Moisture resistant pmoled device and method of making same

Abstract

This invention provides a moisture-resistant PMOLED device and its fabrication method, comprising a substrate, an anode layer disposed on the substrate, at least one organic light-emitting unit (OLED), a PI layer, and an encapsulation layer disposed on the substrate. The substrate and the encapsulation layer together form a cavity, in which the OLED and the PI layer are disposed, and the OLED and the PI layer are disposed on the anode layer. The cavity also contains a SiN barrier layer, an isolation pillar layer, and a cathode layer. SiN barrier layers are disposed on both sides of the OLED, completely covering all surfaces of the PI layer except for the contact anode layer. The isolation pillar layer is disposed on the SiN barrier layer, and the cathode layer covers the OLED and the isolation pillar layer. This moisture-resistant PMOLED device and its fabrication method can significantly improve the waterproof performance and reliability of the PMOLED device, effectively extend its lifespan, and effectively delay pixel shrinkage.

Description

Technical Field

[0001] This invention relates to a PMOLED device resistant to water vapor erosion and its fabrication method, belonging to the field of organic electroluminescent device technology. Background Technology

[0002] OLED devices are widely used in electronic terminals such as mobile phones, wearable devices, and display panels due to their excellent characteristics such as self-emission, high contrast, thinness, and flexibility. However, the organic light-emitting layer and electrode materials in OLED devices are extremely sensitive to moisture and oxygen. Even trace amounts of moisture penetrating into the device can lead to degradation of organic materials and oxidation of electrodes, resulting in problems such as dark spots, decreased luminous efficiency, and shortened lifespan, seriously affecting the reliability and performance of OLED devices. Moisture erosion is a major factor affecting the reliability of OLED devices, and currently, the industry mainly uses two methods to specifically improve it: external blocking and internal absorption. 1. External Barrier: An encapsulation layer is used to prevent external moisture from entering the OLED device. Three common methods for external barrier are UV adhesive encapsulation, FIT encapsulation, and TFE encapsulation. While external barrier methods effectively reduce water and oxygen permeability, they cannot completely block moisture, allowing trace amounts to still penetrate the OLED device.

[0003] 2. Internal absorption: A water-absorbing material is placed inside the device to absorb trace amounts of moisture that are blocked by the encapsulation, thus protecting the OLED device. Internal absorption is usually achieved through a desiccant or a liquid desiccant.

[0004] However, the above-mentioned external barriers and internal absorption still have the following problems: In PMOLED devices, the cathode layer is divided into different regions by the inverted trapezoidal structure of the isolation pillar layer. The trace amount of water vapor that permeates from the outside slowly invades the polyimide layer below, i.e., the PI layer, through the edge of the isolation pillar layer, and then erodes the organic material through the edge of the PI layer, causing pixel shrinkage, resulting in device brightness and product failure, thereby affecting the reliability of OLED devices. Summary of the Invention

[0005] The purpose of this invention is to provide a PMOLED device that is resistant to water vapor erosion and its preparation method, which solves the problems of poor water resistance and pixel shrinkage and shortened lifespan caused by trace amounts of water vapor penetrating from the outside in the prior art.

[0006] The technical solution of this invention is: A PMOLED device resistant to water vapor erosion includes a substrate, an anode layer disposed on the substrate, at least one organic light-emitting unit (OLED), a PI layer, and an encapsulation layer disposed on the substrate. The substrate and the encapsulation layer together form a cavity. The OLED and the PI layer are both disposed within the cavity, and the OLED and the PI layer are disposed on the anode layer. The cavity also contains a SiN barrier layer, an isolation pillar layer, and a cathode layer. SiN barrier layers are disposed on both sides of the OLED. The SiN barrier layers completely cover all surfaces of the PI layer except for the contact anode layer. The isolation pillar layer is disposed on the SiN barrier layer. The cathode layer covers the OLED and the isolation pillar layer.

[0007] Furthermore, the thickness of the SiN barrier layer covering the side surface of the PI layer is 0.5-2 mm.

[0008] Furthermore, the thickness of the SiN barrier layer covering the upper surface of the PI layer is 50-200 nm.

[0009] Furthermore, the thickness of the PI layer is 1-5 μm.

[0010] Furthermore, the SiN barrier layer is prepared using a low-temperature plasma-enhanced chemical vapor deposition process.

[0011] Furthermore, the organic light-emitting unit includes a hole transport layer, an organic light-emitting layer, and an electron transport layer arranged sequentially from bottom to top.

