CN114944461B

CN114944461B - OLED device with optical resonant cavity and OLED panel

Info

Publication number: CN114944461B
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: 2024-07-26
Anticipated expiration: 2042-04-15
Also published as: CN114944461A

Abstract

The invention discloses an OLED device with an optical resonant cavity, which comprises a bottom-emitting OLED device layer with an anode layer, an organic functional layer and a metal cathode layer, and the OLED device further 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 at a position 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 wavelength lambda of the luminescent light of the luminescent layer; the metal cathode layer is of a semitransparent structure and has a thickness of 10nm to 1500nm so as to achieve both electric conduction and light transmission. An OLED panel comprising the OLED device with the optical resonant cavity. The OLED device and the display panel provided by the invention have the advantages that the luminous efficiency and the service life of the OLED device and the display panel are improved, and the material cost is reduced.

Description

OLED device with optical resonant cavity and OLED panel

Technical Field

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

Background

Recently, the development of Organic LIGHT EMITTING Diodes (OLED) has attracted a lot of attention in the scientific 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 meanwhile has the advantages of being bendable, environment-friendly, light and thin, low in temperature, low in power consumption, eye-protecting and the like. In other words, the application prospect of OLED illumination is huge, and the OLED illumination is expected to become the mainstream of future illumination.

Currently, with phosphorescent materials, the internal quantum efficiency of traditional OLED devices is close to 100%, the external quantum efficiency is not more than 30%, and 70-80% of light is confined inside the device, on the one hand due to intrinsic absorption by the metal cathode and on the other hand due to the organic/substrate layers during light extraction; 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 that a grating structure is prepared at one end of the substrate near the ITO, or a layer of light scattering film is coated or stuck on the outside of the substrate, and the principle of the two extraction films is to reduce total reflection between interfaces through scattering.

In the prior art, chinese patent application CN105489632a discloses an OLED array substrate, a method for manufacturing the same, an OLED display panel, and an OLED display device, and specifically discloses a microcavity structure formed by the half mirror layer, the organic material functional layer, the organic film layer, the second electrode, and the first electrode, thereby improving the light emitting efficiency and brightness of the display device, and further greatly improving the aperture opening ratio of the display device while saving the cost. However, firstly, it belongs to a top-emitting OLED device, and since the materials of the substrates of the top-emitting device and the bottom-emitting device are different, the top-emitting device structure related in the patent is not suitable for the bottom-emitting device, and secondly, the light-emitting layer of the OLED device is located in the microcavity structure 100, so that it is more suitable for a monochromatic light-emitting device in the structure, is not suitable for a compound light OLED device structure, and further limits the application range thereof.

Although the luminous efficiency is improved, the overall service life is impaired, and the service life is affected. Therefore, the invention aims to provide a bottom-emitting illumination OLED light-emitting device, and a microcavity structure is introduced into the bottom-emitting 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 solve is: how to introduce the microcavity structure into the OLED bottom light-emitting device under the condition of not influencing the device voltage, the application range is increased on the light color of the light-emitting device while the device efficiency 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 in the prior art, the invention provides an OLED device with an optical resonant cavity, wherein the optical resonant cavity is formed by a metal cathode layer with the thickness of 10nm to 1500nm, which is a semitransparent structure of an OLED device and an optical resonant structure layer, so that the conductivity and the light transmittance of the metal cathode layer are effectively considered, the loss of surface plasmon spp of the OLED device can be brought, and the service life of the OLED device is 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 with an anode layer, an organic functional layer and a metal 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 and close to the anode layer;

The optical length L of the cavity of the optical resonant cavity is the integral multiple of the thickness multiplied by the refractive index of the organic layer and the wavelength lambda/2 of the luminescent light of the luminescent layer;

the metal cathode layer is of a semitransparent structure and has a thickness of 10nm to 1500nm so as to achieve both electric conduction and light transmission.

Further, the OLED device is a composite optical device, and the characteristic response wavelength of the corresponding optical resonant cavity is a wavelength of a single color light in the device.

