A full-color oled device with white balance and a manufacturing method thereof

Abstract

The application discloses a full-color OLED device for realizing white balance and a manufacturing method thereof. The device structure comprises a metal anode, a first hole transport layer, a blue light-emitting layer, a first electron transport layer, a charge generation layer, a second hole transport layer, a green light-emitting layer, a red light-emitting layer, a second electron transport layer, a TCO cathode layer, an optical path regulation encapsulation layer, a blue wave band high reflectivity encapsulation layer, a red and green wave band high reflectivity encapsulation layer and a water and oxygen isolation encapsulation layer which are stacked in sequence. The application can avoid the light loss caused by the SPP effect of the Ag cathode by introducing the TCO cathode and the wavelength-selected high reflectivity encapsulation structure. The optical and electrical designs of the OLED are separated, the design freedom is increased, and the repeatability of the OLED device is improved. The wavelength-selected high reflectivity can freely design the reflectivity wave band and the reflectivity value, and the light emission white balance of the OLED device is realized.

Description

Technical Field

[0001] This invention relates to the field of OLED microdisplay technology, and in particular to a full-color OLED device that achieves white balance and its manufacturing method. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are widely used in consumer electronics displays, AR / VR head-mounted displays, and gun-mounted displays due to their advantages such as high contrast, wide color gamut, high resolution, wide viewing angle, low power consumption, low weight, and rollability.

[0003] To improve the luminous efficiency, maximum brightness, and lifespan of full-color OLED devices, OLED devices employ a double- or even triple-layer top-emitting device structure, paired with a highly reflective anode (such as Al) and cathode metal (such as Ag) across the entire visible light spectrum. This creates optical interference enhancement in the OLED device region, known as the OLED microcavity effect. By adjusting the optical thickness of each organic layer in the OLED device, optical interference enhancement is simultaneously achieved across the RGB color bands, meeting the requirements for full-color OLED displays. In terms of electrical performance, Ag and Al have relatively low resistivity among common metal materials, resulting in relatively low voltage for OLED devices while also meeting the low power consumption requirements. High-transmittance thin-film encapsulation structures, such as metal oxides Al₂O₃ and TiO₂, and silicon-based SiN, are fabricated on top of the Ag metal. x SiO x N y and SiO x It meets the reliability requirements of thin-film encapsulation to isolate moisture and oxygen, while its high light transmittance minimizes light loss caused by encapsulation.

[0004] At the metal-dielectric interface, especially at the Ag cathode-encapsulation layer interface used in the aforementioned OLED device structure, the surface plasmon polariton (SPP) effect inevitably occurs. The SPP effect is a surface electromagnetic mode formed by the coupling of electromagnetic waves with the free electron oscillations on the metal surface. The resulting electromagnetic field is perpendicular to the interface direction, forming surface waves propagating along the interface and evanescent waves perpendicular to the interface with exponentially decaying intensity. Both waves are non-radiative transitions of electromagnetic waves. Combined with the absorption of light by the Ag metal, the SPP effect accounts for approximately 40% of the total light loss in OLED devices, making it the largest source of non-radiative transition loss.

[0005] Furthermore, if the cathode Ag film is too thin, the internal resistance of the device increases, the operating voltage rises, and the lifespan decreases; if the Ag film is too thick, the reflectivity is too high, and the brightness of the device decreases significantly. To balance device voltage and brightness, the process window for the thickness of the cathode Ag is very small. In particular, OLED display products with a maximum brightness >6000 nits exhibit poor brightness repeatability within the same batch and even among products within the same batch. Simultaneously, the small process window makes it impossible to simultaneously enhance RGB light emission while maintaining white balance. The initial CIE coordinates of the OLED device deviate from white, requiring optical adjustments to achieve white balance, resulting in a device efficiency loss of approximately 10%.

