CN117479590A - Organic electroluminescent device and display panel - Google Patents
Organic electroluminescent device and display panel Download PDFInfo
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- CN117479590A CN117479590A CN202310848074.XA CN202310848074A CN117479590A CN 117479590 A CN117479590 A CN 117479590A CN 202310848074 A CN202310848074 A CN 202310848074A CN 117479590 A CN117479590 A CN 117479590A
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- H10K50/00—Organic light-emitting devices
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- H10K50/856—Arrangements for extracting light from the devices comprising reflective means
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- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
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Abstract
The application provides an organic electroluminescent device and display panel, the organic electroluminescent device includes: a substrate; a reflective layer on the substrate; an anode on the reflective layer; a light-emitting functional layer located on the anode, wherein the light-emitting functional layer comprises a plurality of light-emitting units which are stacked; the charge generation layer is positioned between two adjacent layers of the light emitting units; a cathode located on the light-emitting functional layer; wherein the material of the reflecting layer is inorganic nonmetallic material. According to the organic electroluminescent device and the display panel, the SPP effect caused by too close distance between the luminescent layer close to the anode and the metal total reflection layer in the organic electroluminescent device with the serial structure can be effectively reduced, the luminous efficiency of the organic electroluminescent device is improved, and the power consumption is reduced.
Description
Technical Field
The application relates to the technical field of display, in particular to an organic electroluminescent device and a display panel.
Background
In an Organic Light-Emitting Diode (OLED), excitons, after recombination in the Light-Emitting layer, radiate energy primarily in the form of photons, which are free to radiate outward in the form of visible Light in the form of discontinuous Light-wave trains of temporally and spatially discontinuous photons.
In the display field, top emission structures are typically used to obtain more color-pure, more efficient devices, which have certain requirements for both the distance of the light emitting layer from the total reflection layer and the material of the total reflection layer. Especially in a multi-light source serial organic electroluminescent device (Tandem OLED) structure, the Tandem OLED device comprises a substrate, a metal total reflection layer, an anode, a plurality of luminescent layers and a cathode which are sequentially stacked, and as the metal total reflection layer and the luminescent layer close to the anode have the problem of too close distance, the surface plasmon effect (SPP effect) of the luminescent layer close to the anode can be very obvious, so that light waves are restrained in the anode electrode and cannot be emitted, the emergent light efficiency is reduced, and the overall luminescent performance of the organic electroluminescent device is reduced.
Disclosure of Invention
The application provides the organic electroluminescent device and the display panel, which can effectively reduce the SPP effect of a luminescent layer close to an anode in the organic electroluminescent device with a serial structure due to too close distance to a metal total reflection layer, improve the luminous efficiency of the organic electroluminescent device and reduce the power consumption.
The application provides an organic electroluminescent device, comprising:
a substrate;
a reflective layer on the substrate;
an anode on the reflective layer;
a light-emitting functional layer located on the anode, wherein the light-emitting functional layer comprises a plurality of light-emitting units which are stacked;
the charge generation layer is positioned between two adjacent layers of the light emitting units; and
A cathode located on the light-emitting functional layer;
wherein the material of the reflecting layer is inorganic nonmetallic material.
In an alternative embodiment of the present application, the reflective layer is a bragg reflective layer.
In an alternative embodiment of the present application, the bragg reflection layer includes a plurality of film layers that are stacked, wherein refractive indexes of adjacent film layers are different.
In an optional embodiment of the present application, the bragg reflection layer includes at least one first film layer and at least one second film layer, where the first film layer and the second film layer are alternately stacked, and a refractive index of the first film layer is greater than a refractive index of the second film layer.
In an alternative embodiment of the present application, the thickness of each film layer of the bragg reflection layer satisfies the relationship: n is n H t H ＝n L t L ＝λ 0 4, wherein n H N being the refractive index of the first film layer L Is the refractive index of the second film layer, t H T is the thickness of the first film layer L Lambda is the thickness of the second film layer 0 The wavelength of light displayed for the organic electroluminescent device.
