CN114944461A

CN114944461A - OLED device with optical resonant cavity and OLED panel

Info

Publication number: CN114944461A
Application number: CN202210395920.2A
Authority: CN
Inventors: 金凌; 卢泓; 刘纪文
Original assignee: Wuhan Huamei Chenxi Photoelectric Co ltd
Current assignee: Wuhan Huamei Chenxi Photoelectric Co ltd
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2022-08-26
Anticipated expiration: 2042-04-15
Also published as: CN114944461B

Abstract

The invention discloses an OLED device with an optical resonant cavity, which comprises a bottom light-emitting OLED device layer with an anode layer, an organic functional layer and a metal cathode layer, and the OLED device also comprises: an optical resonance structure layer formed on the metal cathode layer; and an optical resonant cavity formed between a portion of the metal cathode layer and the optical resonant structure layer; wherein: the optical resonance structure layer comprises an organic layer and a metal film which are sequentially formed on the metal cathode layer; a luminescent layer is arranged in the organic layer close to the anode layer; the optical length L of the optical resonant cavity is the thickness of the organic layer multiplied by the refractive index, and is also an integral multiple of the luminous wavelength lambda of the luminous layer; the metal cathode layer is of a semitransparent structure, and the thickness of the metal cathode layer is 10nm to 1500nm so as to achieve both electric conduction and light transmission. An OLED panel comprises the OLED device with the optical resonant cavity. The OLED device and the display panel improve the luminous efficiency and the service life of the OLED device and the display panel, and reduce the material cost.

Description

OLED device with optical resonant cavity and OLED panel

Technical Field

The invention relates to the technical field, in particular to an OLED device with an optical resonant cavity and an OLED panel.

Background

Recently, the development of Organic Light Emitting Diodes (OLEDs) has attracted considerable attention in the scientific research and industrial fields. Compared with the traditional LED point light source, the OLED is a surface light source, does not need the assistance of other lamps, can be applied to large-area light source illumination, and simultaneously has the advantages of being bendable, environment-friendly, light, thin, low in temperature, low in power consumption, capable of protecting eyes and the like. In other words, the application prospect of the OLED lighting is huge, and the OLED lighting is expected to become the mainstream of future lighting.

At present, by using phosphorescent materials, the internal quantum efficiency of a traditional OLED device is close to 100%, the external quantum efficiency is not more than 30%, and 70-80% of light is limited in the device, on one hand, due to intrinsic absorption of a metal cathode, and on the other hand, due to an organic layer/substrate layer in the light extraction process; there is a refractive index difference between the substrate layer/air. In order to improve the efficiency of the device, a light extraction film structure is often introduced into the device structure of the OLED, and the light extraction structure generally refers to a grating structure prepared at one end of the substrate close to the ITO, or a layer of light-diffusing film is coated or adhered outside the substrate, and the two extraction films mainly reduce the total reflection between interfaces through scattering.

In the prior art, chinese patent application CN105489632A discloses an OLED array substrate and a manufacturing method thereof, an OLED display panel and an OLED display device, and specifically discloses that the half mirror layer, the organic material functional layer, the organic film layer, the second electrode and the first electrode form a microcavity structure, so as to improve the light emitting efficiency and brightness of the display device, thereby greatly improving the aperture opening ratio of the display device while saving the cost. Firstly, the top-emitting device and the bottom-emitting device are made of different base materials, so that the structure of the top-emitting device is not suitable for the bottom-emitting device, and secondly, the light-emitting layer of the OLED device is positioned in the microcavity structure 100, so that the structure is more suitable for a monochromatic light-emitting device and is not suitable for a composite light OLED device structure, and the application range of the OLED device is limited.

Although the luminous efficiency is improved, the overall service life is impaired, which affects the service life. Therefore, the invention aims to provide the bottom-emitting OLED illuminating device, and the microcavity structure is introduced into the bottom-emitting OLED illuminating device so as to solve the problems of large starting voltage, narrow application range and low efficiency of the microcavity structure.