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

Further, the optical resonance structure layer is a structure of an organic layer and a metal thin film layer stacked.

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

Further, the metal cathode layer is a metal simple substance 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 by Mg: ag is mixed or Mg and Ag are independently prepared, and the transparency is ensured to be 50-80%.

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

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

Further, a substrate is arranged at the bottom of the OLED device, and the top of the OLED device is encapsulated by a thin film encapsulation layer.

Further, 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 desiccant is arranged on the top of the OLED device.

Further, the OLED panel structure may be a white light device or a monochromatic light device, further, the white light device may be a red, green and blue device or a yellow Lan Qijian, 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 efficiency of the OLED device and the display panel is improved.

2. The loss caused by the surface plasmon mode of the OLED 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. The two-stage light diffraction is overlapped, the first-stage light diffraction occurs in the optical resonant cavity, the second-stage light diffraction occurs 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, and the microcavity effect is utilized to perform characteristic response on light with low photoelectric conversion efficiency in composite light, so that the application range of the microcavity structure in the OLED field is improved.

In summary, according to the OLED device and the panel provided by the invention, on one hand, total reflection in the light emitting process of the OLED device can be reduced, and on the other hand, by adjusting the cavity thickness of the optical resonant cavity, the interference peak between the light reflected by the metal cathode layer and the light emitted by the optical resonant cavity is realized on the light emitting surface of the panel. The OLED device has a diffraction process of twice light, namely multi-stage diffraction in the resonant cavity, namely microcavity effect, and diffraction of light emitted from the optical resonant cavity and light emitted from 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 meanwhile, 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 is a schematic diagram showing the multi-order diffraction of light (K _A22) entering an optical cavity in optical cavity 30;

FIG. 4 is a schematic diagram of superimposed optical paths of diffraction occurring in the light-emitting layer 121 of the bottom-emitting OLED device layer 10;

FIG. 5 is a schematic diagram of an embodiment of an OLED device with three light emitting layers 121;

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

FIG. 7 is a schematic diagram of the optical path transmission of an OLED device with multiple light emitting layers 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 gel 60 and cover plate 70;

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

Detailed Description

The present invention will be further described with reference to the drawings and examples, which are only for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.

In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the indicated combinations or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not 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" and "right" in all the figures are all standardized in fig. 1.

As shown in fig. 1, an OLED device 100 with an optical resonant cavity includes a bottom-emitting OLED device layer 10 having an anode layer 11, an organic functional layer 12 and a metal cathode layer 13,

The OLED device further includes:

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

And an optical resonant cavity 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 includes an organic layer 21 and a metal thin film 22 sequentially formed on the metal cathode layer 13; a light-emitting layer 121 is arranged in the organic layer 21 and near the anode layer 11;

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

specifically:

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 typically the number of layers of the organic layer is 1-3.

The metal cathode layer 13 is a semitransparent structure and has a thickness of 10nm to 1500nm, so that conductivity and transmittance of the metal cathode layer 13 can be considered, and in combination with the optical path transmission diagrams of fig. 1 and fig. 2, the metal cathode layer 13 is shared by the optical resonant structure layer 20 and the bottom light-emitting OLED device layer 10, a part of the metal cathode layer 13 functions to form an OLED light-emitting structure with the organic functional layer 12 and the anode layer 11, another part functions to form an optical resonant cavity 30 with the organic layer 21 and the metal thin film 22 so as to form a microcavity effect, as shown in fig. 3, a multi-level diffraction schematic diagram of light (K _A22) entering the optical resonant cavity occurs in the optical resonant cavity 30, that is, multi-level diffraction is performed on light entering the optical resonant cavity 30, and light passing through the optical resonant cavity 30 is again subjected to secondary diffraction from the optical resonant cavity 30 to light path superposition of diffraction occurring with the light-emitting layer 121 of the bottom light-emitting OLED device layer 10 as shown in fig. 4, so that the luminous efficiency of the bottom light-emitting OLED device can be further enhanced.

