Organic electroluminescence device
By introducing a microcavity structure of a distributed Bragg reflector layer and reflective electrodes into an OLED device, narrow-spectrum emission was achieved, solving the problem of insufficient luminous efficiency in photomedical devices and improving the luminous efficiency of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-10
AI Technical Summary
OLED organic light-emitting devices have a wide emission spectrum, which cannot meet the high luminous efficiency requirements of photomedical devices for specific wavelengths.
A microcavity structure is constructed using a distributed Bragg reflector layer and reflective electrodes. Narrow-spectrum emission is achieved through spectral interference and resonance, with the emission spectrum half-width of the microcavity structure being less than 20 nm.
This improves the luminous efficiency and spectral narrowing effect of organic electroluminescent devices, meeting the high luminous efficiency requirements of photomedical devices.
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Figure CN121843350A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of organic light-emitting technology, and in particular to an organic electroluminescent device. BACKGROUND
[0002] Organic light-emitting diodes (OLED) have a wide application prospect in the fields of photomedical devices and wearable devices due to their unique flexibility, thinness, bendability and conformability.
[0003] However, the light-emitting spectrum of an OLED organic electroluminescent device is usually wide, and due to the wide energy level, it cannot meet the high light-emitting efficiency requirement of photomedical devices in the photomedical application field requiring specific wavelength light. SUMMARY
[0004] The present application provides an organic electroluminescent device to provide an organic electroluminescent device with a narrow spectrum and improve the efficiency of the organic electroluminescent device.
[0005] According to an aspect of the present application, an organic electroluminescent device is provided, comprising:
[0006] a substrate, a distributed Bragg reflector, a first electrode, an organic functional layer and a second electrode which are sequentially stacked;
[0007] The second electrode is a reflective electrode;
[0008] The distributed Bragg reflector comprises at least one pair of low-refractive-index material layers and high-refractive-index material layers which are alternately stacked;
[0009] The microcavity structure is formed between the distributed Bragg reflector and the second electrode;
[0010] The light-emitting spectrum half-wave width of the microcavity structure is less than 20 nm.
[0011] Optionally, the light-emitting spectrum half-wave width of the microcavity structure satisfies the following formula:
[0012]
[0013] wherein, λ is the light-emitting peak wavelength of the organic functional layer, L is the cavity length of the microcavity structure, R1 is the reflectivity of the distributed Bragg reflector, and R2 is the reflectivity of the second electrode;
[0014] Optionally, the distributed Bragg reflector comprises less than or equal to four pairs of the low-refractive-index material layers and the high-refractive-index material layers which are alternately stacked; and the refractive index difference between the high-refractive-index material layers and the low-refractive-index material layers is greater than 0.2.
[0015] Optionally, the cavity length L of the microcavity structure satisfies the following formula:
[0016]
[0017] wherein n is the refractive index of each organic material in the organic functional layer; m>2, m is a positive integer.
[0018] Optionally, the low refractive index material layer in contact with the first electrode is a first refractive index material layer; or the high refractive index material layer in contact with the first electrode is a first refractive index material layer.
[0019] The cavity length L of the microcavity structure includes a first cavity length L' or the cavity length L of the microcavity structure includes a second cavity length L".
[0020] The first cavity length L' includes the first electrode and the organic functional layer.
[0021] The second cavity length L" includes the first refractive index material layer, the first electrode and the organic functional layer.
[0022] Optionally, the organic functional layer includes a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and an electron injection layer stacked in sequence.
[0023] Optionally, the hole injection layer is prepared by a wet coating method, the thickness of the organic functional layer 40 ranges from 100 nm to 4000 nm, and the hole injection layer is made of conductive polymer materials such as poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS) and polyaniline (PANI) derivatives.
[0024] Optionally, when the cavity length L of the microcavity structure includes the first cavity length L', the thickness of the first refractive index material layer is equal to λ / 4n.
[0025] Or, when the cavity length L of the microcavity structure includes the second cavity length L", the thickness of the first refractive index material layer is greater than λ / 2n.
[0026] Optionally, the substrate is a transparent or semi-transparent substrate, and the first electrode is a transparent or semi-transparent electrode, both of which are made of light-transmitting materials.
[0027] The second electrode is made of one or more metal materials selected from aluminum, magnesium, silver, indium, calcium and gold.