The technical problem that this patent will be solved is: under the condition that the voltage of the device is not influenced, the microcavity structure is introduced into the OLED bottom light-emitting device, so that the application range of the OLED bottom light-emitting device is improved in the light color of the light-emitting device while the efficiency of the device is improved, and the light-emitting efficiency and the service life of the OLED device are improved.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the OLED device and the OLED device with the optical resonant cavity, wherein the metal cathode layer of the optical resonant structure layer with the thickness of 10nm to 1500nm forms the optical resonant cavity (namely forms the microcavity effect), so that the conductivity and the light transmission of the metal cathode layer are effectively considered, the surface plasmon spp loss of the metal cathode layer can be brought, and the service life of the device is further prolonged.

The technical scheme adopted by the invention is as follows: an OLED device with an optical resonant cavity comprises a bottom-emitting OLED device layer having an anode layer, an organic functional layer, and a metallic cathode layer,

the OLED device further includes:

an optical resonance structure layer formed on the metal cathode layer;

and an optical resonant cavity formed between a portion of the metal cathode layer and the optical resonant structure layer;

wherein: the optical resonance structure layer comprises an organic layer and a metal film which are sequentially formed on the metal cathode layer; a luminescent layer is arranged in the organic layer close to the anode layer;

the cavity optical length L of the optical resonant cavity is the thickness of the organic layer multiplied by the refractive index, and is also an integral multiple of the luminous wavelength lambda/2 of the luminous layer;

the metal cathode layer is of a semitransparent structure, and the thickness of the metal cathode layer is 10nm to 1500nm, so that both electric conduction and light transmission are achieved.

Furthermore, the OLED device is a composite optical device, and the characteristic response wavelength corresponding to the optical resonant cavity is a certain monochromatic light wavelength in the device.

Further, the bottom-emitting OLED device layer has a dual-emitting layer or a triple-emitting layer structure.

Further, the optical resonance structure layer is a structure formed by stacking an organic layer and a metal thin film layer.

Further, the optical resonance structure layer is formed by metal injection molding to form a metal thin film layer on the organic layer.

Furthermore, the metal cathode layer is a metal single layer capable of being made into a semitransparent layer or is formed by doping two or more metals.

Further, the metal cathode layer is formed of Mg: ag is mixed or separately made of Mg and Ag, and the transparency of the prepared alloy is ensured to be between 50 and 80 percent.

Further, the metal cathode layer is formed of Mg: ag, Mg: the Ag ratio is 2: and 8, the transparency of the prepared metal cathode layer is 70%.

An OLED panel comprises the OLED device with the optical resonant cavity.

Furthermore, the bottom of the OLED device is provided with a substrate, and the top of the OLED device is packaged through a thin film packaging layer.

Furthermore, the bottom of the OLED device is provided with a substrate, the side face of the OLED device is provided with UV glue, and the top of the OLED device is covered on the UV glue through a cover plate for packaging;

further, the height of the UV glue is higher than the whole height of the OLED device.

And a drying agent is arranged on the top of the OLED device.

Further, the OLED panel structure may be a white light device or a monochromatic light emitting device, and further, the white light device may be a red, green, blue, or yellow-blue device, where the light emitting efficiency of the blue light device is relatively low, and preferably, when the OLED device is a white light device, the characteristic response wavelength of the microcavity structure is blue light.

Compared with the prior art, the invention has the beneficial effects that:

1. the conductivity and the light transmittance of the metal cathode layer are effectively considered, and the luminous efficacy of the OLED device and the display panel is improved.

2. The loss caused by the OLED surface plasmon mode is reduced, and the service lives of the OLED device and the display panel are prolonged.

3. The thickness of the whole bottom-emitting OLED device is reduced, and the material cost is reduced.

4. Two-stage light diffraction superposition, wherein the first-stage light diffraction is generated in the optical resonant cavity, and the second-stage light diffraction is generated in the light emitting layer of the organic functional layer, so that the light conversion efficiency is greatly improved, and the loss caused by the surface plasmon mode of the OLED is reduced.