As shown in fig. 3, the light is emitted from the semitransparent metal cathode layer 13 in the optical resonator, and is further emitted from the reflecting surface of the metal thin film 22, and the process is repeated a plurality of times in the optical resonator 30, so that the emitted light is normalized in the optical resonator 30 and propagates in the normal direction of the emitting surface. Diffraction, i.e., three beams of K _A1、K_A21 and K _A22, also occurs at the light-emitting layer 121 in the OLED device 100; since the optical length of the cavity of the optical resonant cavity 30 is limited, the phase difference between the K _A21 and the K _A22 is exactly an integer times of lambda/2 of the wavelength, so diffraction maxima exist between the K _A21 and the K _A22 and the semitransparent metal cathode layer 13. 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 is of a semitransparent structure and has a thickness of 10nm to 1500nm 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 reduced, and the starting voltage of the OLED device is reduced.

And secondly, under the condition of near field excitation, the metal cathode layer 13 can absorb part of light emitted by the OLED device, so that the loss of surface plasmon spp can be brought, and the service life of the device is prolonged. That is, the metal cathode layer 13 has two functions, one is used as an OLED conductive cathode to realize the normal operation of the OLED device; another function is to act as a reflecting surface for the cavity.

Finally, the optical resonant cavity 30 is significantly different from the resonant cavity structure described in general, in the OLED resonant cavity structure described in general, 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 optical length of the cavity 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 optical length of the cavity of the optical resonant cavity 30 needs to be defined, and the optical cavity length of the optical resonant cavity 30 is an integer 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, fig. 6 shows a schematic optical path transmission diagram of the OLED device as a single-layer light-emitting layer 121, which is a light path transmission diagram of the light-emitting layer 121, in the light-emitting process, a light wave vector K _A2 incident on the semitransparent metal cathode layer 13 from the light-emitting layer 121 can be simplified and divided into a wave component in the x direction and a wave component in the y direction in the semitransparent metal cathode layer 13, wherein the K _x component is distributed along the surface of the semitransparent cathode to excite a surface plasmon mode to further form heat dissipation, and according to the OLED device structure mentioned in the patent, an organic layer 21 exists above the semitransparent metal cathode layer 13, and a part of energy of the Kx wave component can enter into an optical resonant cavity to further excite microcavity effect. The OLED device is a composite light device, and the characteristic response wavelength of the corresponding optical resonant cavity 30 is a single-color wavelength of the device, and the light utilized in the microcavity structure of the optical resonant cavity 30 is a part of light that is originally utilized in the light-emitting layer, and the part of light includes 50% of light that is transmitted through the semitransparent cathode by the light-emitting layer, so that the problem is avoided.

Unlike 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 dual-light-emitting layer or a three-light-emitting layer structure, and in a specific implementation, the dual-light-emitting layer structure or the three-light-emitting layer structure is a white OLED structure composed of yellow-blue or red-green-blue-white light, so that better anti-fog effect and better light-emitting rate can be achieved. Because of the characteristic response wavelength 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 is preferably a wavelength corresponding to a blue peak. Likewise, the light entering the semitransparent metal cathode layer 13 can be simply divided into the bosh components in the x and y directions, wherein the K _x component is distributed along the surface of the semitransparent cathode, so as to excite the surface plasmon mode and further form heat dissipation, and according to the OLED device structure mentioned in the patent, the organic layer 21 is arranged above the semitransparent metal cathode layer 13, and part of the energy of the K _x bosh component can enter the optical resonant cavity, so as to excite the microcavity effect. According to the OLED device and the panel, besides the light emitting direction of KA2 can be normalized, the loss caused by the surface plasmon mode of the OLED can be reduced due to the optical resonant cavity structure in the panel.

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 is periodically changed in the Z-axis direction, and the structure of periodically changing the refractive index of multiple layers can form the optical effect of negative refractive index in the overall optical resonant cavity structure in the Z-axis direction.

