JPWO2005004546A1 - Electroluminescent device and display device - Google Patents

Abstract

The electroluminescent device (10) includes a pair of positive electrodes (12) and a negative electrode (13) facing each other, and a single layer or a plurality of light emitting layers (14) formed between the pair of positive electrodes and negative electrodes. ), And at least one of the light emitting layers includes a phosphor layer (16) and a wide band gap semiconductor layer (15). The semiconductor layer or the phosphor layer constituting the light emitting layer may be a discontinuous layer in which a part of the layer is discontinuous.

Description

  The present invention relates to an electroluminescent element used for a flat light source and a flat display device.

A light emitting diode, an electroluminescent element (referred to as an EL element), or the like is used in a conventional light emitting device used for a flat light source or a flat display device.
A light-emitting diode is excellent in terms of high luminance and luminous efficiency, but needs to be formed on a compound semiconductor substrate, and it is difficult to increase the area of one semiconductor substrate. Further, in order to increase the size of the flat display device, it is necessary to arrange a large number of light emitting diodes two-dimensionally.
The structure of the EL element will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the configuration of the EL element. The EL element 50 has a cell structure in which a light emitting layer 54 is sandwiched between two electrodes 52 and 55. As shown in FIG. 5, an electrode 52, an insulating layer 53a, a light emitting layer 54, and an insulating layer 53b are formed on a substrate 51. The electrodes 55 are sequentially formed. The light emitting layer 54 is made of a phosphor such as ZnS, and has a thickness of 0.5 μm to 1 μm, for example. Further, an AC power source 56 is connected between the electrode 52 and the electrode 55 outside the EL element 50, and by applying a voltage between the electrode 52 and the electrode 55 by the AC power source 56, the EL element 50 is Emits light. The EL element 50 is not easily limited by the material of the substrate 51 and can have a large area using a single substrate.

However, in order to increase the size of the flat light emitting device using the above-described light emitting diode, a plurality of light emitting diodes are required, and there is a problem that the manufacturing cost increases in proportion to the number of elements.
In addition, the above-described planar light emitting device using the EL element has no problem in increasing the size, and is superior to other displays in terms of thinning, high speed response, wide viewing angle, and high contrast. However, the luminous efficiency and luminance are low, and the lifetime is as short as about 10,000 hours. In addition, it is usually necessary to apply an alternating voltage of several hundred volts at a high frequency of several kHz, and it is difficult to drive an active matrix method using a general-purpose thin film transistor, and there is a problem that the driving circuit is expensive.
In addition, inorganic phosphors such as CaS: Eu and Y ₂ O ₃ : Mn that are generally used in EL devices have Mn contained in crystals of inorganic compounds such as sulfides such as CaS and oxides such as Y ₂ O _3. A luminescent center such as a transition metal such as Eu or a rare earth metal such as Eu is added. Therefore, although light emission by ultraviolet light excitation is realized, on the other hand, even if an electric field is applied, electrons do not easily penetrate into the inorganic phosphor and charging repulsion is strong, so that high-speed electrons accelerated by a high electric field collide with inorganic fluorescence. It is necessary to excite the emission center in the body. For this reason, it is usually necessary to apply an AC voltage of several hundred volts at a high frequency of several kHz, and there is a problem that the drive circuit becomes expensive.
The present invention has been made in view of such a problem, and is a light-emitting element that can be driven (low power consumption) at a low voltage of several volts to several tens of volts, has high luminous efficiency, and can have a large area at low cost. The purpose is to provide.
An electroluminescent device according to the present invention includes a pair of electrodes facing each other,
An electroluminescent device comprising a single layer or a plurality of layers of light emitting layers formed between the pair of electrodes,
At least one of the light emitting layers includes a phosphor and a wide band gap semiconductor.
The light emitting layer may have a laminated structure of a phosphor layer and a wide band gap semiconductor layer.
Furthermore, at least one transparent conductor layer sandwiched between the pair of electrodes may be further provided. The transparent conductor layer may be a discontinuous layer in which a part of the layer is discontinuous. Or a continuous layer may be sufficient.
Further, at least one of the phosphor layer and the semiconductor layer constituting the light emitting layer may be a discontinuous layer in which a part of the layer is discontinuous. In this case, when both the semiconductor layer and the phosphor layer are discontinuous layers, the semiconductor layer is a continuous layer and the phosphor layer is discontinuous. When the semiconductor layer is a discontinuous layer, the phosphor layer is a continuous layer. Or the semiconductor layer and the phosphor layer may be continuous layers.
Furthermore, the light emitting layer may have phosphor particles coated with a semiconductor having at least a part of the surface having a wide band gap.
Still further, the light emitting layer may have phosphor particles coated with a semiconductor having substantially the entire surface having a wide band gap.
Further, the phosphor layer may have a phosphor material in which at least a part of the surface is coated with a semiconductor having a wide band gap and dispersed in a matrix material.
Further, the light emitting layer may be one in which the phosphor particles coated with a semiconductor having substantially the entire surface having a wide band gap are dispersed in a matrix material.
The matrix material may be a transparent conductor.
Furthermore, it is preferable that the semiconductor included in the light emitting layer has a band gap that emits light in a shorter wavelength region than blue when an electric field is applied. As the semiconductor, a compound semiconductor having a band gap of 2.0 eV or more, more preferably 2.5 eV or more can be used. For example, a Group 13-Group 15 compound semiconductor, or a mixed crystal thereof, or a mixture thereof that may be partially segregated, a Group 12-Group 16 compound semiconductor, or a mixed crystal thereof, or Mixtures that may be partially segregated, Group 2 to Group 16 compound semiconductors, or mixed crystals thereof, or mixtures that may be partially segregated, Group 12 to Group Group 13-Group 16 compound semiconductor, or a mixed crystal thereof, or a mixture thereof that may be partially segregated, Group 11-Group 13-Group 16 compound semiconductor, or a mixed crystal thereof, or Mixtures that may be partially segregated, Group 12-Group 14-Group 15 compound semiconductors, or mixed crystals thereof, or mixtures that may be partially segregated A further preferred either of.
Further, in order to improve the flow of electrons in the light emitting layer, an electron transport layer such as an amorphous material such as a metal complex of 8-hydroxyquinoline such as Alq3 or BMB-2T of a thiophene compound is used. It is preferable to be provided between the electrodes.
In order to cause a normal EL element to emit light, it is necessary to cause high acceleration electrons to collide with a phosphor to excite an electron beam, and it is necessary to apply a high voltage of several hundred volts. On the other hand, in the electroluminescence device of the present invention, first, a semiconductor layer or a semiconductor coating layer having a low voltage and a large band gap emits light in an ultraviolet region having a wavelength of 300 to 350 nm to a blue-green region having a wavelength of 500 nm. More preferably, light is emitted from an ultraviolet region having a wavelength of 300 to 350 nm to a blue region of 400 nm band. The phosphor layer or phosphor particles are excited by the light and the entire light emitting layer emits light, so that high luminance and high luminous efficiency can be obtained. The electrons then flow to the adjacent transparent conductor layer and induce the next light emission. Since this light emission mechanism is repeated, the flow of electrons is maintained, and low voltage driving (low power consumption) and long life are realized.
Further, the pair of electrodes may be a positive electrode and a negative electrode. In this case, a DC voltage is applied between the pair of positive electrode and negative electrode. In addition, at least one of the semiconductor layers constituting the light emitting layer may be closer to the negative electrode than the phosphor layer.
The electroluminescent device according to the present invention may further include a thin film transistor connected to one of the pair of electrodes. In the electroluminescent element of the present invention, a thin film transistor can be used because the driving voltage is as low as several volts as described above.
A display device according to the present invention includes an electroluminescent element array in which the electroluminescent elements are two-dimensionally arranged;
A plurality of x electrodes extending parallel to each other in a first direction parallel to the surface of the electroluminescent element array;
A plurality of y-electrodes extending in parallel to a second direction orthogonal to the first direction and parallel to the surface of the electroluminescent element array;
The thin film transistor of the electroluminescent element array is connected to the x electrode and the y electrode, respectively.

The invention's effect

  As described above, according to the electroluminescent device of the present invention, a semiconductor having a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor is excited by the light of the short wavelength, and the entire light emitting layer emits light. Therefore, high brightness and high luminous efficiency can be obtained. Furthermore, since the matrix is made of a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. In addition, since the area can be easily increased, the cost can be reduced.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same components.
FIG. 1 is a cross-sectional view showing the structure of the electroluminescent element according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view showing the structure of the electroluminescent element according to the second embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the structure of the electroluminescent element according to Embodiment 3 of the present invention.
FIG. 4 is a cross-sectional view showing the structure of the electroluminescent element according to Embodiment 4 of the present invention.
FIG. 5 is a cross-sectional view showing the structure of a conventional electroluminescent device.
FIG. 6 is a perspective view of a light-emitting element according to Embodiment 5 of the present invention.
FIG. 7 is a schematic plan view of a display device using the light emitting element according to Embodiment 6 of the present invention.
FIG. 8 is a cross-sectional view showing the structure of the electroluminescent element according to the seventh embodiment of the present invention.
FIG. 9 is a cross-sectional view showing a cross-sectional structure of phosphor particles in which substantially the entire surface is covered with a semiconductor having a large band gap as another example of the seventh embodiment.
FIG. 10 is a cross-sectional view showing the configuration of the electroluminescent element according to Embodiment 8 of the present invention.
FIG. 11 is a perspective view of a light-emitting element according to Embodiment 9 of the present invention.
FIG. 12 is a schematic plan view of a display device using the light emitting element according to Embodiment 10 of the present invention.
FIG. 13 is a cross-sectional view showing the structure of the electroluminescent element according to the eleventh embodiment of the present invention.
FIG. 14 is a cross-sectional view showing the structure of the electroluminescent element according to the twelfth embodiment of the present invention.
FIG. 15 is a cross-sectional view showing the structure of the electroluminescent element according to the thirteenth embodiment of the present invention.