5. The OLED panel can be a composite optical device, characteristic response is carried out on light with low photoelectric conversion efficiency in the composite optical device by utilizing the microcavity effect, and the application range of the microcavity structure in the OLED field is expanded.

In summary, the OLED device and the panel of the present invention can reduce total reflection during the light emitting process of the OLED device, and can realize interference peaks between the reflected light of the metal cathode layer and the light emitted from the optical resonant cavity at the light emitting surface of the panel by adjusting the thickness of the cavity of the optical resonant cavity. And the OLED device has two diffraction processes of light, one is multi-level diffraction inside the resonant cavity, namely microcavity effect, the other is diffraction of light emitted from the optical resonant cavity and the light emitting layer, and besides the diffraction effect, the OLED panel structure can reduce spp loss caused by cathode metal absorption. Therefore, the luminous efficiency and the service life of the OLED device and the display panel are improved, and the material cost is reduced.

Drawings

FIG. 1 is a schematic diagram of an OLED device 100 having an optical resonant cavity;

FIG. 2 is a schematic diagram of the optical path of the light emitting layer 121 of an OLED device 100 having an optical resonant cavity;

FIG. 3 shows light (K) entering the optical cavity _A22 ) A schematic view of the multiple diffraction orders occurring in the optical cavity 30;

FIG. 4 is a schematic view of the superposition of diffracted light paths from light-emitting layer 121 of bottom-emitting OLED device layer 10;

FIG. 5 is a schematic structural diagram of an embodiment in which the OLED device is a three-layer light-emitting layer 121;

fig. 6 is a schematic diagram of optical path transmission of the OLED device as a single light-emitting layer 121;

fig. 7 is a schematic diagram of optical path transmission of the OLED device as a multi-layer light-emitting layer 121;

FIG. 8 is a block diagram of an embodiment of a thin film encapsulation layer 50 disposed on an OLED panel;

FIG. 9 is a block diagram of an embodiment of an OLED panel with UV glue 60 and cover plate 70;

wherein: 100-OLED device, 10-bottom emitting OLED device layer, 11-anode layer, 12-organic functional layer, 121-emitting layer; 13-a metal cathode layer; 20-optical resonance structure layer, 21-organic layer; 22-a metal thin film; 30-optical resonant cavity, 40-substrate, 50-thin film packaging layer, 60-UV glue, 70-cover plate and 80-drying agent.

Detailed Description

For the purpose of enhancing understanding of the present invention, the present invention will be further described with reference to the accompanying drawings and examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the combination or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, are not to be construed as limiting the present invention. In addition, in the description process of the embodiment of the present invention, the positional relationships of the devices such as "upper", "lower", "front", "rear", "left", "right", and the like in all the drawings are based on fig. 1.

As shown in fig. 1, an OLED device 100 with an optical resonator comprises a bottom-emitting OLED device layer 10 with an anode layer 11, an organic functional layer 12 and a metallic cathode layer 13,

the OLED device further includes:

an optical resonance structure layer 20 formed on the metal cathode layer 13;

and an optical resonator 30 formed between a portion of the metal cathode layer 13 and the optical resonator structure layer 20;

wherein: the optical resonance structure layer 20 comprises an organic layer 21 and a metal film 22 which are sequentially formed on the metal cathode layer 13; a light-emitting layer 121 is arranged in the organic layer 21 and close to the anode layer 11;

the cavity optical length L of the optical resonant cavity 30 is an integral multiple of the wavelength λ/2 of the light emitted from the light emitting layer 121 while the refractive index is multiplied by the thickness of the organic layer 21;

specifically, the method comprises the following steps:

wherein: n is the refractive index of the organic layer 21, L is the thickness of the organic layer 21, j is the number of layers of the organic layer 21, and the number of layers of the organic layer is usually 1 to 3.