[0006] In summary, the design of OLED microcavity devices requires precise determination of the Ag thickness and the thickness of each organic layer, while simultaneously satisfying the requirements of enhanced optical interference and low operating voltage. This results in significant design challenges, a small process window, a light extraction efficiency loss exceeding 50%, and an inability to achieve white balance for full-color displays. Summary of the Invention

[0007] Technical Objective: To address the deficiencies in existing technologies, this invention discloses a full-color OLED device and its manufacturing method that achieves white balance. By introducing a TCO cathode and a wavelength-selective high-reflectivity encapsulation structure, this invention avoids light loss caused by the SPP effect of the Ag cathode. Separating the optical and electrical design of the OLED increases design freedom and improves the repeatability of the OLED device. The wavelength-selective high-reflectivity allows for free design of reflectivity bands and values, achieving white balance in the OLED device.

[0008] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution.

[0009] A full-color OLED device that achieves white balance includes a metal anode, a first hole transport layer, a blue light-emitting layer, a first electron transport layer, a charge generation layer, a second hole transport layer, a green light-emitting layer, a red light-emitting layer, a second electron transport layer, a TCO cathode layer, an optical path control encapsulation layer, a blue band high reflectivity encapsulation layer, a red-green band high reflectivity encapsulation layer, and a water-oxygen barrier encapsulation layer stacked sequentially. The OLED device is comprised of a metal anode, which functions as the anode in the OLED device. The structure consists of a first hole transport layer, a blue emitting layer, a first electron transport layer, a charge generation layer, a second hole transport layer, a green emitting layer, a red emitting layer, and a second electron transport layer, forming a dual-layer OLED light-emitting structure. The first layer is a blue emitting layer, used to emit blue light, while the second layer consists of green and red emitting layers, used to emit green and red light. The TCO cathode layer serves as the cathode layer for the OLED device. The optical path control encapsulation layer is used to control the optical path length of the device, ensuring that both RGB light emission is within the optical interference enhancement range. The blue band high reflectivity encapsulation layer and the red-green band high reflectivity encapsulation layer are used to achieve high reflectivity in specific bands and low reflectivity in other bands, enabling the design of specific reflectivity values ​​for the RGB bands.

[0010] The water and oxygen barrier encapsulation layer is used to protect OLED devices from water vapor and oxygen, ensuring device reliability.

[0011] A method for manufacturing a full-color OLED device that achieves white balance includes the following steps: Step 1: Prepare the metal anode; Step 2: Sequentially prepare the first hole transport layer, blue light-emitting layer, first electron transport layer, charge generation layer, second hole transport layer, green light-emitting layer, red light-emitting layer, and second electron transport layer on the metal anode; Step 3: Prepare a TCO cathode layer on the second electron transport layer; Step 4: Fabricate an optical path control encapsulation layer on the TCO cathode layer; Step 5: Sequentially fabricate a blue band high reflectivity encapsulation layer and a red-green band high reflectivity encapsulation layer on the optical path control encapsulation layer; Step 6: Prepare a water-oxygen barrier layer on the high reflectivity encapsulation layer in the red and green bands.

[0012] Beneficial effects: By introducing a TCO cathode and a wavelength-selective high-reflectivity packaging structure, this invention can avoid light loss caused by the SPP effect of the Ag cathode; it separates the optical and electrical design of the OLED, increasing design freedom and improving the repeatability of the OLED device; the wavelength-selective high reflectivity allows for free design of reflectivity bands and reflectivity values, achieving white balance in the light output of the OLED device. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a full-color OLED device that achieves white balance according to an embodiment of the present invention.

[0014] Figure 2 This is a comparison of the TCO cathode spectrum of this invention with the emission spectrum of a traditional Ag metal cathode. Detailed Implementation

[0015] 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 clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application. Example