In an optional embodiment of the present application, the material of the first film layer is silicon oxynitride or silicon nitride, and the material of the second film layer is silicon oxide.
In an alternative embodiment of the present application, the material of the anode is a transparent metal film, and the thickness of the anode is less than or equal to 5nm.
In an alternative embodiment of the present application, the material of the anode is a transparent metal oxide film, and the thickness of the anode is less than or equal to 12nm.
In an alternative embodiment of the present application, the light emitting unit includes a hole transport layer, a light emitting layer, and an electron transport layer that are stacked, where the hole transport layer is located at a side of the light emitting layer near the anode, and the electron transport layer is located at a side of the light emitting layer near the cathode.
The application also provides a display panel comprising the organic electroluminescent device according to any of the embodiments above.
The organic electroluminescent device provided by the application utilizes the reflecting layer of the inorganic nonmetallic material to replace the metal total reflecting layer in the organic electroluminescent device with the existing series structure, the reflecting layer of the application not only has the reflecting function of the traditional metal total reflecting layer, but also is made of the inorganic nonmetallic material, compared with the existing metal total reflecting layer, the SPP effect between the reflecting layer and the luminous layer of the inorganic nonmetallic material is smaller, and the luminous efficiency of the luminous layer close to the anode can be improved. Therefore, the organic electroluminescent device can effectively reduce the SPP effect of the luminescent layer close to the anode due to too close distance to the metal total reflection layer, improve the overall luminous efficiency of the organic electroluminescent device and reduce the power consumption of the organic electroluminescent device.
Drawings
In order to more clearly illustrate the embodiments or the technical solutions in the prior art, the following description will briefly introduce the drawings that are needed in the embodiments or the description of the prior art, it is obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of an organic electroluminescent device in the prior art;
fig. 2 is a schematic structural diagram of an organic electroluminescent device according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a bragg reflection layer of an organic electroluminescent device according to an embodiment of the present application;
fig. 4 is a schematic diagram of a response band of a bragg reflection layer of an organic electroluminescent device according to an embodiment of the present application;
FIG. 5 is a schematic diagram showing spectral contrast between an organic electroluminescent device according to an embodiment of the present disclosure and an organic electroluminescent device according to the prior art;
FIG. 6 is a schematic diagram showing the performance of an organic electroluminescent device according to an embodiment of the present disclosure compared with that of a related art organic electroluminescent device;
fig. 7 is a schematic structural diagram of another organic electroluminescent device according to an embodiment of the present application;
FIG. 8 is a schematic diagram of response bands of a Bragg reflection layer of another organic electroluminescent device according to an embodiment of the present disclosure;
fig. 9 is a schematic structural diagram of a display panel according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of another display panel according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
In the description of the present application, it should be understood that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description of the present application and to simplify the description, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present application, the meaning of "a plurality" is two or more, unless specifically defined otherwise.
The present application may repeat reference numerals and/or letters in the various examples, and such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Referring to fig. 1, a schematic structural diagram of an organic electroluminescent device in the prior art is shown, where the organic electroluminescent device includes a substrate 100, a metal total reflection layer 210, an anode 300, a light-emitting functional layer 400, and a cathode 500, which are sequentially stacked; wherein the light emitting functional layer 400 includes a plurality of light emitting units stacked. As shown in fig. 1, taking an example in which the light emitting functional layer 400 includes two layers of the light emitting units, specifically, the light emitting functional layer 400 includes a first light emitting unit 410 located on the anode 300 and a second light emitting unit 420 located on the first light emitting unit 410; further, the first light emitting unit 410 includes a first hole transport layer 411 (HTL), a first light emitting layer 412 (EL), and a first electron transport layer 413 (ETL) sequentially stacked, and the second light emitting unit 420 includes a second hole transport layer 421 (HTL), a second light emitting layer 422 (EL), and a second electron transport layer 423 (ETL) sequentially stacked, wherein a first charge generation layer 401 (CGL) is further included between the first electron transport layer 413 and the second hole transport layer 421.
