High-efficiency light-emitting display device

Abstract

The present invention relates to a high-efficiency light-emitting display device including a light-emitting element layer, having a defined internal quantum efficiency of light, and including an enhancement layer capable of improving final external quantum efficiency.

Description

High-efficiency light-emitting display device

[0001] The present invention relates to a high-efficiency light-emitting display device.

[0002] LCD and OLED are two major display technologies, each with different operating principles and characteristics. LCDs electrically adjust the arrangement of liquid crystal molecules (LCs) to change the polarization characteristics of incoming light, thereby controlling the transmittance of external light. LCD screen brightness is primarily determined by how well light from an external light source (backlight) is transmitted. As a transmissive display, it lacks self-luminous properties.

[0003] On the other hand, OLED is a self-luminous display that emits light through excitons formed when electrons and holes recombine in the light-emitting layer between the anode and cathode. OLED is divided into bottom emission and top emission depending on the light-emitting direction. Bottom emission technology is mainly used in large displays (such as TVs), and top emission technology is suitable for high-resolution displays. Due to these characteristics, OLED technology can vary depending on the size and density of the pixels.

[0004] OLED luminous efficiency is defined as the product of three main components. The first is the recombination efficiency of electrons and holes, which can be optimized through energy band design. The second is the internal quantum efficiency (IQE). While fluorescence efficiency is limited to 25%, phosphorescent materials can achieve up to 100% efficiency. However, stable blue emission from phosphorescent materials has not yet been technically achieved. The final component is the external quantum efficiency (EQE), which represents the efficiency with which light generated within the OLED is emitted to the outside. With current technology, only about 20% of the light is emitted to the outside, with the remaining 80% being lost internally due to total internal reflection.

[0005] Various technologies are being studied to improve these luminous efficiency issues. A representative example is Micro Lens Array (MLA) technology, which utilizes a dome-shaped lens structure to alleviate total reflection conditions, thereby improving OLED luminous efficiency by approximately 1.8 times. However, MLA technology is only suitable for full-wavelength emission technologies such as white OLED, and has the limitation of requiring individual design for RGB emission displays.

[0006] Another technology is cavity amplification (Fig. 1). This technology creates a cavity structure within the OLED to amplify light of a specific wavelength. This technology is implemented by adjusting the thickness of the transflective electrode and refractive layer, and can improve OLED luminous efficiency. However, this technology also requires a design tailored to each wavelength of the RGB light source, leading to a complex process.

[0007] In conclusion, improving luminous efficiency is a critical challenge for the advancement of light-emitting display technologies like OLED. Addressing the problem of light loss due to total reflection, simplifying the process, and developing stable, high-efficiency materials is expected to improve both display brightness and lifespan. This will have a positive impact not only on OLED but also on next-generation display technologies like QD and Micro LED.

[0008] The purpose of the present invention is to provide a high-efficiency light-emitting display device that can solve the problem of low light-emitting efficiency in the conventional display devices described above.

[0009] As a means of solving the above problem, according to one embodiment of the present disclosure, a high-efficiency light-emitting display device can be provided, which includes a light-emitting element layer, in which light has a defined internal quantum efficiency, and includes an improvement layer for improving the final external quantum efficiency.

[0010] Meanwhile, the enhancement layer may include a nano-length cavity resonance structure.

[0011] Meanwhile, the enhancement layer may include materials having different refractive indices to have a Dielectrical Bragg Reflector effect.

[0012] Furthermore, the improvement layer includes a first dielectric layer having a refractive index of n1 and a second dielectric layer having a refractive index of n2, and the first dielectric layer and the second dielectric layer can be repeatedly stacked.

[0013] Meanwhile, the first dielectric layer and the second dielectric layer can be formed by any one of deposition, coating, and e-beam processes.

[0014] Meanwhile, the improvement layer may include a chiral liquid crystal having a refractive index of n1 and n2 depending on the rotation angle as a birefringent medium.

[0015] Additionally, the improvement layer may be composed of a chiral liquid crystal having a left and / or right rotational direction.

[0016] Furthermore, the light emitting element layer may include a light source configured to generate light having a wavelength within a range of 200 nm to 2000 nm.

[0017] Meanwhile, the light-emitting element layer may be configured to include one light-emitting element (Single Emission) or may be configured to include two or more light-emitting elements (Tandem Emission).

[0018] Meanwhile, the improvement layer can determine the repetition cycle pitch length of the two dielectric repeating layers according to the wavelength of light generated from the light emitting element layer.

[0019] Additionally, the improvement layer may be composed of chiral liquid crystals having the same pitch length or having multiple pitches that are different from each other.

[0020] Meanwhile, the improvement layer may include a bank so that the area of ​​each pixel of the light-emitting element can be distinguished, or may include a chiral liquid crystal with pixel boundaries distinguished by an organic or metal black matrix.

[0021] Meanwhile, the improvement layer may include chiral liquid crystals of different pitches in at least some of the regions separated by banks.

[0022] Meanwhile, the improvement layer can be formed using a chiral liquid crystal and a curable material.

[0023] At this time, the improvement layer can be configured to enable UV curing.

[0024] Meanwhile, it can be formed by hardening into a predetermined pattern using a photolithography process.

[0025] Meanwhile, the thickness of the improvement layer can be configured to be less than 1 mm.

[0026] Meanwhile, the light-emitting element layer may be composed of any one of organic, inorganic, organic-inorganic hybrid, quantum dot, perovskite, quantum nanowire, and organic light-emitting semiconductor.