[0016] As attached Figure 1 As shown, a full-color OLED device for achieving white balance in this embodiment includes a metal anode 1, a first hole transport layer 2, a blue light-emitting layer 3, a first electron transport layer 4, a charge generation layer 5, a second hole transport layer 6, a green light-emitting layer 7, a red light-emitting layer 8, a second electron transport layer 9, a TCO cathode layer 10, an optical path control encapsulation layer 11, a blue band high reflectivity encapsulation layer 12, a red-green band high reflectivity encapsulation layer 13, and a water-oxygen barrier encapsulation layer 14, which are stacked sequentially. Among them, the metal anode 1 is used to realize the anode function of the OLED device, so that the overall reflectivity in the visible light band is >90%, ensuring top emission light emission; The dual-layer OLED light-emitting structure, consisting of a first hole transport layer 2, a blue light-emitting layer 3, a first electron transport layer 4, a charge generation layer 5, a second hole transport layer 6, a green light-emitting layer 7, a red light-emitting layer 8, and a second electron transport layer 9, is made entirely of organic materials. The thickness of each organic material layer ranges from 1 nm to 40 nm. The first layer, blue light-emitting layer 3, is used to achieve blue light emission. The second layer, consisting of green and red light-emitting layers 7 and 8, is used to achieve green and red light emission. This dual-layer OLED light-emitting structure incorporates RGB light-emitting materials and, combined with driving circuitry and color filtering technology, enables full-color light emission display. The TCO cathode layer 10 serves as the cathode layer for OLED devices, ensuring an overall reflectivity of >85% in the visible light band and minimizing the impact on the preset optical interference of the device; the TCO cathode layer is also known as a transparent conductive oxide cathode layer. The optical path control encapsulation layer 11 is used to control the optical path length of the device to ensure that the RGB light output is within the optical interference enhancement range. The blue band high reflectivity encapsulation layer 12 and the red-green band high reflectivity encapsulation layer 13 are used to achieve high reflectivity in a specific band and low reflectivity in other bands, thereby achieving the design of specific reflectivity values ​​for the RGB band. The water and oxygen barrier encapsulation layer 14 is used to protect the OLED device from water vapor and oxygen, ensuring device reliability.

[0017] This invention avoids light loss caused by the SPP effect of Ag cathodes by introducing a TCO cathode and a wavelength-selective high-reflectivity packaging structure; it separates the optical and electrical design of OLEDs, increasing design freedom and improving the repeatability of OLED devices; the wavelength-selective high-reflectivity allows for free design of reflectivity bands and reflectivity values, achieving white balance in the light output of OLED devices.

[0018] This invention does not use Ag material as the cathode, but instead uses TCO material to prepare the TCO cathode layer 10, avoiding the SPP effect generated at the Ag-dielectric interface, thus avoiding the light loss caused by this effect, and significantly improving the luminous brightness of the OLED top-emitting device, with a luminous brightness improvement ratio of >100%; TCO material preparation for TCO cathode layer 10, SiN with visible light transmittance >90% x The prepared optical path control encapsulation layer 11, blue band high reflectivity encapsulation layer 12, and red-green band high reflectivity encapsulation layer 13, as high reflectivity layers for specific wavelengths, can avoid the need for Ag as a single material to simultaneously meet the optical and electrical performance requirements of OLED devices. This improves the freedom of device design and the process window of the product, and is beneficial to improving the repeatability of device performance. Using a TCO cathode, the total optical path between the cathode and anode can be controlled by changing the thickness of the TCO cathode layer. The thickness range of the TCO cathode layer is 100nm-300nm, which is a larger adjustable optical path range compared to the control range of organic material thickness (1nm-40nm). This increases the adjustment and optimization space of device design, and is beneficial to improving the device's luminous brightness and luminous efficiency. By not using Ag material as the cathode, design variables are reduced, the design difficulty of OLED top-emitting devices is lowered, and the process window is expanded, improving the repeatability of device structure and performance stability. Using a packaging structure to design high-reflectivity layers for specific wavelengths eliminates the need to meet other performance requirements. Optimal reflectivity layers can be designed for each RGB emission wavelength separately. For example, designing a high-reflectivity packaging layer for the blue light band would require reflectivity of less than 5% for the green and red bands, minimizing the impact on optical interference in the red and green bands. The principle for designing high-reflectivity packaging layers for the red and green bands is the same. Using this dual-layer packaging layer with multiple reflectivity centers allows for precise control of the optical interference effect and interference enhancement ratio in the RGB bands, achieving white balance in OLED device emission and avoiding brightness loss caused by product optical adjustments.

[0019] All film layers are processed sequentially from bottom to top to form an OLED top-emitting device.

[0020] The present invention also provides a method for manufacturing a full-color OLED device that achieves white balance, comprising the following steps: Step 1: Prepare metal anode 1. The material of metal anode 1 is usually Al, with a thickness ranging from 30nm to 60nm. It is prepared using physical vapor deposition (PVD) with a sputtering power of 6000W-12000W and a sputtering temperature of room temperature.