[0028] Optionally, the low-refractive-index material layer is made of one or more of lithium-ion-doped silicon dioxide, porous aluminum oxide; and the high-refractive-index material layer is made of one or more of indium tin oxide doped with titanium dioxide, aluminum-doped zinc oxide (AZO) doped with tantalum pentoxide (Ta2O5), germanium (Ge).
[0029] The organic electroluminescent device provided by the embodiment of the present application comprises a substrate, a distributed Bragg reflector, a first electrode, an organic functional layer and a second electrode which are sequentially stacked; a microcavity structure is formed between the distributed Bragg reflector and the second electrode, and the light emission spectrum half-width of the microcavity structure is less than 20 nm, so that the organic electroluminescent device with high light emission efficiency and narrow half-width is obtained.
[0030] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS
[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0032] Figure 1 is a schematic diagram of a first organic electroluminescent device provided by the embodiment of the present application;
[0033] Figure 2 is a schematic diagram of a second organic electroluminescent device provided by the embodiment of the present application;
[0034] Figure 3 is a schematic diagram of a third organic electroluminescent device provided by the embodiment of the present application. DETAILED DESCRIPTION
[0035] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.
[0036] It should be noted that the terms "first", "second", and the like in the description and claims of the application and the above drawings are used to distinguish between similar objects, and are not necessarily used to describe a particular sequential or chronological order. It should be understood that the data thus used can be interchanged, where appropriate, so that the embodiments of the application described herein can be carried out in other than the order shown or described herein. Furthermore, the terms "comprise" and "have", and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a list of steps or units is not necessarily limited to those steps or units that are clearly listed, but can include other steps or units that are not clearly listed or inherent to such processes, methods, products, or apparatuses.
[0037] The embodiment of the application provides an organic electroluminescence device, Figure 1 is a schematic diagram of the first organic electroluminescence device provided by the embodiment of the application, referring to Figure 1 The organic electroluminescence device comprises:
[0038] The substrate 10, the distributed Bragg reflector 20, the first electrode 30, the organic functional layer 40 and the second electrode 50 are sequentially stacked.
[0039] The second electrode 50 is a reflective electrode.
[0040] The distributed Bragg reflector 20 comprises at least one pair of low-refractive material layers 21 and high-refractive material layers 22 which are alternately stacked.
[0041] The distributed Bragg reflector 20, the first electrode 30, the organic functional layer 40 and the second electrode 50 form a microcavity structure.
[0042] The microcavity structure has a half-wave width of an emission spectrum lower than 20 nm.
[0043] The microcavity structure is formed between the distributed Bragg reflector 20 and the second electrode 50, the distributed Bragg reflector 20 serves as a reflective functional layer to reflect light emitted from the organic functional layer 40, the first electrode 30 serves as a functional layer for transmitting an anode signal, the light emitted from the organic functional layer 40 forms a microcavity resonance between the distributed Bragg reflector 20 and the reflective second electrode 50, interference of photons of a specific wavelength emitted from the organic functional layer 40 is constructive, and the photons are continuously superimposed and strengthened in the microcavity, so that the light-emitting efficiency of the organic electroluminescence device is improved. In addition, the distributed Bragg reflector 20 itself has the characteristics of narrow-band high reflection, the reflection wavelength is accurately matched with the emission peak wavelength of the organic functional layer 40, only photons near the emission wavelength of the organic functional layer 40 are allowed to remain in the cavity and participate in resonance, and photons of non-peak wavelength are filtered out, so that the effect of spectral narrowing is achieved.
[0044] Specifically, when the half wave width of the light emission spectrum of the microcavity structure is less than 20 nm, the light emission spectrum is further limited by setting the half wave width of the light emission spectrum of the microcavity structure, so that a narrower half wave width is obtained, thereby meeting the requirement of high light emission efficiency of a specific wavelength required by the optical medical device.
[0045] On the basis of the above embodiment, optionally, the half wave width FWHM of the light emission spectrum of the microcavity structure satisfies the following formula 1:
[0046]
[0047] wherein λ is the peak wavelength of the light emission of the organic functional layer 40, L is the cavity length of the microcavity structure, R1 is the reflectivity of the distributed Bragg reflector 20, and R2 is the reflectivity of the second electrode 50.
[0048] According to the above formula 1, when the half wave width FWHM of the light emission spectrum of the microcavity structure is less than 20 nm, the reflectivity R2 of the second electrode 50 changes little, so that the cavity length L of the microcavity structure or the reflectivity R1 of the distributed Bragg reflector 20 needs to be increased to further narrow the light emission spectrum of the microcavity structure and ensure the efficiency of the organic electroluminescent device.