In the OLED device, the light emitting functional layer 400 is located between the anode 300 and the cathode 500, and is electrically connected to the anode 300 and the cathode 500. When a current is applied, holes generated by the anode 300 and electrons generated by the cathode 500 move under the action of an electric field, and are respectively injected into the hole transport layer and the electron transport layer and migrate to the light emitting layer, and when the hole transport layer and the electron transport layer meet at the light emitting layer, energy excitons are generated, and after the excitons are combined in the light emitting layer, energy is mainly radiated outwards in the form of photons, so that visible light is generated.
For the Tandem OLED device, the light emitting functional layer 400 includes a plurality of light emitting units stacked in series, the plurality of light emitting units share a pair of anode 300 and cathode 500, two adjacent light emitting units are connected through the charge generating layer, and the Tandem OLED device can improve the lifetime and the light emitting efficiency of the device by connecting the plurality of light emitting units in series.
In the OLED device, when the light emitting layer emits light and propagates outward, there is an SPP effect at the metal/medium interface, which causes a decrease in the efficiency of emitted light, thereby decreasing the light emitting performance of the OLED device.
Surface plasmons (Surface Plasmon Polarition, SPP), when free electrons of light waves (electromagnetic waves) incident on a metal surface generate collective oscillation, near-field electromagnetic waves propagating along the metal surface are formed by coupling the free electrons of the electromagnetic waves and the metal surface, resonance is generated if the oscillation frequency of the electrons is consistent with the frequency of the incident light waves, and the energy of the electromagnetic field is converted into collective vibration energy of the free electrons of the metal surface in a resonance state, so that a special electromagnetic mode is formed: the electromagnetic field is confined to a very small area of the metal surface and enhanced, a phenomenon known as surface plasmon phenomenon.
Because SPP effect increases exponentially along with the decrease of the distance from the metal surface, in the Tandem OLED device, the problem that the distance between the light-emitting layer close to the anode and the metal total reflection layer on one side of the anode is too close is caused, so that the SPP effect of the light-emitting layer close to the anode is very obvious, light waves are restrained in the anode electrode and cannot be emitted, the light-emitting efficiency of the light-emitting layer close to the anode is reduced, namely, the light-emitting efficiency of the light-emitting layer close to the metal total reflection layer is obviously lower than that of the light-emitting layer far from the metal total reflection layer, and the overall light-emitting performance of the organic electroluminescent device is reduced.
As shown in fig. 1, the distance from the first light emitting layer 412 to the metal total reflection layer 210 is far smaller than the distance from the second light emitting layer 422 to the metal total reflection layer 210, which means that there is a large SPP loss in the first light emitting layer 412, and the light emitting efficiency of the first light emitting layer 412 is far smaller than the light emitting efficiency of the second light emitting layer 422, so that the overall light emitting performance of the organic electroluminescent device is reduced, and the power consumption is increased.
In order to solve the above problems, the present application provides an organic electroluminescent device and a display panel, so as to reduce the SPP effect and improve the light emitting efficiency of the organic electroluminescent device.
The organic electroluminescent device and the display panel provided by the present application will be described in detail below with reference to specific embodiments and drawings.
Referring to fig. 2, the present application provides an organic electroluminescent device, including: a substrate 100; a reflective layer on the substrate 100; an anode 300 on the reflective layer; a light emitting function layer 400 on the anode 300, the light emitting function layer 400 including a plurality of light emitting units stacked; the charge generation layer is positioned between two adjacent layers of the light emitting units; and a cathode 500 on the light emitting functional layer 400; wherein the material of the reflecting layer is inorganic nonmetallic material.
Further, the reflective layer is a bragg reflective layer 220.
Further, the light emitting unit includes a hole transporting layer, a light emitting layer, and an electron transporting layer, which are stacked, the hole transporting layer is located at a side of the light emitting layer near the anode 300, and the electron transporting layer is located at a side of the light emitting layer near the cathode 500.