[0021] Step 2: Sequentially prepare the following layers on the metal anode 1: first hole transport layer 2, blue luminescent layer 3, first electron transport layer 4, charge generation layer 5, second hole transport layer 6, green luminescent layer 7, red luminescent layer 8, and second electron transport layer 9; thus preparing each layer of organic material. Vacuum deposit each layer of organic material sequentially until the second electron transport layer 9 is completed. All layers from 2 to 9 are organic materials, with a single-layer thickness of 1-40 nm. Specifically, layers 3, 7, and 8 are blue, green, and red luminescent materials, respectively. Two different organic materials are simultaneously vacuum deposited to form a doped structure, with the luminescent material acting as the dopant, and the doping ratio ranging from 1% to 10%. The evaporation temperature for all organic materials from layers 2 to 9 is 150℃-300℃.

[0022] Step 3: Fabricate a TCO cathode layer 10 on the second electron transport layer 9. The TCO cathode layer has a transmittance of >80% in the visible light band of 380nm-780nm and a thickness ranging from 100-300nm. It is fabricated using a low-damage magnetron sputtering process with a sputtering power of 2000W-4000W.

[0023] Step 4: Fabricate an optical path control encapsulation layer 11 on the TCO cathode layer 10. A monolayer SiN is fabricated using PECVD (plasma-enhanced chemical vapor deposition) technology. x The thin film, serving as the optical path control encapsulation layer 11, has a thickness ranging from 200nm to 500nm and a refractive index ranging from 1.8 to 2.0, with a transmittance >90% in the visible light band of 380nm-780nm. The purpose of this layer is to adjust the light-emitting optical path of the entire microcavity structure of the OLED device, ensuring high light extraction efficiency for all three RGB emission peaks while also maintaining RGB white balance. The process temperature is 80℃-120℃ to avoid excessively high temperatures that could cause the OLED organic materials to fail.

[0024] Step 5: Sequentially fabricate a blue-band high-reflectivity encapsulation layer 12 and a red-green-band high-reflectivity encapsulation layer 13 on the optical path control encapsulation layer 11. This involves fabricating high-reflectivity encapsulation layers for specific wavelengths. Both the blue-band high-reflectivity encapsulation layer 12 and the red-green-band high-reflectivity encapsulation layer 13 utilize a high / low refractive index overlapping structure, with the high refractive index material being SiN. x The refractive index ranges from 2.0 to 2.2, and the low refractive index material is SiO₂. xThe refractive index ranges from 1.4 to 1.6, and the stacked SiN x and SiO x Each layer has the same thickness. To achieve high reflectivity in both the blue and red-green light bands, a high / low refractive index overlapping structure is used, with reflectivity center wavelengths of 460nm and 580nm selected to achieve high reflectivity in the blue and red-green light bands, respectively. The film thicknesses of both high-refractive-index SiNx and low-refractive-index SiOx satisfy the formula L=mλ / 4n. Here, m is the order, and in this invention, m=1; λ is the designed reflectivity center wavelength, i.e., 460nm and 580nm; n is the SiO₂ thickness. x and SiN x The refractive index. The total number of layers of high refractive index / low refractive index overlapping material is 3-10 layers. The high reflectivity encapsulation layer for a specific wavelength band is fabricated using PECVD process, which is the same as the process in step four.

