Packaging method of organic light-emitting layer and display panel

Abstract

The invention discloses a packaging method of an organic light-emitting layer and a display panel, and relates to the field of semiconductors, and the method comprises the steps: introducing a gaseous precursor and a first carrier gas, carrying out the shape following on one side, far away from a substrate, of the organic light-emitting layer to obtain a first packaging film, and enabling the first packaging film to cover the top surface and the side surface of the organic light-emitting layer; introducing the gaseous precursor and a second carrier gas, and carrying out shape following on one side, far away from the organic light-emitting layer, of the first packaging film to obtain a second packaging film; the second carrier gas comprises helium and nitrogen. Through the design of the temperature gradient, multiple layers of films with different structures are deposited on the organic light-emitting layer, so that the first packaging film which is not compact but insulated in a low-temperature state and the second packaging film which is compact in a high-temperature state are formed, the packaging effect is improved, meanwhile, helium is adopted as carrier gas of the second packaging film, and the packaging efficiency is improved. The thermal diffusivity of the precursor is improved, and the packaging quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and particularly relates to a packaging method for an organic light-emitting layer and a display panel. Background Technology

[0002] Currently, atomic layer deposition (ALD) technology is widely used in OLED packaging due to its excellent step coverage and film uniformity. However, existing ALD packaging technologies still have the following technical problems: First, to protect the thermosensitive organic light-emitting layer, a low-temperature deposition process is required, but the film density is low at low temperatures, making it prone to pinhole defects and leading to a decrease in moisture barrier performance; second, in high aspect ratio structures, precursor diffusion is restricted, resulting in unsatisfactory film thickness uniformity and difficulty in meeting step coverage requirements; in addition, traditional processes often require high-temperature annealing to improve film performance, but this can damage the organic light-emitting layer, limiting its application on thermosensitive substrates.

[0003] In existing technologies, packaging performance is generally improved by optimizing process parameters, but it is often difficult to simultaneously solve the problems of density in low-temperature deposition and coverage of high aspect ratio structures. This is especially true in applications with extremely high packaging requirements, such as microdisplays, where it is impossible to achieve high density and excellent step coverage while protecting the organic light-emitting layer.

[0004] Based on this, the present invention designs an encapsulation method for an organic light-emitting layer and a display panel. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art, and to propose a method for encapsulating an organic light-emitting layer and a display panel.

[0006] In a first aspect, the present invention discloses a method for encapsulating an organic light-emitting layer, comprising: S1: A gaseous precursor and a first carrier gas are introduced at a first temperature to form a first encapsulation film on the side of the organic light-emitting layer away from the substrate. The first encapsulation film covers the top and side surfaces of the organic light-emitting layer. The first temperature is not higher than 110°C. S2: The gaseous precursor and the second carrier gas are introduced at a second temperature, and a second encapsulation film is formed on the side of the first encapsulation film away from the organic light-emitting layer. The second temperature is greater than the first temperature and not higher than 120°C. The second carrier gas includes helium and nitrogen.

[0007] In the above method, the volume percentage of helium is 20% to 40%.

[0008] In the above method, the first temperature range is 80~90℃; the second temperature range is 110~120℃.

[0009] In the above method, the first carrier gas includes any one or both of nitrogen and helium.

[0010] In the above method, in step S2, water vapor is injected simultaneously with the introduction of the second carrier gas.

[0011] The above method also includes the following steps: S3: The gaseous precursor and the third carrier gas are introduced at a third temperature, and a third encapsulation film is formed on the side of the second encapsulation film away from the first encapsulation film. The third temperature is lower than the first temperature.

[0012] In the above method, the third temperature is set to 60~90℃.

[0013] In the above method, the third carrier gas includes any one or both of nitrogen and helium.

[0014] In the above method, step S3 further includes applying radio frequency plasma-assisted deposition, wherein the power of the radio frequency plasma is 50W and the frequency is 15MHz.

[0015] Secondly, the present invention provides a display panel, including an organic light-emitting layer and an encapsulation structure obtained by the above-described encapsulation method.