An electroluminescent element according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.
(Embodiment 1)
An electroluminescent element according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the configuration of the electroluminescent element 10 according to the first embodiment. The electroluminescent element 10 has a multi-layer structure, and includes a pair of positive electrodes 12 and negative electrodes 13 facing each other on a substrate 11. Further, a light emitting layer 14 composed of a semiconductor layer 15 and a phosphor layer 16 is repeatedly laminated between the positive electrode 12 and the negative electrode 13 via a transparent conductor layer 17. The semiconductor layer 15 and the phosphor layer 16 constituting the light emitting layer 14 are discontinuous layers, and a discontinuous portion between the respective light emitting layers 14 is filled with a transparent conductor layer 17. In FIG. 1, only two sets of light emitting layers 14 are illustrated, but the present invention is not limited to this, and may be one set or three or more sets. Moreover, the electroluminescent element 10 emits light by applying a low voltage of several volts to several tens of volts between the positive electrode 12 and the negative electrode 13 by a direct current power source. The positive electrode 12 is a transparent electrode, and light emitted from the light emitting layer 14 is extracted from the positive electrode 12 side.
Next, each member which comprises this electroluminescent element is demonstrated.
First, the substrate 11 is preferably made of quartz, glass, or ceramic having good translucency. The positive electrode 12 is formed on the substrate 11. As the positive electrode 12, transparent conductor ITO (In ₂ O ₃ doped with SnO ₂ ), InZnO, tin oxide, zinc oxide or the like is preferable. A negative electrode 13 is provided opposite to the positive electrode 12. Pt, Ir, or the like can be used for the negative electrode 13. Further, a material having a low work function, for example, Al, In, Mg, Ti, MgAg, AlLi, or the like may be used.
In addition, a light emitting layer 14 composed of a semiconductor layer 15 and a phosphor layer 16 is repeatedly laminated between the positive electrode 12 and the negative electrode 13 via a transparent conductor layer 17. The semiconductor layer 15 and the phosphor layer 16 constituting the light emitting layer 14 are discontinuous layers, and a discontinuous portion between the respective light emitting layers 14 is filled with a transparent conductor layer 17.
The transparent conductor layer 17 is preferably made of ITO, InZnO, tin oxide or the like. In this way, it is possible to prevent charging, prevent repulsion of subsequent electrons, and extract light to the outside without blocking the light emitted from the light emitting layer 14. Other suitable examples include metal oxides such as ZnO, In ₂ O ₃ , and Ga ₂ O ₃ and composite oxides containing these. Furthermore, a transparent conductive resin material may be used as the transparent conductor layer 17. Suitable examples of the transparent conductive resin material include polyacetylene, polyparaphenylene, polyphenylene vinylene, polyphenylene sulfide, polyphenylene represented by polyphenylene oxide, polypyrrole, polythiophene, polyfuran, polyselenophene, and polytellurophene. And heterocyclic polymers, ionic polymer typified by polyaniline, polyacene, polyoxadiazole, metal phthalocyanine, polyvinyl and the like, derivatives, copolymers and mixtures thereof. Still more preferably, poly-N-vinylcarbazole (PVK), polyethylenedioxythiophene (PEDOT), polystyrene sulfonic acid (PSS), polymethylphenylsilane (PMPS), poly- [2-methoxy-5- (2- Ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene] (CN-PPV), polyquinoxaline, and the like. For the purpose of adjusting conductivity, these may be doped with H ₂ SO ₄ or the like. Further, a mode in which a low molecular weight electron transporting material described later is molecularly dispersed in the conductive resin or non-conductive resin, or a mode in which the structure is incorporated in a molecular chain may be used. Still further, a conductive or semiconductive inorganic material such as the aforementioned metal oxide or composite metal oxide may be dispersed in the conductive resin or nonconductive resin to provide conductivity. .
The semiconductor layer 15 having a large band gap preferably has a band gap that emits light in a shorter wavelength region than blue when an electric field is applied. Specifically, a compound semiconductor having a band gap of 2.0 eV or more can be used, and more preferably, a compound semiconductor having a band gap of 2.5 eV or more can be used. Examples of the semiconductor include AlN (band gap: 5.7 eV), AlP (2.4 eV), AlAs (2.2 eV), GaN (3.4 eV), and GaP, which are Group 13-Group 15 compound semiconductors. (2.3 eV) and the like, mixed crystals thereof (for example, AlGaN, AlGaP, AlGaAs, GaInN, GaInP, InGaAlN, InGaAlP, etc.), or a mixture thereof that may be partially segregated, and the group 12 -Group 16 compound semiconductors ZnO (3.2 eV), ZnS (3.7 eV), ZnSe (2.6 eV), ZnTe (2.3 eV), CdO (2.1 eV), CdS (2.5 eV), HgS (2.0 eV), etc. and mixed crystals thereof (for example, ZnCdS, ZnCdSe, ZnCdTe, ZnSSe, ZnCdSSe, Zn) dSeTe, etc.), or a mixture thereof that may be partially segregated, and further, BeSe (3.8 eV), BeTe (3.4 eV), MgS (4. 5 eV), MgSe (3.6 eV), MgTe (3.2 eV), etc., mixed crystals thereof (for example, ZnMgSSe, ZnMgBeSe, etc.), or a mixture that may be partially segregated, or further Examples of ternary compounds include Group 12 to Group 13 such as (Zn, Cd)-(Al, Ga, In)-(O, S, Se) represented by ZnGa ₂ O ₄ (4.4 eV). group - and group 16 compound semiconductor, a mixed crystal thereof or partially optionally segregated mixtures thereof, still further, group 11 - group 13 - CuAlS ₂ is a group 16 compound semiconductor _{3.5eV), CuAlSe 2 (2.7eV)} , CuAlTe 2 (2.1eV), CuGaS 2 (2.4eV), AgAlS 2 (3.1eV), AgAlSe 2 (2.6eV), AgAlTe 2 (2. 3 eV), AgGaS ₂ (2.7 eV), etc., mixed crystals thereof, mixtures thereof that may be partially segregated, and further, Group 12-Group 14-Group 15 compound semiconductors. there _{ZnSiP 2 (3.0eV), ZnSiAs 2} (2.1eV), ZnGeP 2 (2.3eV), and CdSiP 2 (2.5eV) and the like, mixed crystals thereof, or be partially segregated Any of these good mixtures are more preferred. In addition, the above-mentioned compound example is an example, Comprising: It is not limited to these. Furthermore, the band gap may be adjusted by doping one or more impurity elements that serve as donors and acceptors into these compound semiconductors. For example, Li, Na, Cu, Ag, Au, Be, Mg, Zn, Cd, B, Al, Ga, In, C, Si, Ge, Sn, Pb, N, P, As, O, S, Se, Te, F, Cl, Br, I, Ti, Cr, Mn, Fe, Co, Ni and other metals and non-metallic elements, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Selected from rare earth elements such as fluorides such as TbF ₃ and PrF ₃ , and oxides such as ZnO and CdO.
Further, the phosphor layer 16 is made of a group 2 to group 16 compound fluorescent material such as CaS, SrS, CaSe, and SrSe represented by CaS: Eu described above, and a 12th group such as ZnS, CdS, ZnSe, CdSe, and ZnTe. Group-Group 16 compound fluorescent materials, mixed crystals of the above compounds such as ZnMgS, CaSSe, and CaSrS, or a mixture that may be partially segregated, and further, CaGa ₂ S ₄ , SrGa ₂ S ₄ , BaGa ₂ Thiogallate-based fluorescent materials such as S ₄ , thioaluminate fluorescent materials such as CaAl ₂ S ₄ , SrAl ₂ S ₄ and BaAl ₂ S ₄ , and further Ga ₂ O ₃ , Y ₂ O ₃ , CaO, GeO ₂ , SnO ₂ , ZnO, and other metal oxide fluorescent materials, and further Zn ₂ SiO ₄ , Zn ₂ GeO ₄ , ZnGa ₂ O ₄ , Ca _{Ga 2 O 4, CaGeO 3,} MgGeO 3, Y 4 GeO 8, Y 2 GeO 5, Y 2 Ge 2 O 7, Y 2 SiO 5, BeGa 2 O 4, Sr 3 Ga 2 O 6, (Zn 2 SiO 4 _{-Zn 2 GeO 4), (Ga} 2 O 3 -Al 2 O 3), (CaO-Ga 2 O 3), include multiple oxide fluorescent material such as _{(Y 2 O 3 -GeO 2)} . These fluorescent materials include Mn, Cu, Ti, Cr, Fe, Ni, Ag, Au, Al, Ga, Sn, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, At least one element selected from the group such as Er, Tm, and Yb may be activated as an activator. The activator may be a non-metallic element such as Cl or I, or a fluoride such as TbF ₃ or PrF _3, and two or more of these may be simultaneously activated. In addition, if it is the fluorescent substance used for EL elements, it will not specifically limit.
As described above, according to the electroluminescent element of this embodiment, a semiconductor with a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor particles are excited by the light of the short wavelength, so that the entire light emitting layer is Since it emits light, high luminance and high luminous efficiency can be obtained. Furthermore, since the matrix material is a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. Further, since the area can be easily increased, there is an effect that the cost is low.
(Embodiment 2)
An electroluminescent element 20 according to Embodiment 2 of the present invention will be described with reference to FIG. The electroluminescent device 20 is different from the electroluminescent device according to the first embodiment in that the semiconductor layer 25 having a large band gap constituting the light emitting layer 24 is a continuous layer.
(Embodiment 3)
An electroluminescent element 30 according to Embodiment 3 of the present invention will be described with reference to FIG. The electroluminescent device 30 is different from the electroluminescent device according to the first embodiment in that both the semiconductor layer 35 having a large band gap and the phosphor layer 36 constituting the light emitting layer 34 are continuous layers.
(Embodiment 4)
An electroluminescent element 40 according to Embodiment 4 of the present invention will be described with reference to FIG. Compared with the electroluminescent element according to Embodiment 1, the electroluminescent element 40 has an electron transport layer 18 between the light emitting layer 14 and the positive electrode 12, and an electron transport layer between the light emitting layer 14 and the negative electrode 13. 19 is different in that 19 is further provided. By providing this electron transport layer, the flow of electrons in the light emitting layer can be improved.
The electron transport layers 18 and 19 include, in particular, a metal complex of 8-hydroxyquinoline such as tris (8-quinolinolato) aluminum (Alq3) or 5,5′-bis (dimesitylboryl) -2,2′bithiophene of a thiophene compound. An amorphous material such as (BMB-2T) can be used. As other suitable examples, in low molecular weight materials, oxadiazole derivatives, triazole derivatives, 1,10-phenanthroline derivatives, fluorene derivatives, quinone derivatives, styrylbenzene derivatives, silole derivatives and the like, dimers thereof, A trimer is mentioned. Among them, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD), 2,5-bis (1-naphthyl) -1,3,4- Oxadiazole (BND), 2,5-bis [1- (3-methoxy) -phenyl] -1,3,4-oxadiazole (BMD), 1,3,5-tris [5- (4- tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (TPOB), 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -1, 2,4-triazole (TAZ), 3- (4-biphenyl) -4- (4-ethylphenyl) -5- (4-tert-butylphenyl) -1,2,4-triazole (p-EtTAZ), 4,7-diphenyl-1,10-fe Nthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 3,5-dimethyl-3 ′, 5′-di-tert-butyl-4,4′-diphenoquinone (MBDQ), 2,5-bis [2- (5-tert-butylbenzoxazolyl)]-thiophene (BBOT), trinitrofluorenone (TNF) and the like. Furthermore, examples of the polymer material include the above-described CN-PPV and polyquinoxaline, or a polymer in which a molecular structure exhibiting an electron transport property in a low molecular system is incorporated in a molecular chain. These may be a single species or a mixture of a plurality of species, but are not limited thereto. In addition, a single crystal of an inorganic material such as an n-type compound semiconductor or an n-type oxide semiconductor, a polycrystal, and a resin dispersion layer of the particle powder thereof may be used. The electron transport layer 18 provided on the positive electrode 12 side also functions as a hole block layer.
In Embodiments 1 to 4, the case where a DC voltage is applied between the electrodes 12 and 13 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage is applied. Also good.
In the first to fourth embodiments, the emission color extracted from the light-emitting element is determined by the semiconductor layer 15 and the phosphor layer 16 constituting the light-emitting layer 14, but multicolor display, white display, and RGB colors. In order to adjust the color purity, a color conversion layer may be further provided in front of the light emitting layer 14 in the light extraction direction, or a color conversion material may be mixed in the transparent conductor layer 17. The color conversion layer and the color conversion material may be any material that emits light using light as an excitation source, and known phosphors, pigments, dyes, and the like can be used regardless of organic materials or inorganic materials. If it is an inorganic material, the material used as the above-mentioned phosphor layer 16 can be used. Organic materials include polycyclic aromatic hydrocarbon compounds such as naphthalene, perylene, rubrene, anthracene, pyrene, naphthacene and derivatives thereof, coumarin, quinoline, oxadiazole, lophine, nile red, 4H-pyranylidene. Heteroaromatic compounds such as propanedinitrile and phenoxazone and their derivatives are used. Still other light emitting materials include polymethine compounds such as cyanine, oxole, azulenium, and pyrylium, styrylbenzene compounds such as bis- (diphenylvinyl) biphenyl, porphyrin compounds such as chlorophyll, aluminum quinolinol complexes, zinc hydroxyphenyloxazole Complex, chelate metal complex such as zinc hydroxyphenylthiazole complex, azomethine metal complex, chelate lanthanide complex, xanthene compounds such as phenolphthalein, malachite green, fluorescein, rhodamine B, rhodamine 6G, quinacridone, diketopyrrolopyrrole, magnesium phthalocyanine And these derivatives are used, but not particularly limited thereto.
In addition, the electroluminescent elements according to Embodiments 1 to 4 are formed by ceramic formation methods such as doctor blade method, hot pressing method, HIP method, sol-gel method, vapor deposition method, sputtering method, ion plating method, molecular beam epitaxial method. It can be produced by a thin film forming method such as (MBE) method, a thin film processing method such as wet etching or ion etching, a spin coating method, an ink jet method or the like.
(Embodiment 5)
An electroluminescent element 60 according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 6 is a perspective view showing an electrode configuration of the electroluminescent element 60. The light emitting element 60 further includes a thin film transistor 62 connected to the positive electrode 12 of the electroluminescent element 10 according to the first embodiment. An x electrode 64 and a y electrode 66 are connected to the thin film transistor 62. In this light emitting element 60, the wide band gap semiconductor layer 15 and the phosphor layer 16 are laminated adjacent to each other, so that the phosphor layer 16 is excited by blue light emission or ultraviolet light emission of the semiconductor layer 15 even when driven at a low voltage. Thus, the thin film transistor 62 can be used. Further, by using the thin film transistor 62, the electroluminescent device 60 can have a memory function. As the thin film transistor 62, a low temperature polysilicon, an amorphous silicon thin film transistor or the like is used. Furthermore, the organic thin-film transistor comprised by the thin film containing an organic material may be sufficient.
(Embodiment 6)