[0025] Step Six: Fabricate a water-oxygen barrier encapsulation layer 14 on the red-green band high-reflectivity encapsulation layer 13. To achieve low water vapor transmittance and high light transmittance, the entire water-oxygen barrier encapsulation layer 14 uses Al2O3, TiO2, and SiN. x SiO x N y SiO x Five materials were used: Al2O3 and TiO2 were fabricated using atomic layer deposition (ALD) technology, and SiN... x SiO x N y SiO x The refractive index ranges of the five materials are 1.5-1.7, 2.3-2.5, 1.8-2.2, 1.6-1.8, and 1.4-1.6, respectively, achieved using plasma-enhanced chemical vapor deposition (PECVD). Both processes are performed at temperatures between 80℃ and 120℃ to avoid excessively high temperatures that could cause OLED organic material failure. The fabrication process of the water-oxygen barrier encapsulation layer 14 includes: First, using ALD (Al2O3) technology, Al2O3 and TiO2 are stacked in layers of 4-8 layers. The thickness of each Al2O3 and TiO2 layer ranges from 2nm to 8nm, ensuring that the total thickness of the Al2O3 and TiO2 films prepared by ALD is <120nm to avoid excessive film stress that could lead to ALD film cracking and peeling. Then, using PECVD, a high-refractive-index material, SiN, is prepared. x / Medium refractive index material SiO x N y Low refractive index material SiO xThe H / M / L reflectivity structure, with each PECVD-prepared film having a thickness ranging from 50nm to 500nm and a total thickness in the range of 600nm to 1200nm, ensures that the transmittance of the encapsulated film in the 380nm-780nm visible light band is >90%. Therefore, the water and oxygen barrier encapsulation layer 14 based on ALD and PECVD processes has a water and oxygen transmittance (WVTR) < 5*10⁻⁶. -5 g / m 2 / day, meeting the packaging reliability requirements of organic semiconductor devices, while the light transmittance is >85% in the 380nm-780nm band, with little impact on the light output efficiency of the device.

[0026] The organic and metal layers of the OLED device are fabricated using high-vacuum evaporation equipment; the TCO cathode uses a low-damage magnetron sputtering process to avoid damage to the OLED material during sputtering, which could lead to device failure; the optical path control encapsulation layer is fabricated using a low-temperature PECVD process, and the specific wavelength high-reflectivity encapsulation layer is fabricated using a PECVD process, with SiN materials of 2.0-2.2 selected for high and low refractive indices respectively. x and 1.4-1.6 SiO x The material overlap structure and the water and oxygen isolation encapsulation process, in addition to the previously mentioned low-temperature PECVD process, also require the use of ALD (Alternating Deposition) technology. This structure does not increase the number of process steps and offers the advantages of controllable process effects and good repeatability.

[0027] The verification is performed based on the content of this embodiment, that is, by comparing the light emission spectrum of the TCO cathode in this application with that of a traditional Ag metal cathode, as shown in the attached figure. Figure 2 As shown, the metal anode 1 is pixelated using photolithography, and a driving circuit supplies voltage to each pixel. All other processes are the same, fabricating the aforementioned TCO cathode OLED device (a full-color OLED device achieving white balance according to this application) and an Ag cathode OLED device (an OLED device using Ag as the cathode in the prior art). The CIE coordinates of both OLED devices are adjusted to (0.285, 0.320). Maintaining a power consumption of 80mW for both devices, the brightness of the TCO cathode OLED device and the Ag cathode OLED device are 921 nit and 1916 nit, respectively, with color gamuts of 82.72% and 82.85% based on the CIE1931 standard, respectively. These indicators demonstrate that, under the same power consumption conditions, using the white-balanced full-color OLED device technology of this invention, the luminous brightness is increased by 108%, meaning the luminous efficiency of the OLED device is increased by 108%, while the CIE1931 color gamut value of the device does not decrease, achieving white-balanced full-color illumination.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A full-color OLED device for achieving white balance, characterized in that, It includes a metal anode, a first hole transport layer, a blue light-emitting layer, a first electron transport layer, a charge generation layer, a second hole transport layer, a green light-emitting layer, a red light-emitting layer, a second electron transport layer, a TCO cathode layer, an optical path control encapsulation layer, a blue band high reflectivity encapsulation layer, a red and green band high reflectivity encapsulation layer, and a water and oxygen barrier encapsulation layer stacked in sequence. The OLED device is comprised of a metal anode, which functions as the anode; a first hole transport layer, a blue emitting layer, a first electron transport layer, a charge generation layer, a second hole transport layer, a green emitting layer, a red emitting layer, and a second electron transport layer, forming a dual-layer OLED light-emitting structure. The first layer is a blue emitting layer, used to emit blue light, while the second layer consists of green and red emitting layers, used to emit green and red light; a TCO cathode layer serves as the cathode layer; an optical path control encapsulation layer is used to control the optical path length of the device, ensuring that the RGB light emission is within the optical interference enhancement range; a blue band high reflectivity encapsulation layer and a red-green band high reflectivity encapsulation layer are used to achieve high reflectivity in specific bands and low reflectivity in other bands, enabling the design of specific reflectivity values ​​for the RGB bands; and a water-oxygen barrier encapsulation layer protects the OLED device from water vapor and oxygen, ensuring device reliability.

