CN108511618B - Organic electroluminescent device - Google Patents
Organic electroluminescent device Download PDFInfo
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- CN108511618B CN108511618B CN201810470437.XA CN201810470437A CN108511618B CN 108511618 B CN108511618 B CN 108511618B CN 201810470437 A CN201810470437 A CN 201810470437A CN 108511618 B CN108511618 B CN 108511618B
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- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
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- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
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- H10K50/00—Organic light-emitting devices
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- H10K50/852—Arrangements for extracting light from the devices comprising a resonant cavity structure, e.g. Bragg reflector pair
Abstract
The invention relates to the technical field of display, and discloses an organic electroluminescent device which comprises m luminous units with different luminous wavelengths, wherein each luminous unit is a monochromatic light organic luminous unitThe light emitting diode comprises at least one organic light emitting diode with a microcavity structure, wherein at least two light emitting layers are arranged in the organic light emitting diode, and the thicknesses of first electrode layers in the organic light emitting diodes corresponding to light emitting units with different light emitting wavelengths are not all the same; the microcavity optical length L of the organic light-emitting diode with the microcavity structure and the light-emitting wavelength lambda of the corresponding light-emitting unit satisfy the following relational expression: l isi＝niλi(ii) a Wherein n is more than or equal to 2, n is a positive integer, and n corresponding to at least one organic light-emitting diode is more than or equal to 3. Namely, n-order microcavity effect can be realized in the organic light-emitting diode with the microcavity structure, and n is a positive integer greater than or equal to 2, so that a second-order microcavity, a third-order microcavity or a higher-order microcavity can be realized, the microcavity effect is enhanced, the spectrum is further narrowed, and the color gamut area is further improved.
Description
Technical Field
The invention relates to the technical field of display, in particular to an organic electroluminescent device.
Background
An Organic Light Emitting Display (abbreviated as OLED) is an active Light Emitting Display device, and has the advantages of high contrast, wide viewing angle, low power consumption, and thinner volume, and can be prepared by an inkjet printing technology and a roll-to-roll (roll) process, so that flexible Display is easy to implement, and is one of the most concerned technologies in the current flat panel Display technology.
With the continuous development of OLED technology, higher and higher requirements are put on the performance of display devices. For example, to improve color gamut, etc. The color gamut is a method for encoding a color and also refers to the sum of colors that a technical system is capable of producing. Fig. 1 is a color coordinate diagram prepared by NTSC (National Television Standards Committee), and it can be seen from the diagram that the larger the color gamut area is, the richer the display color of the display device is, and the better the viewing experience is.
In order to adapt to the development trend of the times, the color gamut area is generally increased by improving the purity of three primary colors in the prior art. Specifically, the method comprises the following steps: firstly, synthesizing a narrow-spectrum luminescent material, and improving the luminescent color purity of a pixel by using the narrow-spectrum luminescent material; and secondly, introducing quantum dots, and improving the color purity by utilizing the narrow spectral characteristics of the quantum dots.
However, the above solutions all have their own drawbacks, for example, in the first solution, the organic light emitting material has large design and synthesis workload, low yield, and high development cost due to a large amount of experimental verification; in the second scheme, although the introduction of the quantum dot technology can improve the color gamut, the quantum dot technology is substantially photoluminescence, is not electroluminescence, and has low luminous efficiency.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is that the color gamut of the OLED device is not high enough in the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the embodiment of the invention provides an organic electroluminescent device, which comprises m light-emitting units with different light-emitting wavelengths, wherein each light-emitting unit is a monochromatic light organic light-emitting diode or a white light organic light-emitting diode provided with a light filter;
at least one of the organic light emitting diodes has a microcavity structure;
the organic light emitting diode comprises a first electrode layer, a light emitting layer and a second electrode layer which are arranged in a stacked mode; at least one organic light-emitting diode with a microcavity structure is provided with at least two light-emitting layers, and the thicknesses of the first electrode layers in the organic light-emitting diodes corresponding to light-emitting units with different light-emitting wavelengths are not all the same;
the microcavity optical length L of the organic light-emitting diode with the microcavity structure and the light-emitting wavelength lambda of the corresponding light-emitting unit satisfy the following relational expression:
Li＝niλi
wherein n isi≥2，niN is a positive integer corresponding to at least one organic light emitting diodeiGreater than or equal to 3; m is more than or equal to i and more than or equal to 1, and i and m are positive integers.
Optionally, all the organic light emitting diodes have a microcavity structure; m is 3, lambda1＞λ2＞λ3(ii) a And n is2＞n1，n2＞n3。
Alternatively, 577nm ≧ λ2≥492nm，n2≥3。
Optionally, the first electrode layer includes a reflective layer and an anode layer stacked, the anode layer being disposed adjacent to the light emitting layer.
Optionally, the thicknesses of the reflective layers in the organic light emitting diodes corresponding to the light emitting units with different light emitting wavelengths are the same, and the thicknesses of the anode layers are not all the same.