The metal cathode layer 13 has a semitransparent structure, has a thickness of 10nm to 1500nm, and can simultaneously achieve electrical conductivity and light transmittance, and the electrical conductivity and light transmittance of the metal cathode layer 13 can be simultaneously achieved, in combination with the optical path transmission diagrams of fig. 1 and 2, that is, the optical resonance structure layer 20 and the bottom light-emitting OLED device layer 10 share the metal cathode layer 13, one part of the metal cathode layer 13 has a function of forming an OLED light-emitting structure with the organic functional layer 12 and the anode layer 11, and the other part of the metal cathode layer has a function of forming an optical resonant cavity 30 with the organic layer 21 and the metal thin film 22 to form a microcavity effect, and as shown in fig. 3, light (K) entering the optical resonant cavity is shown _A22 ) A schematic diagram of multi-order diffraction occurs in the optical resonant cavity 30, that is, light entering the optical resonant cavity 30 is subjected to multi-order diffraction, and the light passing through the optical resonant cavity 30 is emitted from the optical resonant cavity 30 to the light emitted from the bottom surface 121 of the light emitting layer of the organic functional layer 12 for secondary diffraction, as shown in fig. 4, a schematic diagram of light path superposition of diffraction occurs in the light emitting layer 121 of the bottom-emitting OLED device layer 10, so that the light emitting efficiency of the bottom-emitting OLED device can be further enhanced.

Specifically, as shown in fig. 3, the light is emitted from the semitransparent metal cathode layer 13 in the optical resonant cavity, is further emitted from the reflective surface of the metal thin film 22, and is repeated in the optical resonant cavity 30 for a plurality of times, so that the emitted light is normalized in the optical resonant cavity 30And is transformed and propagated along the normal direction of the emitting surface. Diffraction, i.e., K, also occurs at the light-emitting layer 121 in the OLED device 100 _A1 、K _A21 And K _A22 Three beams of light; the K is defined by the optical length of the cavity of the optical resonant cavity 30 _A21 And K _A22 The phase difference between the two is exactly the integral multiple of lambda/2 of the wavelength, so that K is between the two and the semitransparent metal cathode layer 13 _A21 And K _A22 There is a diffraction maximum. That is, for the OLED device 100, the diffraction intensity of the light emitting layer 121 is mainly defined by the optical thickness of the electron transport layer, that is, the thickness of the metal cathode layer 13, so that the metal cathode layer 13 has a semi-transparent structure and a thickness of 10nm to 1500nm, so as to achieve both electrical conduction and light transmission.

In addition, since the optical resonant cavity 30 is included in the microcavity structure, the voltage during the OLED is easily decreased, reducing the start-up voltage of the OLED device.

Secondly, under the condition of near-field excitation, the metal cathode layer 13 can absorb part of light reflection rays emitted by the OLED device, so that the loss of the surface plasmon spp can be brought, and the service life of the device is further prolonged. Namely, the metal cathode layer 13 has two functions, one function is as an OLED conductive cathode, and normal operation of an OLED device is realized; the other function is as a reflecting surface of the resonant cavity.

Finally, the optical resonant cavity 30 is obviously different from the conventional resonant cavity structure, in the conventional OLED resonant cavity structure, the OLED light emitting layer exists in the resonant cavity, and further, the optical distance between the light emitting layer and the reflective layer and the cavity optical length of the optical resonant cavity need to be defined, but the optical resonant structure layer 20 described in this patent does not include the light emitting layer, so that the cavity optical length of the optical resonant cavity 30 needs to be defined, and the optical cavity length of the optical resonant cavity 30 is an integral multiple of 1/2OLED light emitting wavelength (λ).

