JP2006005012A - Organic electroluminescence element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescenece element having a small display unit suitable for high definition and having the small dispersion of a lifetime. <P>SOLUTION: An electroluminescence light-emitter is composed of a plurality of light-emitting layers held between a cathode 101 and an anode 109. In the electroluminescence light-emitter, transportation layers 104, 106 and 108 are formed to the upper sections of each light-emitting layer 103, 105 and 107. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescent device.

  In recent years, an electroluminescence element having a plurality of light emitting layers having different wavelengths has been studied. The structure of Patent Document 1 is shown in FIG. An anode 1 is formed by sputtering ITO on a transparent glass substrate 10, and a hole transport layer 11 is formed on the anode 1. On the hole transport layer 11, a blue light emitting layer 3a is formed. On top of that, the electron transport layer 12 is formed, and the cathode 2 is formed.

Similarly, the green light emitting layer 3 b is formed on the hole transport layer 11. On top of this, the electron transport layer 12 is formed, and the cathode 2 is formed. A red light emitting layer 3 c is formed on the hole transport layer 11. On top of that, a cathode 2 is formed.
JP 2002-164170 A

  As described above, since each pixel is formed in a stripe shape in the above element, there is a first drawback that a full color electroluminescence display portion of blue, green, and red becomes large. In addition, there is a second disadvantage that there are variations in luminous efficiency and lifetime due to variations in the production of the light emitting layer of the electroluminescent element. In view of the above-described disadvantages of the present invention, the present invention is a full-color organic electroluminescence device suitable for high definition and a white organic electroluminescence device with improved whiteness, with a small display portion and little variation in lifetime. A luminescent device is provided.

  In order to solve the above-mentioned problem, in the present invention of claim 1, in the electroluminescent light-emitting portion composed of a plurality of light-emitting layers sandwiched between the cathode and the anode, a transport layer is provided above each light-emitting layer. It was.

  According to the second aspect of the present invention, in the electroluminescence light-emitting portion composed of two or more light-emitting layers, each light-emitting layer has a light-emitting organic material such that the value of the energy band gap of the light-emitting organic material increases in order from the cathode side. The material is doped.

  According to the third aspect of the present invention, in the electroluminescence light-emitting portion composed of two or more light-emitting layers, each light-emitting layer has a light-emitting organic material such that the value of the energy band gap of the light-emitting organic material increases in order from the cathode side. The material was doped, and the light emitting layer with the smallest band gap was sandwiched between them.

  In this invention of Claim 4, each light emitting layer is doped with the luminescent organic substance so that the value of the energy band gap of a luminescent organic substance may become large in order from the said cathode side.

  In the present invention of claim 5, each light emitting layer is doped with a light emitting organic material so that the energy band gap value of the light emitting organic material increases in order from the cathode side, and the light emission having the smallest band gap therebetween. Sandwiched the layers.

  According to the sixth aspect of the present invention, the electroluminescent light emitting portion comprises an electron transport layer, a first light emitting layer, a transport layer, a second light emitting layer, and a hole transport layer between the cathode and the anode.

  According to the seventh aspect of the present invention, the electroluminescent light emitting part includes an electron transport layer, a first light emitting layer, a transport layer having a width smaller than that of the first light emitting layer, and a second light emitting layer between the cathode and the anode. And a hole transport layer.

  In this invention of Claim 8, an electroluminescent light emission part has an electron carrying layer, a 1st light emitting layer, a 1st transport layer, a 2nd light emitting layer, a 2nd transport layer between a cathode and an anode. And a third light emitting layer and a hole transport layer.

  In this invention of Claim 9, an electroluminescent light emission part is an electron carrying layer between a cathode and an anode, a 1st light emitting layer, a 1st transport layer whose width | variety is narrower than a 1st light emitting layer, and 2nd light emission. A layer, a second transport layer, a third light emitting layer, and a hole transport layer.

  In this invention of Claim 10, an electroluminescent light emission part is an electron carrying layer between a cathode and an anode, a 1st light emitting layer, a 1st transport layer whose width | variety is narrower than a 1st light emitting layer, and 2nd light emission. A layer, a second transport layer that is narrower than the second light-emitting layer, a third light-emitting layer, and a hole transport layer.

  In the present invention of claim 11, the first light emitting layer is orange and the second light emitting layer is blue green.

  In the present invention of claim 12, the first light emitting layer is yellow and the second light emitting layer is blue.

  In the present invention of claim 13, the first light emitting layer is red, the second light emitting layer is green, and the third light emitting layer is blue.

  In the present invention of claim 14, the first light emitting layer 3 is green, the second light emitting layer 4 is red, and the third light emitting layer is blue.

  In the present invention of claim 15, the light emitting layer is formed of the same host layer.

  In the present invention of claim 16, the light emitting layer contains Alq3.

  In the present invention of claim 17, each light emitting layer has an emission spectrum different from each other.

  In the present invention of claim 18, the emission color is blue light, green light, or red light depending on the combination of the light emitting layers.

  In the present invention of claim 19, the emission color is white light by the combination of the light emitting layers.

  In the present invention of claim 20, the upper and lower sides of the transport layer sandwiched between the light emitting layers are arranged to be aligned.

  In the present invention of claim 21, the transport layers sandwiched between the light emitting layers are placed on the top and bottom, and the functions of the top and bottom transport layers are made different.

  In the present invention of claim 22, the transport layers whose width between the light emitting layers is narrower than that of the light emitting layers are placed on top and bottom, and the functions of the upper and lower transport layers are made different.

  In the present invention of claim 23, the light amount of the light emitting layer is adjusted by changing the width of the transport layer sandwiched between the light emitting layers.

  By the above means, according to the organic electroluminescent element of the present invention, the light emitting layer can be selected by forming the transport layer on the plurality of light emitting layers, and the light emitting region can be designated by the shape of the transport layer. Since the space between the light emitting portions can be reduced by the transport layer, the display area can be reduced and high definition can be obtained.

  In addition, by inserting a transport layer that is the same as the width of the light emitting layer or narrower than the width of the light emitting layer between these light emitting layers, the recombination rate of electrons and holes is improved, and light is extracted by extracting light from the anode. The extraction efficiency can be increased. As a result, the output is improved, the chromaticity characteristics are improved, the life variation is reduced, and the long life is obtained. In addition, current consumption can be reduced and light can be emitted with a single drive voltage.

  Hereinafter, details of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a basic configuration of an organic electroluminescence (EL) element 100 according to the best mode 1 for carrying out the present invention.

  In FIG. 1, a cathode 101 is made of aluminum or the like. Lithium fluoride LiF is deposited on the cathode 101 by a thickness of 5 angstroms, and PBD with a LUMO 2.6 eV and HOMO 6.3 eV energy band gap of 3.7 eV is deposited on the lithium fluoride by 200 angstroms. 102 is formed.