Optionally, the number of the light emitting layers in the organic light emitting diodes corresponding to the light emitting units with different light emitting wavelengths is not all the same.
Optionally, a transparent connecting layer is arranged between adjacent light emitting layers, and the thickness of the transparent connecting layer is 1nm-100 nm.
Optionally, the second electrode layer in at least one of the organic light emitting diodes includes several layers of metal oxide and metal layers alternately arranged.
Optionally, the thicknesses of the metal oxide layer and/or the metal layer in the organic light emitting diode corresponding to the light emitting units with different light emitting wavelengths are not all the same.
Optionally, the light transmittance of the second electrode layer is not less than 15%, and the refractive index is greater than 1 and less than 2.
The technical scheme of the invention has the following advantages:
the organic electroluminescent device provided by the embodiment of the invention comprises m luminescent units with different luminescent wavelengths, namely, m luminescent wavelengths of light are mixed together to realize full-color display. The light emitting unit is a monochromatic light organic light emitting diode or a white light organic light emitting diode provided with a light filter, namely, the light emitting unit can be formed by combining a plurality of monochromatic light organic light emitting diodes with different light emitting wavelengths, so that full-color display is realized; or a plurality of white light organic light emitting diodes are combined, and light with different wavelengths is filtered out by the optical filter and mixed to be displayed in full color; the full-color display can also be formed by a monochromatic organic light emitting diode and a white organic light emitting diode with different light emitting wavelengths. Therefore, the organic light emitting diode is suitable for different organic light emitting diodes and has a wide application range.
The microcavity optical length L and the luminous wavelength lambda of each organic light-emitting diode with the microcavity structure satisfy the following relational expression:
Li＝niλi
wherein n isi≥2，niN is a positive integer corresponding to at least one organic light emitting diodeiMore than or equal to 3, m is more than or equal to i and more than or equal to 1, and i and m are positive integers.
In the microcavity of the organic light emitting diode, when the cavity length and the wavelength of the light wave are in the same order of magnitude, the light with a specific wavelength can be selected and enhanced, so that the spectrum narrowing is realized, namely the microcavity effect is generated.
The microcavity optical length L of the organic light-emitting diode with the microcavity structure in the organic electroluminescent device provided by the embodiment of the invention is n times of the light-emitting wavelength of the corresponding light-emitting unit, namely, n-order microcavity effect can be realized in the organic light-emitting diode with the microcavity structure, and n is a positive integer greater than or equal to 2, so that a second-order microcavity, a third-order microcavity, a fourth-order microcavity or a higher-order microcavity can be realized, the microcavity effect is enhanced, the spectrum is further narrowed, and the color gamut area is further increased.
In addition, in this embodiment, at least one of the organic light emitting diodes having the microcavity structure has at least two light emitting layers, that is, two light emitting layers or three or more light emitting layers may be disposed in one or more organic light emitting diodes according to actual requirements. Therefore, on one hand, the microcavity optical path of one or more organic light-emitting diodes is increased, the microcavity effect is enhanced, the color gamut area is increased, and the integral high color gamut of the organic electroluminescent device is ensured; on the other hand, the luminous flux is obviously increased, and the luminous efficiency and the luminous effect are improved.
The thicknesses of the first electrode layers in the organic light emitting diodes corresponding to the light emitting units with different light emitting wavelengths are not all the same, that is, the first electrode layers with different thicknesses can be arranged according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the microcavity is adjusted, the organic light emitting diodes with different emergent light correspond to different microcavity intensities, and the high color gamut and the narrow spectrum of the whole organic electroluminescent device are ensured.
For example, the color coordinates of the blue light device are closer to those of the blue light with high color gamut standard, the red light device can realize the color gamut expansion through the spectrum red shift, and the green light device is difficult to realize the color gamut expansion like the red light device and the blue light device due to the self limitation. Therefore, the thickness of the first electrode layer of the green device can be set to be larger than that of the red device and the blue device, so that the optical path of the green device can be increased in a targeted manner, the microcavity order of the green device can be improved, the microcavity effect of the green device can be enhanced, the high color gamut of the whole organic electroluminescent device can be matched with the high color gamut of the red device and the high color gamut of the blue device, and the high color gamut of the whole organic electroluminescent device can be realized.
In the organic electroluminescent device provided by the embodiment of the invention, all the organic light emitting diodes have a microcavity structure; m is 3, lambda1＞λ2＞λ3(ii) a And n is2＞n1，n2＞n3. That is, the organic electroluminescent device includes light-emitting units with three light-emitting wavelengths, such as λ1At red wavelength, λ2At green wavelength, λ3And the full-color display is realized by traditional three primary colors for blue light wavelength.