A display device according to Embodiment 6 of the present invention will be described with reference to FIG. FIG. 7 is a schematic plan view showing an active matrix constituted by the x electrode 64 and the y electrode 66 which are orthogonal to each other in the display device 70. The display device 70 is an active matrix display device having thin film transistors. This active matrix display device 70 includes a light emitting element array in which a plurality of electroluminescent elements 60 each including the thin film transistor 62 shown in FIG. 6 are two-dimensionally arranged, and a first direction parallel to the surface of the electroluminescent element array. A plurality of x electrodes 64 extending in parallel to each other and a plurality of y electrodes 66 extending in parallel to a second direction orthogonal to the first direction and parallel to the surface of the light emitting element array. With. The thin film transistor 62 of the light emitting element array is connected to the x electrode 64 and the y electrode 66, respectively. The light emitting element specified by the pair of x electrode 64 and y electrode 66 is one pixel. According to the active matrix display device 70, as described above, the phosphor layer 16 constituting the light emitting element of each pixel is laminated adjacent to the semiconductor layer 15 having a wide band gap. Accordingly, the phosphor layer 16 can emit light by causing the semiconductor 15 having a wide band gap to emit blue light or ultraviolet light even when driven at a low voltage. Since low voltage driving is possible in this way, the thin film transistor 62 can be used and the memory effect can be utilized. Further, since it is driven at a low voltage, a long-life display device can be obtained. In the case of a color display device, the light emitting layer may be formed by color-coding each color of RGB. Or you may laminate | stack the light emission unit for every color of RGB pinched | interposed by the electrode. Furthermore, in the case of a color display device of another example, each color of RGB can be displayed using a color filter and / or a color conversion filter after creating a display device with a single color or two color light emitting layers.
(Embodiment 7)
An electroluminescent element 80 according to Embodiment 7 of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view showing the structure of the electroluminescent element 80. The electroluminescent element 80 has a multilayer structure, and is formed on a substrate 81 between a pair of positive electrode 82 and negative electrode 87 facing each other, and between the positive electrode 82 and negative electrode 87. A single light emitting layer 83. A low voltage of several volts to several tens of volts is applied between the positive electrode 82 and the negative electrode 87 by a DC power source. The positive electrode 82 is a transparent electrode, and light emitted from the light emitting layer 83 is extracted from the positive electrode 82 side.
A light emitting layer 83 is formed on the positive electrode 82. The light emitting layer 83 is obtained by dispersing phosphor particles 86 in a matrix material made of a transparent conductor 84. It is preferable that at least a part of the surface of the phosphor particle 86 is covered with a semiconductor 85 having a large band gap, preferably chemisorbed. Furthermore, as shown in FIG. 9, it is more preferable to cover substantially the entire surface of the phosphor particles 86 with the semiconductor 85. By covering almost the entire surface in this way, there is a great effect on the moisture prevention of the phosphor particles 86. Note that the transparent conductor 84, the phosphor particles 86, and the semiconductor 85 that covers the phosphor particles 86 constituting the electroluminescent element 80 are respectively transparent conductor layers constituting the electroluminescent element 10 according to the first embodiment. 17, the phosphor layer 16 and the semiconductor layer 15 are substantially the same and will not be described in detail. Further, other constituent members of the electroluminescent element 80 are substantially the same as those of the electroluminescent element 10 according to the first embodiment, and detailed description thereof is omitted.
As described above, according to the electroluminescent element of this embodiment, a semiconductor with a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor particles are excited by the light of the short wavelength, so that the entire light emitting layer is Since it emits light, high luminance and high luminous efficiency can be obtained. Furthermore, since the matrix material is a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. Further, since the area can be easily increased, there is an effect that the cost is low.
(Embodiment 8)
An electroluminescent element 100 according to Embodiment 8 of the present invention will be described with reference to FIG. FIG. 10 is a cross-sectional view showing the configuration of this electroluminescent element. Compared with the electroluminescent device 80 according to the seventh embodiment, the electroluminescent device 100 has an electron transport layer 88 between the light emitting layer 83 and the positive electrode 82 and an electron transport between the light emitting layer 83 and the negative electrode 87. The difference is that a layer 89 is provided. The electron transport layers 88 and 89 are provided to improve the flow of electrons in the light emitting layer 83. The electron transport layers 88 and 89 constituting the electroluminescent element 100 are substantially the same as the electron transport layers 18 and 19 constituting the electroluminescent element 40 according to Embodiment 4, and detailed description thereof is omitted. To do.
In the seventh and eighth embodiments, the case where a DC voltage is applied between the electrodes 82 and 87 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage is applied. Also good.
In addition, the electroluminescent elements according to Embodiments 7 and 8 include a doctor blade method, a hot press method, a HIP method, a ceramic forming method such as a sol-gel method, a vapor deposition method, a sputtering method, an ion plating method, a molecular beam epitaxial method. It can be produced by a thin film formation method such as (MBE) method, spin coating method, ink jet method or the like.
(Embodiment 9)
An electroluminescent element 110 according to Embodiment 9 of the present invention will be described with reference to FIG. FIG. 11 is a perspective view showing an electrode configuration of the electroluminescent element 110. The electroluminescent element 110 further includes a thin film transistor 112 connected to the positive electrode 82 of the electroluminescent element 80 according to the seventh embodiment. An x electrode 114 and a y electrode 116 are connected to the thin film transistor 112. In the light emitting element 110, the phosphor particles 86 are covered with the wide band gap semiconductor 85, so that the light emitting element 110 can be driven at a low voltage and the thin film transistor 112 can be used. In addition, by using the thin film transistor 112, the electroluminescent element 110 can have a memory function. As the thin film transistor 112, a low temperature polysilicon, an amorphous silicon thin film transistor or the like is used. Furthermore, the organic thin-film transistor comprised by the thin film containing an organic material may be sufficient.
(Embodiment 10)
A display device 120 according to Embodiment 10 of the present invention will be described with reference to FIG. FIG. 12 is a schematic plan view showing an active matrix constituted by the x electrode 114 and the y electrode 116 orthogonal to each other of the display device 120. The display device 120 is an active matrix display device having thin film transistors. The active matrix display device 120 includes a light emitting element array in which a plurality of electroluminescent elements 110 including the thin film transistors 112 shown in FIG. 11 are two-dimensionally arranged, and a first direction parallel to the surface of the electroluminescent element array. A plurality of x electrodes 114 extending in parallel to each other and a plurality of y electrodes 116 extending in parallel to a second direction perpendicular to the first direction and parallel to the surface of the light emitting element array. With. The thin film transistor 112 of the light emitting element array is connected to the x electrode 114 and the y electrode 116, respectively. A light emitting element specified by the pair of x electrode 114 and y electrode 116 is one pixel. According to this active matrix display device 120, as described above, the light emitting layer 83 constituting the light emitting element of each pixel has the phosphor particles 86 covering the surface with the semiconductor 85 having a wide band gap as the transparent conductor. Dispersed in 84 matrix materials. As a result, the phosphor particles 86 can emit light by causing blue emission or ultraviolet light excitation of the semiconductor 85 having a wide band gap even when driven at a low voltage. Thus, since it can be driven at a low voltage, a thin film transistor can be used and a memory effect can be utilized. Further, since it is driven at a low voltage, a long-life display device can be obtained. In the case of a color display device, the light emitting layer may be formed by color-coding each color of RGB. Or you may laminate | stack the light emission unit for every color of RGB pinched | interposed by the electrode. Furthermore, in the case of a color display device of another example, each color of RGB can be displayed using a color filter and / or a color conversion filter after creating a display device with a single color or two color light emitting layers.
(Embodiment 11)
An electroluminescent element 130 according to Embodiment 11 of the present invention will be described with reference to FIG. FIG. 13 is a cross-sectional view showing the structure of the electroluminescent element 130. The electroluminescent element 130 has a multilayer structure, and a pair of first electrode 132 and second electrode 137 facing each other on a substrate 131, and between the first electrode 132 and second electrode 137. And a single light emitting layer 133 formed thereon. In addition, a voltage of several tens of volts is applied between the first electrode 132 and the second electrode 137 by an AC power source.
Further, the light emitting layer 133 is obtained by dispersing phosphor particles 136 in a matrix material made of a transparent conductor 134. It is preferable that at least a part of the surface of the phosphor particles 136 is covered with a semiconductor 135 having a large band gap, and preferably chemisorbed. Furthermore, it is more preferable to cover substantially the entire surface of the phosphor particles 136 with the semiconductor 135. By covering substantially the entire surface in this way, there is a great effect on moisture prevention of the phosphor particles 136.
A transparent conductive resin can be used for the transparent conductor 134 constituting the electroluminescent element 130. The transparent conductive resin is inferior in conductivity to ITO, InZnO, tin oxide, etc. which are examples of the transparent conductive layer layer 17 and the transparent conductor 84 described above, but defects such as pinholes are less likely to occur, and pressure resistance Is preferable. Even when an AC voltage of several tens of volts to several hundreds of volt is applied, stable element characteristics can be obtained. In addition, since a suitable example as this transparent conductive resin material is substantially the same as the material used for the transparent conductor layer 17 of the electroluminescent element 10 according to Embodiment 1, detailed description is omitted. The other constituent members of the electroluminescent element 130 are substantially the same as those of the electroluminescent element 80 according to the seventh embodiment, and detailed description thereof is omitted. In the configuration of the electroluminescent element 130, the first electrode 132 is a transparent electrode, and light is extracted from the first electrode 132 side.
As described above, according to the electroluminescent element of the present embodiment, a semiconductor with a large band gap emits light in the ultraviolet region or blue, and phosphor particles are excited by light of the short wavelength, so that the entire light emitting layer emits light. High luminance and high luminous efficiency can be obtained. Further, since the area can be easily increased, there is an effect that the cost is low.
(Embodiment 12)
An electroluminescent element 140 according to Embodiment 12 of the present invention will be described with reference to FIG. FIG. 14 is a cross-sectional view showing the structure of the electroluminescent element 140. The electroluminescent element 140 is different from the electroluminescent element 130 according to the eleventh embodiment in that fine particles 138 made of a semiconductor having a large band gap are further dispersed in a matrix material. Therefore, as in the above-described embodiment, an electroluminescent element with high luminance and high luminous efficiency can be provided. Further, since the area can be easily increased, there is an effect that the cost is low. Note that the light emitting layer 133 may include both phosphor particles 136 in which at least a part of the surface is covered with the semiconductor 135 having a large band gap. The constituent members of the electroluminescent element 140 are substantially the same as those of the electroluminescent element 130 according to the eleventh embodiment, and detailed description thereof is omitted.
In Embodiments 11 and 12, the case where an AC voltage is applied between the electrodes 132 and 137 has been described. However, the present invention is not limited to this, and a DC voltage or a pulse voltage is applied. Also good.
In addition, the electroluminescent elements according to the eleventh and twelfth embodiments described above are formed by ceramic forming methods such as doctor blade method, hot pressing method, HIP method, sol-gel method, vapor deposition method, sputtering method, ion plating method, molecular beam epitaxial method. It can be produced by a thin film formation method such as (MBE) method, spin coating method, ink jet method or the like.
(Embodiment 13)
An electroluminescent element 150 according to Embodiment 13 of the present invention will be described with reference to FIG. FIG. 15 is a cross-sectional view showing the structure of the electroluminescent element 150. The electroluminescent element 150 has a multilayer structure and is formed on a substrate 151 between a pair of positive electrode 152 and negative electrode 154 facing each other, and between the positive electrode 152 and the negative electrode 154. A single light emitting layer 153. Further, a low voltage of several volts to several tens of volts is applied between the positive electrode 152 and the negative electrode 156 by a DC power source. The positive electrode 152 is a transparent electrode, and light emitted from the light emitting layer 153 is extracted from the positive electrode 152 side.
Further, the light emitting layer 153 is made of a phosphor material and a semiconductor material having a large band gap, and is formed by co-evaporation. Therefore, as in the above-described embodiment, an electroluminescent element with high luminance and high luminous efficiency can be provided. Further, since the area can be easily increased, there is an effect that the cost is low. The constituent members of the electroluminescent element 150 are substantially the same as those of the electroluminescent element 10 according to Embodiment 1, and detailed description thereof is omitted.
In the thirteenth embodiment, the case where a DC voltage is applied between the electrodes 152 and 154 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage may be applied. .
In Embodiments 7, 8, and 11 to 13, the emission color extracted from the light-emitting element is determined by the phosphor material and the semiconductor material in the light-emitting layers 83, 133, and 153. In order to adjust the color purity of each color of white display and RGB, a color conversion layer may be further provided in front of the light extraction direction of the light emitting layer, or a color conversion material may be mixed in the light emitting layer.
As described above, the present invention has been described in detail with reference to the preferred embodiments. However, the present invention is not limited to these embodiments, and many of them are within the technical scope of the present invention described in the following claims. It will be apparent to those skilled in the art that preferred variations and modifications can be made.