  Next, on this electron transport layer 102, a host layer Alq3 doped with 1% by weight of red dopant DCJTB having a LUMO of 3.2 eV and a HOMO of 5.3 eV and an energy band gap of 2.1 eV is deposited by a thickness of 200 Å. A red light emitting layer 103 is formed.

  On the red light emitting layer 103, NBP is deposited to a thickness of 400 Å using a mask 1 (not shown), and a first transport layer (hole) with LUMO 2.45 eV, HOMO 5.46 eV, and energy band gap 3.0 eV. Transport layer) 104 is formed. On the first transport layer 104, a green light emitting layer 105 doped with 1 wt% of a green dopant Coumarin 6 having an energy band gap of 2.36 eV with a LUMO of 2.9 eV and a HOMO of 5.3 eV is formed on the host layer Alq3 by 500 angstrom deposition. Is done.

  On the green light emitting layer 105, using a mask 2 (not shown), NBP is deposited to a thickness of 400 angstroms to form a second transport layer (hole transport layer) 106. On the second transport layer 106, a host layer BAlq having a LUMO of 2.6 eV, a HOMO of 5.3 eV and an energy band gap of 2.7 eV, doped with 1% by weight of dopant Perylene, is deposited by a thickness of 500 Å, and emits blue light. The blue light emitting layer 107 is formed of the organic light emitting material.

  On the blue light emitting layer 107, NBP is deposited to a thickness of 400 angstroms to form a hole transport layer 108 with LUMO 2.3V, HOMO 5.5eV, and energy band gap 3.2eV.

  Next, CuPc is deposited by a thickness of 20 nm on the hole transport layer 108, and an anode 109 is formed on the CuPc. The anode 109 is formed by vacuum evaporation by heating and evaporating ITO with 10% SnO 2 with an electron gun to a film thickness of about 0.4 μm. An ITO film having a thickness of 300 nm is formed on the ITO film by a sputtering apparatus. In the first embodiment, since the anode 109 is made of ITO and the cathode 101 is made of Al, it is not necessary to use a special electrode material because it is made of the same material as the conventional one.

  In addition, since light from the light emitting layers 103, 105, and 107 is extracted to the outside through the anode 109, the light extraction efficiency is increased. Here, when a positive voltage is applied to the anode 109 and a negative voltage is applied to the cathode 101, the electrons transported to the light emitting layers 103, 105, and 107 through the electron transport layer 102 and the holes transported through the hole transport layer 108 are Light is emitted by recombination within the red light emitting layer 103, the green light emitting layer 105, and the blue light emitting layer 107.

  Here, in the organic light emitting device (full color electroluminescent light emitting device) 100 of the present invention, in the light emitting portions 103, 105, and 107 formed in three layers, the LUMO band gap energy difference between the light emitting layer and the dopant. Becomes 0.3 eV or more. Therefore, the dopant layer emits light. Further, the first transport layer 104 and the second transport layer 106 are sandwiched between the three light emitting layers. Each of the light emitting layers 103, 105, and 107 has two layers of Alq3 sandwiched between the first transport layers 104, and further one layer of BAlq sandwiched between the second transport layers 106 with each organic substance. It is formed.

  Since the first transport layer 104 and the second transport layer 106 do not pass electrons through holes, electrons do not move upward in the lower portion of the first transport layer 104, and holes pass through the first transport layer 104 and the cathode 101. Proceed to As a result, the electrons from the cathode 101 and the holes that have passed through the first transport layer 104 recombine at the lower portion of the first transport layer 104, so that the red light emitting layer 103 emits red light at the lower portion of the first transport layer 104. .

The second transport layer 106 does not pass electrons injected from the cathode 101, and the second transport layer 106 passes holes transported from the anode 109. Therefore, the green light emitting layer 105 emits green light at a portion below the second transport layer 106 and excluding the first transport layer 104. Electrons injected from the cathode 101 travel toward the anode 109, but the second transport layer 106 does not pass electrons. Since holes injected from the anode 109 pass through the hole transport layer 108, the blue light emitting layer 107 is a portion excluding the second transport layer 106, and the electrons and holes are recombined to emit blue light. The blue material has a larger energy band gap than other green and red materials, and therefore, charge injection tends to be poor. (High energy barrier for charge injection)
The present invention is characterized in that the blue light emitting layer 107 having a large energy band gap is disposed under the hole transport layer 108 below the anode 109. Since it is located under the hole transport layer 108, charge injection does not deteriorate.

  Further, since the green light emitting layer 105 formed under the blue light emitting layer 107 and the host layer of the red light emitting layer 103 are composed of the same or similar electron transport layer material as the electron transport layer 102, the electron transport is performed. Is also efficient. Each of the light emitting layers 103, 105, and 107 is formed in a multi-layered manner. However, a layer having a different emission color is selected by the first transport layer 104, the second transport layer 106, and the hole transport layer 108. There is a feature of the present invention.

  Also in the red light emitting layer 103 farthest from the anode 109, holes are transported through the hole transport layer 108, the second transport layer 106, and the first transport layer 104, and the electron transport layer 102 is formed below the red light emitting layer 103. Therefore, since electrons are transported, the recombination efficiency is good. For this reason, compared with the case where red, green, and blue are obtained using a color filter and a white light-emitting layer, since there is no absorption by the color filter, three times the brightness can be obtained. The same amount of light can be obtained with about a third of the current when a conventional white light emitting layer is used.

  Further, by forming the three layers 103, 105, and 107 so as to overlap each other, the film thickness variation is smaller than the film thickness variation of the single-layer electroluminescent element. As a result, the variation in luminous efficiency is improved, and the current consumption is reduced to 1/3, so that the variation in current and the variation in life are also improved. Compared to the white element obtained by individually emitting the blue, green, and red driving voltages, the three layers 103, 105, and 107 overlap, so a single voltage may be used, compared to FIG. Driving is easy and the circuit can be omitted.

  In addition, compared with the white element obtained by individually emitting blue, green, and red in FIG. 15, the present element 100 emits solid light, and therefore, for example, it does not require a light emission width of 0.5 mm and a pitch of 0.5 mm. The light emitting area can be halved compared to the conventional one. As a result, the same amount of light emission can be obtained in an area of ½, so that high definition and high luminance can be achieved.