[0049] On the basis of the above embodiment, optionally, the distributed Bragg reflector 20 includes less than or equal to 4 pairs of low refractive index material layers 21 and high refractive index material layers 22 alternately stacked.
[0050] When the half wave width of the light emission spectrum of the microcavity structure is less than 20 nm, the reflectivity R1 of the distributed Bragg reflector 20 needs to be increased, that is, the number of pairs of low refractive index material layers 21 and high refractive index material layers 22 in the distributed Bragg reflector 20 is increased, but further increasing the reflectivity R1 will cause the efficiency of the organic electroluminescent device to decrease, so that the distributed Bragg reflector 20 includes less than or equal to 4 pairs of low refractive index material layers 21 and high refractive index material layers 22, which can increase the reflectivity R1 of the distributed Bragg reflector 20 while having little effect on the efficiency of the organic electroluminescent device, thereby obtaining a higher quality organic electroluminescent device.
[0051] Further, the refractive index difference between the low refractive index material layer 21 and the high refractive index material layer 22 is greater than 0.2.
[0052] Specifically, when the difference between the refractive index of the low refractive index material layer 21 and the high refractive index material layer 22 is greater than 0.2, the reflectivity R1 of the distributed Bragg reflector 20 can be greatly improved, and a better reflection effect can be achieved when the number of pairs of the low refractive index material layer 21 and the high refractive index material layer 22 is less than or equal to 4. The reduction in the number of the distributed Bragg reflector 20 can reduce the overall thickness of the organic electroluminescent device, reduce the time and cost of material preparation, and reduce the accumulation of internal stress of the multiple low refractive index material layers 21 and high refractive index material layers 22, thereby improving the long-term reliability of the organic electroluminescent device.
[0053] On the basis of the above-mentioned embodiments, the cavity length L of the microcavity structure satisfies the following formula 2:
[0054]
[0055] wherein n is the refractive index of each layer of organic material in the organic functional layer 40; m>2, m is a positive integer.
[0056] Specifically, when the half-wave width of the light emission spectrum of the microcavity structure is less than 20 nm, the cavity length L of the microcavity structure needs to be increased. According to the above formula 2, when the refractive index n of each layer of organic material in the organic functional layer 40 does not change much, m is a positive integer greater than 2, which can increase the cavity length L of the microcavity structure, so as to obtain an organic electroluminescent device which can ensure the light emission efficiency and has a narrow half-wave width.
[0057] Figure 2 is a schematic diagram of a second organic electroluminescent device provided by the embodiments of the present application, which is based on the above-mentioned embodiments, and optionally, Figures 1-2 the first refractive index material layer 23 in the low refractive index material layer 21 contacts the first electrode 30, or the first refractive index material layer 23 in the high refractive index material layer 22 contacts the first electrode 30;
[0058] The cavity length L of the microcavity structure includes a first cavity length L', or the cavity length L of the microcavity structure includes a second cavity length L";
[0059] The first cavity length L' includes the first electrode 30 and the organic functional layer 40;
[0060] The second cavity length L" includes the first refractive index material layer 23, the first electrode 30 and the organic functional layer 40.
[0061] Specifically, the first refractive index material layer 23 is in contact with the first electrode 30 in the low refractive index material layer 21, or the first refractive index material layer 23 is in contact with the first electrode 30 in the high refractive index material layer 22 (not shown in the figure); preferably, the refractive index difference between the first refractive index material layer 23 and the first electrode 30 is less than or equal to 0.2, which can make the cavity length of the microcavity structure more accurate and reduce the loss caused by the refractive index difference between the interfaces.
[0062] The first cavity length L' includes the film layer thicknesses of the first electrode 30 and the organic functional layer 40, and increasing the cavity length of the first cavity length L' of the microcavity structure can be achieved by increasing the film layer thickness of the first electrode 30 or the organic functional layer 40. Since the thickness of the organic functional layer 40 is more easily increased in the preparation of the organic electroluminescent device, the first cavity length L' of the microcavity structure is increased by increasing the film layer thickness of the organic functional layer 40, so that the organic electroluminescent device with good reliability and narrow half-wave width can be obtained.
[0063] Further, the second cavity length L'' includes the film layer thicknesses of the first refractive index material layer 23, the first electrode 30 and the organic functional layer 40. Since the thickness of the first refractive index material layer 23 in contact with the first electrode 30 is more easily controlled, the increase of the second cavity length L'' is achieved by increasing the thickness of the first refractive index material layer 23.