Further, the organic electroluminescent device further includes an encapsulation layer 600, and the encapsulation layer 600 is located on the cathode 500.
Specifically, as shown in fig. 2, the organic electroluminescent device includes a substrate 100, a bragg reflection layer 220, an anode 300, a first hole transport layer 411, a first light emitting layer 412, a first electron transport layer 413, a first charge generation layer 401, a second hole transport layer 421, a second light emitting layer 422, a second electron transport layer 423, a cathode 500, and an encapsulation layer 600, which are sequentially stacked.
The substrate 100 may be glass or a flexible material for supporting other layers of film on the substrate 100.
The bragg reflection layer 220 is made of an inorganic nonmetallic material, such as silicon oxynitride, silicon nitride, silicon oxide, etc., and is used for reflecting light emitted by the light emitting layer, and the light emitted by the light emitting layer generates microcavity resonance between the bragg reflection layer 220 and the cathode 500, so that the light emitting efficiency, the color purity, etc. can be improved.
The anode 300 may be a metal or metal oxide, such as Ag, al, au, ITO, etc., for providing holes. Further, the anode 300 may be made of a highly transparent material to improve light reflectivity.
The cathode 500 may be Ag, al, li, mg or the like or an alloy thereof for supplying electrons.
The first hole transport layer 411/the second hole transport layer 421 are used to transport holes injected from the anode 300 to the first light emitting layer 412/the second light emitting layer 422, and to block electrons from the cathode 500 from being directly transported to the anode 300; the first electron transport layer 413/second electron transport layer 423 is used to transport electrons injected from the cathode 500 to the first light emitting layer 412/second light emitting layer 422, and to block holes from the anode 300 from being directly transported to the cathode 500, so that the transport rate of holes and the transport rate of electrons are balanced, and holes and electrons can be effectively recombined in the light emitting layer.
The first charge generation layer 401 is used to connect a plurality of the light emitting cells in series, and provide electrons and holes. The first charge generation layer 401 is composed of an n-doped layer and a p-doped layer for injecting electrons and holes, respectively, electrons and holes in the Tandem OLED device are supplied from the first charge generation layer 401 and the electrode, electrons and holes consumed in the first charge generation layer 401 are refilled with electrons and holes injected from the cathode 500 and the anode 300, respectively, and then the bipolar current gradually reaches a steady state.
The encapsulation layer 600 may be an organic or inorganic film layer for protecting other film layers between the substrate 100 and the encapsulation layer 600.
In the conventional Tandem OLED device, the total reflection layer on the anode 300 is usually made of a metal material such as silver, and the first light-emitting layer 412 has a significant SPP effect due to the too close distance from the metal total reflection layer 210. The present application replaces the existing metal total reflection layer 210 with the bragg reflection layer 220 made of inorganic nonmetallic materials, and the SPP effect between the inorganic film layer and the first light-emitting layer 412 is far smaller than the SPP effect between the metal film layer and the first light-emitting layer 412, meanwhile, the bragg reflection layer 220 has a better reflection effect than the metal total reflection layer 210, so that the organic electroluminescent device of the present application can effectively reduce the SPP effect of the first light-emitting layer 412 caused by too short distance from the metal total reflection layer 210, improve the light-emitting efficiency of the organic electroluminescent device, and reduce the power consumption of the organic electroluminescent device.
In an alternative embodiment of the present application, the bragg reflection layer 220 includes a plurality of stacked film layers, and refractive indexes of adjacent film layers are different. The materials of the plurality of film layers in the bragg reflection layer 220 may be the same or different. When light passes through the films with different refractive indexes, the light reflected by the films is subjected to enhanced interference due to the change of phase angles, and then is combined with each other to obtain strong reflected light, namely strong emission exists at the interface of the anode 300 and the Bragg reflection layer 220, so that the reflectivity of visible light is improved, and the luminous efficiency of the organic electroluminescent device is improved.