  Next, an organic electroluminescence device 119a according to the best mode 2 for carrying out the present invention will be described with reference to the schematic diagram of FIG. The portion below the electron transport layer 102 is the same as FIG. On the electron transport layer 102, a dopant DCM2 having a LUMO 3.11 and HOMO 5.26 eV energy band gap of 2.65 eV was deposited by 2 wt% on a host layer Alq3 having a LUMO 2.85 eV and HOMO 5.62 eV energy band gap of 2.77 eV. An orange layer 110 is formed. On the orange layer 110, using a mask 3 (not shown), NBP is deposited to a thickness of 400 Å to form a transport layer (hole transport layer) 111. A blue-green layer 112 is formed on the transport layer 111 by depositing a host layer Alq3 doped with 1 wt% dopant CuPc copper phthalocyanine to a thickness of 500 Å. A hole transport layer 208 is formed on the blue-green layer 112 as in FIG.

  In the portion above the hole transport layer 208, the anode 209 is formed as in FIG. Here, in the (white) organic electroluminescent device 119a, the difference between the LUMO band gap energy of the light emitting host layer and the dopant is 0.3 eV or less for the orange layer 110 and the blue-green layer 112 formed in two layers. is there. Therefore, the present invention is characterized in that both the host layer and the dopant layer emit light. Since the transport layer 111 does not pass electrons through holes, electrons injected from the cathode 101 move upward, but the electrons are stopped by the transport layer 111.

  Since the holes pass through the transport layer 111 to the cathode 101, the electrons from the cathode 101 recombine with the holes that have passed through the transport layer 111 at the bottom of the transport layer 111, so the orange layer 110 is below the transport layer 111. Emits orange light. Since the hole transport layer 208 does not pass electrons through the holes, electrons injected from the cathode 101 move upward, but the electrons are stopped at the hole transport layer 208 portion.

Since the holes travel through the hole transport layer 208 to the cathode 101, the electrons from the cathode 101 and the holes that have passed through the hole transport layer 208 recombine at the bottom of the hole transport layer 208. Therefore, the blue-green layer 112 emits blue-green light under the hole transport layer 208 except for the transport layer 111. That is, in terms of spectrum, the green color due to Alq3 and the red color due to DCM2 emit orange, and the green color due to Alq3 and blue color due to CuPc are combined across the transport layer 111, and blue-green color is emitted. Therefore, the whiteness can be obtained in a well-balanced manner. The blue material has a larger energy band gap than other green and red materials, and therefore, charge injection tends to be poor. (High energy barrier for charge injection)
The present invention is characterized in that the blue-green light emitting layer 112 having a large energy band gap is disposed under the hole transport layer 208 below the anode 209. Since it is located under the hole transport layer 208, charge injection does not deteriorate.

  Furthermore, since the host layer of the orange light-emitting layer 110 formed under the blue-green light-emitting layer 112 is composed of the same Alq3 as the electron transport layer 102, the electron transport is also efficient. Further, since each of the light emitting layers 110 and 112 has a common host layer of Alq3, the same material can be used, so that productivity is good. Moreover, since the light emitting layers 110 and 112 have different spectra and the transport layer 111 is sandwiched between the light emitting layers 110 and 112, the movement of holes becomes efficient. The orange light emitting unit 110 has a transport layer 111 on the light emitting layer 110 and an electron transport layer 102 below the light emitting layer 110. Therefore, the recombination of holes and electrons is about twice that in the case where the transport layer 111 is not provided, and the white electroluminescent element 119a having a high output that is about twice that of the prior art can be obtained. Since the white electroluminescent element 119a has about twice the efficiency, the same amount of light can be obtained with half the current. In addition, by forming two layers in an overlapping manner, the film thickness variation can be improved as compared with the film thickness variation of a single-layer electroluminescent element.

  Since the variation in the film thickness can be reduced, the variation in the light emission efficiency is also improved, and the current consumption is also improved since the consumption current is halved. In this way, the current consumption is halved, so that the variation in life is also improved. With respect to the driving voltage, since a single voltage may be used as compared with a white element obtained by separately emitting blue-green and orange light, driving is easy and the circuit can be omitted.

  In addition, compared with the white element obtained by individually emitting blue, green, and red shown in FIG. 15, the two layers are stacked with the transport layer 111 interposed therebetween, so that the emission area can be reduced to 1/3. As a result, the light emission area can be halved because, for example, the light emission width of 0.5 mm and the pitch of 0.5 mm are not necessary since the light emission is solid, not the stripe light emission shown in FIG. By combining these, the same amount of light emission can be obtained with an area of 1/6, so that high definition and high luminance can be achieved.

  Next, an organic electroluminescence device 119b according to the best mode 3 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 119b, the orange layer 110 and the subsequent layers are the same as those in FIG. On the orange layer 110, using a mask 4 (not shown), NBP is deposited to a thickness of 400 Å to form a transport layer 211. The top of the transport layer 211 is the same as in FIG.

  Next, an organic electroluminescence device 119c according to the best mode 4 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 119c, the electron transport layer 102 and the subsequent layers are the same as those in FIG. Using a mask 5 (not shown) on the orange layer 110, NBP is deposited to a thickness of 400 Å to form a transport layer 311. The top of the transport layer 311 is the same as FIG. 3 and 4, the same effect as in FIG. 2 can be obtained.

  Instead of the orange layer 110 shown in FIG. 2, FIG. 3 and FIG. 4, the LUMO 2.85 eV, HOMO 5.62 eV energy band gap 2.77 eV host layer Alq3, LUMO 3.15, HOMO 5.36 eV energy band gap 2 A yellow layer 210 (not shown) may be formed by depositing 5 wt% of a 21 eV dopant lebran. On the yellow layer 210, NBP is deposited to a thickness of 400 angstroms using masks 3, 4, 5 (not shown), and the transport layers 111, 211, 311 are formed as shown in FIGS. 3 and FIG.

  A blue layer 212 (not shown) is formed on the hole transport layers 111, 211, and 311 by depositing a host layer BAlq doped with 1% by weight of dopant Perylene to a thickness of 500 angstroms. A hole transport layer 208 is formed on the blue layer 212 in the same manner as in FIGS. The portion above the hole transport layer 208 is the same as in FIG.

  In the yellow layer 210 and the blue layer 212 formed in two layers, the dopant layer emits light because the LUMO band gap energy difference between the host layer of the light emitting layer and the dopant is 0.3 eV or more. Since the transport layers 111, 211, and 311 pass holes and do not pass electrons, electrons injected from the cathode 101 move upward, but the electrons are stopped at the transport layers 111, 211, and 311 parts. The holes travel to the cathode 101 through the hole transport layers 111, 211, 311. Therefore, electrons from the cathode 101 and holes passing through the transport layers 111, 211, 311 recombine at the lower part of the transport layers 111, 211, 311, so that the yellow layer 210 is below the hole transport layers 111, 211, 311. Emits yellow light.