[0064] Figure 3 is a schematic diagram of a third organic electroluminescent device provided by the embodiment of the present application, which is based on the above-mentioned embodiments. Optionally, with reference to Figure 3 The organic functional layer 40 includes a hole injection layer 41, a hole transport layer 42, a light-emitting layer 43, an electron transport layer 44 and an electron injection layer 45 which are stacked in sequence.
[0065] Specifically, the hole injection layer 41 and the hole transport layer 42 are arranged on the side of the light-emitting layer 43 close to the first electrode 30, and the hole transport layer 42 is close to the light-emitting layer 43. The hole injection layer 41 is used to improve the hole injection efficiency, and the hole transport layer 42 is used to improve the hole transport rate. The electron transport layer 44 and the electron injection layer 45 are arranged on the side of the light-emitting layer 43 close to the second electrode 50, and the electron transport layer 44 is close to the light-emitting layer 43. The electron injection layer 45 is used to improve the electron injection efficiency, and the electron transport layer 44 is used to improve the electron transport rate.
[0066] On the basis of the above-mentioned embodiments, the thickness of the organic functional layer 40 can be 100 nm-4000 nm, and can be set to 100 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, or 4000 nm, etc. according to requirements. The hole injection layer 41 is prepared by a wet coating method, and the hole injection layer 41 is made of conductive polymer materials such as poly (3,4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT:PSS), polyaniline (PANI) derivatives, etc.
[0067] The hole injection layer 41 is usually prepared by an evaporation method, but the evaporation method needs to be performed in a high-vacuum environment, has high cost, and the prepared film layer is thin, and it is difficult to increase the thickness of the organic functional layer 40. The hole injection layer 41 is prepared by a wet coating method, the coating parameters can be adjusted to realize uniform film formation, and the thickness of the hole injection layer 41 can be obviously increased, so that the thickness of the organic functional layer 40 is more easily 100 nm-4000 nm. Therefore, in the embodiment, the hole injection layer 41 is preferably prepared by a wet coating method, the thickness of the organic functional layer 40 is increased to increase the cavity length of the first cavity length L', and the effect of narrowing the light emission spectrum of the microcavity structure is achieved.
[0068] Further, the increase of the thickness of the organic functional layer 40 can cover the particles generated in the process of preparing the substrate by the organic functional layer 40 with a relatively thick thickness, and reduce the risk of short circuit of the organic electroluminescent device, thereby further improving the reliability of the organic electroluminescent device.
[0069] In addition, the hole injection layer 41 prepared by the wet coating method is made of PEDOT:PSS, polyaniline (PANI) derivatives, and other conductive polymer materials, and the conductive performance is better by relying on the conjugated structure of the polymer molecular chain and the charge transfer of the doping ions. The hole injection layer 41 has good wettability with the first electrode 30, chemical compatibility with the subsequently prepared hole transport layer 42, and a more close interface contact with the anode substrate of the organic electroluminescent device, which can reduce the interface defects, make the film layer of the organic functional layer 40 more uniform, and obtain the organic electroluminescent device with higher quality.
[0070] The hole injection layer 41 is prepared by a wet coating method, the thickness of the organic functional layer 40 is 100 nm-4000 nm, the organic functional layer 40 with higher quality and thicker thickness can be obtained, and the cavity length of the first cavity length L' can be increased, and the organic electroluminescent device with high quality, high light emission efficiency, and narrow half-wave width can be obtained.
[0071] On the basis of the above-mentioned embodiments, the thickness of the organic functional layer 40 can be 100 nm-4000 nm, and can be set to 100 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, or 4000 nm, etc. according to requirements. The hole injection layer 41 is prepared by a wet coating method, and the hole injection layer 41 is made of conductive polymer materials such as poly (3,4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT:PSS), polyaniline (PANI) derivatives, etc. Figures 1-2When the cavity length L of the microcavity structure is the first cavity length L', the thickness of the first refractive index material layer 23 is equal to λ / 4n', where n' is the refractive index of the first refractive index material layer 23.
[0072] Alternatively, when the cavity length L of the microcavity structure is the second cavity length L'', the thickness of the first refractive index material layer 23 is greater than λ / 2n', where n' is the refractive index of the first refractive index material layer 23.
