transport material include 1,1-bis (4-di-para-triaminophenyl) cyclohexane, 1,1′-bis (4-di-para-tolylaminophenyl) -4-phenyl-cyclohexane. Arylcycloalkane compounds such as 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetraphenyl-1,1′-biphenyl-4,4′-diamine, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (TPD1), N, N′-diphenyl-N, N′-bis (3-methoxyfeh ) -1,1′-biphenyl-4,4′-diamine (TPD2), N, N, N ′, N′-tetrakis (4-methoxyphenyl) -1,1′-biphenyl-4,4′- Arylamine compounds such as diamine (TPD3), TPTE, 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine (1-TNATA), N, N, N ′, N′— Tetraphenyl-para-phenylenediamine, N, N, N ′, N′-tetra (para-tolyl) -para-phenylenediamine, N, N, N ′, N′-tetra (meta-tolyl) -meta-phenylene Phenylenediamine compounds such as diamine (PDA), carbazole, N-isopropylcarbazole, carbazole compounds such as N-phenylcarbazole, stilbene, 4-di- Stilbene compounds such as para-tolylaminostilbene, oxazole compounds such as OxZ, triphenylmethane compounds such as triphenylmethane and m-MTDATA, 1-phenyl-3- (para-dimethylaminophenyl) pyrazoline Pyrazoline compounds such as benzine (cyclohexadiene) compounds, triazole compounds such as triazole, imidazole compounds such as imidazole, 1,3,4-oxadiazole, 2,5-di (4-dimethyl) Oxadiazole compounds such as aminophenyl) -1,3,4, -oxadiazole, anthracene, anthracene compounds such as 9- (4-diethylaminostyryl) anthracene, fluorenone, 2,4,7,- Trinitro-9-fluorenone, 2,7 Fluorenone compounds such as bis (2-hydroxy-3- (2-chlorophenylcarbamoyl) -1-naphthylazo) fluorenone, aniline compounds such as polyaniline, silane compounds, 1,4-dithioketo-3,6-diphenyl A pyrrole compound such as pyrrolo- (3,4-c) pyrrolopyrrole, a fluorene compound such as florene, a porphyrin, a porphyrin compound such as metal tetraphenylporphyrin, a quinacridone compound such as quinacridone, a phthalocyanine, Metals such as copper phthalocyanine, tetra (t-butyl) copper phthalocyanine, iron phthalocyanine or metal-free phthalocyanine compounds, copper naphthalocyanine, vanadyl naphthalocyanine, monochlorogallium naphthalocyanine or Metal naphthalocyanine compounds, N, N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine, benzidine compounds such as N, N, N ′, N′-tetraphenylbenzidine, etc. Can be used. In the case of using a low molecular material, the hole transport layer 217 can be formed by using, for example, an evaporation method.

  On the other hand, examples of the polymer-based hole transport material include those having an arylamine skeleton such as polyarylamine, those having a fluorene skeleton such as a fluorene-bithiophene copolymer, and fluorene-arylamine copolymers. Having both an arylamine skeleton and a fluorene skeleton, such as poly (N-vinylcarbazole), polyvinylpyrene, polyvinylanthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly (p-phenylenevinylene), polytinylene Vinylene, pyrene formaldehyde resin, ethylcarbazole formaldehyde resin or a derivative thereof can be used. When a high molecular weight hole transport material is used, the hole transport layer 217 can be formed by a spin coating method or an ink jet method.

  In addition, examples of using BH215 (made by Idemitsu Kosan) + BD102 (made by Idemitsu Kosan), Alq3 + rubrene + DCM2, BH215 (made by Idemitsu Kosan) + GD206 (made by Idemitsu Kosan) as the blue light emitting layer 216, the red light emitting layer 215, and the green light emitting layer 214 Explains. In this case, instead of these light emitting materials, for example, as low molecular weight light emitting materials, benzene compounds such as distyrylbenzene (DSB) and diaminodistyrylbenzene (DADSB), naphthalene compounds such as naphthalene and nile red are used. Phenanthrene compounds such as phenanthrene, chrysene, chrysene compounds such as 6-nitrochrysene, perylene, N, N′-bis (2,5-di-t-butylphenyl) -3,4,9,10 Perylene compounds such as perylene-di-carboximide (BPPC), coronene compounds such as coronene, anthracene compounds such as anthracene and bisstyrylanthracene, pyrene compounds such as pyrene, 4- (di- Cyanomethylene) -2-methyl-6- (para-dimethylaminostyryl) Pyran compounds such as -4H-pyran (DCM), acridine compounds such as acridine, stilbene compounds such as stilbene, thiophene compounds such as 2,5-dibenzoxazole thiophene, benzos such as benzoxazole Oxazole compounds, benzimidazole compounds such as benzimidazole, benzothiazole compounds such as 2,2 ′-(para-phenylenedivinylene) -bisbenzothiazole, bistyryl (1,4-diphenyl-1,3- Butadiene), butadiene compounds such as tetraphenylbutadiene, naphthalimide compounds such as naphthalimide, coumarin compounds such as coumarin, perinone compounds such as perinone, oxadiazole compounds such as oxadiazole , Rudazine compounds, cyclopentadiene compounds such as 1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (PPCP), quinacridone compounds such as quinacridone and quinacridone red, pyrrolopyridine, and thiadia Pyridine compounds such as zolopyridine, spiro compounds such as 2,2 ′, 7,7′-tetraphenyl-9,9′-spirobifluorene, metals such as phthalocyanine (H2Pc), copper phthalocyanine or non-metal Phthalocyanine compounds, fluorene compounds such as fluorene, tris (4-methyl-8quinolinolate) aluminum (III) (Almq3), 8-hydroxyquinoline zinc (Znq2), (1,10-phenanthroline) -tris- ( 4,4,4-trifluoro-1- (2-thieni ) -Butane-1,3-dionate) europium (III) (Eu (TTA) 3 (phen)), factory (2-phenylpyridine) iridium (Ir (ppy) 3), 2, 3, 7, 8, Various metal complexes such as 12, 13, 17, 18-octaethyl-21H, 23H-porphine platinum (II) can be used.