Wherein n is2＞n1，n2＞n3That is, the intensity of the microcavity effect of the organic light emitting diode corresponding to the green light is greater than the intensity of the microcavity effect of the organic light emitting diodes corresponding to the red light and the blue light. This is due to the blueThe color coordinates of the optical device are relatively close to those of blue light with high color gamut standard, the red light device can realize color gamut expansion through spectrum red shift, and the green light device is difficult to realize color gamut expansion like the red light device and the blue light device due to the self limitation, so that the embodiment of the invention emphasizes the enhancement of the microcavity effect of the green light device to be matched with the high color gamuts of the red light device and the blue light device, and the high color gamut of the whole organic electroluminescent device is realized.
The organic electroluminescent device provided by the embodiment of the invention has 577nm ≥ lambda2≥492nm，n2The microcavity order of the organic light emitting diode corresponding to the green light wavelength is 3 or higher, and the color gamut area of the organic light emitting diode is expanded by enhancing the microcavity intensity of the organic light emitting diode corresponding to the green light wavelength.
In the organic electroluminescent device according to the embodiment of the present invention, the first electrode layer includes a reflective layer and an anode layer that are stacked, and the anode layer is disposed adjacent to the light emitting layer. The reflecting layer and the anode layer jointly form a first electrode layer, so that on one hand, the thickness of the first electrode layer is increased, the optical path is increased, and further the microcavity effect is enhanced; on the other hand, the reflective layer is independently arranged, so that the reflective effect of the first electrode layer is improved, and the microcavity effect is further enhanced.
In the organic electroluminescent device provided by the embodiment of the invention, the thicknesses of the reflective layers in the organic light emitting diodes corresponding to the light emitting units with different light emitting wavelengths are the same, and the thicknesses of the anode layers are not all the same. In practical application, the anode layers with different thicknesses can be set according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the microcavity is adjusted, the organic light-emitting diodes with different emergent light correspond to different microcavity intensities, and the high color gamut and the narrow spectrum of the whole organic electroluminescent device are ensured.
In the organic electroluminescent device provided by the embodiment of the invention, the number of the light emitting layers in the organic light emitting diodes corresponding to the light emitting units with different light emitting wavelengths is not all the same. The light emitting layers with different numbers can be arranged for the organic light emitting diodes corresponding to different light emitting units according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the corresponding microcavity is adjusted, and the organic light emitting diodes with different emergent light correspond to different microcavity intensities.
In the organic electroluminescent device provided by the embodiment of the present invention, the second electrode layer in at least one organic light emitting diode includes a plurality of metal oxide layers and metal layers alternately disposed. Therefore, by arranging the plurality of layers of metal oxides or metal layers, the thickness of the second electrode layer in the corresponding organic light-emitting diode is increased, the microcavity optical path is increased, and the microcavity effect is further enhanced.
In the organic electroluminescent device provided by the embodiment of the invention, the thicknesses of the metal oxide layer and/or the metal layer in the organic light emitting diode corresponding to the light emitting units with different light emitting wavelengths are not all the same. The thicknesses of different metal oxide layers and/or metal layers can be correspondingly set according to different types of emergent light, so that the microcavity optical path corresponding to the emergent light of each type can be adjusted in a targeted manner, the microcavity strength can be adjusted, and the optimal color gamut area and the color gamut area which are matched with each other can be achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a prior art NTSC color gamut diagram;
fig. 2a is a schematic structural diagram of an embodiment of an organic electroluminescent device according to an embodiment of the present invention;
FIG. 2b is a schematic structural diagram of an embodiment of an organic electroluminescent device according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an embodiment of an organic electroluminescent device according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an embodiment of an organic electroluminescent device according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an embodiment of an organic electroluminescent device according to an embodiment of the present invention;
reference numerals:
1-an organic light emitting diode; 11-a first electrode layer; 111-a reflective layer; 112-anode layer; 12-a light emitting layer; 13-a second electrode layer; 131-a metal oxide layer; 132-a metal layer; 14-a transparent tie layer; 15-light extraction layer; 16-an optical compensation layer; 161-hole injection layer; 162-a hole transport layer; 163-electron blocking layer; 164-a hole blocking layer; 165-electron transport layer; 166-electron injection layer; 17-optical filter.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
An embodiment of the present invention provides an organic electroluminescent device, including a plurality of light emitting units with m different light emitting wavelengths, as shown in fig. 2a and 2b, the light emitting units are monochromatic organic light emitting diodes 1 or white organic light emitting diodes 1 provided with optical filters 17, and the types of the optical filters are selected to be red optical filters, green optical filters or blue optical filters according to the wavelength of light to be emitted.
That is, in the organic electroluminescent device, m kinds of light having different emission wavelengths are mixed together to realize full-color display. As shown in fig. 2a, the light emitting unit may be a combination of monochromatic organic light emitting diodes 1 with different light emitting wavelengths, such as a combination of red organic light emitting diode, green organic light emitting diode, and blue organic light emitting diode, to realize full color display; as shown in fig. 2b, the display device may also be formed by combining a plurality of white organic light emitting diodes 1, and light with different wavelengths is filtered out by the optical filter 17 on the light emitting surface of the white organic light emitting diodes 1, for example, red light, green light, and blue light are filtered out and mixed to form a full color display; the full-color display can also be formed by a monochromatic organic light emitting diode and a white organic light emitting diode with different light emitting wavelengths. Therefore, the organic light emitting diode is suitable for different types of organic light emitting diodes and has a wide application range.