[0073] When the cavity length L of the microcavity structure is the first cavity length L', the first cavity length L' includes the film layer thicknesses of the first electrode 30 and the organic functional layer 40, and thus the thickness of the first refractive index material layer is equal to λ / 4n', where n' is the refractive index of the first refractive index material layer 23, and the effect of the multiple pairs of low-refractive-index material layers 21 and high-refractive-index layers 22 in the distributed Bragg reflection layer 20 is satisfied.
[0074] Specifically, when the cavity length L of the microcavity structure is the second cavity length L'', the second cavity length L'' includes the film layer thicknesses of the first refractive index material layer 23, the first electrode 30, and the organic functional layer 40, and thus the thickness of the first refractive index material layer 23 is greater than λ / 2n', where n' is the refractive index of the first refractive index material layer 23, which is equivalent to increasing the thickness of the first refractive index material layer 23, i.e., increasing the cavity length of the second cavity length L''. The effect of narrowing the light emission spectrum of the microcavity structure is achieved by increasing the cavity length, and a higher-quality organic electroluminescent device is obtained. In addition, the thickness of the first refractive index material layer 23 is more controllable and simpler to change, so that an organic electroluminescent device with higher quality and narrower spectrum can be obtained at a lower cost.
[0075] On the basis of the above-mentioned embodiments, optionally, the substrate 10 is a transparent or semi-transparent substrate, and the first electrode 30 is a semi-transparent electrode, both of which are made of a light-transmitting material.
[0076] The substrate 10 is made of one or more materials selected from the group consisting of glass, polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polyimide, and polycarbonate; and the first electrode 30 is made of one or more materials selected from the group consisting of indium tin oxide, zinc oxide-based material, fluorine-doped tin oxide, and silver nanowire.
[0077] Specifically, the substrate 10 is a transparent or semi-transparent substrate made of a light-transmitting material, for example, glass, light-transmitting glass, light-transmitting film, light-transmitting ceramic, etc. In the present embodiment, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polyimide (PI), polycarbonate (PC), etc. can be selected. The first electrode 30 is a transparent anode made of a light-transmitting material, for example, indium tin oxide (ITO), zinc oxide-based material (e.g., AZO, GZO), fluorine-doped tin oxide (FTO), silver nanowire, etc. The transparent anode can also be made of other light-transmitting materials, which are not limited herein. The substrate 10 and the first electrode 30 are both made of light-transmitting materials, which can ensure that the light emitted by the organic functional layer 40 can be transmitted through the first electrode 30 and the substrate 10 after being reflected by the distributed Bragg reflection structure 20 and the second electrode 50, thereby ensuring the overall transmittance of the organic electroluminescent device and improving the light-emitting efficiency of the organic electroluminescent device.
[0078] On the basis of the above-mentioned embodiments, the second electrode 50 can be made of one or more metal materials selected from aluminum, magnesium, silver, indium, calcium, and gold.
[0079] Specifically, the second electrode 50 is a cathode made of one or more reflective metal materials selected from aluminum, magnesium, silver, indium, and gold, which can ensure that most of the photons are reflected back into the cavity for secondary resonance, thereby avoiding emission from the organic electroluminescent device and improving the light-emitting efficiency of the organic electroluminescent device.
[0080] On the basis of the above-mentioned embodiments, the low-refractive material layer 221 can be made of one or more materials selected from lithium-ion-doped silicon dioxide and porous aluminum oxide; and the high-refractive material layer 222 can be made of one or more materials selected from indium tin oxide doped with titanium dioxide, aluminum-doped zinc oxide (AZO) doped with tantalum pentoxide (Ta2O5), and germanium (Ge).
[0081] Specifically, the low-refractive material layer 221 can be made of one or more materials selected from Li⁺-doped SiO2 and porous Al2O3; and the high-refractive material layer 222 can be made of one or more materials selected from ITO doped with TiO2, AZO (aluminum-doped zinc oxide) doped with Ta2O5, and Ge. The large refractive index difference between the low-refractive material layer 221 and the high-refractive material layer 222 can ensure high reflectivity, and at the same time, the low distributed Bragg reflection layer 20 can also have certain transparency, thereby ensuring the overall transmittance of the organic electroluminescent device and improving the light-emitting efficiency of the organic electroluminescent device.