[0016] The beneficial effects of this invention are as follows: 1. By designing a temperature gradient, it is possible to deposit multiple thin films with different structures on the organic light-emitting layer. By controlling the deposition temperature, a first encapsulation film with thermal insulation is formed at a low temperature, and a dense second encapsulation film is formed at a higher temperature. This protects the organic light-emitting layer and ensures the density of the encapsulation film. 2. In the deposition preparation of the second encapsulation film, the present invention dops helium into the carrier gas. Taking advantage of the strong diffusivity of helium, which makes it easier to deposit as a carrier gas, the movement rate of the precursor is increased and the diffusion rate of the precursor is increased under temperature constraints. This improves the step coverage of the deposited film and enhances the encapsulation quality. Attached Figure Description

[0017] Figure 1 This is a flowchart of an organic light-emitting layer encapsulation method disclosed in this invention; Figure 2 This is a schematic diagram of the formation of the first encapsulation film in an organic light-emitting layer encapsulation method disclosed in this invention; Figure 3 This is a schematic diagram illustrating the formation of the second encapsulation film in an organic light-emitting layer encapsulation method disclosed in this invention; Figure 4This is a schematic diagram of the formation of the third encapsulation film in an organic light-emitting layer encapsulation method disclosed in this invention; Figure 5 This is a schematic diagram of a comparative encapsulation structure in an organic light-emitting layer encapsulation method disclosed in this invention; Figure 6 This is a schematic diagram of the packaging structure disclosed in this invention. Detailed Implementation

[0018] To facilitate understanding of this application and to make the aforementioned objectives, features, and advantages of this application more apparent, a detailed description of specific embodiments of this application is provided below in conjunction with the accompanying drawings. Numerous specific details are set forth in the following description to provide a thorough understanding of this application, and preferred embodiments are shown in the accompanying drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. This application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified. It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementations. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is only for describing particular implementations and is not intended to limit the scope of this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] Reference Figures 1-6 A method for encapsulating an organic light-emitting layer, comprising: S1: At a first temperature, a gaseous precursor and a first carrier gas are introduced. Using atomic layer deposition (ALD) technology, a first encapsulation film is formed on the surface of the organic light-emitting layer away from the substrate. This layer can also be called an island-shaped core layer. The first encapsulation film completely covers the top and side surfaces of the organic light-emitting layer, forming a preliminary encapsulation structure. The first temperature is no higher than 110°C to avoid damage to the organic light-emitting layer material. The gaseous precursor is a key reactive material in the ALD deposition process, capable of forming a uniform and dense film layer by layer on the surface of the organic light-emitting layer through self-limiting surface chemical reactions. The first carrier gas is used to transport the precursor in the first deposition stage of ALD and remove residual reactive gases to ensure film quality. The core purpose of this step is to construct a continuous, defect-free protective film on the surface of the organic light-emitting layer under low-temperature conditions, achieving preliminary encapsulation of the top and side surfaces. S2: At the second temperature, the same gaseous precursor and the second carrier gas are introduced, and a second encapsulation film is deposited conformally on the side of the first encapsulation film away from the organic light-emitting layer using the ALD process. The second carrier gas is used to continue to transport the precursor and remove residual reactive gases in the second deposition stage of ALD. The conformal deposition allows the second encapsulation film to extend a layer on both the top and sides of the first encapsulation film. This film can effectively supplement the first encapsulation film. In specific implementation, the second encapsulation film layer serves as the main layer of the encapsulation structure, undertaking the main functions of blocking water and oxygen and inhibiting device aging. The second temperature is higher than the first temperature but not higher than 120°C, ensuring the film density while avoiding thermal damage to the underlying organic material. The second carrier gas is a mixture of helium and nitrogen, which has higher thermal conductivity and stability, helping to improve reaction uniformity and film step coverage. By fully covering the top and sides of the first encapsulation film with the second encapsulation film, any micropores and defects that may exist are further filled, forming an overall encapsulation layer with excellent step coverage, significantly enhancing the reliability and service life of the device.