In an alternative embodiment of the present application, referring to fig. 3, the bragg reflection layer 220 includes at least one first film layer 221 and at least one second film layer 222, where the first film layer 221 and the second film layer 222 are alternately stacked, and the refractive index of the first film layer 221 is greater than the refractive index of the second film layer 222. The first film 221 is a high refractive index film, the second film 222 is a low refractive index film, and the bragg reflection layer 220 is formed by alternately laminating two films having different refractive indexes. In actual production, the number of layers of the bragg reflection layer 220 may be set according to the requirements of different organic electroluminescent devices on luminous efficiency, so as to obtain a product meeting the requirements.
When the Bragg reflection layer 220 is formed by overlapping a high refractive index film layer and a low refractive index film layer, the reflectivity thereof is satisfiedWherein N is the number of film layers; n is n a A refractive index of the film layer on the side of the Bragg reflection layer 220 away from the substrate 100; n is n b Folded for the substrate 100Emissivity of the material; n is n H Taking the refractive index of the high refractive index material; n is n L Is a low refractive index material refractive index.
The photon forbidden band Δλ of the bragg reflection layer 220 satisfiesWherein lambda is 0 In order to respond to the central wavelength of the band, such as blue light is about 460nm, green light is about 530nm, red light is about 630nm, and the photon forbidden band determines the range of the bragg reflection layer 220 capable of realizing the total reflection function, which is closely related to the optical refractive index of the materials, and in general, the larger the refractive index difference between the materials is, the wider the bandwidth of the response can be.
Further, the thickness of each film layer of the bragg reflection layer 220 needs to satisfy the relationship: n is n H t H ＝n L t L ＝λ 0 4, wherein n H N, the refractive index of the first film 221 L Is the refractive index, t, of the second film 222 H Is the thickness, t, of the first film 221 L Lambda is the thickness of the second film layer 222 0 For responding to the center wavelength of the band, i.e. the wavelength of light displayed by the organic electroluminescent device.
In an alternative embodiment of the present application, the first film 221 is a high refractive index film, for example, a high refractive index material such as silicon oxynitride or silicon nitride may be selected; the second film 222 is a low refractive index film, and may be made of a low refractive index material such as silicon oxide.
In the conventional OLED device, the anode 300 and the metal total reflection layer 210 are generally both silver metal materials, because silver has better reflection properties. Therefore, in the process, a portion of the anode 300 is generally used as the metal total reflection layer 210, and thus the overall film layer of the anode 300 is generally thicker. After the Bragg reflection layer 220 is utilized to replace the existing metal reflection layer, the thickness of the film layer of the anode 300 can be reduced, the anode 300 material can be a thin metal material or a thin metal oxide material, the deposition process of the anode 300 can be simplified, and the cost is reduced.
In an alternative embodiment of the present application, when the material of the anode 300 is a transparent metal film, the thickness of the anode 300 is less than or equal to 5nm.
In an alternative embodiment of the present application, when the material of the anode 300 is a metal oxide film, the thickness of the anode 300 is less than or equal to 12nm.
In an alternative embodiment of the present application, the organic electroluminescent device may be a monochromatic light device, such as a blue OLED device, a red OLED device, a green OLED device, or the like.
Taking a blue light OLED device as an example, comparing the performances of the organic electroluminescent device with the performances of the existing organic electroluminescent device, wherein the structure of the existing organic electroluminescent device is shown in fig. 1, the structure of the organic electroluminescent device is shown in fig. 2, and the difference between the structure of the existing organic electroluminescent device and the structure of the existing organic electroluminescent device is that the existing organic electroluminescent device adopts a silver metal total reflection layer 210, the organic electroluminescent device of the application adopts a Bragg reflection layer 220, and other film structures and materials are the same. As shown in fig. 3, the bragg reflector 220 is formed by alternately stacking a first film 221 and a second film 222, wherein the first film 221 is a high refractive index film with a refractive index n H 2.02, the second film 222 is a low refractive index film with a refractive index n L 1.4, refractive index n of substrate 100 b Taking 1.51, the refractive index n of the organic film layer on the side of the Bragg reflection layer 220 far from the substrate 100 a Taking 1.75; thickness t of the first film 221 H And thickness t of the second film layer 222 L Satisfy the relation n H t H ＝n L t L ＝λ 0 /4。
Referring to fig. 4, fig. 4 is a schematic diagram of a response band of a bragg reflection layer of an organic electroluminescent device according to an embodiment of the present application. In fig. 4, the abscissa indicates wavelength and the ordinate indicates reflectance. As can be seen from fig. 4, when n=10, the bragg reflection layer 220 can already satisfy a reflection effect of 95% or more, and when n=20, the bragg reflection layer 220 can already achieve 100% reflection at blue light.