[0012] Furthermore, a desiccant is provided inside the packaging layer.

[0013] Furthermore, the substrate is made of rigid glass, the encapsulation layer is made of grooved glass, and the encapsulation layer is bonded to the substrate with UV adhesive.

[0014] A method for fabricating a water-resistant PMOLED device as described in any one of the above claims includes the following steps: Step 1, Substrate fabrication: After physical and chemical cleaning of high-transmittance glass with a light transmittance ≥90%, the high-transmittance glass is dried with high-purity nitrogen (N2) to ensure that the surface of the high-transmittance glass is free of scratches, impurities, and oxide layer, thus obtaining the substrate. Step 2, Anode layer fabrication: The substrate is placed in a magnetron sputtering device, using an ITO target. The sputtering environment is a mixture of argon and oxygen in a volume ratio of 10:1, with a sputtering power of 200-300W and a substrate temperature of 150-200℃. This results in the formation of an ITO thin film layer. Then, a positive photolithography process is used to pattern the ITO thin film layer. After exposure, development, etching, and stripping processes, an electrode pattern is formed, resulting in the anode layer. Step 3, PI layer preparation: After coating the anode layer with PI using a spin coating process, the PI layer is prepared through exposure and development processes; Step 4, SiN barrier layer preparation: SiN thin films are deposited on all surfaces of the PI layer except the contact anode layer using a low-temperature PECVD process. Then, the surface of the SiN barrier layer is post-treated by radio frequency, i.e., plasma post-treatment process. After exposure, development and baking, the SiN barrier layer is formed. Step 5, Preparation of the isolation pillar layer: The isolation pillar layer is prepared using negative photoresist by spin coating or roll coating, followed by photolithography. The pattern of the isolation pillars is set by a mask. The isolation pillars are arranged in parallel and spaced apart, and are perpendicular to the ITO anode lines of the anode layer. After curing and baking at 150-180℃ for 20-30 minutes, the isolation pillar layer is obtained. Step 6, Organic light-emitting unit fabrication: The organic light-emitting unit is prepared by vacuum thermal evaporation, in which a hole transport layer, an organic light-emitting layer, and an electron transport layer are sequentially deposited under high vacuum to obtain the organic light-emitting unit. Step 7, Cathode layer preparation: Using an aluminum evaporation source, control the evaporation rate to 0.5-1.0 nm / s, the evaporation thickness to 100-200 nm, and control the substrate temperature to 80-100℃ during the evaporation process. After evaporation, the metal layer tightly covers the surface of the organic light-emitting unit and the isolation pillar layer to obtain the cathode layer. Step 8, Encapsulation layer preparation: Inside a nitrogen glove box, apply 2-3 circles of desiccant in a U-shape to the groove of the encapsulation cover plate. Then, apply UV adhesive to the encapsulation area of ​​the encapsulation cover plate with a width of 0.5-1mm. Then, attach the substrate and the encapsulation cover plate together. After UV curing and baking, the large-format PMOLED device is prepared. After cutting, the PMOLED device is obtained.

[0015] Furthermore, in step 4, during the low-temperature PECVD process, the reaction gases are silane (SiH4), ammonia (NH3), and nitrogen (N2) in a volume ratio of 1:3:5, where SiH4 is the Si source, NH3 is the N source, and N2 is used as a dilution gas. The reaction chamber pressure is 1-9 Torr, the RF power is 100-2000 W, the deposition rate is 5-10 nm / min, the deposition temperature is 30-90℃, and the total thickness of the deposited SiN film is controlled at 50-200 nm.

[0016] The beneficial effects of this invention are: I. This invention relates to a PMOLED device and its fabrication method that are resistant to water vapor erosion. Compared with existing technologies, this invention significantly improves the waterproof performance and reliability of PMOLED devices by fabricating a SiN barrier layer on the PI layer, ensuring that the SiN barrier layer completely covers all surfaces of the PI layer except for the contact anode layer. This effectively extends the lifespan of PMOLED devices and slows down pixel shrinkage. By utilizing the high density and low water vapor permeability of SiN material, this invention directly blocks the penetration path of water vapor through the pores and edge gaps of the PI layer surface, preventing water vapor from eroding the materials and electrodes of the organic light-emitting unit at the source. This effectively solves the problems of pixel shrinkage and shortened lifespan caused by water vapor penetration at the edges of the PI layer in existing PMOLED devices.