[0020] The key to improving film density through at least two thin-film encapsulation lies in the initial deposition at a lower temperature. This allows for the formation of a thinner film without damaging the organic light-emitting layer. Due to the lower deposition temperature, this first film has limited molecular migration during deposition. While its density is relatively low, it continuously covers the substrate surface, providing initial protection and effectively isolating the organic light-emitting layer from the external environment, forming a physical barrier. When depositing the second film on this foundation, the protection of the first film prevents thermal damage to the underlying organic light-emitting layer, even at higher deposition temperatures. This second film, serving as the main encapsulation layer, is typically significantly thicker than the first. High-temperature processing promotes the full diffusion and reaction of the precursor, resulting in a dense film structure with fewer defects, thus providing superior water and oxygen barrier properties and mechanical strength.

[0021] In the fabrication of the second encapsulation film in this scheme, a mixture of helium and nitrogen is specifically used as the carrier gas. The advantages are: helium has extremely high thermal conductivity and strong diffusion ability, which can effectively improve the transport efficiency and reaction uniformity of the precursor material at relatively low deposition temperatures, enhancing the step coverage of the film layer. Especially for the undulating structure formed by the existing first film layer, it can achieve a more consistent and void-free deposition effect. Simultaneously, the presence of nitrogen helps maintain the stability of the process atmosphere, further optimizing the film quality. This gas combination works synergistically, not only improving the deposition rate and density of the second film layer but also significantly enhancing the protection effect on the underlying structure, thereby comprehensively improving the overall encapsulation performance and reliability of the organic light-emitting device. Furthermore, a mixture of nitrogen and helium can also be used as the first carrier gas. However, since the second encapsulation film is used for the protection of the main layer in this scheme, its density is more critical, while the first encapsulation film is more important for forming a thermally insulating deposition layer. Therefore, the choice of whether or not to add helium as the first carrier gas is optional.

[0022] In one feasible embodiment, the volume percentage of helium is 20% to 40%.

[0023] In one feasible embodiment, the first temperature range is 80~90°C; the second temperature range is 110~120°C, wherein the two-layer encapsulation with different functions is achieved by setting a temperature gradient.

[0024] In one feasible embodiment, the first carrier gas includes any one or both of nitrogen and helium.

[0025] In one feasible embodiment, in step S2, water vapor is injected simultaneously with the introduction of the second carrier gas. The role of the water vapor is to absorb the carbon residue after the precursor has acted, thereby increasing the temperature of the membrane. When the water vapor is introduced, the carbon residue can be cyclically absorbed in a periodic manner.

[0026] In one feasible embodiment, the following steps are also included: S3: The gaseous precursor and the third carrier gas are introduced at a third temperature, and a third encapsulation film is formed on the surface of the second encapsulation film away from the first encapsulation film by chemical vapor deposition. The third temperature is lower than the first temperature. This temperature setting helps to achieve uniform film coverage under lower heat load conditions, while avoiding thermal damage to the underlying structure. In the configuration of the third carrier gas, nitrogen can be directly selected as the carrier gas, or a mixture of nitrogen and helium can be used. Nitrogen is a commonly used carrier gas due to its chemical stability and economy, while helium has high thermal conductivity and diffusion ability, making it suitable for scenarios that require enhanced precursor transport efficiency. However, in this scheme, since the third encapsulation film is mainly used to fill the microscopic gaps and defects in the second encapsulation film, its requirements for thermal diffusion performance are relatively low. Therefore, there is greater flexibility in the selection of the third carrier gas: helium can be added or not added according to actual process requirements, thereby optimizing process cost and complexity while ensuring encapsulation quality. This third encapsulation layer further improves the integrity and barrier performance of the device encapsulation structure.