Referring to fig. 5, fig. 5 is a schematic diagram showing spectral contrast between an organic electroluminescent device according to an embodiment of the present application and an organic electroluminescent device according to the prior art. In fig. 5, the abscissa indicates the wavelength, the ordinate indicates the intensity, a indicates the light emission spectrum of the organic electroluminescent device of the present application, and b indicates the light emission spectrum of the conventional organic electroluminescent device. As can be seen from fig. 5, compared with the existing organic electroluminescent device using the silver metal total reflection layer 210, the organic electroluminescent device using the bragg reflection layer 220 of the present application has narrower spectrum, higher Peak value Peak and higher color purity in the blue light band.
Referring to fig. 6, fig. 6 is a schematic diagram illustrating performance comparison between an organic electroluminescent device according to an embodiment of the present application and an organic electroluminescent device according to the prior art. In fig. 6, the abscissa indicates wavelength, the ordinate indicates intensity, c indicates light extraction efficiency of the organic electroluminescent device of the present application, d indicates light extraction efficiency of the conventional organic electroluminescent device, e indicates SPP loss of the organic electroluminescent device of the present application, and f indicates SPP loss of the conventional organic electroluminescent device. As can be seen from fig. 6, compared with the existing organic electroluminescent device using the silver metal total reflection layer 210, the SPP effect of the organic electroluminescent device of the present application is only about 20% of that of the conventional organic electroluminescent device, and the light extraction efficiency of the organic electroluminescent device of the present application is improved by about 30%.
From the above, the bragg reflection layer 220 has excellent performance at short wavelengths, which means that it also has better performance in white light Tandem OLED devices. Therefore, the organic electroluminescent device may be not only a monochromatic light device but also a polychromatic light device.
For example, the Bragg reflection layer 220 is prepared with the center wavelength of 490nm, so that the total reflection in the range of 425-600 nm can be realized, and a TV device of blue+Green+CF is prepared based on the total reflection, compared with the conventional Tandem OLED device of the metal total reflection layer 210, the luminous efficiency of the organic electroluminescent device can be further improved due to the substantial weakening of SPP effect.
Referring to fig. 7, a schematic structural diagram of another organic electroluminescent device according to an embodiment of the present application is taken as an example of a white light Tandem OLED device. The organic electroluminescent device comprises a substrate 100, a Bragg reflection layer 220, an anode 300, a light emitting function layer 400, a cathode 500, a light extraction layer 700 (CPL), a packaging layer 600 and a quantum dot color film layer 800 which are sequentially stacked. The light emitting functional layer 400 includes a first light emitting unit 410, a second light emitting unit 420, a third light emitting unit 430, and a fourth light emitting unit 440, which are sequentially stacked. Specifically, as shown in fig. 7, the light-emitting functional layer 400 includes a first hole-transporting layer 411, a first light-emitting layer 412, a first electron-transporting layer 413, a first charge-generating layer 401, a second hole-transporting layer 421, a second light-emitting layer 422, a second electron-transporting layer 423, a second charge-generating layer 402, a third hole-transporting layer 431, a third light-emitting layer 432, a third electron-transporting layer 433, a third charge-generating layer 403, a fourth hole-transporting layer 441, a fourth light-emitting layer 442, and a fourth electron-transporting layer 443, which are sequentially stacked; the first light-emitting layer 412, the second light-emitting layer 422 and the third light-emitting layer 432 emit blue light, the fourth light-emitting layer 442 emits green light, and the combination of the light-emitting layers with different colors finally forms a white light-emitting Tandem OLED device. Fig. 8 is a schematic diagram of response bands of the bragg reflection layer 220 of the organic electroluminescent device according to the present embodiment.