In the present embodiment, at least one organic light emitting diode 1 has a microcavity structure. Specifically, as shown in fig. 2a and 2b, the organic light emitting diode 1 includes a first electrode layer 11, a light emitting layer 12, and a second electrode layer 13, which are stacked, typically, the first electrode layer 11 is a reflective electrode layer, the second electrode layer 13 is a transflective electrode layer, and a microcavity structure is formed between the first electrode layer 11 and the second electrode layer 13. In the microcavity structure, when the cavity length and the wavelength of the light wave are in the same order of magnitude, the light with a specific wavelength can be selected and enhanced, so that the spectrum narrowing is realized, namely the microcavity effect is generated.
The microcavity optical length L of the organic light emitting diode 1 having a microcavity structure and the emission wavelength λ of the corresponding light emitting unit satisfy the following relation:
Li＝niλi
wherein n isi≥2，niN is a positive integer corresponding to at least one organic light emitting diodeiGreater than or equal to 3; m is more than or equal to i and more than or equal to 1, and i and m are positive integers.
L specifically refers to a propagation path of light emitted from the light emitting layer during the process of being reflected by the first electrode layer, reflected by the second electrode layer, and returned to the starting position, and an equivalent path generated by reflection phase shift of the first electrode layer and the second electrode layer. The propagation path is typically twice the sum of the products of the thickness of the layers through which the light passes and the corresponding refractive indices.
The microcavity optical length L of the organic light-emitting diode with the microcavity structure in the organic electroluminescent device provided by the embodiment of the invention is n times of the light-emitting wavelength of the corresponding light-emitting unit, namely, n-order microcavity effect can be realized in the organic light-emitting diode with the microcavity structure, and n is a positive integer greater than or equal to 2, so that a second-order microcavity, a third-order microcavity, a fourth-order microcavity or a higher-order microcavity can be realized, the microcavity effect is enhanced, the spectrum is further narrowed, and the color gamut area is further increased.
Preferably, niThe orders of the microcavity effects, i.e., the intensities, in the organic light emitting diodes are not all the same, i.e., different orders of the microcavity effects can be set according to different properties (such as wavelength, spectrum, and the like) of the emitted light, so as to achieve the optimal spectrum narrowing effect and the optimal color gamut area.
In the present embodiment, at least one organic light emitting diode 1 having a microcavity structure has at least two light emitting layers 12. That is, two light emitting layers or three or more light emitting layers may be disposed in one or more organic light emitting diodes according to actual requirements. On one hand, the microcavity length is increased by increasing the number of the luminescent layers, so that the microcavity optical path is increased, the microcavity strength is improved, the color gamut area is improved, and the integral high color gamut of the organic electroluminescent device is ensured; on the other hand, the luminous flux can be effectively increased, and the luminous efficiency and the luminous effect of the organic light-emitting diode are improved.
As an alternative embodiment, a transparent connection layer 14 is disposed between adjacent light-emitting layers 12, the transparent connection layer 14 being selected from but not limited to Li2CO3、HAT-CN、TAPC、Li2CO3HAT-CN, TAPC HAT-CN, Ag, ITO, etc., or a multilayer laminated composite structure, for example, Li2CO3HAT-CN/TAPC, etc. The thickness of the transparent connecting layer 14 is 1nm to 100 nm. .
In this embodiment, the thicknesses of the first electrode layers 11 in the organic light emitting diodes 1 corresponding to the light emitting units with different light emitting wavelengths are not all the same. The first electrode layers with different thicknesses can be arranged according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the microcavity is adjusted, the organic light emitting diodes of different emergent light correspond to different microcavity intensities, and the integral high color gamut and narrow spectrum of the organic electroluminescent device are ensured.
For example, the color coordinates of the blue light device are closer to those of the blue light with high color gamut standard, the red light device can realize the color gamut expansion through the spectrum red shift, and the green light device is difficult to realize the color gamut expansion like the red light device and the blue light device due to the self limitation. Therefore, the thickness of the first electrode layer of the green device can be set to be larger than that of the red device and the blue device, so that the optical path of the green device can be increased in a targeted manner, the microcavity order of the green device can be improved, the microcavity effect of the green device can be enhanced, the high color gamut of the whole organic electroluminescent device can be matched with the high color gamut of the red device and the high color gamut of the blue device, and the high color gamut of the whole organic electroluminescent device can be realized.