  Examples of the polymer luminescent material include polyacetylene compounds such as trans-polyacetylene, cis-polyacetylene, poly (di-phenylacetylene) (PDPA), poly (alkyl, phenylacetylene) (PAPA), and poly ( Para-phenvinylene) (PPV), poly (2,5-dialkoxy-para-phenylenevinylene) (RO-PPV), cyano-substituted-poly (para-phenvinylene) (CN-PPV), poly (2- Polyparaphenylene vinylene compounds such as dimethyloctylsilyl-para-phenylene vinylene (DMOS-PPV), poly (2-methoxy, 5- (2′-ethylhexoxy) -para-phenylene vinylene) (MEH-PPV), Poly (3-alkylthiophene) (PAT), poly (oxypropioxy) Polythiophene-based compounds such as N) triol (POPT), poly (9,9-dialkylfluorene) (PDAF), α, ω-bis [N, N′-di (methylphenyl) aminophenyl] -poly [9, 9-bis (2-ethylhexyl) fluorene-2,7-diyl] (PF2 / 6am4), poly (9,9-dioctyl-2,7-divinylenefluorenyl-ortho-co (anthracene-9,10-) Polyfluorene compounds such as diyl), poly (para-phenylene) (PPP), polyparaphenylene compounds such as poly (1,5-dialkoxy-para-phenylene) (RO-PPP), poly (N -Polycarbazole compounds such as (vinylcarbazole) (PVK), poly (methylphenylsilane) (PMPS), poly (naphthylphenylsilane) Down) (PnPs), it is possible to use a polysilane compound such as poly (biphenylyl phenyl silane) (pBPS) or the like.

  In addition, an example in which Alq3 is used as the electron transporting layer 213 has been described, which is 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene (TPQ1), 1 , 3,5-tris [{3- (4-t-butylphenyl) -6-trisfluoromethyl} quinoxalin-2-yl] benzene (TPQ2), a benzene compound (starburst compound), naphthalene Naphthalene compounds such as phenanthrene, chrysene compounds such as chrysene, perylene compounds such as perylene, anthracene compounds such as anthracene, pyrene compounds such as pyrene, acridine Acridine compounds, stilbene compounds such as stilbene, BBOT Thiophene compounds, butadiene compounds such as butadiene, coumarin compounds such as coumarin, quinoline compounds such as quinoline, bistyryl compounds such as bistyryl, pyrazine compounds such as pyrazine and distyrylpyrazine, quinoxaline Quinoxaline compounds such as benzoquinone, benzoquinone compounds such as 2,5-diphenyl-para-benzoquinone, naphthoquinone compounds such as naphthoquinone, anthraquinone compounds such as anthraquinone, oxadiazole, 2- (4- Biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (PBD), oxadiazole compounds such as BMD, BND, BDD, BAPD, triazole, 3,4,5 -Triphenyl-1,2, -Triazole compounds such as triazole, oxazole compounds, anthrone compounds such as anthrone, fluorenones, fluorenone compounds such as 1,3,8-trinitro-fluorenone (TNF), diphenoquinones such as diphenoquinone and MBDQ Compounds, stilbene quinones, stilbene quinone compounds such as MBSQ, anthraquinodimethane compounds, thiopyrandioxide compounds, fluorenylidene methane compounds, diphenyldicyanoethylene compounds, fluorene compounds such as fluorene, phthalocyanines Various metal complexes such as metal or metal-free phthalocyanine compounds such as copper phthalocyanine and iron phthalocyanine, and complexes having benzoxazole and benzothiazole as a ligand can be used. Noh. Further, polymer materials such as oxadiazole polymer (polyoxadiazole) and triazole polymer (polytriazole) may be used.