  The present invention relates to an electroluminescent element used for a flat light source and a flat display device.

  A light emitting diode, an electroluminescent element (referred to as an EL element), or the like is used in a conventional light emitting device used for a flat light source or a flat display device.

  A light-emitting diode is excellent in terms of high luminance and luminous efficiency, but needs to be formed on a compound semiconductor substrate, and it is difficult to increase the area of one semiconductor substrate. Further, in order to increase the size of the flat display device, it is necessary to arrange a large number of light emitting diodes two-dimensionally.

  The structure of the EL element will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the configuration of the EL element. The EL element 50 has a cell structure in which a light emitting layer 54 is sandwiched between two electrodes 52 and 55. As shown in FIG. 5, an electrode 52, an insulating layer 53a, a light emitting layer 54, and an insulating layer 53b are formed on a substrate 51. The electrodes 55 are sequentially formed. The light emitting layer 54 is made of a phosphor such as ZnS, and has a thickness of 0.5 μm to 1 μm, for example. Further, an AC power source 56 is connected between the electrode 52 and the electrode 55 outside the EL element 50, and by applying a voltage between the electrode 52 and the electrode 55 by the AC power source 56, the EL element 50 is Emits light. The EL element 50 is not easily limited by the material of the substrate 51 and can have a large area using a single substrate.

JP-A-8-250281 JP-A-8-306485 JP-A 63-66282 JP 2000-340366 A JP 2003-115385 A

  However, in order to increase the size of the flat light emitting device using the above-described light emitting diode, a plurality of light emitting diodes are required, and there is a problem that the manufacturing cost increases in proportion to the number of elements.