As an alternative embodiment, as shown in fig. 3, the first electrode layer 11 includes a reflective layer 111 and an anode layer 112 stacked, and the anode layer 112 is disposed adjacent to the light emitting layer 12. The reflecting layer and the anode layer jointly form a first electrode layer, so that on one hand, the thickness of the first electrode layer is increased, the optical path is increased, and further the microcavity effect is enhanced; on the other hand, the reflective layer is independently arranged, so that the reflective effect of the first electrode layer is improved, and the microcavity effect is further enhanced.
The reflective layer 111 may be a metal material layer, such as a metal silver layer. The anode layer may be a high work function layer, such as an ITO layer.
As an alternative embodiment, the thicknesses of the reflective layers 111 and the anode layers 112 in the organic light emitting diodes 1 corresponding to the light emitting units with different light emitting wavelengths are not all the same. In practical application, the anode layers with different thicknesses can be set according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the microcavity is adjusted, the organic light-emitting diodes with different emergent light correspond to different microcavity intensities, and the high color gamut and the narrow spectrum of the whole organic electroluminescent device are ensured. Generally, the thickness of the anode layer of the organic light emitting diode corresponding to the green light emitting wavelength may be set to be greater than the thickness of the anode layer of the organic light emitting diode corresponding to the red and blue light emitting wavelengths, and the adjustment of the microcavity length corresponding to the emitting wavelength may be achieved by adjusting the thickness of the anode layer.
As an alternative embodiment, the number of the light emitting layers 12 in the organic light emitting diode 1 corresponding to the light emitting units with different light emitting wavelengths is not all the same. The light emitting layers with different numbers can be arranged for the organic light emitting diodes corresponding to different light emitting units according to the attributes (such as wavelength, spectrum and the like) of different emergent light, so that the optical path of the emergent light transmitted in the corresponding microcavity is adjusted, and the organic light emitting diodes with different emergent light correspond to different microcavity intensities.
For example, the number of light emitting layers in the organic light emitting diode corresponding to the green light emission wavelength is set to 2, and the number of light emitting layers in the organic light emitting diode corresponding to the red and blue light emission wavelengths is set to 1; or the number of the light emitting layers in the organic light emitting diodes corresponding to the green light emitting wavelength and the blue light emitting wavelength is set to be two, and the number of the light emitting layers in the organic light emitting diodes corresponding to the red light emitting wavelength is set to be one; or the number of the light emitting layers of the organic light emitting diodes corresponding to the green light emitting wavelength and the red light emitting wavelength is set to be two, and the number of the light emitting layers 12 of the organic light emitting diodes corresponding to the blue light emitting wavelength is set to be one.
As an alternative embodiment, as shown in fig. 4, the second electrode layer 13 in at least one organic light emitting diode 1 includes several layers of metal oxide layers 131 and/or metal layers 132 alternately arranged. Specifically, the second electrode layer may include a metal oxide layer and a metal layer which are sequentially stacked; or two metal oxide layers which are sequentially stacked; the device also can comprise a metal oxide layer, a metal layer and a metal oxide layer which are sequentially stacked, can also be in other combination modes, and can be set according to actual requirements. Therefore, by arranging the plurality of metal oxide layers or metal layers, the thickness of the second electrode layer in the corresponding organic light-emitting diode is increased, the microcavity optical path is increased, and the microcavity effect is further enhanced.
In this embodiment, the metal oxide layer 131 may be MoO3Or WO3Or IZO or the like; the metal layer 132 may be Ag, Mg, or the like. The second electrode layer may be specifically MoO3/Ag/MoO3Or IZO/Ag/IZO, etc.
As an alternative embodiment, the thicknesses of the metal oxide layer 131 and/or the metal layer 132 in the organic light emitting diode 1 corresponding to the light emitting units with different light emitting wavelengths are not all the same. The thicknesses of different metal oxide layers and/or metal layers can be correspondingly set according to different types of emergent light, so that the microcavity optical path corresponding to the emergent light of each type can be adjusted in a targeted manner, the microcavity strength can be adjusted, and the optimal color gamut area and the color gamut area which are matched with each other can be achieved.
As an alternative embodiment, the light transmittance of the second electrode layer 13 is not less than 15%, and the refractive index is greater than 1 and less than 2.
As an alternative embodiment, all the organic light emitting diodes 1 have a microcavity structure; m is 3, lambda1＞λ2＞λ3(ii) a And n is2＞n1，n2＞n3. That is, the organic electroluminescent device includes light-emitting units with three light-emitting wavelengths, such as λ1At red wavelength, λ2At green wavelength, λ3And the full-color display is realized by traditional three primary colors for blue light wavelength.
Wherein n is2＞n1，n2＞n3That is, the intensity of the microcavity effect of the organic light emitting diode corresponding to the green light is greater than the intensity of the microcavity effect of the organic light emitting diodes corresponding to the red light and the blue light. The color coordinates of the blue light device are relatively close to those of the blue light with high color gamut standard, the red light device can realize color gamut expansion through spectrum red shift, and the green light device is difficult to realize color gamut expansion like the red light device and the blue light device due to self limitation, so that the embodiment of the invention emphasizes the enhancement of the microcavity effect of the green light device so as to be matched with the high color gamuts of the red light device and the blue light device, and realize the high color gamut of the whole organic electroluminescent device.