2. The full-color OLED device for achieving white balance according to claim 1, characterized in that, The dual-layer OLED light-emitting structure contains light-emitting materials of three colors: RGB. Combined with driving circuits and color filtering technology, it can achieve full-color light-emitting display.

3. A full-color OLED device for achieving white balance according to claim 1, characterized in that: In the dual-layer OLED light-emitting structure, each layer is a thin film structure, and the thickness of a single layer material ranges from 1nm to 40nm.

4. A full-color OLED device for achieving white balance according to claim 1, characterized in that: The TCO cathode layer has a transmittance of >80% in the visible light band of 380nm-780nm, and a thickness range of 100nm-300nm.

5. A full-color OLED device for achieving white balance according to claim 1, characterized in that: Both the blue-band high-reflectivity encapsulation layer and the red-green-band high-reflectivity encapsulation layer use a high / low refractive index overlapping structure, with the high refractive index material being SiN. x The refractive index ranges from 2.0 to 2.2, and the low refractive index material is SiO₂. x The refractive index ranges from 1.4 to 1.6, and the stacked SiN x and SiO x Each layer has the same thickness, and the structure of overlapping high / low refractive indices has reflectivity center wavelengths of 460nm and 580nm, respectively, achieving high reflectivity in the blue light band and red / green light band.

6. A full-color OLED device for achieving white balance according to claim 1, characterized in that: The optical path control encapsulation layer material is a SiNx thin film with a thickness range of 200nm-500nm and a refractive index range of 1.8-2.

0. The transmittance in the visible light band of 380nm-780nm is >90%.

7. A full-color OLED device for achieving white balance according to claim 1, characterized in that: The organic materials used in the blue, green, and red luminescent layers employ a doped structure, with the luminescent material serving as the dopant and the doping ratio ranging from 1% to 10%.

8. A full-color OLED device for achieving white balance according to claim 1, characterized in that: The water and oxygen barrier encapsulation layer uses Al2O3, TiO2, and SiN. x SiO x N y SiO x Five materials were used: Al2O3 and TiO2 were achieved using atomic layer deposition (ALD) technology, and SiN... x SiO x N y SiO x The five materials were achieved using plasma-enhanced chemical vapor deposition (PECVD) with refractive index ranges of 1.5-1.7, 2.3-2.5, 1.8-2.2, 1.6-1.8, and 1.4-1.6, respectively.

9. A method for manufacturing a full-color OLED device that achieves white balance, characterized in that: Includes the following steps: Step 1: Prepare the metal anode; Step 2: Sequentially prepare the first hole transport layer, blue light-emitting layer, first electron transport layer, charge generation layer, second hole transport layer, green light-emitting layer, red light-emitting layer, and second electron transport layer on the metal anode; Step 3: Prepare a TCO cathode layer on the second electron transport layer; Step 4: Fabricate an optical path control encapsulation layer on the TCO cathode layer; Step 5: Sequentially fabricate a blue band high reflectivity encapsulation layer and a red-green band high reflectivity encapsulation layer on the optical path control encapsulation layer; Step 6: Prepare a water-oxygen barrier layer on the high reflectivity encapsulation layer in the red and green bands.

10. A method for manufacturing a full-color OLED device achieving white balance according to claim 9, characterized in that: The process of preparing the water-oxygen barrier encapsulation layer includes: Atomic layer deposition was used to prepare Al2O3 and TiO2 in a stack of 4-8 layers. The thickness of a single Al2O3 or TiO2 layer ranged from 2 nm to 8 nm, and the total thickness was less than 120 nm. High-refractive-index material SiN was prepared using plasma-enhanced chemical vapor deposition (PECVD). x / Medium refractive index material SiO x N y Low refractive index material SiO x The H / M / L reflectivity structure, with each thin film having a thickness ranging from 50nm to 500nm and a total thickness ranging from 600nm to 1200nm, ensures that the transmittance of the encapsulated thin film in the 380nm-780nm visible light band is >90%.

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