  In addition, the above-described planar light emitting device using the EL element has no problem in increasing the size, and is superior to other displays in terms of thinning, high speed response, wide viewing angle, and high contrast. However, the luminous efficiency and luminance are low, and the lifetime is as short as about 10,000 hours. In addition, it is usually necessary to apply an alternating voltage of several hundred volts at a high frequency of several kHz, and it is difficult to drive an active matrix method using a general-purpose thin film transistor, and there is a problem that the driving circuit is expensive.

In addition, inorganic phosphors such as CaS: Eu and Y ₂ O ₃ : Mn that are generally used in EL devices have Mn contained in crystals of inorganic compounds such as sulfides such as CaS and oxides such as Y ₂ O _3. A luminescent center such as a transition metal such as Eu or a rare earth metal such as Eu is added. Therefore, although light emission by ultraviolet light excitation is realized, on the other hand, even if an electric field is applied, electrons do not easily penetrate into the inorganic phosphor and charging repulsion is strong, so that high-speed electrons accelerated by a high electric field collide with inorganic fluorescence. It is necessary to excite the emission center in the body. For this reason, it is usually necessary to apply an AC voltage of several hundred volts at a high frequency of several kHz, and there is a problem that the drive circuit becomes expensive.

  The present invention has been made in view of such a problem, and is a light-emitting element that can be driven (low power consumption) at a low voltage of several volts to several tens of volts, has high luminous efficiency, and can have a large area at low cost. The purpose is to provide.

An electroluminescent device according to the present invention includes a pair of electrodes facing each other,
An electroluminescent device comprising a single layer or a plurality of layers of light emitting layers formed between the pair of electrodes,
At least one of the light emitting layers includes a phosphor and a wide band gap semiconductor.

  The light emitting layer may have a laminated structure of a phosphor layer and a wide band gap semiconductor layer.

  Furthermore, at least one transparent conductor layer sandwiched between the pair of electrodes may be further provided. The transparent conductor layer may be a discontinuous layer in which a part of the layer is discontinuous. Or a continuous layer may be sufficient.

  Further, at least one of the phosphor layer and the semiconductor layer constituting the light emitting layer may be a discontinuous layer in which a part of the layer is discontinuous. In this case, when both the semiconductor layer and the phosphor layer are discontinuous layers, the semiconductor layer is a continuous layer and the phosphor layer is discontinuous. When the semiconductor layer is a discontinuous layer, the phosphor layer is a continuous layer. Or the semiconductor layer and the phosphor layer may be continuous layers.

  Furthermore, the light emitting layer may have phosphor particles coated with a semiconductor having at least a part of the surface having a wide band gap.

  Still further, the light emitting layer may have phosphor particles coated with a semiconductor having substantially the entire surface having a wide band gap.

  Further, the phosphor layer may have a phosphor material in which at least a part of the surface is coated with a semiconductor having a wide band gap and dispersed in a matrix material.

  Further, the light emitting layer may be one in which the phosphor particles coated with a semiconductor having substantially the entire surface having a wide band gap are dispersed in a matrix material.

  The matrix material may be a transparent conductor.

  Furthermore, it is preferable that the semiconductor included in the light emitting layer has a band gap that emits light in a shorter wavelength region than blue when an electric field is applied. As the semiconductor, a compound semiconductor having a band gap of 2.0 eV or more, more preferably 2.5 eV or more can be used. For example, a Group 13-Group 15 compound semiconductor, or a mixed crystal thereof, or a mixture thereof that may be partially segregated, a Group 12-Group 16 compound semiconductor, or a mixed crystal thereof, or Mixtures that may be partially segregated, Group 2 to Group 16 compound semiconductors, or mixed crystals thereof, or mixtures that may be partially segregated, Group 12 to Group Group 13-Group 16 compound semiconductor, or a mixed crystal thereof, or a mixture thereof that may be partially segregated, Group 11-Group 13-Group 16 compound semiconductor, or a mixed crystal thereof, or Mixtures that may be partially segregated, Group 12-Group 14-Group 15 compound semiconductors, or mixed crystals thereof, or mixtures that may be partially segregated A further preferred either of.

  Further, in order to improve the flow of electrons in the light emitting layer, an electron transport layer such as an amorphous material such as a metal complex of 8-hydroxyquinoline such as Alq3 or BMB-2T of a thiophene compound is used. It is preferable to be provided between the electrodes.

  In order to cause a normal EL element to emit light, it is necessary to cause high acceleration electrons to collide with a phosphor to excite an electron beam, and it is necessary to apply a high voltage of several hundred volts. On the other hand, in the electroluminescence device of the present invention, first, a semiconductor layer or a semiconductor coating layer having a low voltage and a large band gap emits light in an ultraviolet region having a wavelength of 300 to 350 nm to a blue-green region in the 500 nm band. More preferably, light is emitted from an ultraviolet region having a wavelength of 300 to 350 nm to a blue region of 400 nm band. The phosphor layer or phosphor particles are excited by the light and the entire light emitting layer emits light, so that high luminance and high luminous efficiency can be obtained. The electrons then flow to the adjacent transparent conductor layer and induce the next light emission. Since this light emission mechanism is repeated, the flow of electrons is maintained, and low voltage driving (low power consumption) and long life are realized.

  Further, the pair of electrodes may be a positive electrode and a negative electrode. In this case, a DC voltage is applied between the pair of positive electrode and negative electrode. In addition, at least one of the semiconductor layers constituting the light emitting layer may be closer to the negative electrode than the phosphor layer.

  The electroluminescent device according to the present invention may further include a thin film transistor connected to one of the pair of electrodes. In the electroluminescent element of the present invention, a thin film transistor can be used because the driving voltage is as low as several volts as described above.

A display device according to the present invention includes an electroluminescent element array in which the electroluminescent elements are two-dimensionally arranged;
A plurality of x electrodes extending parallel to each other in a first direction parallel to the surface of the electroluminescent element array;
A plurality of y-electrodes extending in parallel to a second direction orthogonal to the first direction and parallel to the surface of the electroluminescent element array;
The thin film transistor of the electroluminescent element array is connected to the x electrode and the y electrode, respectively.

  As described above, according to the electroluminescent device of the present invention, a semiconductor having a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor is excited by the light of the short wavelength, and the entire light emitting layer emits light. Therefore, high brightness and high luminous efficiency can be obtained. Furthermore, since the matrix is made of a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. In addition, since the area can be easily increased, the cost can be reduced.

  An electroluminescent element according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
An electroluminescent element according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the configuration of the electroluminescent element 10 according to the first embodiment. The electroluminescent element 10 has a multi-layer structure, and includes a pair of positive electrodes 12 and negative electrodes 13 facing each other on a substrate 11. Further, a light emitting layer 14 composed of a semiconductor layer 15 and a phosphor layer 16 is repeatedly laminated between the positive electrode 12 and the negative electrode 13 via a transparent conductor layer 17. The semiconductor layer 15 and the phosphor layer 16 constituting the light emitting layer 14 are discontinuous layers, and a discontinuous portion between the respective light emitting layers 14 is filled with a transparent conductor layer 17. In FIG. 1, only two sets of light emitting layers 14 are illustrated, but the present invention is not limited to this, and may be one set or three or more sets. Moreover, the electroluminescent element 10 emits light by applying a low voltage of several volts to several tens of volts between the positive electrode 12 and the negative electrode 13 by a direct current power source. The positive electrode 12 is a transparent electrode, and light emitted from the light emitting layer 14 is extracted from the positive electrode 12 side.

Next, each member which comprises this electroluminescent element is demonstrated.
First, the substrate 11 is preferably made of quartz, glass, or ceramic having good translucency. The positive electrode 12 is formed on the substrate 11. As the positive electrode 12, transparent conductor ITO (In ₂ O ₃ doped with SnO ₂ ), InZnO, tin oxide, zinc oxide or the like is preferable. A negative electrode 13 is provided opposite to the positive electrode 12. Pt, Ir, or the like can be used for the negative electrode 13. Further, a material having a low work function, for example, Al, In, Mg, Ti, MgAg, AlLi, or the like may be used.

  In addition, a light emitting layer 14 composed of a semiconductor layer 15 and a phosphor layer 16 is repeatedly laminated between the positive electrode 12 and the negative electrode 13 via a transparent conductor layer 17. The semiconductor layer 15 and the phosphor layer 16 constituting the light emitting layer 14 are discontinuous layers, and a discontinuous portion between the respective light emitting layers 14 is filled with a transparent conductor layer 17.

The transparent conductor layer 17 is preferably made of ITO, InZnO, tin oxide or the like. In this way, it is possible to prevent charging, prevent repulsion of subsequent electrons, and extract light to the outside without blocking the light emitted from the light emitting layer 14. Other suitable examples include metal oxides such as ZnO, In ₂ O ₃ , and Ga ₂ O ₃ and composite oxides containing these. Furthermore, a transparent conductive resin material may be used as the transparent conductor layer 17. Suitable examples of the transparent conductive resin material include polyacetylene, polyparaphenylene, polyphenylene vinylene, polyphenylene sulfide, polyphenylene represented by polyphenylene oxide, polypyrrole, polythiophene, polyfuran, polyselenophene, and polytellurophene. And heterocyclic polymers, ionic polymer typified by polyaniline, polyacene, polyoxadiazole, metal phthalocyanine, polyvinyl and the like, derivatives, copolymers and mixtures thereof. Still more preferably, poly-N-vinylcarbazole (PVK), polyethylenedioxythiophene (PEDOT), polystyrene sulfonic acid (PSS), polymethylphenylsilane (PMPS), poly- [2-methoxy-5- (2- Ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene] (CN-PPV), polyquinoxaline, and the like. For the purpose of adjusting conductivity, these may be doped with H ₂ SO ₄ or the like. Further, a mode in which a low molecular weight electron transporting material described later is molecularly dispersed in the conductive resin or non-conductive resin, or a mode in which the structure is incorporated in a molecular chain may be used. Still further, a conductive or semiconductive inorganic material such as the aforementioned metal oxide or composite metal oxide may be dispersed in the conductive resin or nonconductive resin to provide conductivity. .