As an alternative, 577nm ≧ λ2≥492nm，n2Not less than 3. I.e. green light wavelength mappingThe order of the microcavity of the organic light emitting diode is set to 3 or higher, and the color gamut area of the organic light emitting diode is expanded by enhancing the microcavity intensity of the organic light emitting diode corresponding to the wavelength of green light.
As an alternative embodiment, as shown in fig. 4, a light extraction layer 15 is further provided on the second electrode layer 13. The arrangement of the light extraction layer improves the utilization rate of light and the luminous efficiency of the organic electroluminescent device.
In this embodiment, the thickness of the light extraction layer 15 is preferably 20 to 100nm, and the refractive index of the light extraction layer 15 is 1.4 to 3.0. The light extraction layer is selected from, but not limited to, TAPC, NPB, TPBi, and the like.
As an alternative embodiment, as shown in fig. 5, a light compensation layer 16 is disposed between the first electrode layer 11 and the second electrode layer 13 of the organic light emitting diode 1 corresponding to the light emitting unit of at least one of the light emitting wavelengths in the organic electroluminescent device. The light compensation layer 16 is at least one of a hole injection layer 161, a hole transport layer 162, an electron blocking layer 163, a hole blocking layer 164, an electron transport layer 165, and an electron injection layer 166. On the one hand, the carrier transmission efficiency is improved, and the luminous efficiency of the device is further improved. On the other hand, the method is beneficial to increasing the length of the micro-cavity in the corresponding organic light-emitting diode, namely increasing the optical length of the micro-cavity, further improving the order of the micro-cavity, enhancing the micro-cavity effect and further realizing the narrowing of the chromatogram and the expansion of the color gamut area.
It should be noted that, the microcavity length can be further adjusted by adjusting the thickness of the hole transport layer, because the thickness of the hole transport layer has a small influence on the electrical performance of the organic light emitting diode, and the microcavity strength is adjusted while ensuring good electrical performance.
Example 1
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The organic electroluminescent device in this embodiment includes monochromatic light organic light emitting diodes of 3 kinds of light emitting wavelengths, which are a red light organic light emitting diode, a green light organic light emitting diode, and a blue light organic light emitting diode, respectively. Wherein, all three organic light emitting diodes have a microcavity structure.
Each organic light emitting diode includes a first electrode layer, a light emitting layer, and a second electrode layer stacked. The green organic light emitting diode comprises two light emitting layers connected by a transparent connecting layer, wherein the transparent connecting layer is Li2CO3HAT-CN/TAPC, thickness 40nm, refractive index 1.8. The blue and red organic light emitting diodes have a light emitting layer therein, respectively.
The thickness of the first electrode layer of the green organic light emitting diode is larger than that of the first electrode layer of the red and blue organic light emitting diodes.
The light transmittance of the second electrode layer was 15%, and the refractive index was 1.5.
In this embodiment, λ corresponding to the red organic light emitting diode1＝630nm，n1＝2，L1＝1260nm；
Lambda corresponding to green light organic light emitting diode2＝520nm，n2＝3，L2＝1560nm；
Lambda corresponding to blue light organic light emitting diode3＝460nm，n3＝2，L3＝920nm。
The structure of the red organic light emitting diode is as follows: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (200nm)/CBP Ir (piq)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)
The device structure of the green organic light emitting diode is as follows: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (100nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/Li2CO3(1nm)/HAT-CN(10nm)/CuPc(20nm)/TPD(100nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)。
The structure of the blue light organic light emitting diode is Ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (110nm)/CBP, DPVBi (3%, 30nm)/TPBi (40nm)/LiF (1nm)/Mg, Ag (20%, 15nm)/NPB (60 nm).
Example 2
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The structure is the same as that of example 1, and is different from the organic electroluminescent device provided in example 1 in that:
the second electrode layer of the green organic light emitting diode comprises two metal oxide layers which are arranged in a stacked mode, and a metal layer arranged between the two metal oxide layers.
The device structure of the green organic light emitting diode is as follows: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (100nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/Li2CO3(1nm)/HAT-CN(10nm)/CuPc(20nm)/TPD(100nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/MoO3/Ag/MoO3(5nm/5nm/5nm)/NPB(60nm)。
Example 3
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The structure is the same as that of example 1, and is different from the organic electroluminescent device provided in example 1 in that:
the transparent connecting layer is TAPC, the thickness is 1nm, and the refractive index is 1.8.
The device structure of the green organic light emitting diode in this embodiment is: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (120nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/TAPC(1nm)/TPD(120nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)。
Example 4
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The structure is the same as that of example 1, and is different from the organic electroluminescent device provided in example 1 in that:
the light transmittance of the second electrode layer was 20%, and the refractive index was 1.8.