[0027] In this embodiment, a lower-temperature deposition stage is added, forming a third encapsulation film that primarily serves as a sealant. Its purpose is to further fill any microscopic pores and surface defects that may exist in the second deposition stage, thereby significantly improving the overall density and integrity of the encapsulation layer. Through this three-layer stacked structure, the second encapsulation film, as the main functional layer, fully utilizes its barrier properties, while the third layer acts as an effective supplementary and protective layer, together achieving efficient encapsulation and protection for the organic light-emitting device.

[0028] In practice, during the first temperature stage deposition process on the organic light-emitting layer surface, the substrate temperature is strictly controlled at a low temperature (typically maintained at 50–80°C). Using trimethylaluminum (TMA) and ozone (O3) as precursors, and driven by high-purity nitrogen carrier gas, atomic layer deposition (ALD) is used to precisely deposit 50 cycles, forming a first encapsulation film with a thickness of approximately 5 nm. This low-temperature process not only effectively avoids the thermal degradation and structural damage that high temperatures may cause to the organic light-emitting materials, but also enables the formation of a uniform and dense initial Al2O3 layer under mild conditions, providing an excellent nucleation interface and bonding foundation for subsequent film deposition.

[0029] The second temperature stage of deposition then proceeds, raising the substrate temperature to approximately 150–200°C. TMA and O3 are continued as precursors, and a second encapsulation film with a thickness of approximately 20 nm is formed through 200 deposition cycles. In this stage, the carrier gas is changed from pure nitrogen to a mixture of nitrogen and helium. Helium, with its lower molecular weight and higher diffusion coefficient, significantly improves the transport efficiency of precursor molecules and the uniformity of their distribution within the reaction zone, thereby enhancing the deposition rate and overall quality of the film and contributing to the formation of a low-defect, high-barrier main encapsulation layer.

[0030] Finally, a third-stage deposition process is performed, with the temperature moderately reduced to approximately 100–120°C. Using the same TMA and O3 precursors, 50 deposition cycles are completed to form a third encapsulation film approximately 5 nm thick. This layer is deposited at a relatively low temperature, which avoids secondary thermal impacts on the underlying film and effectively fills any remaining micropores and grain boundaries in the intermediate layer, ultimately achieving surface planarization and a perfect seal in the encapsulation structure.

[0031] In one feasible embodiment, during the second temperature stage deposition process, water vapor can be pulsed and injected every five cycles. This cycle interval is chosen based on a balance between optimizing reaction kinetics and avoiding excessive oxidation, ensuring that water vapor can fully penetrate into the film. The pulsed injection method helps control the local concentration of water vapor, preventing droplet formation or condensation, thereby maintaining the stability of the deposition environment. This operation effectively removes residual unreacted organometallic groups and carbon impurities from the film through a hydrolysis reaction. Specifically, water molecules undergo nucleophilic substitution reactions with organometallic species, generating volatile byproducts such as carbon dioxide or methane. These byproducts are subsequently carried away by the carrier gas, significantly reducing the carbon content and improving the chemical purity and insulating properties of the film, for example, reducing the dielectric constant to an ideal range. Meanwhile, the higher deposition temperature in this stage (typically between 300°C and 500°C) significantly enhances the migration ability of precursor molecules on the substrate surface. By reducing the surface diffusion activation energy, it promotes atomic-level rearrangement, making the film formation process more closely aligned with the theoretical growth direction. This can achieve epitaxial or quasi-epitaxy growth modes, reduce the formation of grain boundaries and pores, and ultimately obtain a more compact microstructure and superior mechanical and barrier properties for the encapsulation film. Its density can approach the bulk material value, and the water and oxygen permeability is significantly reduced.

[0032] In one feasible embodiment, in step S3, radio frequency plasma-assisted treatment can also be applied simultaneously. The radio frequency plasma has a power of 50W and a frequency of 15MHz. This parameter combination aims to achieve a balance between high ion density and low ion energy, avoiding sputtering damage to the film. This low-temperature plasma is mainly used to treat and repair surface defects in the host layer. For example, it fills microcracks and promotes surface smoothing by reacting active species such as oxygen or nitrogen radicals with dangling bonds or vacancies. At the same time, the electron collision process in the plasma can excite surface atoms, enhance chemical bonding, further improve the compactness of the film, reduce surface roughness to the nanometer level, and improve the adhesion performance between the film and subsequent layers.