The optical resonant structure layer 20 of the OLED device is formed by metal injection molding to form the metal thin film layer 22 on the organic layer 21, and the refractive index may also be formed in the Z-axis direction to exhibit periodic variation, and the structure of the periodic variation of the refractive index of the multiple layers may form an optical effect of negative refractive index in the overall optical resonant cavity structure in the Z-axis direction.

The metal cathode layer 13 of the OLED device is a metal simple substance layer capable of forming a semitransparent layer or a film forming layer doped with two or more metals, such as a semitransparent metal layer and a transparent metal layer.

More preferably, the metal cathode layer 13 of the OLED device is made of Mg: the Ag is mixed or made of Mg and Ag singly, and the transparency is ensured to be 50% -80%, so that the metal cathode layer 13 can be ensured to have a good reflection effect and an extremely high diffraction effect, and a good microcavity effect.

The metal cathode layer 13 of the OLED device consists of Mg: ag is mixed and prepared, mg: the Ag ratio is 2:8, the transparency of the metal cathode layer 13 obtained was 70%.

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

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

In the embodiment of the OLED panel shown in fig. 9, the bottom of the OLED device is provided with a substrate 40, the side is provided with UV glue 60, and the top of the OLED device is covered on the UV glue 60 by a cover plate 70 for encapsulation;

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 the light emitting surface, and the light emitting efficiency of the whole OLED panel is improved. When the OLED panel is manufactured, the desiccant 80 can be arranged at the top of the OLED device layer, so that the overall dryness of the OLED panel is maintained, certain humidity is avoided, and the service life of the OLED panel is prolonged.

The embodiments of the present invention are disclosed as preferred embodiments, but not limited thereto, and those skilled in the art will readily appreciate from the foregoing description that various extensions and modifications can be made without departing from the spirit of the present invention.

Claims

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

the OLED device further includes:

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

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); the metal film (22) is used for reflecting light, and a light-emitting layer (121) is arranged in the organic functional layer (12) at a position close to the anode layer (11); the metal cathode layer (13) is of a semitransparent structure and has a thickness of 10nm to 1500nm so as to achieve both electric conduction and light transmission;

The optical resonance structure layer (20) and the bottom light-emitting OLED device layer (10) share a metal cathode layer (13), and part of functions of the metal cathode layer (13), the anode layer (11) and the organic functional layer (12) form an OLED light-emitting structure to serve as an OLED conductive cathode; another part of the functions of the metal cathode layer (13) and the organic layer (21) and the metal film (22) form an optical resonant cavity (30) so as to form a microcavity effect;

The cavity optical length L of the optical resonant cavity (30) is the integral multiple of the light emitting wavelength lambda/2 of the light emitting layer (121) while the refractive index is multiplied by the thickness of the organic layer (21).

2. An OLED device with an optical resonant cavity as claimed in claim 1, wherein:

the OLED device is a compound light device, and the characteristic response wavelength of the corresponding optical resonant cavity (30) is a wavelength of a single color light in the device.

3. An OLED device with an optical resonant cavity as claimed in claim 1, wherein:

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

4. An OLED device with an optical resonant cavity as claimed in claim 1, wherein:

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

5. An OLED device with an optical resonant cavity as claimed in claim 1, wherein:

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

6. An OLED device with an optical resonant cavity as claimed in claim 1, wherein:

the metal cathode layer (13) is a metal simple substance layer capable of being made into a semitransparent layer or a film forming layer doped with two or more metals.

7. An OLED device with an optical cavity as claimed in claim 6, wherein:

the metal cathode layer (13) is composed of Mg: ag is mixed or Mg and Ag are independently prepared, and the transparency is ensured to be 50-80%.

8. An OLED device with an optical resonant cavity as claimed in claim 7, wherein:

the metal cathode layer (13) is composed of Mg: ag is mixed and prepared, mg: the Ag ratio is 2:8, the transparency of the metal cathode layer (13) obtained was 70%.

9. An OLED panel characterized by: an OLED device (100) comprising an 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 packaged by a thin film packaging layer (50) at the top.

11. The OLED panel of claim 9, wherein:

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

And 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:

A desiccant (80) is arranged on the top of the OLED device (100).