Referring to fig. 9 to 10, the present application further provides a method for preparing an organic electroluminescent device, the method comprising the steps of:
s1, providing a substrate 110, and manufacturing a thin film transistor on the substrate 110. The substrate 110 is a flexible material, which may be polyimide PI, for example.
Further, the fabrication of the thin film transistor on the substrate 110 specifically includes: an active layer 120, a gate insulating layer 130, a gate electrode 140, an interlayer insulating layer 150, a source and drain electrode layer (including a source electrode 161 and a drain electrode 162), and a planarization layer 170 are sequentially formed on the substrate 110.
In some embodiments, the thin film transistor may include a multi-layer gate structure, as shown in fig. 9 to 10, including a first gate insulating layer 131 on the active layer 120, a first gate 141 on the first gate insulating layer 131, a second gate insulating layer 132 on the first gate 141, and a second gate 142 on the second gate insulating layer 132.
It should be noted that the structure of the thin film transistor is not limited to the above structure, and may be any structure in the prior art.
S2, forming a bragg reflection layer 220 on the flat layer 170, wherein the bragg reflection layer 220 is formed by alternately stacking a first film layer 221 and a second film layer 222, and the refractive index of the first film layer 221 is greater than the refractive index of the second film layer 222.
Further, first, a first film layer 221 is deposited on the flat layer 170, then a second film layer 222 is deposited on the first film layer 221, and then the first film layer 221 is deposited on the second film layer 222, so that the first film layer 221 and the second film layer 222 are stacked alternately. The material of the first film 221 may be an inorganic material such as silicon oxynitride or silicon nitride, and the second film 222 may be an inorganic material such as silicon oxide. The first film 221 and the second film 222 may be formed by a CVD process.
And S3, forming an anode 300 on the Bragg reflection layer 220.
Further, a via hole is formed on the bragg reflection layer 220 and the planarization layer 170, and an anode 300 is formed on the bragg reflection layer 220, and the anode 300 is electrically connected to the source electrode through the via hole. The process of achieving the overlap of the anode 300 may be an etching and PVD process, wherein the vias may be realized by one via, or a plurality of vias. As shown in fig. 9, the anode 300 is overlapped with the source electrode 161 through the first via 310; as shown in fig. 10, the anode 300 is overlapped with the source electrode 161 through the first via 310 and the second via 320. The overlapping position (via hole connection) of the anode 300 needs to deviate from the position right below the pixel anode 300, so as to avoid uneven anode 300 caused by the process and ensure the stability of the film structure of the anode 300. The material of the anode 300 is a metal or a metal oxide, and the anode 300 is a highly transparent material. When the anode 300 is a metal, it may be Ag, AL, au, or the like; when the anode 300 is a metal oxide, it may be ITO or the like.
S4, forming a pixel defining layer 900 on the anode 300, wherein the pixel defining layer 900 has an opening, forming a light emitting function layer 400 in the opening, and the light emitting function layer 400 includes a plurality of stacked light emitting units.
Specifically, taking the example that the light emitting functional layer 400 includes two layers of light emitting units, forming the light emitting functional layer 400 in the opening includes: a first hole transport layer 411, a first light emitting layer 412, a first electron transport layer 413, a first charge generation layer 401, a second hole transport layer 421, a second light emitting layer 422, and a second electron transport layer 423 are sequentially formed in the opening, wherein the first charge generation layer 401 is used to connect two light emitting units.
S5, forming a cathode 500 on the light emitting functional layer 400.
And S6, forming an encapsulation layer 600 on the cathode 500 to obtain the organic electroluminescent device.
The present application also provides a display panel comprising an organic electroluminescent device as described in any one of the embodiments above.