The semiconductor layer 15 having a large band gap preferably has a band gap that emits light in a shorter wavelength region than blue when an electric field is applied. Specifically, a compound semiconductor having a band gap of 2.0 eV or more can be used, and more preferably, a compound semiconductor having a band gap of 2.5 eV or more can be used. Examples of the semiconductor include AlN (band gap: 5.7 eV), AlP (2.4 eV), AlAs (2.2 eV), GaN (3.4 eV), and GaP, which are Group 13-Group 15 compound semiconductors. (2.3 eV) and the like, mixed crystals thereof (for example, AlGaN, AlGaP, AlGaAs, GaInN, GaInP, InGaAlN, InGaAlP, etc.), or a mixture thereof that may be partially segregated, and the group 12 -Group 16 compound semiconductors ZnO (3.2 eV), ZnS (3.7 eV), ZnSe (2.6 eV), ZnTe (2.3 eV), CdO (2.1 eV), CdS (2.5 eV), HgS (2.0 eV), etc. and mixed crystals thereof (for example, ZnCdS, ZnCdSe, ZnCdTe, ZnSSe, ZnCdSSe, Zn) dSeTe, etc.), or a mixture thereof that may be partially segregated, and further, BeSe (3.8 eV), BeTe (3.4 eV), MgS (4. 5 eV), MgSe (3.6 eV), MgTe (3.2 eV), etc., mixed crystals thereof (for example, ZnMgSSSe, ZnMgBeSe, etc.), or mixtures thereof that may be partially segregated, Another example of a ternary compound is a group 12-group such as (Zn, Cd)-(Al, Ga, In)-(O, S, Se) represented by ZnGa ₂ O ₄ (4.4 eV). A group 13-group 16 compound semiconductor, a mixed crystal thereof, a mixture thereof which may be partially segregated, or a CuAlS ₂ which is a group 11-group 13-group 16 compound semiconductor. _{(3.5eV), CuAlSe 2 (2.7eV} ), CuAlTe 2 (2.1eV), CuGaS 2 (2.4eV), AgAlS 2 (3.1eV), AgAlSe 2 (2.6eV), AgAlTe 2 (2 .3 eV), AgGaS ₂ (2.7 eV), etc., mixed crystals thereof, or mixtures thereof that may be partially segregated, and further, Group 12-Group 14-Group 15 compound semiconductors ZnSiP _{2 (3.0eV) is, ZnSiAs 2 (2.1eV), ZnGeP} 2 (2.3eV), and CdSiP 2 (2.5eV) and the like, mixed crystals thereof or, optionally partially segregated More preferred are any of these mixtures. In addition, the above-mentioned compound example is an example, Comprising: It is not limited to these. Furthermore, the band gap may be adjusted by doping one or more impurity elements that serve as donors and acceptors into these compound semiconductors. For example, Li, Na, Cu, Ag, Au, Be, Mg, Zn, Cd, B, Al, Ga, In, C, Si, Ge, Sn, Pb, N, P, As, O, S, Se, Te, F, Cl, Br, I, Ti, Cr, Mn, Fe, Co, Ni and other metals and non-metallic elements, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Selected from rare earth elements such as fluorides such as TbF ₃ and PrF ₃ , and oxides such as ZnO and CdO.

Further, the phosphor layer 16 is made of a group 2 to group 16 compound fluorescent material such as CaS, SrS, CaSe, and SrSe represented by CaS: Eu described above, and a 12th group such as ZnS, CdS, ZnSe, CdSe, and ZnTe. Group-Group 16 compound fluorescent materials, mixed crystals of the above compounds such as ZnMgS, CaSSe, and CaSrS, or a mixture that may be partially segregated, and further, CaGa ₂ S ₄ , SrGa ₂ S ₄ , BaGa ₂ Thiogallate-based fluorescent materials such as S ₄ , thioaluminate fluorescent materials such as CaAl ₂ S ₄ , SrAl ₂ S ₄ and BaAl ₂ S ₄ , and further Ga ₂ O ₃ , Y ₂ O ₃ , CaO, GeO ₂ , SnO ₂ , ZnO, and other metal oxide fluorescent materials, and further Zn ₂ SiO ₄ , Zn ₂ GeO ₄ , ZnGa ₂ O ₄ , Ca _{Ga 2 O 4, CaGeO 3,} MgGeO 3, Y 4 GeO 8, Y 2 GeO 5, Y 2 Ge 2 O 7, Y 2 SiO 5, BeGa 2 O 4, Sr 3 Ga 2 O 6, (Zn 2 SiO 4 _{-Zn 2 GeO 4), (Ga} 2 O 3 -Al 2 O 3), (CaO-Ga 2 O 3), include multiple oxide fluorescent material such as _{(Y 2 O 3 -GeO 2)} . These fluorescent materials include Mn, Cu, Ti, Cr, Fe, Ni, Ag, Au, Al, Ga, Sn, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, At least one element selected from the group such as Er, Tm, and Yb may be activated as an activator. The activator may be a non-metallic element such as Cl or I, or a fluoride such as TbF ₃ or PrF _3, and two or more of these may be simultaneously activated. In addition, if it is the fluorescent substance used for EL elements, it will not specifically limit.

  As described above, according to the electroluminescent element of this embodiment, a semiconductor with a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor particles are excited by the light of the short wavelength, so that the entire light emitting layer is Since it emits light, high luminance and high luminous efficiency can be obtained. Furthermore, since the matrix material is a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. Further, since the area can be easily increased, there is an effect that the cost is low.

(Embodiment 2)
An electroluminescent element 20 according to Embodiment 2 of the present invention will be described with reference to FIG. The electroluminescent device 20 is different from the electroluminescent device according to the first embodiment in that the semiconductor layer 25 having a large band gap constituting the light emitting layer 24 is a continuous layer.

(Embodiment 3)
An electroluminescent element 30 according to Embodiment 3 of the present invention will be described with reference to FIG. The electroluminescent device 30 is different from the electroluminescent device according to the first embodiment in that both the semiconductor layer 35 having a large band gap and the phosphor layer 36 constituting the light emitting layer 34 are continuous layers.

(Embodiment 4)
An electroluminescent element 40 according to Embodiment 4 of the present invention will be described with reference to FIG. Compared with the electroluminescent element according to Embodiment 1, the electroluminescent element 40 has an electron transport layer 18 between the light emitting layer 14 and the positive electrode 12, and an electron transport layer between the light emitting layer 14 and the negative electrode 13. 19 is different in that 19 is further provided. By providing this electron transport layer, the flow of electrons in the light emitting layer can be improved.

  The electron transport layers 18 and 19 include, in particular, a metal complex of 8-hydroxyquinoline such as tris (8-quinolinolato) aluminum (Alq3) or a 5,5′-bis (dimesitylboryl) -2,2′bithiophene of a thiophene compound. An amorphous material such as (BMB-2T) can be used. As other suitable examples, in low molecular weight materials, oxadiazole derivatives, triazole derivatives, 1,10-phenanthroline derivatives, fluorene derivatives, quinone derivatives, styrylbenzene derivatives, silole derivatives and the like, dimers thereof, A trimer is mentioned. Among them, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD), 2,5-bis (1-naphthyl) -1,3,4- Oxadiazole (BND), 2,5-bis [1- (3-methoxy) -phenyl] -1,3,4-oxadiazole (BMD), 1,3,5-tris [5- (4- tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (TPOB), 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -1, 2,4-triazole (TAZ), 3- (4-biphenyl) -4- (4-ethylphenyl) -5- (4-tert-butylphenyl) -1,2,4-triazole (p-EtTAZ), 4,7-diphenyl-1,10-fe Nthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 3,5-dimethyl-3 ′, 5′-di-tert-butyl-4,4′-diphenoquinone (MBDQ), 2,5-bis [2- (5-tert-butylbenzoxazolyl)]-thiophene (BBOT), trinitrofluorenone (TNF) and the like. Furthermore, examples of the polymer material include the above-described CN-PPV and polyquinoxaline, or a polymer in which a molecular structure exhibiting an electron transport property in a low molecular system is incorporated in a molecular chain. These may be a single species or a mixture of a plurality of species, but are not limited thereto. In addition, a single crystal of an inorganic material such as an n-type compound semiconductor or an n-type oxide semiconductor, a polycrystal, and a resin dispersion layer of the particle powder thereof may be used. The electron transport layer 18 provided on the positive electrode 12 side also functions as a hole block layer.

  In Embodiments 1 to 4, the case where a DC voltage is applied between the electrodes 12 and 13 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage is applied. Also good.

  In the first to fourth embodiments, the emission color extracted from the light-emitting element is determined by the semiconductor layer 15 and the phosphor layer 16 constituting the light-emitting layer 14, but multicolor display, white display, and RGB colors. In order to adjust the color purity, a color conversion layer may be further provided in front of the light emitting layer 14 in the light extraction direction, or a color conversion material may be mixed in the transparent conductor layer 17. The color conversion layer and the color conversion material may be any material that emits light using light as an excitation source, and known phosphors, pigments, dyes, and the like can be used regardless of organic materials or inorganic materials. If it is an inorganic material, the material used as the above-mentioned phosphor layer 16 can be used. Organic materials include polycyclic aromatic hydrocarbon compounds such as naphthalene, perylene, rubrene, anthracene, pyrene, naphthacene and derivatives thereof, coumarin, quinoline, oxadiazole, lophine, nile red, 4H-pyranylidene. Heteroaromatic compounds such as propanedinitrile and phenoxazone and their derivatives are used. Still other light emitting materials include polymethine compounds such as cyanine, oxole, azulenium, and pyrylium, styrylbenzene compounds such as bis- (diphenylvinyl) biphenyl, porphyrin compounds such as chlorophyll, aluminum quinolinol complexes, zinc hydroxyphenyloxazole Complex, chelate metal complex such as zinc hydroxyphenylthiazole complex, azomethine metal complex, chelate lanthanide complex, xanthene compounds such as phenolphthalein, malachite green, fluorescein, rhodamine B, rhodamine 6G, quinacridone, diketopyrrolopyrrole, magnesium phthalocyanine And these derivatives are used, but not particularly limited thereto.