  Since the hole transport layer 208 does not pass electrons through holes, electrons injected from the cathode 101 move upward, but the electrons are stopped at the hole transport layer 208 portion. The holes travel through the hole transport layer 208 to the cathode 101. Therefore, electrons from the cathode 101 and holes that have passed through the hole transport layer 208 are recombined at the bottom of the hole transport layer 208. As a result, the blue layer 212 emits blue light under the hole transport layer 208 except for the transport layers 111, 211, and 311. That is, in terms of spectrum, yellow by LeBlanc and blue by Perylene are mixed with the transport layers 111, 211, and 3311 in between. Therefore, the whiteness can be obtained with a good balance. This has the same effect as the previous examples of FIGS.

  Next, an organic electroluminescence element 219a according to the best mode 5 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 219a, the first transport layer (hole transport layer) 113 and the second transport are provided between the red light-emitting layer 103, the green light-emitting layer 105, and the blue light-emitting layer 107 in FIG. The layer (hole transport layer) 114 is sandwiched therebetween.

  The first transport layer 113 and the second transport layer 114 are formed by depositing NBP by 400 Å using masks 6 and 7 (not shown), respectively. Since each of the light emitting layers 103 and 105 includes the host layer Alq3 and the light emitting layer 107 includes the host layer BAlq, the movement of holes and electrons is improved.

In FIG. 5, since the first transport layer 113 does not pass electrons through holes, the electrons injected from the cathode 101 and the holes injected from the anode 209 are recombined below the first transport layer 113 to form red The light emitting layer 103 emits red light below the first transport layer 113. Since electrons pass through the portion other than the first transport layer 113, the holes and electrons are relocated at the lower portion of the second transport layer 114 at the portion other than the first transport layer 113. Join. Therefore, the green light emitting layer 105 emits green light below the second transport layer 114 excluding the first transport layer 113. Since electrons are stopped by the second transport layer 114, the electrons pass inside the second transport layer 114. Since the electrons and holes that have passed through the hole transport layer 208 are recombined, blue light is emitted from the blue layer 107 under the hole transport layer 208 except for the second transport layer 114. A blue material has a larger energy band gap than other green and red materials, and therefore, charge injection tends to deteriorate. (High energy barrier for charge injection)
The present invention is characterized in that the blue light emitting layer 107 having a large energy band gap is disposed below the hole transport layer 208 below the anode 209. Since it is located under the hole transport layer 208, charge injection does not deteriorate. Further, the green light-emitting layer 105 formed under the blue light-emitting layer 107 and the host layer of the red light-emitting layer 103 are made of the same or similar electron transport layer material as the electron transport layer 102, so that electron transport is performed. Is also efficient. Moreover, the light quantity of each light emitting layer can be controlled by the inner width of the first transport layer 113 and the second transport layer 114. Thereby, the whiteness of the (white) organic electroluminescent element 219a can be adjusted.

  Next, an organic electroluminescence element 219b according to the best mode 6 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 219b, the portion below the electron transport layer 102 is the same as that in FIG. On the electron transport layer 102, a first transport layer (hole transport layer) narrower than the width of the light emitting layer 105 between the red light emitting layer 103, the green light emitting layer 105, and the blue light emitting layer 107 shown in FIG. 213 and the second transport layer (hole transport layer) 114 are sandwiched.

  The first transport layer 213 and the second transport layer 114 are formed by depositing NBP with a thickness of 400 Å using masks 8 and 7 (not shown). Since each of the light emitting layers 103 and 105 is the host layer Alq3 and the light emitting layer 107 is the host layer BAlq, the movement of holes and electrons is more efficient.

  In FIG. 6, since the first transport layer 213 does not pass electrons through holes, electrons injected from the cathode 101 and holes injected from the anode 209 are recombined at the lower portion of the first transport layer 213 to emit red light. The layer 103 emits red light below the first transport layer 213. Since the electron passes through the portion other than the first transport layer 213, it is positioned on the first transport layer 213, and the hole and the electron are recombined in the portion other than the first transport layer 213 below the second transport layer 114. To do. Therefore, the green light emitting layer 105 emits green light below the second transport layer 114 excluding the first transport layer 213. Since electrons are stopped by the second transport layer 114, the electrons pass inside the second transport layer 114. Since the electrons and holes that have passed through the hole transport layer 208 are recombined, blue light is emitted in the blue layer 107 below the hole transport layer 208 inside the second transport layer 114. The light quantity of each light emitting layer can be controlled by the width of the first transport layer 213 and the second transport layer hole 114. Thereby, the whiteness of the (white) organic electroluminescent element 219b can be adjusted.

  Next, an organic electroluminescence element 219c according to the best mode 7 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 219c, the portion below the electron transport layer 102 is the same as that in FIG. On the electron transport layer 102, a first transport layer (hole transport layer) 213 narrower than the width of the light emitting layer 105 and a light emitting layer are disposed between the red light emitting layer 103, the green light emitting layer 105, and the blue light emitting layer 107 in FIG. A second transport layer (hole transport layer) 120 narrower than the width of the layer 107 is sandwiched.

  The first transport layer 213 and the second transport layer 120 are formed by depositing NBP with a thickness of 400 Å using masks 8 and 9 (not shown). Since each of the light emitting layers 103 and 105 is the host layer Alq3 and the light emitting layer 107 is the host layer BAlq, the movement of holes and electrons is more efficient.

  In FIG. 7, since the first transport layer 213 does not pass electrons through holes, the electrons injected from the cathode 101 and the holes injected from the anode 209 are recombined at the lower portion of the first transport layer 213 to emit red light. The layer 103 emits red light below the first transport layer 213. Since electrons pass through portions other than the first transport layer 213, they are located on the first transport layer 213, and holes and electrons recombine at portions other than the first transport layer 213 below the second transport layer 120. . Therefore, the green light emitting layer 105 emits green light below the second transport layer 120 excluding the first transport layer 213. Since electrons are stopped by the second transport layer 120, the electrons pass outside the second transport layer 120. Since the electrons and holes that have passed through the hole transport layer 208 are recombined, blue light is emitted under the hole transport layer 208 except for the second transport layer 120 in the blue layer 107. The light quantity of each light emitting layer can be controlled by the width of the first transport layer 213 and the second transport layer 120. Thereby, the whiteness of the (white) organic electroluminescent element 219c can be adjusted.

  Next, an organic electroluminescence element 219d according to the best mode 8 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 219d, the portion below the electron transport layer 102 is the same as in FIG. A first transport layer (hole transport layer) 313 narrower than the width of the light-emitting layer 105 is disposed between the red light-emitting layer 103, the green light-emitting layer 105, and the blue light-emitting layer 107 in FIG. A second transport layer (hole transport layer) 120 narrower than the width of the layer 107 is sandwiched.

  The first transport layer 313 and the second transport layer 120 are formed by depositing NBP with a thickness of 400 Å using masks 10 and 9 (not shown). Since each of the light emitting layers 103 and 105 is the host layer Alq3 and the light emitting layer 107 is the host layer BAlq, the movement of holes and electrons is more efficient.