[0082] The organic electroluminescence device of the embodiment of the present application comprises a substrate, a distributed Bragg reflector, a first electrode, an organic functional layer and a second electrode which are sequentially stacked; a microcavity structure is formed between the distributed Bragg reflector and the second electrode, and the half-width of the light emission spectrum of the microcavity structure is less than 20 nm, so that the organic electroluminescence device with high light emission efficiency and narrow half-width is obtained. The distributed Bragg reflector of the embodiment of the present application comprises less than or equal to 4 pairs of low refractive index material layers and high refractive index material layers which are alternately stacked to ensure the light emission efficiency of the organic electroluminescence device. In the embodiment of the present application, the thickness of the organic functional layer is thickened or the thickness of the first refractive index material layer in contact with the first electrode is increased by using the wet coating method to prepare the hole injection layer, so that the cavity length is increased, the light emission spectrum of the microcavity structure is further narrowed, and the organic electroluminescence device with high quality, high light emission efficiency and narrow half-width is obtained.
[0083] It should be understood that the various forms of flow shown above can be reordered, added to, or deleted from without departing from the scope of the present application. For example, the steps described in the present application can be executed in parallel, in series, or in different orders, and the present application is not limited herein as long as the desired results of the technical solutions of the present application can be achieved.
[0084] The above detailed description does not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. An organic electroluminescent device, characterized by comprising: Comprising: a substrate, a distributed Bragg reflector, a first electrode, an organic functional layer and a second electrode which are sequentially stacked; the second electrode is a reflective electrode; the distributed Bragg reflector comprises at least one pair of low refractive index material layers and high refractive index material layers which are alternately stacked; the microcavity structure is formed between the distributed Bragg reflector and the second electrode; the microcavity structure has a half width of light emission spectrum less than 20 nm.
2. The organic electroluminescent device according to claim 1, wherein: the half width of light emission spectrum of the microcavity structure satisfies the following formula: wherein λ is the peak wavelength of light emission of the organic functional layer, L is the cavity length of the microcavity structure, R1 is the reflectivity of the distributed Bragg reflector, and R2 is the reflectivity of the second electrode.
3. The organic electroluminescent device according to claim 1, wherein: the distributed Bragg reflector comprises less than or equal to 4 pairs of the low refractive index material layers and the high refractive index material layers which are alternately stacked; the difference between the refractive indexes of the low refractive index material layers and the high refractive index material layers is greater than 0.
2.
4. The organic electroluminescent device according to claim 2, wherein: the cavity length L of the microcavity structure satisfies the following formula: wherein n is the refractive index of each organic material layer in the organic functional layer, and m is a positive integer greater than 2.
5. The organic electroluminescent device according to claim 3, wherein: the first refractive index material layer in the low refractive index material layers is in contact with the first electrode; alternatively, the first refractive index material layer in the high refractive index material layers is in contact with the first electrode; the cavity length L of the microcavity structure comprises a first cavity length L' or a second cavity length L"; the first cavity length L' comprises the first electrode and the organic functional layer; the second cavity length L" comprises the first refractive index material layer, the first electrode and the organic functional layer.
6. The organic electroluminescent device according to claim 5, wherein: the organic functional layer comprises a hole injection layer, a hole transport layer, a light emission layer, an electron transport layer and an electron injection layer which are sequentially stacked.
7. The organic electroluminescent device according to claim 6, wherein: the thickness of the organic functional layer ranges from 100 nm to 4000 nm, the hole injection layer is prepared by a wet coating method, and the hole injection layer is made of conductive polymer materials such as poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS) and polyaniline (PANI) derivatives.
8. The organic electroluminescent device according to claim 5, wherein: when the cavity length L of the microcavity structure comprises the first cavity length L', the thickness of the first refractive index material layer is equal to λ / 4n; alternatively, when the cavity length L of the microcavity structure comprises the second cavity length L", the thickness of the first refractive index material layer is greater than λ / 2n.
9. The organic electroluminescent device according to claim 1, wherein: The substrate is a transparent or semi-transparent substrate, and the first electrode is a transparent or semi-transparent electrode, both of which are made of a light-transmitting material. The second electrode is made of one or more metal materials selected from aluminum, magnesium, silver, indium, calcium, and gold.
10. The organic electroluminescent device according to claim 9, characterized in that: The low-refractive-index material layer is made of one or more materials selected from lithium-ion-doped silicon dioxide and porous aluminum oxide; and the high-refractive-index material layer is made of one or more materials selected from indium tin oxide doped with titanium dioxide, aluminum-doped zinc oxide (AZO) doped with tantalum pentoxide (Ta2O5), and germanium (Ge).