In addition, although an example in which LiF is used as the electron injection layer 212 has been described, examples of the inorganic insulating material include alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, and alkalis. Examples thereof include metal halides and alkaline earth metal halides, and one or more of these can be used in combination. By forming the electron injection layer using these as main materials, the electron injection property can be further improved. Examples of the alkali metal chalcogenide include Li ₂ O, LiO, Na ₂ S, Na ₂ Se, and NaO. Examples of the alkaline earth metal chalcogenide include CaO, BaO, SrO, BeO, BaS, MgO, and CaSe. Examples of the alkali metal halide include CsF, NaF, KF, LiCl, KCl, and NaCl. Examples of the alkaline earth metal halide include CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ , and BeF ₂ .

  Moreover, as an inorganic semiconductor material, for example, an oxide containing at least one element of Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb, and Zn , Nitrides, oxynitrides, and the like, and one or more of these can be used in combination.

  In addition, examples of the organic material include 8-hydroxyquinoline, oxadiazole, or derivatives thereof (for example, metal chelate oxinoid compounds containing 8-hydroxyquinoline). Two or more types can be used in combination (for example, as a multi-layer laminate).

  Moreover, although the example which uses aluminum (Al) as the cathode 211 was demonstrated, this is Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Cs, Rb or And alloys containing these and Al, and at least one of them can be used.

(Example of mounting on electronic equipment)
Hereinafter, with reference to FIG. 7, an electronic apparatus including the above-described color organic EL display 1 will be described. FIG. 7A shows the configuration of a mobile personal computer including the color organic EL display 1. The personal computer 2000 includes a color organic EL display 1 and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. FIG. 7B shows a configuration of a mobile phone provided with the color organic EL display 1. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and a color organic EL display 1 as a display unit. By operating the scroll button 3002, the screen displayed on the color organic EL display 1 is scrolled. FIG. 7C shows the configuration of a portable information terminal (PDA) to which the color organic EL display 1 is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the color organic EL display 1 as a display unit. When the power switch 4002 or the operation button 4001 is operated, various kinds of information such as an address book and a schedule book are displayed on the color organic EL display 1.

  The electronic devices on which the color organic EL display 1 is mounted include those shown in FIG. 7, a digital still camera, a liquid crystal television, a viewfinder type, a monitor direct-view type video tape recorder, a car navigation device, a pager, and an electronic notebook. , Calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. And the color organic EL display 1 mentioned above is applicable as a display part of these various electronic devices.

The schematic diagram which shows the wiring structure of a color organic electroluminescent display. The top view which shows typically the structure of a color organic EL display. The schematic cross section of the organic EL element which comprises a color organic EL display. The schematic cross section which shows the laminated structure of the light emitting layer which comprises one organic EL element. The energy diagram of the blue light emitting layer, the red light emitting layer, and the green light emitting layer when no driving voltage is applied. The energy diagram which a blue light emitting layer, a red light emitting layer, and a green light emitting layer show at the time of a drive voltage application. (A)-(c) The perspective view of the electronic device carrying a color organic EL display.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color organic EL display, 3 ... Pixel part, 4 ... Actual display area, 5 ... Dummy area, 17 ... Organic EL element, 20 ... Substrate, 20A ... Substrate, 21 ... Cover layer, 23 ... Pixel electrode, 40 ... Sub Pixels 41... Display unit pixels 80. Scanning line driving circuit 90 90 Inspection circuit 100 Data line driving circuit 101 Scanning line 102 Signal line 103 Power supply line 113 Retention capacitor 122 TFT , 123 ... TFT, 200 ... color filter, 211 ... cathode, 212 ... electron injection layer, 213 ... electron transport layer, 214 ... green light emission layer, 215 ... red light emission layer, 216 ... blue light emission layer, 217 ... hole transport layer 218 ... Hole injection layer, 219 ... Anode, 2000 ... Personal computer, 2001 ... Power switch, 2002 ... Keyboard, 2010 ... Main body, 3000 ... Mobile phone, 3 01 ... operation button, 3002 ... scroll button, 4000 ... portable information terminal, 4001 ... operation button, 4002 ... power switch, h ⁺ ... hole, e ^- ... electrons.

Claims (3)

A first light emitting layer;
A second light emitting layer;
It is sandwiched between the first light-emitting layer and the second light-emitting layer, and has a higher energy level of HOMO (highest occupied molecular orbital) and LUMO (lowest non-light-emitting layer) than the first light-emitting layer and the second light-emitting layer. And a third light-emitting layer having a low energy level of occupied molecular orbitals).   2. The color organic EL display according to claim 1, wherein an energy level of the third light emitting layer is different from an energy level of the first light emitting layer and the second light emitting layer in HOMO. A color organic EL display, wherein the energy level difference in LUMO is 0.5 eV or less.   An electronic apparatus comprising the color organic EL display according to claim 1.

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