  In FIG. 8, since the first transport layer 313 does not pass electrons through holes, electrons injected from the cathode 101 and holes injected from the anode 209 are recombined at the lower portion of the first transport layer 313. The red light emitting layer 103 emits red light below the first transport layer 313. Since electrons pass through the portion other than the first transport layer 313, it is located on the first transport layer 313, and recombines holes and electrons in the portion other than the first transport layer 313 below the second transport layer 120. To do. Therefore, the green light emitting layer 105 emits green light below the second transport layer 120 excluding the first transport layer 313. Since electrons are stopped by the second transport layer 120, the electrons pass outside the second transport layer 120. Since the electrons and holes that have passed through the hole transport layer 208 are recombined, the blue layer 107 emits blue light below the hole transport layer 208 except for the second transport layer 120. The light quantity of each light emitting layer can be controlled by the width of the first transport layer hole transport layer 313 and the second transport layer 120. Thereby, the whiteness of the (white) organic electroluminescent element 219d can be adjusted.

  Next, an organic electroluminescence element 319 according to the best mode 9 for carrying out the present invention will be described with reference to the schematic diagram of FIG. In the (white) organic electroluminescence element 319, the portion below the electron transport layer 102 is the same as that in FIG. The host layer Alq3 having an LUMO 2.85 eV, HOMO 5.62 eV energy band gap of 2.77 eV on the electron transport layer 102 is doped with 1 wt% of the dopant Coumarin 6 having an LUMO of 2.9 eV, an HOMO 5.3 eV energy band gap of 2.36 eV. The light emitting layer 105 is deposited and formed to a thickness of 500 angstroms.

  On the green light emitting layer 105, a host layer Alq3 is deposited with a dopant of 1 wt% LUMO 3.2 eV, HOMO 5.3 eV and a red dopant DCJTB with an energy band gap of 2.1 eV at a thickness of 200 angstroms to emit red light. Layer 103 is formed. A host layer BAlq having a LUMO of 2.6 eV and a HOMO of 5.3 eV and an energy band gap of 2.7 eV doped with 1 wt% of dopant Perylene is deposited on the red light emitting layer 103 at a thickness of 500 angstroms, and emits blue light. The blue light emitting layer 107 is formed from the organic light emitting material.

  On the blue light emitting layer 107, TPD is deposited to a thickness of 400 angstroms to form a hole transport layer 208 having LUMO 2.3 eV, HOMO 5.5 eV, and energy band gap 3.2 eV. Next, CuPc is deposited on the hole transport layer 208 at a thickness of 20 nm, and an anode 209 is formed on the CuPc.

When a positive voltage is applied to the anode 209 and a negative voltage is applied to the cathode 101, the electrons injected into the light-emitting layers 105, 103, and 107 through the electron transport layer 102 and the holes injected through the hole transport layer 208 are band gaps. Red light is emitted by recombination in the red light emitting layer 103 having the smallest energy. As the voltage is increased, the green layer 105 and the blue layer 107 emit light. The blue material has a larger energy band gap than other green and red materials, and therefore, charge injection tends to be poor. (High energy barrier for charge injection)
The present invention is characterized in that the blue light emitting layer 107 having a large energy band gap is disposed below the hole transport layer 208 under the anode 209. Since it is located under the hole transport layer 208, charge injection does not deteriorate. Furthermore, since the host layers of the red light emitting layer 103 and the green light emitting layer 105 formed below the blue light emitting layer 107 are made of the same electron transport layer material as the electron transport layer 102, the electron transport is also efficient. Since the green light emitting layer 105 is far from the anode 209, the hole transport efficiency is poor. Therefore, the red light emitting layer 103 having the smallest band gap energy is provided on the green light emitting layer 105 to increase the hole transport efficiency and improve the red, green and blue light emission balance to increase the whiteness. Features.

  Next, an organic electroluminescence element 419a according to the best mode 10 for carrying out the present invention will be described with reference to the schematic diagram of FIG. The portion below the electron transport layer 102 is the same as FIG. On the electron transport layer 102, a host layer Alq3 having a LUMO of 2.85 eV and a HOMO of 5.62 eV with an energy band gap of 2.77 eV was doped with 1 wt% of a dopant Coumarin6 having a LUMO of 2.9 eV and a HOMO of 5.3 eV with an energy band gap of 2.36 eV. The green light emitting layer 105 is deposited and formed with a thickness of 500 angstroms. On the green light emitting layer 105, NBP is vapor-deposited with a thickness of 400 Å using the mask 7 to form a transport layer (hole transport layer) 114.

  On the transport layer 114, a host layer Alq3 is deposited with a thickness of 200 angstroms of a red dopant DCJTB doped with LUMO 3.2 eV, HOMO 5.3 eV and an energy band gap of 2.1 eV. Is formed. An electron transport layer 214 made of Alq3 having an LUMO 2.85 eV and a HOMO 5.62 eV energy band gap of 2.77 eV is formed on the red light emitting layer 103 using the mask 7.

  On the electron transport layer 214, a host layer BAlq having a LUMO of 2.6 eV and a HOMO of 5.3 eV and an energy band gap of 2.7 eV doped with 1% by weight of dopant Perylene is deposited at a thickness of 500 angstroms to emit blue light. The blue light emitting layer 107 is formed of the organic light emitting material.

  On the blue light emitting layer 107, TPD is deposited to a thickness of 400 angstroms to form a hole transport layer 208 having LUMO 2.3 eV, HOMO 5.5 eV, and energy band gap 3.2 eV. Next, CuPc is deposited on the hole transport layer 208 at a thickness of 20 nm, and an anode 209 is formed on the CuPc.

  When a positive voltage is applied to the anode 209 and a negative voltage is applied to the cathode 101, electrons transported through the electron transport layer 102 cannot pass through the transport layer 114 in FIG. However, it spreads toward the electron transport layer 214 formed on the red light emitting layer 103. On the other hand, since the holes transported through the hole transport layer 208 do not pass through the electron transport layer 214 in FIG. 10, they are directed below the opening of the electron transport layer 214, but are formed under the red light emitting layer 103. It spreads toward the transport layer 114. For this reason, electrons and holes recombine at the portion of the red light emitting layer 103 shown in FIG. When the voltage is increased, holes transported from the opening of the electron transport layer 214 expand toward the transport layer 114.