In a preferred embodiment, the bottom-emitting OLED device layer 10 is a single-layer light-emitting layer structure, and FIG. 6 is a schematic diagram illustrating the optical path transmission of the OLED device with a single-layer light-emitting layer 121, wherein the light is incident from the light-emitting layer 121 to the semi-transparent layer during the light-emitting processLight wave vector K of the clear metal cathode layer 13 _A2 In a semi-transparent metal cathode layer 13, the division into the x and y wavesh components can be simplified, wherein K is _x The components are distributed along the surface of the semitransparent cathode to further excite a surface plasmon mode to further form heat dissipation, in the OLED device structure mentioned in the patent, an organic layer 21 exists above the semitransparent metal cathode layer 13, and part of energy of the Kx wave components can enter an optical resonant cavity to further excite a microcavity effect. The OLED device is a composite light device, the characteristic response wavelength corresponding to the optical resonant cavity 30 is a certain monochromatic light wavelength in the device, light originally utilized in the micro-cavity structure of the optical resonant cavity 30 is partial light in the light-emitting layer, and the partial light comprises light of which the light-emitting layer penetrates through the semitransparent cathode by 50%, so that the problem cannot be caused, the application scene of the micro-cavity structure in the field of OLED can be expanded by using the composite light device, and the composite light device can be made into white light or light with other colors.

Different from the embodiment of fig. 6, when the OLED device is a multi-layer light emitting layer 121, as shown in fig. 5 and 7, the bottom-emitting OLED device layer 10 has a double-light emitting layer structure or a triple-light emitting layer structure, and in a specific implementation process, the double-light emitting layer structure or the triple-light emitting layer structure is a white OLED structure formed by yellow blue or red, green, blue and white light, and can achieve better antifogging and obtain better light emitting efficiency. Since the characteristic response wavelength exists in the microcavity structure of the optical resonant cavity 30, the characteristic response wavelength of the microcavity structure in the embodiment is a wavelength with low photoelectric conversion efficiency, and preferably a wavelength corresponding to a blue peak. Similarly, the light entering the semi-transparent metal cathode layer 13 can be simply divided into x and y wavesh components, where K is the component of the light _x The components are distributed along the surface of the translucent cathode to excite surface plasmon modes to form heat losses, whereas in the OLED device structure mentioned in this patent there is an organic layer 21 above the translucent metal cathode layer 13, and K is _x The waveform has partial energy entering into the optical resonant cavity to excite the microcavity effect. The OLED device and the panel can be used for normalizing the output of KA2In the light direction, the optical resonator structure in the panel can also reduce losses due to OLED surface plasmon modes.

In another preferred embodiment of the OLED device, the optical resonant structure layer 20 is formed by stacking the organic layer 21 and the metal thin film layer 22, so that the refractive index varies periodically in the Z-axis direction, and the multi-layer structure with periodic variation of refractive index can form an optical effect with negative refractive index in the Z-axis direction.

The optical resonant structure layer 20 of the OLED device is formed by metal injection molding to form a metal thin film layer 22 on an organic layer 21, and may also form a structure with a periodic refractive index change in the Z-axis direction, and the multilayer structure with a periodic refractive index change may form an optical effect with a negative refractive index in the Z-axis direction.

The metal cathode layer 13 of the OLED device is a metal single layer capable of being made into a semitransparent layer or a film layer formed by doping two or more metals, such as a semitransparent metal layer or a transparent metal layer.

In a more preferred implementation, said metal cathode layer 13 of the OLED device is made of Mg: the Ag is mixed or made of Mg and Ag separately, and the transparency is ensured to be between 50 and 80 percent, so that the metal cathode layer 13 can have a better reflection effect, can have a very high diffraction effect and can have a better microcavity effect.

The metal cathode layer 13 of the OLED device is made of Mg: ag, Mg: the Ag proportion is 2: 8, the transparency of the prepared metal cathode layer 13 was 70%.

The OLED panel comprises the OLED device with the optical resonant cavity, and the same beneficial effects can be achieved, so that a light-emitting device can be better sold and applied.

In the embodiment of the OLED panel shown in fig. 8, the OLED device is provided with a substrate 40 at the bottom and encapsulated at the top by a thin film encapsulation layer 50.