[0017] II. This type of PMOLED device that is resistant to water vapor erosion and its fabrication method do not require additional complex fabrication steps. The SiN barrier layer has both water vapor barrier and insulation functions, which can reduce the number of internal functional layers of the device and reduce the device thickness, thus meeting the development needs of OLED devices to be thinner and lighter. Moreover, the structure is simple, the fabrication process is mature, and it is easy to carry out large-scale industrial production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the longitudinal cross-sectional structure of a PMOLED device resistant to water vapor erosion according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of a PMOLED device that is resistant to water vapor erosion in an embodiment. Figure 3 This is a schematic diagram of the structure of an embodiment with two organic light-emitting units; Wherein: 1-substrate, 2-anode layer, 3-PI layer, 4-SiN barrier layer, 5-isolation pillar layer, 6-organic light-emitting unit, 7-cathode layer, 8-encapsulation layer, 9-cavity; 61-Hole transport layer, 62-Organic light-emitting layer, 63-Electron transport layer. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] An embodiment provides a PMOLED device that is resistant to water vapor corrosion, such as Figure 1 and Figure 2The device includes a substrate 1, an anode layer 2 disposed on the substrate 1, at least one organic light-emitting unit 6, a PI layer 3, and an encapsulation layer 8 disposed on the substrate 1. The substrate 1 and the encapsulation layer 8 together form a cavity 9. The organic light-emitting unit and the PI layer 3 are both disposed in the cavity 9, and the organic light-emitting unit 6 and the PI layer 3 are disposed on the anode layer 2. The cavity 9 is also provided with a SiN barrier layer 4, an isolation pillar layer 5, and a cathode layer 7. The organic light-emitting unit 6 is provided with SiN barrier layers 4 on both sides. The SiN barrier layers 4 completely cover all surfaces of the PI layer 3 except for the contact anode layer 2. The isolation pillar layer 5 is disposed on the SiN barrier layer 4. The cathode layer 7 covers the organic light-emitting unit 6 and the isolation pillar layer 5.

[0021] Compared with existing technologies, this invention provides a PMOLED device resistant to water vapor erosion. By fabricating a SiN barrier layer 4 on the PI layer 3, and ensuring that the SiN barrier layer 4 completely covers all surfaces of the PI layer 3 except for the contact anode layer 2, this significantly improves the waterproof performance and reliability of the PMOLED device, effectively extends its lifespan, and delays pixel shrinkage. By utilizing the high density and low water vapor permeability of SiN material, this invention directly blocks the penetration path of water vapor through the surface pores and edge gaps of the PI layer 3, preventing water vapor from eroding the materials and electrodes of the organic light-emitting unit 6 at the source. This effectively solves the problems of pixel shrinkage and shortened lifespan caused by water vapor penetration from the edges of the PI layer 3 in existing PMOLED devices.

[0022] In this type of moisture-resistant PMOLED device, the thickness of the SiN barrier layer 4 covering the side surface of the PI layer 3 is 0.5-2 mm. The thickness of the SiN barrier layer 4 covering the upper surface of the PI layer 3 is 50-200 nm. This achieves a water vapor transmission rate (WVTR) of ≤10 for the SiN barrier layer 4. -4 g / m²·day, ensuring effective water vapor barrier. The thickness of PI layer 3 is 1-5 μm. SiN barrier layer 4 is prepared using a low-temperature plasma-enhanced chemical vapor deposition process, with a deposition temperature of 30-90℃. Figure 3 Two organic light-emitting units 6 are disposed within the cavity 9. Each organic light-emitting unit 6 includes a hole transport layer 61, an organic light-emitting layer 62, and an electron transport layer 63 arranged sequentially from bottom to top. A desiccant is disposed within the encapsulation layer 8. The substrate 1 is made of rigid glass, and the encapsulation layer 8 is made of grooved glass. The encapsulation layer 8 is bonded to the substrate 1 with UV adhesive to form a sealed area. A U-shaped desiccant is coated inside the encapsulation layer 8.

[0023] In this type of moisture-resistant PMOLED device, when moisture invades the device, the encapsulation layer 8 completely blocks the moisture from above, and the UV adhesive around the encapsulation layer 8 can block most of the moisture. When a trace amount of residual moisture invades the device, some of the moisture is absorbed by the liquid desiccant; the remaining moisture is blocked by the dense cathode layer 7 below and cannot pass through. It can only enter the device from the edge of the isolation pillar layer 5. However, because a SiN barrier layer 4 is provided below the isolation pillar layer 5 in this embodiment, the moisture is further blocked and cannot quickly corrode the organic materials, thereby improving the reliability of the device.