  In addition, the electroluminescent elements according to Embodiments 1 to 4 are formed by ceramic formation methods such as doctor blade method, hot pressing method, HIP method, sol-gel method, vapor deposition method, sputtering method, ion plating method, molecular beam epitaxial method. It can be produced by a thin film forming method such as (MBE) method, a thin film processing method such as wet etching or ion etching, a spin coating method, an ink jet method or the like.

(Embodiment 5)
An electroluminescent element 60 according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 6 is a perspective view showing an electrode configuration of the electroluminescent element 60. The light emitting element 60 further includes a thin film transistor 62 connected to the positive electrode 12 of the electroluminescent element 10 according to the first embodiment. An x electrode 64 and a y electrode 66 are connected to the thin film transistor 62. In this light emitting element 60, the wide band gap semiconductor layer 15 and the phosphor layer 16 are laminated adjacent to each other, so that the phosphor layer 16 is excited by blue light emission or ultraviolet light emission of the semiconductor layer 15 even when driven at a low voltage. Thus, the thin film transistor 62 can be used. Further, by using the thin film transistor 62, the electroluminescent device 60 can have a memory function. As the thin film transistor 62, a low temperature polysilicon, an amorphous silicon thin film transistor or the like is used. Furthermore, the organic thin-film transistor comprised by the thin film containing an organic material may be sufficient.

(Embodiment 6)
A display device according to Embodiment 6 of the present invention will be described with reference to FIG. FIG. 7 is a schematic plan view showing an active matrix constituted by the x electrode 64 and the y electrode 66 which are orthogonal to each other in the display device 70. The display device 70 is an active matrix display device having thin film transistors. This active matrix display device 70 includes a light emitting element array in which a plurality of electroluminescent elements 60 each including the thin film transistor 62 shown in FIG. 6 are two-dimensionally arranged, and a first direction parallel to the surface of the electroluminescent element array. A plurality of x electrodes 64 extending in parallel to each other and a plurality of y electrodes 66 extending in parallel to a second direction orthogonal to the first direction and parallel to the surface of the light emitting element array. With. The thin film transistor 62 of the light emitting element array is connected to the x electrode 64 and the y electrode 66, respectively. The light emitting element specified by the pair of x electrode 64 and y electrode 66 is one pixel. According to the active matrix display device 70, as described above, the phosphor layer 16 constituting the light emitting element of each pixel is laminated adjacent to the semiconductor layer 15 having a wide band gap. Accordingly, the phosphor layer 16 can emit light by causing the semiconductor 15 having a wide band gap to emit blue light or ultraviolet light even when driven at a low voltage. Since low voltage driving is possible in this way, the thin film transistor 62 can be used and the memory effect can be utilized. Further, since it is driven at a low voltage, a long-life display device can be obtained. In the case of a color display device, the light emitting layer may be formed by color-coding each color of RGB. Or you may laminate | stack the light emission unit for every color of RGB pinched | interposed by the electrode. Furthermore, in the case of a color display device of another example, each color of RGB can be displayed using a color filter and / or a color conversion filter after creating a display device with a single color or two color light emitting layers.

(Embodiment 7)
An electroluminescent element 80 according to Embodiment 7 of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view showing the structure of the electroluminescent element 80. The electroluminescent element 80 has a multilayer structure, and is formed on a substrate 81 between a pair of positive electrode 82 and negative electrode 87 facing each other, and between the positive electrode 82 and negative electrode 87. A single light emitting layer 83. A low voltage of several volts to several tens of volts is applied between the positive electrode 82 and the negative electrode 87 by a DC power source. The positive electrode 82 is a transparent electrode, and light emitted from the light emitting layer 83 is extracted from the positive electrode 82 side.

  A light emitting layer 83 is formed on the positive electrode 82. The light emitting layer 83 is obtained by dispersing phosphor particles 86 in a matrix material made of a transparent conductor 84. It is preferable that at least a part of the surface of the phosphor particle 86 is covered with a semiconductor 85 having a large band gap, preferably chemisorbed. Furthermore, as shown in FIG. 9, it is more preferable to cover substantially the entire surface of the phosphor particles 86 with the semiconductor 85. By covering almost the entire surface in this way, there is a great effect on the moisture prevention of the phosphor particles 86. Note that the transparent conductor 84, the phosphor particles 86, and the semiconductor 85 that covers the phosphor particles 86 constituting the electroluminescent element 80 are respectively transparent conductor layers constituting the electroluminescent element 10 according to the first embodiment. 17, the phosphor layer 16 and the semiconductor layer 15 are substantially the same and will not be described in detail. Further, other constituent members of the electroluminescent element 80 are substantially the same as those of the electroluminescent element 10 according to the first embodiment, and detailed description thereof is omitted.

  As described above, according to the electroluminescent element of this embodiment, a semiconductor with a low voltage and a large band gap emits light in the ultraviolet region or blue, and the phosphor particles are excited by the light of the short wavelength, so that the entire light emitting layer is Since it emits light, high luminance and high luminous efficiency can be obtained. Furthermore, since the matrix material is a transparent conductor, the flow of electrons is sustained, and low voltage driving (low power consumption) and long life are realized. Further, since the area can be easily increased, there is an effect that the cost is low.

(Embodiment 8)
An electroluminescent element 100 according to Embodiment 8 of the present invention will be described with reference to FIG. FIG. 10 is a cross-sectional view showing the configuration of this electroluminescent element. Compared with the electroluminescent device 80 according to the seventh embodiment, the electroluminescent device 100 has an electron transport layer 88 between the light emitting layer 83 and the positive electrode 82 and an electron transport between the light emitting layer 83 and the negative electrode 87. The difference is that a layer 89 is provided. The electron transport layers 88 and 89 are provided to improve the flow of electrons in the light emitting layer 83. The electron transport layers 88 and 89 constituting the electroluminescent element 100 are substantially the same as the electron transport layers 18 and 19 constituting the electroluminescent element 40 according to Embodiment 4, and detailed description thereof is omitted. To do.

  In the seventh and eighth embodiments, the case where a DC voltage is applied between the electrodes 82 and 87 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage is applied. Also good.

  In addition, the electroluminescent elements according to Embodiments 7 and 8 include a doctor blade method, a hot press method, a HIP method, a ceramic forming method such as a sol-gel method, a vapor deposition method, a sputtering method, an ion plating method, a molecular beam epitaxial method. It can be produced by a thin film formation method such as (MBE) method, spin coating method, ink jet method or the like.

(Embodiment 9)
An electroluminescent element 110 according to Embodiment 9 of the present invention will be described with reference to FIG. FIG. 11 is a perspective view showing an electrode configuration of the electroluminescent element 110. The electroluminescent element 110 further includes a thin film transistor 112 connected to the positive electrode 82 of the electroluminescent element 80 according to the seventh embodiment. An x electrode 114 and a y electrode 116 are connected to the thin film transistor 112. In the light emitting element 110, the phosphor particles 86 are covered with the wide band gap semiconductor 85, so that the light emitting element 110 can be driven at a low voltage and the thin film transistor 112 can be used. In addition, by using the thin film transistor 112, the electroluminescent element 110 can have a memory function. As the thin film transistor 112, a low temperature polysilicon, an amorphous silicon thin film transistor or the like is used. Furthermore, the organic thin-film transistor comprised by the thin film containing an organic material may be sufficient.

(Embodiment 10)
A display device 120 according to Embodiment 10 of the present invention will be described with reference to FIG. FIG. 12 is a schematic plan view showing an active matrix constituted by the x electrode 114 and the y electrode 116 orthogonal to each other of the display device 120. The display device 120 is an active matrix display device having thin film transistors. The active matrix display device 120 includes a light emitting element array in which a plurality of electroluminescent elements 110 including the thin film transistors 112 shown in FIG. 11 are two-dimensionally arranged, and a first direction parallel to the surface of the electroluminescent element array. A plurality of x electrodes 114 extending in parallel to each other and a plurality of y electrodes 116 extending in parallel to a second direction perpendicular to the first direction and parallel to the surface of the light emitting element array. With. The thin film transistor 112 of the light emitting element array is connected to the x electrode 114 and the y electrode 116, respectively. A light emitting element specified by the pair of x electrode 114 and y electrode 116 is one pixel. According to this active matrix display device 120, as described above, the light emitting layer 83 constituting the light emitting element of each pixel has the phosphor particles 86 covering the surface with the semiconductor 85 having a wide band gap as the transparent conductor. Dispersed in 84 matrix materials. As a result, the phosphor particles 86 can emit light by causing blue emission or ultraviolet light excitation of the semiconductor 85 having a wide band gap even when driven at a low voltage. Thus, since it can be driven at a low voltage, a thin film transistor can be used and a memory effect can be utilized. Further, since it is driven at a low voltage, a long-life display device can be obtained. In the case of a color display device, the light emitting layer may be formed by color-coding each color of RGB. Or you may laminate | stack the light emission unit for every color of RGB pinched | interposed by the electrode. Furthermore, in the case of a color display device of another example, each color of RGB can be displayed using a color filter and / or a color conversion filter after creating a display device with a single color or two color light emitting layers.

(Embodiment 11)
An electroluminescent element 130 according to Embodiment 11 of the present invention will be described with reference to FIG. FIG. 13 is a cross-sectional view showing the structure of the electroluminescent element 130. The electroluminescent element 130 has a multilayer structure, and a pair of first electrode 132 and second electrode 137 facing each other on a substrate 131, and between the first electrode 132 and second electrode 137. And a single light emitting layer 133 formed thereon. In addition, a voltage of several tens of volts is applied between the first electrode 132 and the second electrode 137 by an AC power source.