In the embodiment of the OLED panel shown in fig. 9, the OLED device has a substrate 40 on the bottom, a UV glue 60 on the side, and a cover plate 70 on the top covering the UV glue 60 for packaging;

meanwhile, the height of the UV glue 60 is higher than the overall height of the OLED device, so that light rays emitted by the OLED device can be effectively gathered on a light emitting surface, and the light emitting efficiency of the whole OLED panel is improved. When the OLED panel is manufactured, the drying agent 80 can be arranged at the top of the OLED device layer and used for keeping the overall drying degree of the OLED panel, avoiding certain humidity and prolonging the service life of the OLED panel.

The embodiments of the present invention are disclosed as the preferred embodiments, but not limited thereto, and those skilled in the art can easily understand the spirit of the present invention and make various extensions and changes without departing from the spirit of the present invention.

Claims

1. An OLED device with an optical resonator comprising a bottom emitting OLED device layer (10) with an anode layer (11), an organic functional layer (12) and a metallic cathode layer (13), characterized in that:

the OLED device further includes:

an optical resonance structure layer (20) formed on the metal cathode layer (13);

and an optical resonator (30) formed between a portion of the metal cathode layer (13) and the optical resonant structure layer (20);

wherein: the optical resonance structure layer (20) comprises an organic layer (21) and a metal film (22) which are sequentially formed on the metal cathode layer (13); a light-emitting layer (121) is arranged in the organic layer (21) and close to the anode layer (11);

the cavity optical length L of the optical resonant cavity (30) is the thickness of the organic layer (21) multiplied by the refractive index, and is also an integral multiple of the luminous wavelength lambda/2 of the luminous layer (121);

the metal cathode layer (13) is of a semitransparent structure, and the thickness of the metal cathode layer is 10nm to 1500nm, so that both electric conduction and light transmission are achieved.

2. An OLED device having an optical resonant cavity according to claim 1 wherein:

the OLED device is a composite optical device, and the characteristic response wavelength of the corresponding optical resonant cavity (30) is a certain monochromatic light wavelength in the device.

3. An OLED device having an optical resonant cavity according to claim 1 wherein:

the bottom-emitting OLED device layer (10) has a dual-emitting layer or a triple-emitting layer structure.

4. An OLED device having an optical resonator according to claim 1 wherein:

the optical resonance structure layer (20) is a structure formed by stacking an organic layer (21) and a metal thin film layer (22).

5. An OLED device having an optical resonant cavity according to claim 1 wherein:

the optical resonance structure layer (20) is formed by metal injection molding on the organic layer (21) to form a metal film layer (22).

6. An OLED device having an optical resonant cavity according to claim 1 wherein:

the metal cathode layer (13) is a metal single layer which can be made into a semitransparent layer or a film layer formed by doping two or more metals.

7. An OLED device having an optical resonant cavity as set forth in claim 6, wherein:

the metal cathode layer (13) is formed of Mg: ag is mixed or separately made of Mg and Ag, and the transparency of the prepared alloy is ensured to be between 50 and 80 percent.

8. An OLED device having an optical resonant cavity according to claim 7, wherein:

the metal cathode layer (13) is formed of Mg: ag, Mg: the Ag proportion is 2: 8, the transparency of the prepared metal cathode layer (13) is 70%.

9. An OLED panel, characterized in that: OLED device (100) comprising the ribbon optical resonator according to any of claims 1-8.

10. The OLED panel of claim 9, wherein:

the OLED device (100) is provided with a substrate (40) at the bottom and is encapsulated at the top by a thin film encapsulation layer (50).

11. The OLED panel of claim 9, wherein:

the bottom of the OLED device (100) is provided with a substrate (40), the side face of the OLED device is provided with UV glue (60), and the top of the OLED device is covered on the UV glue (60) through a cover plate (70) for packaging;

meanwhile, the height of the UV glue (60) is higher than the whole height of the OLED device.

12. The OLED panel of claim 11, wherein:

the top of the OLED device (100) is provided with a desiccant (80).