[0024] A method for fabricating a water-resistant PMOLED device as described in any one of the above claims includes the following steps: Step 1, Substrate 1 fabrication: Physically and chemically clean the 0.5mm thick high-transmittance glass with a transmittance ≥90% to remove oil, organic residues and microparticles from the surface of substrate 1. Use high-purity nitrogen (N2) to dry the high-transmittance glass to avoid water stains and ensure that the surface of the high-transmittance glass is free of scratches, impurities and oxide layer, thus obtaining substrate 1.

[0025] Step 2, Fabrication of anode layer 2: The substrate 1 is placed in a magnetron sputtering apparatus, using an ITO target. The sputtering environment is a mixed atmosphere of argon and oxygen with a volume ratio of 10:1, the sputtering power is 200-300W, and the substrate 1 temperature is 150-200℃. Finally, an ITO thin film layer with a thickness of 150nm is formed. Then, a positive photolithography process is used to pattern the ITO thin film layer. After exposure, development, etching, and demolding processes, an electrode pattern is formed, and anode layer 2 is obtained.

[0026] Step 3, Preparation of PI layer 3: After coating PI onto the anode layer 2 using a spin coating process, PI layer 3 is prepared through exposure and development processes.

[0027] Step 4: Preparation of SiN barrier layer 4: After depositing SiN thin films on all surfaces of PI layer 3 except for contact anode layer 2 using low-temperature PECVD process, the surface of SiN barrier layer 4 is post-processed using radio frequency, i.e., plasma post-processing process. After exposure, development and baking processes, SiN barrier layer 4 is formed.

[0028] In step 4, during the low-temperature PECVD process, the reaction gases are silane (SiH4), ammonia (NH3), and nitrogen (N2) in a volume ratio of 1:3:5. SiH4 is the Si source, NH3 is the N source, and N2 is used as a dilution gas. The reaction chamber pressure is 1-9 Torr, the RF power is 100-2000 W, the deposition rate is 5-10 nm / min, the deposition temperature is 30-90℃, and the total thickness of the deposited SiN film is controlled at 50-200 nm.

[0029] In step 4, a low-temperature PECVD process is used to prepare the SiN barrier layer 4. The deposition temperature is controlled between 30-90℃, preferably 60℃, to avoid damage to the flexibility and structural stability of the PI layer 3 caused by high temperatures. This also ensures the density of the SiN layer and its adhesion to the PI layer 3, and is compatible with the fabrication process of the flexible substrate 1. Simultaneously, after deposition, the flow of SiH4 is stopped, and the density of the SiN barrier layer 4 is improved through radio frequency post-processing, further reducing water vapor permeability. This balances barrier performance and process compatibility, allowing direct integration into the existing OLED substrate 1 fabrication process without significant modifications to production equipment, thus reducing production costs.

[0030] Step 5, Preparation of isolation pillar layer 5: It is prepared by negative photoresist, and the coating method is spin coating or roll coating. Then, photolithography is performed. The pattern of isolation pillars is set by a mask. The isolation pillars are arranged in parallel and spaced apart, and are perpendicular to the ITO anode line direction of the anode layer 2. The spacing between adjacent isolation pillars matches the pixel size. After curing and baking at a temperature of 150-180℃ for 20-30 minutes, isolation pillar layer 5 is obtained.

[0031] In step 5, the isolation pillars are hard and uniform in size, and are used to separate different pixel areas to form different cathode patterns.

[0032] Step 6, Preparation of organic light-emitting unit 6: The organic light-emitting unit 6 is prepared by vacuum thermal evaporation process. Hole transport layer 61, organic light-emitting layer 62 and electron transport layer 63 are sequentially deposited in a high vacuum environment to obtain organic light-emitting unit 6.

[0033] Step 7, Preparation of cathode layer 7: Using an aluminum evaporation source, the evaporation rate is controlled at 0.5-1.0 nm / s, and the evaporation thickness is 100-200 nm. During the evaporation process, the temperature of substrate 1 is controlled at 80-100℃ to avoid high temperature damage to the organic functional layer. After evaporation, the metal layer tightly covers the surface of organic light-emitting unit 6 and isolation pillar layer 5 to obtain cathode layer 7.

[0034] In step 7, the cathode layer 7 uses an aluminum electrode with a thickness of 1200 nm.