  Further, the light emitting layer 133 is obtained by dispersing phosphor particles 136 in a matrix material made of a transparent conductor 134. It is preferable that at least a part of the surface of the phosphor particles 136 is covered with a semiconductor 135 having a large band gap, and preferably chemisorbed. Furthermore, it is more preferable to cover substantially the entire surface of the phosphor particles 136 with the semiconductor 135. By covering substantially the entire surface in this way, there is a great effect on moisture prevention of the phosphor particles 136.

  A transparent conductive resin can be used for the transparent conductor 134 constituting the electroluminescent element 130. The transparent conductive resin is inferior in conductivity to ITO, InZnO, tin oxide, etc. which are examples of the transparent conductive layer layer 17 and the transparent conductor 84 described above, but defects such as pinholes are less likely to occur, and pressure resistance Is preferable. Even when an AC voltage of several tens of volts to several hundreds of volt is applied, stable element characteristics can be obtained. In addition, since a suitable example as this transparent conductive resin material is substantially the same as the material used for the transparent conductor layer 17 of the electroluminescent element 10 according to Embodiment 1, detailed description is omitted. The other constituent members of the electroluminescent element 130 are substantially the same as those of the electroluminescent element 80 according to the seventh embodiment, and detailed description thereof is omitted. In the configuration of the electroluminescent element 130, the first electrode 132 is a transparent electrode, and light is extracted from the first electrode 132 side.

  As described above, according to the electroluminescent element of the present embodiment, a semiconductor with a large band gap emits light in the ultraviolet region or blue, and phosphor particles are excited by light of the short wavelength, so that the entire light emitting layer emits light. High luminance and high luminous efficiency can be obtained. Further, since the area can be easily increased, there is an effect that the cost is low.

(Embodiment 12)
An electroluminescent element 140 according to Embodiment 12 of the present invention will be described with reference to FIG. FIG. 14 is a cross-sectional view showing the structure of the electroluminescent element 140. The electroluminescent element 140 is different from the electroluminescent element 130 according to the eleventh embodiment in that fine particles 138 made of a semiconductor having a large band gap are further dispersed in a matrix material. Therefore, as in the above-described embodiment, an electroluminescent element with high luminance and high luminous efficiency can be provided. Further, since the area can be easily increased, there is an effect that the cost is low. Note that the light emitting layer 133 may include both phosphor particles 136 in which at least a part of the surface is covered with the semiconductor 135 having a large band gap. The constituent members of the electroluminescent element 140 are substantially the same as those of the electroluminescent element 130 according to the eleventh embodiment, and detailed description thereof is omitted.

  In Embodiments 11 and 12, the case where an AC voltage is applied between the electrodes 132 and 137 has been described. However, the present invention is not limited to this, and a DC voltage or a pulse voltage is applied. Also good.

  In addition, the electroluminescent elements according to the eleventh and twelfth embodiments described above are formed by ceramic forming methods such as doctor blade method, hot pressing method, HIP method, sol-gel method, vapor deposition method, sputtering method, ion plating method, molecular beam epitaxial method. It can be produced by a thin film formation method such as (MBE) method, spin coating method, ink jet method or the like.

(Embodiment 13)
An electroluminescent element 150 according to Embodiment 13 of the present invention will be described with reference to FIG. FIG. 15 is a cross-sectional view showing the structure of the electroluminescent element 150. The electroluminescent element 150 has a multilayer structure and is formed on a substrate 151 between a pair of positive electrode 152 and negative electrode 154 facing each other, and between the positive electrode 152 and the negative electrode 154. A single light emitting layer 153. Further, a low voltage of several volts to several tens of volts is applied between the positive electrode 152 and the negative electrode 156 by a DC power source. The positive electrode 152 is a transparent electrode, and light emitted from the light emitting layer 153 is extracted from the positive electrode 152 side.

  Further, the light emitting layer 153 is made of a phosphor material and a semiconductor material having a large band gap, and is formed by co-evaporation. Therefore, as in the above-described embodiment, an electroluminescent element with high luminance and high luminous efficiency can be provided. Further, since the area can be easily increased, there is an effect that the cost is low. The constituent members of the electroluminescent element 150 are substantially the same as those of the electroluminescent element 10 according to Embodiment 1, and detailed description thereof is omitted.

  In the thirteenth embodiment, the case where a DC voltage is applied between the electrodes 152 and 154 has been described. However, the present invention is not limited to this, and an AC voltage or a pulse voltage may be applied. .

  In Embodiments 7, 8, and 11 to 13, the emission color extracted from the light-emitting element is determined by the phosphor material and the semiconductor material in the light-emitting layers 83, 133, and 153. In order to adjust the color purity of each color of white display and RGB, a color conversion layer may be further provided in front of the light extraction direction of the light emitting layer, or a color conversion material may be mixed in the light emitting layer.

  As described above, the present invention has been described in detail with reference to the preferred embodiments. However, the present invention is not limited to these embodiments, and many of them are within the technical scope of the present invention described in the following claims. It will be apparent to those skilled in the art that other preferred variations and modifications are possible.

It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 4 of this invention. It is sectional drawing which shows the structure of the conventional electroluminescent element. It is a perspective view of the light emitting element which concerns on Embodiment 5 of this invention. It is the plane schematic diagram of the display apparatus using the light emitting element which concerns on Embodiment 6 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 7 of this invention. As another example of Embodiment 7, it is sectional drawing which shows the cross-section of the fluorescent substance particle which coat | covered the substantially whole surface with the semiconductor with a big band gap. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 8 of this invention. It is a perspective view of the light emitting element which concerns on Embodiment 9 of this invention. It is a plane schematic diagram of the display apparatus using the light emitting element concerning Embodiment 10 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 11 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 12 of this invention. It is sectional drawing which shows the structure of the electroluminescent element which concerns on Embodiment 13 of this invention.

Claims (24)

A pair of electrodes facing each other;
An electroluminescent device comprising a single layer or a plurality of layers of light emitting layers formed between the pair of electrodes,
At least one of the light emitting layers includes a phosphor and a wide band gap semiconductor. The electroluminescent device according to claim 1, wherein the light emitting layer has a laminated structure of a phosphor layer and a wide band gap semiconductor layer. The electroluminescent device according to claim 2, further comprising at least one transparent conductor layer sandwiched between the pair of electrodes. 4. The electroluminescent device according to claim 3, wherein the transparent conductor layer is a discontinuous layer in which a part of the layer is discontinuous. 5. The method according to claim 2, wherein at least one of the phosphor layer and the semiconductor layer constituting the light emitting layer is a discontinuous layer in which a part of the layer is discontinuous. Electroluminescent device. The electroluminescent device according to claim 1, wherein the light emitting layer includes phosphor particles coated with a semiconductor having at least a part of a surface having a wide band gap. The electroluminescent device according to claim 1, wherein the light emitting layer has phosphor particles coated with a semiconductor having substantially the entire surface having a wide band gap. The electroluminescent device according to claim 1, wherein the phosphor particles in which at least a part of the surface of the light emitting layer is coated with a semiconductor having a wide band gap are dispersed in a matrix material. 2. The electroluminescent device according to claim 1, wherein the phosphor layer, in which the phosphor layer is coated with a semiconductor having a wide band gap on substantially the entire surface, is dispersed in a matrix material. The electroluminescent device according to claim 8, wherein the matrix material is a transparent conductor. The electroluminescent element according to claim 1, wherein the semiconductor constituting the light emitting layer has a band gap that emits light in a shorter wavelength region than blue when an electric field is applied. The electroluminescent device according to claim 1, wherein the semiconductor constituting the light emitting layer has a band gap of 2.0 eV or more. The electroluminescent device according to claim 1, wherein the semiconductor constituting the light emitting layer has a band gap of 2.5 eV or more. 14. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a group 13-group 15 compound semiconductor, a mixed crystal thereof, or a mixture thereof which may be partially segregated. The electroluminescent element according to claim 1. 14. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a group 12-group 16 compound semiconductor, a mixed crystal thereof, or a mixture thereof that may be partially segregated. The electroluminescent element according to claim 1. 14. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a Group 2 to Group 16 compound semiconductor, a mixed crystal thereof, or a mixture thereof that may be partially segregated. The electroluminescent element according to claim 1. 12. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a group 12-group 13-group 16 compound semiconductor, a mixed crystal thereof, or a mixture thereof which may be partially segregated. The electroluminescent element as described in any one of 1 to 13. 12. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a Group 11-Group 13-Group 16 compound semiconductor, a mixed crystal thereof, or a mixture that may be partially segregated. The electroluminescent element as described in any one of 1 to 13. 12. The semiconductor according to claim 11, wherein the semiconductor is mainly composed of a group 12-group 14-group 15 compound semiconductor, a mixed crystal thereof, or a mixture that may be partially segregated. The electroluminescent element as described in any one of 1 to 13. The electroluminescent element according to claim 1, further comprising an electron transporting layer between the light emitting layer and at least one of the electrodes. 21. The electroluminescent element according to claim 1, wherein the pair of electrodes is a positive electrode and a negative electrode. The electroluminescent device according to claim 21, wherein at least one of the semiconductor layers constituting the light emitting layer is located on the negative electrode side with respect to the phosphor layer. The electroluminescent device according to any one of claims 1 to 22, further comprising a thin film transistor connected to one of the pair of electrodes. An electroluminescent element array in which the electroluminescent elements according to claim 23 are two-dimensionally arranged;
A plurality of x electrodes extending parallel to each other in a first direction parallel to the surface of the electroluminescent element array;
A plurality of y-electrodes extending in parallel to a second direction orthogonal to the first direction and parallel to the surface of the electroluminescent element array;
The display device, wherein the thin film transistor of the electroluminescent element array is connected to the x electrode and the y electrode, respectively.

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