In this embodiment, λ corresponding to the red organic light emitting diode1＝630nm，n1＝2，L1＝1260nm；
Lambda corresponding to green light organic light emitting diode2＝520nm，n2＝3，L2＝1560nm；
Lambda corresponding to blue light organic light emitting diode3＝460nm，n3＝2，L3＝920nm。
Red light organic light emitting diodeThe device structure of the tube is as follows: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (200nm)/CBP Ir (piq)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/IZO/Ag(40nm/60nm)/NPB(15nm)；
The device structure of the green organic light emitting diode is as follows: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (100nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/Li2CO3(1nm)/HAT-CN(10nm)/CuPc(20nm)/TPD(100nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/IZO/Ag(40nm/60nm)/NPB(15nm)；
The structure of the blue light organic light emitting diode is Ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (110nm)/CBP, DPVBi (3%, 30nm)/TPBi (40nm)/LiF (1nm)/IZO/Ag (40nm/60nm)/NPB (15 nm).
Example 5
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The structure is the same as that of example 1, and is different from the organic electroluminescent device provided in example 1 in that:
the light compensation layer is included in the micro-cavity structure of the green organic light emitting diode. In this embodiment, the optical compensation layer is a hole transport layer TPD, and the thicknesses thereof are 80nm and 80nm, respectively.
In this embodiment, the device structure of the green organic light emitting diode is as follows: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (800nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/Li2CO3(1nm)/HAT-CN(10nm)/CuPc(20nm)/TPD(180nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)。
Example 6
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The structure is the same as that of example 1, and differs from that of the organic electroluminescent devices provided in examples 1 to 6 in that:
in this embodiment, λ corresponding to the red organic light emitting diode1＝630nm，n1＝3，L1＝1890nm；
Lambda corresponding to green light organic light emitting diode2＝520nm，n2＝4，L2＝2080nm；
Lambda corresponding to blue light organic light emitting diode3＝460nm，n3＝2，L3＝1260nm。
The device structure of the red organic light emitting diode in the embodiment is as follows: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (380nm)/CBP Ir (piq)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)；
The device structure of the green organic light emitting diode in this embodiment is: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (170nm)/CBP Ir (ppy)3(10％,30nm)/TPBi(40nm)/Li2CO3(1nm)/HAT-CN(10nm)/CuPc(20nm)/TPD(170nm)/CBP:Ir(ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)；
The device structure of the blue organic light emitting diode in this embodiment is: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (110nm)/CBP DPVBi (3%, 30nm)/TPBi (40nm)/LiF (1nm)/Mg Ag (20%, 15nm)/NPB (60 nm).
Example 7
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The device structure was the same as in example 1. The difference from the organic electroluminescent device provided in example 1 is that:
the organic electroluminescent device in this embodiment is composed of a white organic light emitting diode, and a red light filter, a green light filter and a blue light filter are respectively disposed on a light emitting surface of the white organic light emitting diode.
Red light unit: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (20nm)/CBP Ir (ppy)3 (15%): Ir (piq)3 (0.2%) (30nm)/TPBi (30nm)/Li2CO3(1nm)/HAT-CN (10nm)/CuPc (20nm)/TPD (20nm)/CBP DPVBi (3%, 30nm)/TPBi (30nm)/LiF (1nm)/Mg: Ag (20%, 15nm)/NPB (60 nm);
green light unit: ag (10nm)/ITO (180nm)/CuPc (20nm)/TPD (20nm)/CBP Ir (ppy)3 (15%): Ir (piq)3 (0.2%) (30nm)/TPBi (30nm)/Li2CO3(1nm)/HAT-CN (10nm)/CuPc (20nm)/TPD (20nm)/CBP DPVBi (3%, 30nm)/TPBi (30nm)/LiF (1nm)/Mg: Ag (20%, 15nm)/NPB (60 nm);
blue light unit: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (20nm)/CBP Ir (ppy)3 (15%): Ir (piq)3 (0.2%) (30nm)/TPBi (30nm)/Li2CO3(1nm)/HAT-CN (10nm)/CuPc (20nm)/TPD (20nm)/CBP DPVBi (3%, 30nm)/TPBi (30nm)/LiF (1nm)/Mg: Ag (20%, 15nm)/NPB (60 nm);
the wavelengths of the red light filter, the green light filter and the blue light filter are respectively as follows: 630nm, 522nm and 456 nm.
Example 8
Embodiments of the present invention provide a specific example of an organic electroluminescent device. The device structure was the same as in example 1. The difference from the organic electroluminescent device provided in example 1 is that:
the red and blue organic light emitting diodes do not have a microcavity structure.
Comparative example 1
This comparative example provides an organic electroluminescent device having the same structure as that of example 1, differing from the organic electroluminescent device provided in example 1 in that:
the green, red and blue organic light emitting diodes each have a light emitting layer.