[0035] Step 8, Preparation of Encapsulation Layer 8: Inside a nitrogen glove box, apply 2-3 circles of desiccant in a U-shape to the groove of the encapsulation cover plate. Then, apply UV adhesive to the encapsulation area of ​​the encapsulation cover plate with a width of 0.5-1mm. Then, attach the substrate 1 to the encapsulation cover plate together. After UV curing and baking, the large-plate preparation of the PMOLED device is completed. After cutting, the PMOLED device is obtained.

[0036] This type of water vapor-resistant PMOLED device and its fabrication method do not require additional complex fabrication steps. The SiN barrier layer 4 has both water vapor barrier and insulation functions, which can reduce the number of internal functional layers of the device and reduce the device thickness, thus meeting the development needs of OLED devices to be thinner and lighter. Moreover, the structure is simple, the fabrication process is mature, and it is easy to carry out large-scale industrial production.

[0037] This novel PMOLED device, protected against water vapor erosion, and its fabrication method involve preparing a silicon nitride (SiN) barrier layer 4 on a PI layer 3 of substrate 1. The high density and excellent water vapor barrier properties of the SiN barrier layer 4 block the penetration path of water vapor from the isolation pillar layer 5 through the PI layer 3, preventing water vapor from eroding the organic light-emitting material and extending the lifespan of the OLED device. Furthermore, by placing the PI layer 3 between the anode layer 2 and the SiN barrier layer 4, compared to replacing both the SiN barrier layer 4 and the PI layer 3 entirely with SiN material, the breakdown of the SiN material can be effectively prevented, ensuring the stable electrical performance of the PMOLED device.

[0038] This type of moisture-resistant PMOLED device features a substrate 1 with good flexibility and mechanical strength, an anode layer 2 made of ITO conductive film with good light transmittance and conductivity, and a PI layer 3 made of high-temperature resistant flexible PI material, which serves to protect the substrate 1 and provide insulation.

[0039] The PMOLED device resistant to water vapor erosion in this embodiment was experimentally verified as follows: In this embodiment, the SiN barrier layer 4 has a thickness of 100 nm, and the isolation pillar layer 5 has a thickness of 5-10 μm. The substrate 1 has a thickness of 0.5 mm and dimensions of 370*470 mm; the anode layer 2 has a thickness of 150 nm and a sheet resistance of 10 Ω / L; the PI layer 3 has a thickness of 2 μm, and 64 organic light-emitting units 6 are disposed in the cavity 9, with the organic light-emitting units 6 directly disposed on the anode layer 2.

[0040] The difference between Comparative Example 1 and the Example is that the edge of the SiN barrier layer 4 does not extend beyond the edge of the PI layer 3, while the rest of the structure is the same as the Example.

[0041] The difference between Comparative Example 2 and the Example is that SiN barrier layer 4 is not provided, but the rest of the structure is the same as that of the Example.

[0042] The OLED devices prepared in Examples 1 and 2 had a light-emitting size of 2.42 inches, a resolution of 128*64, and a product model of DPM128064W05. Substrate 1 was cut into 63 modules. After preparation, the OLED devices were stored at 85°C and 85% relative humidity for 500 and 1000 hours, respectively. The pixel shrinkage comparison results of the OLED devices prepared in Examples 1 and 2 are shown in Table 1. Table 1. Comparison of pixel shrinkage results between the OLED devices prepared in the Example and Comparative Examples 1 and 2.

[0043] As can be seen from the results in Table 1, the solution provided by the present invention can improve the reliability of the device by more than 50%, and the improvement effect is very obvious.

[0044] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the scope of protection of the present invention.

Claims

1. A PMOLED device resistant to water vapor corrosion, comprising a substrate, an anode layer disposed on the substrate, at least one organic light-emitting unit (OLED), a PI layer, and an encapsulation layer disposed on the substrate, wherein the substrate and the encapsulation layer together form a cavity, the OLED and the PI layer are both disposed within the cavity, and the OLED and the PI layer are disposed on the anode layer, characterized in that: The cavity also contains a SiN barrier layer, an isolation pillar layer, and a cathode layer. SiN barrier layers are provided on both sides of the organic light-emitting unit. The SiN barrier layer completely covers all surfaces of the PI layer except for the contact anode layer. The isolation pillar layer is located on the SiN barrier layer. The cathode layer covers the organic light-emitting unit and the isolation pillar layer.

2. The PMOLED device resistant to water vapor erosion as described in claim 1, characterized in that: The thickness of the SiN barrier layer covering the side surface of the PI layer is 0.5-2 mm.