Therefore, the hole formed in the transport layer 114 and the electron transported above the electron transport layer 102 are recombined below the transport layer 114, and the green light-emitting layer 105 below the transport layer 114 emits green light. Similarly, when the voltage is further increased, electrons transported from the opening of the transport layer 114 spread toward the electron transport layer 214. Therefore, the electron transported by the electron transport layer 214 and the hole transported below the hole transport layer 208 are recombined at the upper part of the electron transport layer 214 and the blue light emitting layer 107 above the electron transport layer 214 emits blue light. . A blue material has a larger energy band gap than other green and red materials, and thus tends to deteriorate charge injection. (High energy barrier for charge injection)
The present invention is characterized in that the blue light emitting layer 107 having a large energy band gap is disposed below the hole transport layer 208 under the anode 209. Since it is located under the hole transport layer 208, charge injection does not deteriorate. Furthermore, since the host layer of the red light emitting layer 103 and the green light emitting layer 105 formed under the blue light emitting layer 107 is composed of the same electron transport layer material as the electron transport layer 102, the electron transport is also efficient. .

  The green light-emitting layer 105 is farthest from the anode 209, but has a feature in that a red light-emitting layer having the smallest band gap is provided on the top, and the hole mobility is made efficient by the transport layer 114. Here, currents related to green light emission and blue light emission pass through the transport layer 114 and the central opening of the electron transport layer 214. And since it does not pass through a red light emission part (triangle part of FIG. 10), since it does not become an energization current of a red light emission part, there exists the characteristic which is not related to the time-dependent change of the red light emission layer 103. For this reason, the energization life of the red light emitting layer 103 can be extended. Furthermore, by managing the widths of the transport layer 114 and the electron transport layer 214, it is possible to improve the balance of white light emission and increase the whiteness.

  Next, an organic electroluminescence element 419b according to the best mode 11 for carrying out the present invention will be described with reference to the schematic diagram of FIG. The portion below the electron transport layer 102 is the same as FIG. On the electron transport layer 102, a host layer Alq3 having a LUMO of 2.85 eV and a HOMO of 5.62 eV with an energy band gap of 2.77 eV was doped with 1 wt% of a dopant Coumarin6 having a LUMO of 2.9 eV and a HOMO of 5.3 eV with an energy band gap of 2.36 eV. The green light emitting layer 105 is deposited and formed with a thickness of 500 angstroms.

  On the green light emitting layer 105, using a mask 8 (not shown), NBP is vapor-deposited with a thickness of 400 angstroms to form a transport layer (hole transport layer) 213. On the transport layer 213, a host layer Alq3 is doped with 1 wt% of a red dopant DCJTB having a LUMO of 3.2 eV and a HOMO of 5.3 eV and an energy band gap of 2.1 eV. Is formed.

  On the red light emitting layer 103, an electron transport layer 214 made of Alq 3 with LUMO 2.85 eV and HOMO 5.62 eV energy band gap 2.77 eV is formed using a mask 7 (not shown).

  On the electron transport layer 214, a host layer BAlq having a LUMO of 2.6 eV and a HOMO of 5.3 eV with an energy band gap of 2.7 eV doped with 1% by weight of dopant Perylene is deposited at a thickness of 500 Å, and is blue. The blue light emitting layer 107 is formed of a light emitting organic light emitting material.

  On the blue light emitting layer 107, TPD is vapor-deposited with a thickness of 400 angstroms to form a hole transport layer 208 with LUMO 2.3 eV, HOMO 5.5 eV, and energy band gap 3.2 eV.

  On the hole transport layer 208, CuPc is deposited in a thickness of 20 nm, and an anode 209 is formed on the CuPc. When a positive voltage is applied to the anode 209 and a negative voltage is applied to the cathode 101, electrons transported through the electron transport layer 102 cannot pass through the transport layer 213 in FIG. Therefore, it goes upward from the opening of the transport layer 213, but goes to the electron transport layer 214 formed on the red light emitting layer 103.

  On the other hand, since the holes transported through the hole transport layer 208 do not pass through the electron transport layer 214 in FIG. 11, the holes travel downward from the opening of the electron transport layer 214, but are formed below the red light emitting layer 103. To the transport layer 213 formed. For this reason, electrons and holes recombine at the portion of the red light emitting layer 103 shown in FIG.

  When the voltage is further increased, holes transported from the opening of the electron transport layer 214 are directed to the transport layer 213. Therefore, the holes formed by the transport layer 213 and the electrons transported above the electron transport layer 102 are recombined below the transport layer 213, and the green light emitting layer 105 below the transport layer 213 emits green light.

  Similarly, when the voltage is further increased, electrons transported from the opening of the transport layer 213 are directed to the electron transport layer 214. Therefore, electrons from the electron transport layer 214 and the holes transported below the hole transport layer 208 are recombined above the electron transport layer 214, and blue light is emitted from the blue light emitting layer 107 above the electron transport layer 214. .

  Here, since the current related to green light emission and blue light emission passes through the transport layer 213 and the central opening of the electron transport layer 214 and does not pass through the red light emission portion (the triangular portion shown in FIG. 11), the red light emission. Therefore, there is a feature that is not related to the temporal change of the red light emitting layer 103. Furthermore, by managing the widths of the transport layer 213 and the electron transport layer 214, it is possible to improve the balance of white light emission and increase whiteness.

  Next, an organic electroluminescence element 419c according to the best mode 12 for carrying out the present invention will be described with reference to the schematic diagram of FIG. The portion below the electron transport layer 102 is the same as FIG. On the electron transport layer 102, a host layer Alq3 having a LUMO of 2.85 eV and a HOMO of 5.62 eV with an energy band gap of 2.77 eV is doped with 1 wt% of a dopant Coumarin6 having a LUMO of 2.9 eV and a HOMO of 5.3 eV with an energy band gap of 2.36 eV. A green light emitting layer 105 is deposited and formed to a thickness of 500 angstroms.

  On the green light emitting layer 105, using a mask 11 (not shown), NBP is deposited to a thickness of 400 angstroms to form a transport layer (hole transport layer) 313. On the transport layer 313, a host layer Alq3 doped with 1 wt% red dopant DCJTB with LUMO 3.2 eV, HOMO 5.3 eV energy band gap 2.1 eV is deposited at a thickness of 200 angstroms to emit red light Layer 103 is formed.

  On the red light emitting layer 103, an electron transport layer 121 made of Alq 3 with LUMO 2.85 eV and HOMO 5.62 eV energy band gap 2.77 eV is formed using a mask 11 (not shown). On the electron transport layer 121, a host layer BAlq having a LUMO of 2.6 eV and a HOMO of 5.3 eV and an energy band gap of 2.7 eV doped with 1% by weight of dopant Perylene is deposited at a thickness of 500 angstroms. The blue light emitting layer 107 is formed of a light emitting organic light emitting material.

  On the blue light emitting layer 107, TPD is vapor-deposited with a thickness of 400 angstroms to form a hole transport layer 208 with LUMO 2.3 eV, HOMO 5.5 eV, and energy band gap 3.2 eV.