[0033] The first temperature stage can be controlled within the range of 80-90℃ to ensure the safety of the organic light-emitting layer; the second temperature stage is controlled within the range of 110-120℃ to balance the film density and precursor migration rate; the third temperature stage is controlled within the range of 60-90℃ to ensure the repair effect while avoiding thermal damage to the underlying structure.

[0034] In one feasible embodiment, the volume percentage of helium in the carrier gas is 20% to 40%. The carrier gas is doped with helium because helium is lightweight and has a high thermal motion rate. Thus, a carrier gas doped with helium can improve the movement of the precursor and increase the diffusion rate.

[0035] Furthermore, this invention also provides a packaging structure prepared by the above method. The structure includes a first encapsulation film formed directly on the surface of the organic light-emitting layer. This first encapsulation film is formed by low-temperature deposition and serves to protect the organic light-emitting layer. A second encapsulation film is formed on the first encapsulation film, deposited at a higher temperature to provide the primary barrier function. A third encapsulation film is formed on the second encapsulation film. This capping layer is formed at a lower temperature using plasma-assisted processing, effectively filling any microscopic defects that may exist in the main layer.

[0036] Comparison: Traditional Packaging Method like Figure 4 As shown, a single-temperature (100℃) deposition process was used with pure nitrogen as the carrier gas. The results showed that the thickness of the step surface was 38.30 nm and the film thickness was 40.67 nm. Therefore, the step coverage was 94%, and there were obvious pinhole defects in the film.

[0037] like Figure 5 As shown, in the implementation of the encapsulation method of the present invention, the thickness of the step surface is 30.04 nm and the thickness of the film is 30.17 nm, thus achieving 99% step coverage, significantly higher than the comparative example. Furthermore, in the water vapor barrier performance test, the water vapor transmission rate of the encapsulation structure of the present invention reaches 10%.-6 g / m 2 This meets the long-term reliability requirements of display devices.

[0038] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A method of encapsulating an organic light emitting layer, characterized by, The method comprises the following steps: S1: introducing a gaseous precursor and a first carrier gas at a first temperature to form a first encapsulation film on the side of the organic light-emitting layer away from the substrate, the first encapsulation film covering the top surface and side surface of the organic light-emitting layer; the first temperature is not higher than 110℃; S2: introducing the gaseous precursor and a second carrier gas at a second temperature to form a second encapsulation film on the side of the first encapsulation film away from the organic light-emitting layer, the second temperature being greater than the first temperature and not higher than 120℃; the second carrier gas comprises helium and nitrogen.

2. The packaging method according to claim 1, characterized in that, The volume ratio of the helium is 20%-40%.

3. The packaging method of claim 1, wherein, The first temperature ranges from 80-90℃; the second temperature ranges from 110-120℃.

4. The packaging method of claim 1, wherein, The first carrier gas comprises any one or both of nitrogen and helium.

5. The packaging method of claim 1, wherein, In the step S2, water vapor is injected while the second carrier gas is introduced.

6. The packaging method according to any one of claims 1-5, characterized in that, The method further comprises the following step: S3: introducing the gaseous precursor and a third carrier gas at a third temperature to form a third encapsulation film on the side of the second encapsulation film away from the first encapsulation film, the third temperature being less than the first temperature.

7. The packaging method according to any one of claim 6, characterized in that, The third temperature is set to range from 60-90℃.

8. The packaging method according to any one of claim 6, characterized in that, The third carrier gas comprises any one or both of nitrogen and helium.

9. The encapsulation method according to any one of claim 6, in step S3, further comprising applying a radio frequency plasma assisted deposition, wherein, The power of the radio frequency plasma is 50W, and the frequency is 15MHz.

10. A display panel, characterized by, The encapsulation structure comprises an organic light-emitting layer and is obtained by the encapsulation method according to any one of claims 1-9.

Images