3. The PMOLED device resistant to water vapor erosion as described in claim 1, characterized in that: The thickness of the SiN barrier layer covering the upper surface of the PI layer is 50-200nm.

4. The PMOLED device with water vapor erosion resistant according to any one of claims 1-3, characterized in that: The thickness of the PI layer is 1-5 μm.

5. The PMOLED device resistant to water vapor erosion as described in any one of claims 1-3, characterized in that: The SiN barrier layer was prepared using a low-temperature plasma-enhanced chemical vapor deposition process.

6. The PMOLED device resistant to water vapor erosion as described in any one of claims 1-3, characterized in that: The organic light-emitting unit includes a hole transport layer, an organic light-emitting layer, and an electron transport layer arranged sequentially from bottom to top.

7. The PMOLED device with water vapor erosion resistant according to any one of claims 1-3, characterized in that: A desiccant is placed inside the packaging layer.

8. The waterproof and vapor-resistant PMOLED device according to any one of claims 1-3, characterized in that: The substrate is made of rigid glass, the encapsulation layer is made of grooved glass, and the encapsulation layer is bonded to the substrate with UV adhesive.

9. A method for fabricating a waterproof and vapor-resistant PMOLED device according to any one of claims 1-8, characterized in that: Includes the following steps, Step 1, Substrate fabrication: After physical and chemical cleaning of high-transmittance glass with a light transmittance ≥90%, the high-transmittance glass is dried with high-purity nitrogen (N2) to ensure that the surface of the high-transmittance glass is free of scratches, impurities, and oxide layer, thus obtaining the substrate. Step 2, Anode layer fabrication: The substrate is placed in a magnetron sputtering device, using an ITO target. The sputtering environment is a mixture of argon and oxygen in a volume ratio of 10:1, with a sputtering power of 200-300W and a substrate temperature of 150-200℃. This results in the formation of an ITO thin film layer. Then, a positive photolithography process is used to pattern the ITO thin film layer. After exposure, development, etching, and stripping processes, an electrode pattern is formed, resulting in the anode layer. Step 3, PI layer preparation: After coating the anode layer with PI using a spin coating process, the PI layer is prepared through exposure and development processes; Step 4, SiN barrier layer preparation: SiN thin films are deposited on all surfaces of the PI layer except the contact anode layer using a low-temperature PECVD process. Then, the surface of the SiN barrier layer is post-treated by radio frequency, i.e., plasma post-treatment process. After exposure, development and baking, the SiN barrier layer is formed. Step 5, Preparation of the isolation pillar layer: The isolation pillar layer is prepared using negative photoresist by spin coating or roll coating, followed by photolithography. The pattern of the isolation pillars is set by a mask. The isolation pillars are arranged in parallel and spaced apart, and are perpendicular to the ITO anode lines of the anode layer. After curing and baking at 150-180℃ for 20-30 minutes, the isolation pillar layer is obtained. Step 6, Organic light-emitting unit fabrication: The organic light-emitting unit is prepared by vacuum thermal evaporation, in which a hole transport layer, an organic light-emitting layer, and an electron transport layer are sequentially deposited under high vacuum to obtain the organic light-emitting unit. Step 7, Cathode layer preparation: Using an aluminum evaporation source, control the evaporation rate to 0.5-1.0 nm / s, the evaporation thickness to 100-200 nm, and control the substrate temperature to 80-100℃ during the evaporation process. After evaporation, the metal layer tightly covers the surface of the organic light-emitting unit and the isolation pillar layer to obtain the cathode layer. Step 8, Encapsulation layer preparation: Inside a nitrogen glove box, apply 2-3 circles of desiccant in a U-shape to the groove of the encapsulation cover plate. Then, apply UV adhesive to the encapsulation area of ​​the encapsulation cover plate with a width of 0.5-1mm. Then, attach the substrate and the encapsulation cover plate together. After UV curing and baking, the large-format PMOLED device is prepared. After cutting, the PMOLED device is obtained.

10. The PMOLED device resistant to water vapor erosion as described in claim 9, characterized in that: In step 4, during the low-temperature PECVD process, the reaction gases are silane (SiH4), ammonia (NH3), and nitrogen (N2) in a volume ratio of 1:3:

5. SiH4 is the Si source, NH3 is the N source, and N2 is used as a dilution gas. The reaction chamber pressure is 1-9 Torr, the RF power is 100-2000 W, the deposition rate is 5-10 nm / min, the deposition temperature is 30-90℃, and the total thickness of the deposited SiN film is controlled at 50-200 nm.

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