  On the hole transport layer 208, CuPc is deposited in a thickness of 20 nm, and an anode 209 is formed on the CuPc. When a positive voltage is applied to the anode 209 and a negative voltage is applied to the cathode 201, electrons transported through the electron transport layer 102 cannot pass through the transport layer 313 in FIG. Therefore, the electrons travel upward from the opening of the transport layer 313 but travel toward the electron transport layer 121 formed on the red light emitting layer 103.

  On the other hand, the holes transported through the hole transport layer 208 cannot pass through the electron transport layer 121 of FIG. For this reason, the holes go downward from the opening of the electron transport layer 121, but go to the transport layer 313 formed below the red light emitting layer 103. For this reason, electrons and holes recombine at a portion indicated by a triangle in the red light emitting layer 103 in FIG. 12 to emit red light.

  When the voltage is further increased, holes transported from the opening of the electron transport layer 121 are directed to the transport layer 313. Therefore, the hole formed by the transport layer 313 and the electron transported above the electron transport layer 102 are recombined below the transport layer 313, and the green light emitting layer 105 below the transport layer 313 emits green light.

  Similarly, when the voltage is increased, electrons transported from the opening of the transport layer 313 are directed to the electron transport layer 121. Therefore, the electron transported by the electron transport layer 121 and the hole transported below the hole transport layer 208 are recombined above the electron transport layer 121, and blue light is emitted from the blue light emitting layer 107 above the electron transport layer 121. .

  Here, currents related to green light emission and blue light emission pass through the red light emitting layer 103 facing the transport layer 313 and the electron transport layer 121 and do not pass through the red light emitting portion (the triangular portion shown in FIG. 12). The red light emitting layer 103 has a characteristic that it does not become an energizing current. For this reason, since it is not related to the time-dependent change of the red light emitting layer 103, a lifetime can be extended. Furthermore, by managing the widths of the transport layer 313 and the electron transport layer 121, it is possible to improve the balance of white light emission and increase the whiteness.

  Next, an organic electroluminescence element 419d according to the best mode 13 for carrying out the present invention will be described with reference to the schematic diagram of FIG. The portion below the electron transport layer 102 is the same as FIG. On the electron transport layer 102, a host layer Alq3 having a LUMO of 2.85 eV and a HOMO of 5.62 eV with an energy band gap of 2.77 eV is doped with 1 wt% of a dopant Coumarin6 having a LUMO of 2.9 eV and a HOMO of 5.3 eV with an energy band gap of 2.36 eV. A green light emitting layer 105 is deposited and formed to a thickness of 500 angstroms.

  On the green light emitting layer 105, using a mask 6 (not shown), NBP is vapor-deposited to a thickness of 400 angstroms to form a transport layer (hole transport layer) 213. On the transport layer 213, a host layer Alq3 doped with 1 wt% red dopant DCJTB with LUMO 3.2 eV, HOMO 5.3 eV energy band gap 2.1 eV is deposited at a thickness of 200 Å, and emits red light. Layer 103 is formed.

  On the red light emitting layer 103, an electron transport layer 122 made of Alq 3 with LUMO 2.85 eV and HOMO 5.62 eV energy band gap 2.77 eV is formed using a mask 8 (not shown). A host layer BAlq with LUMO 2.6 eV, HOMO 5.3 eV energy band gap 2.7 eV doped with 1 wt% dopant Perylene is deposited on the electron transport layer 122 at a thickness of 500 angstroms, and emits blue light. A blue light emitting layer 107 is formed of the light emitting material.

  On the blue light emitting layer 107, TPD is vapor-deposited with a thickness of 400 angstroms to form a hole transport layer 208 with LUMO 2.3 eV, HOMO 5.5 eV, and energy band gap 3.2 eV.

  On the hole transport layer 208, CuPc is deposited in a thickness of 20 nm, and an anode 209 is formed on the CuPc. When a positive voltage is applied to the anode 209 and a negative voltage is applied to the cathode 101, electrons transported through the electron transport layer 102 cannot pass through the transport layer 213 in FIG. For this reason, the electrons travel upward from the opening of the transport layer 213, but travel toward the electron transport layer 122 formed on the red light-emitting layer 103.

  On the other hand, since the holes transported through the hole transport layer 208 do not pass through the electron transport layer 122 in FIG. 13, the holes travel downward from the opening of the electron transport layer 122, but are formed below the red light emitting layer 103. To the transport layer 213 formed. For this reason, electrons and holes are recombined at a portion indicated by a triangle in the red light emitting layer 103 in FIG. 13 to emit red light.

  As the voltage is increased, holes transported from the opening of the electron transport layer 122 are directed toward the transport layer 213. Therefore, the hole formed by the transport layer 213 and the electron transported above the electron transport layer 102 are recombined below the transport layer 213, and the green light emitting layer 105 below the transport layer 213 emits green light.

  Similarly, when the voltage is further increased, electrons transported from the opening of the transport layer 213 are directed to the electron transport layer 122. Therefore, the electron transported by the electron transport layer 122 and the hole transported below the hole transport layer 208 are recombined above the electron transport layer 122, and blue light is emitted from the blue light emitting layer 107 above the electron transport layer 122. .

  Here, currents related to green light emission and blue light emission pass through the transport layer 213 and the red light-emitting layer 103 facing the electron transport layer 122 and do not pass through the red light-emitting portion (the triangular portion shown in FIG. 13). For this reason, the current does not become an energization current of the red light emitting portion and is not related to the change with time of the red light emitting layer 103, so that the lifetime can be extended. Furthermore, by managing the widths of the transport layer 213 and the electron transport layer 122, the balance of white light emission can be improved and the whiteness can be increased. Above, description of organic electroluminescent element 419d is completed. In addition, the formal names of the materials described in the above names are as follows.

  PBD is 2- (4-biphenyl) -5- (4-tert-butyphenyl) -1,3,4-oxadiazole.

  NBP is N, N'-Di ((naphthalene-1-yl) -N, N'-diphenyl-benzidine).

  Alq3 is Tris (8-hydroxyquinolinato) aluminum.

  DCJTB is (2- (1,1-Dimethylethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tertmethyl-1H, 5H-benzo [ij] quinolizin- 9-yl) ethenyl) -4H-pyran-4-ylidene) preparedintrile. It is.

  Coumarin 6 is a 3- (2-Benzothiazolyl) -7- (diethylamino) coumarin. It is.

  BAlq was prepared from (1,1'-Bisphenyl-4-Olato) bis (2-methyl-8-quinolineplate-N1,08) Aluminum. It is.

  TPD is (4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenyline).