In summary, the present application provides an organic electroluminescent device and a display panel, where the organic electroluminescent device provided herein uses a reflective layer made of an inorganic nonmetallic material to replace a metal total reflective layer in an organic electroluminescent device with an existing serial structure, and the reflective layer of the present application has a reflective function of a traditional metal total reflective layer, and meanwhile, the material of the reflective layer of the present application is an inorganic nonmetallic material, compared with the existing metal total reflective layer, the SPP effect between the reflective layer and the luminescent layer made of an inorganic nonmetallic material is smaller, so that the light-emitting efficiency of the luminescent layer close to the anode can be improved. Therefore, the organic electroluminescent device can effectively reduce the SPP effect of the luminescent layer close to the anode due to too close distance to the metal total reflection layer, improve the overall luminous efficiency of the organic electroluminescent device and reduce the power consumption of the organic electroluminescent device.
In summary, although the present application has been described with reference to the preferred embodiments, the preferred embodiments are not intended to limit the application, and those skilled in the art can make various modifications and adaptations without departing from the spirit and scope of the application, and the scope of the application is therefore defined by the claims.
Claims (10)
1. An organic electroluminescent device, comprising:
a substrate;
a reflective layer on the substrate;
an anode on the reflective layer;
a light-emitting functional layer located on the anode, wherein the light-emitting functional layer comprises a plurality of light-emitting units which are stacked;
the charge generation layer is positioned between two adjacent layers of the light emitting units; and
A cathode located on the light-emitting functional layer;
wherein the material of the reflecting layer is inorganic nonmetallic material.
2. The organic electroluminescent device of claim 1, wherein the reflective layer is a bragg reflective layer.
3. The organic electroluminescent device of claim 2, wherein the bragg reflection layer comprises a plurality of film layers arranged in a stack, wherein refractive indices of adjacent film layers are not the same.
4. The organic electroluminescent device of claim 3, wherein the bragg reflector layer comprises at least a first film layer and at least a second film layer, the first film layer and the second film layer are alternately stacked, and the refractive index of the first film layer is greater than the refractive index of the second film layer.
5. The organic electroluminescent device of claim 4, wherein each film layer of the Bragg reflection layer is thickThe degree satisfies the relation: n is n H t H ＝n L t L ＝λ 0 4, wherein n H N being the refractive index of the first film layer L Is the refractive index of the second film layer, t H T is the thickness of the first film layer L Lambda is the thickness of the second film layer 0 The wavelength of light displayed for the organic electroluminescent device.
6. The organic electroluminescent device according to claim 4, wherein the material of the first film layer is silicon oxynitride or silicon nitride, and the material of the second film layer is silicon oxide.
7. The organic electroluminescent device according to any one of claims 1 to 6, wherein the material of the anode is a transparent metal thin film, and the thickness of the anode is less than or equal to 5nm.
8. The organic electroluminescent device of any one of claims 1 to 6, wherein the anode is made of a transparent metal oxide thin film, and the anode has a thickness of 12nm or less.
9. The organic electroluminescent device according to any one of claims 1 to 6, wherein the light emitting unit comprises a hole transport layer, a light emitting layer, and an electron transport layer, which are stacked, the hole transport layer being located at a side of the light emitting layer near the anode, and the electron transport layer being located at a side of the light emitting layer near the cathode.
10. A display panel comprising an organic electroluminescent device as claimed in any one of claims 1 to 9.
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| CN202310848074.XA CN117479590A (en) | 2023-07-11 | 2023-07-11 | Organic electroluminescent device and display panel |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310848074.XA CN117479590A (en) | 2023-07-11 | 2023-07-11 | Organic electroluminescent device and display panel |
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| CN117479590A true CN117479590A (en) | 2024-01-30 |
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| CN202310848074.XA Pending CN117479590A (en) | 2023-07-11 | 2023-07-11 | Organic electroluminescent device and display panel |
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| Country | Link |
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| CN (1) | CN117479590A (en) |
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