Comparative example 2
This comparative example provides an organic electroluminescent device having the same structure as that of example 1, differing from the organic electroluminescent device provided in example 1 in that:
the thicknesses of the first electrode layers of the green, red and blue organic light emitting diodes are the same.
Comparative example 3
This comparative example provides an organic electroluminescent device having the same structure as that of example 1, differing from the organic electroluminescent device provided in example 1 in that:
the light transmittance of the second electrode layer was 10%, and the refractive index was 0.8.
Comparative example 4
This comparative example provides a specific example of an organic electroluminescent device, which has the same structure as that of example 1, and differs from the organic electroluminescent device provided in example 1 in that: n is1＝n2＝n3＝2。
The structure of the red organic light emitting diode in the comparative example is as follows: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (200nm)/CBP Ir (piq)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)。
The device structure of the green organic light emitting diode in the comparative example is as follows: ag (10nm)/ITO (160nm)/CuPc (20nm)/TPD (140nm)/CBP Ir (ppy)3(3％,30nm)/TPBi(40nm)/LiF(1nm)/Mg:Ag(20％,15nm)/NPB(60nm)。
The device structure of the blue organic light emitting diode in the comparative example is as follows: ag (10nm)/ITO (100nm)/CuPc (20nm)/TPD (110nm)/CBP DPVBi (3%, 30nm)/TPBi (40nm)/LiF (1nm)/Mg Ag (20%, 15nm)/NPB (60 nm).
The performance of the above devices was tested and the results are shown in the following table:
as can be seen from the data in the table above, the organic electroluminescent device provided by the embodiment of the invention can effectively improve the color purity and increase the color gamut area; meanwhile, the organic electroluminescent device provided by the embodiment of the invention can also effectively improve the luminous efficiency of the device.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (8)
1. An organic electroluminescent device, characterized by comprising m kinds of light-emitting units with different light-emitting wavelengths, wherein the light-emitting units are monochromatic organic light-emitting diodes (1) or white organic light-emitting diodes (1) provided with optical filters (17);
all the organic light-emitting diodes (1) have a microcavity structure;
the organic light-emitting diode (1) comprises a first electrode layer (11), a light-emitting layer (12) and a second electrode layer (13) which are arranged in a stacked manner; at least two light-emitting layers (12) are arranged in at least one organic light-emitting diode (1) with a microcavity structure, and the thicknesses of the first electrode layers (11) in the organic light-emitting diodes (1) corresponding to light-emitting units with different light-emitting wavelengths are not all the same;
the microcavity optical length L of the organic light-emitting diode (1) with the microcavity structure and the light-emitting wavelength lambda of the corresponding light-emitting unit satisfy the following relation:
Li＝niλi
wherein n isi≥2，niN is a positive integer corresponding to at least one organic light emitting diodeiGreater than or equal to 3; m is more than or equal to i and more than or equal to 1, and i and m are positive integers;
the organic light emitting diode corresponding to the green light emitting wavelength is provided with two light emitting layers (12), the organic light emitting diode corresponding to the red light and the blue light emitting wavelengths is provided with a single light emitting layer (12), and a transparent connecting layer (14) is arranged between the two light emitting layers (12) of the organic light emitting diode corresponding to the green light emitting wavelength; the intensity of the microcavity effect of the organic light emitting diode corresponding to the green light emitting wavelength is greater than the intensity of the microcavity effect of the organic light emitting diode corresponding to the red light emitting wavelength and the blue light emitting wavelength.
2. The organic electroluminescent device according to claim 1, wherein m is 3, λ1＞λ2＞λ3(ii) a And n is2＞n1，n2＞n3。
3. The organic electroluminescent device according to claim 1 or 2, wherein 577nm ≧ λ2≥492nm，n2≥3。
4. The organic electroluminescent device according to claim 1 or 2, characterized in that the first electrode layer (11) comprises a reflective layer (111) and an anode layer (112) stacked, the anode layer (112) being arranged close to the light emitting layer (12).
5. The organic electroluminescent device according to claim 4, wherein the thickness of the reflective layer (111) in the organic light emitting diode (1) corresponding to the light emitting units with different light emitting wavelengths is the same, and the thickness of the anode layer (112) is not all the same.
6. The organic electroluminescent device according to claim 1 or 2, characterized in that the second electrode layer (13) in at least one of the organic light emitting diodes (1) comprises several layers of alternately arranged metal oxide layers (131) and/or metal layers (132).
7. The organic electroluminescent device according to claim 6, wherein the thicknesses of the metal oxide layer (131) and/or the metal layer (132) in the organic light emitting diode (1) corresponding to the light emitting units of different light emitting wavelengths are not all the same.
8. The organic electroluminescent device according to claim 1 or 2, characterized in that the light transmittance of the second electrode layer (13) is not less than 15% and the refractive index is greater than 1 and less than 2.
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