  Next, with respect to each of the electroluminescent elements shown in the best modes 1 to 13 and the conventional example (FIG. 15), a driving current of 10 mA / square cm was supplied and measurement was performed. Shown in Luminance was measured with a luminance meter, and luminous efficiency and CIE chromaticity were measured with a multichannel analyzer. Moreover, about the lifetime, the time when a brightness | luminance becomes half from the initial stage was measured.

  The present invention is not limited to the best modes 1 to 13 described above, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention. Absent. In the present invention, a three-layer full-color element, a three-layer, and a two-layer white element have been described. However, by stacking n stages as one light emitting unit excluding the cathode, anode, and both electrodes, Since the drive current is 1 / (2-3) n, current consumption and power consumption can be reduced. Moreover, although the present invention has been described with respect to an organic electroluminescence element using fluorescence, it can also be applied to an organic electroluminescence element that emits phosphorescence.

1 is a schematic view showing a basic configuration of a (full color) organic electroluminescent element 100 according to the best mode 1 for carrying out the present invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 119a which concerns on the best form 2 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 119b which concerns on the best form 3 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 119c which concerns on the best form 4 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 219a which concerns on the best form 5 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 219b which concerns on the best form 6 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 219c which concerns on the best form 7 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 219d which concerns on the best form 8 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 319 which concerns on the best form 9 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 419a which concerns on the best form 10 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 419b which concerns on the best form 11 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 419c which concerns on the best form 12 for implementing this invention. It is the schematic which shows the basic composition of the (white) organic electroluminescent element 419d which concerns on the best form 13 for implementing this invention. It is a characteristic table | surface at the time of measuring by supplying the drive current of 10 mA / square cm with respect to the electroluminescent element shown in the said forms 1-13 and the prior art example. It is the schematic which shows the basic composition of the conventional organic electroluminescent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Organic electroluminescent element 101 Cathode 102 Electron carrying layer 103 Red light emitting layer 104 1st transport layer 105 Green light emitting layer 106 2nd transport layer 107 Blue light emitting layer 108 Hole transport layer 109 Anode

Claims (23)

An organic electroluminescent device comprising a plurality of light emitting layers sandwiched between a cathode and an anode, wherein a transport layer is provided above each light emitting layer. In the electroluminescence light-emitting portion composed of two or more light-emitting layers, each light-emitting layer is doped with a light-emitting organic material so that the value of the energy band gap of the light-emitting organic material increases in order from the cathode side. An organic electroluminescence device characterized. In an electroluminescent light emitting part composed of two or more light emitting layers, each light emitting layer is doped with a light emitting organic material so that the energy band gap value of the light emitting organic material increases in order from the cathode side, and a band is interposed between them. An organic electroluminescence device characterized by sandwiching a light emitting layer having the smallest gap. 2. The organic electroluminescent device according to claim 1, wherein each light emitting layer is doped with a light emitting organic material so that an energy band gap value of the light emitting organic material becomes larger in order from the cathode side. . Each light-emitting layer is doped with a light-emitting organic material so that the value of the energy band gap of the light-emitting organic material increases in order from the cathode side, and the light-emitting layer with the smallest band gap is sandwiched therebetween. The organic electroluminescent element according to claim 1. The electroluminescent light emitting unit includes an electron transport layer, a first light emitting layer, a transport layer, a second light emitting layer, and a hole transport layer between the cathode and the anode. The organic electroluminescent element of Claim 1 or Claim 2. The electroluminescent light emitting unit includes an electron transport layer, a first light emitting layer, a transport layer having a width smaller than that of the first light emitting layer, a second light emitting layer, and a hole transport layer between the cathode and the anode. The organic electroluminescent device according to claim 1 or 2, characterized by comprising: The electroluminescent light emitting unit includes an electron transport layer, a first light emitting layer, a first transport layer, a second light emitting layer, a second transport layer, and a third light emitting layer between the cathode and the anode. 4. The organic electroluminescent element according to claim 1, wherein the organic electroluminescent element comprises a hole transport layer. The electroluminescent light emitting unit includes an electron transport layer, a first light emitting layer, a first transport layer that is narrower than the first light emitting layer, a second light emitting layer, a second light emitting layer, and a second light emitting layer, between the cathode and the anode. The organic electroluminescent element according to any one of claims 1 to 3, comprising a two transport layer, a third light emitting layer, and a hole transport layer. The electroluminescent light emitting unit includes an electron transport layer, a first light emitting layer, a first transport layer having a width narrower than the first light emitting layer, a second light emitting layer, a width between the cathode and the anode. The organic electroluminescent device according to claim 1, comprising: a second transport layer narrower than the second light-emitting layer, a third light-emitting layer, and a hole transport layer. . The organic electroluminescence according to any one of claims 1, 2, 6, and 7, wherein the first light emitting layer is orange and the second light emitting layer is blue-green. Sense element. The organic electroluminescence according to any one of claims 1, 2, 6, and 7, wherein the first light emitting layer is yellow and the second light emitting layer is blue. element. The said 1st light emitting layer is made into red, the said 2nd light emitting layer is made into green, and the said 3rd light emitting layer is made into blue, The claim | item 1, Claim 2, Claim 8, Claim 9 characterized by the above-mentioned. 10. The organic electroluminescent element according to any one of 10 above. The first light-emitting layer 3 is green, the second light-emitting layer 4 is red, and the third light-emitting layer is blue. The claim 1, claim 3, claim 8, claim 9, The organic electroluminescent element of any one of Claims 10. The organic electroluminescent element according to claim 1, wherein the light emitting layer is formed of the same host layer. The organic light-emitting device according to claim 1, wherein the light-emitting layer contains Alq 3. The organic electroluminescent element according to claim 1, wherein each of the light emitting layers has an emission spectrum different from each other. 3. The organic electroluminescent element according to claim 1, wherein an emission color is blue light, green light, or red light depending on a combination of the light emitting layers. The organic electroluminescent element according to any one of claims 1 to 14, wherein an emission color is white light by a combination of the light emitting layers. The organic electroluminescence device according to any one of claims 1, 8, and 10, wherein the transport layers sandwiched between the light emitting layers are arranged vertically. 11. The structure according to claim 1, wherein the transport layers sandwiched between the light-emitting layers are placed on the upper and lower sides, and the functions of the upper and lower transport layers are made different. 11. The organic electroluminescent element of description. 11. The transport layer having a width between the light emitting layers narrower than that of the light emitting layer is placed so that the upper and lower sides of the transport layer are aligned, and the functions of the upper and lower transport layers are made different. 2. The organic electroluminescent element according to item 1. The light quantity of the said light emitting layer was adjusted by changing the width | variety of the said transport layer pinched | interposed by the said light emitting layer, Any of Claim 6, Claim 8, Claim 9, Claim 10 characterized by the above-mentioned. 2. The organic electroluminescent element according to item 1.

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