[0027] Meanwhile, the improvement layer can be configured so that the pitch length of the genetic repeats and the wavelength of the light that is selectively reflected and resonates vary depending on the temperature.

[0028] Additionally, the improvement layer can be composed of geometric patterns.

[0029] Meanwhile, an improvement layer may be provided on at least one of the front and rear surfaces of the light-emitting element so as to reflect and resonate the emitted light.

[0030] Furthermore, the selection wavelength range of the improvement layer may include the wavelength of the light-emitting element.

[0031] Meanwhile, the improvement layer may be provided with one or more wavelengths that match the wavelength of the light-emitting element.

[0032] Meanwhile, the improvement layer using chiral liquid crystals has the same range and center position of the selective reflection wavelength, but the rotation of the circular polarization can be the same or opposite.

[0033] The high-efficiency light-emitting display device according to the present invention has the effect of maximizing the light-emitting efficiency of red / green / blue light by using a single improved layer structure without the complex process and manufacturing of thickness refractive index control.

[0034] Fig. 1 is a cross-sectional view of a display device that describes cavity amplification technology as a prior art.

[0035] FIG. 2 is a cross-sectional view of a pixel in a high-efficiency light-emitting display device according to one embodiment of the present disclosure.

[0036] FIG. 3 is a diagram illustrating the concept of an improvement layer in one embodiment of the present disclosure.

[0037] FIG. 4 is a diagram illustrating a wavelength range amplified by an improvement layer in one embodiment of the present disclosure.

[0038] FIG. 5 is a diagram illustrating a conceptual diagram of an improvement layer in another embodiment of the present disclosure.

[0039] FIG. 6 is a diagram illustrating the pitch of liquid crystal molecules in an improvement layer in another embodiment of the present disclosure.

[0040] Figure 7 is a graph showing the change in pitch of a chiral liquid crystal according to temperature.

[0041] Figure 8 is a graph showing the wavelength of light amplified in a chiral liquid crystal depending on temperature.

[0042] FIG. 9 is a diagram illustrating an example of a molecular structure included in an improvement layer in another embodiment of the present disclosure.

[0043] FIGS. 10a, 10b, 10c and 10d are conceptual diagrams illustrating a process for forming an improvement layer in a high-efficiency light-emitting display device according to another embodiment of the present disclosure.

[0044] Figure 11 is a drawing illustrating the concept of forming an improvement layer using a photolithography process.

[0045] FIG. 12 is a conceptual diagram illustrating a modified example of the pattern of the improvement layer in another embodiment of the present disclosure.

[0046] FIG. 13 is a plan view illustrating multiple pixels in another embodiment of the present disclosure.

[0047] Hereinafter, a high-efficiency light-emitting display device according to an embodiment of the present invention will be described in detail with reference to the attached drawings. In the following description of the embodiments, the names of each component may be referred to by different names in the art. However, if there is functional similarity and identity between them, even if a modified embodiment is adopted, it can be viewed as an equivalent configuration. In addition, the symbols added to each component are described for the convenience of explanation. However, the content depicted in the drawings in which these symbols are described does not limit each component to the scope within the drawings. Similarly, even if an embodiment with some modifications to the configuration in the drawings is adopted, it can be viewed as an equivalent configuration if there is functional similarity and identity. In addition, if it is recognized as a component that should be included naturally in light of the general level of a technician in the relevant technical field, a description thereof will be omitted.

[0048] FIG. 2 is a cross-sectional view of a pixel in a high-efficiency light-emitting display device according to one embodiment of the present disclosure.

[0049] Referring to FIG. 2, a high-efficiency light-emitting display device (1) according to one embodiment of the present disclosure may be configured to include a light-emitting layer, an encapsulation layer (200), and an improvement layer in a pixel. The light-emitting element may be configured to include R / G / B light-emitting elements as subpixels. Each light-emitting element may refer to an element configured to emit light of a predetermined wavelength, such as an OLED, a QD (Quantum dot), or a micro LED. In addition, the light-emitting layer may be provided with at least one electrode.

[0050] Meanwhile, although not shown, the display device (1) in the present disclosure may be configured to employ widely used components, such as TFTs that perform light emission and control in conventional display devices. However, since such components are widely used, further detailed description thereof will be omitted.

[0051] The encapsulation layer (200) is configured to protect the light-emitting element from the external environment and maintain the performance and lifespan of the element.

[0052] An enhancement layer may be provided on the upper side of each subpixel. Each enhancement layer may be configured to amplify light of different wavelengths. Each enhancement layer may be configured to have a size corresponding to the area of ​​the subpixel.

[0053] The enhancement layers may be configured to amplify light of different wavelengths. For example, a first enhancement layer (410) may be provided on the upper side of the R light-emitting element (110) and may be configured to amplify light of a red wavelength. Meanwhile, a second enhancement layer (420) may be provided on the upper side of the G light-emitting element (120) and may be configured to amplify light of a green wavelength. In addition, a third enhancement layer (430) may be provided on the upper side of the B light-emitting element (130) and may be configured to amplify light of a blue wavelength.

[0054] Meanwhile, each improvement layer (410, 420, 430) may be provided in an area separated by a bank (bank, 300).

[0055] FIG. 3 is a diagram illustrating the concept of an improvement layer in one embodiment of the present disclosure.

[0056] Referring to FIG. 3, the enhancement layer may include a multilayer dielectric thin film formed by repeating two dielectric materials having two refractive indices (n1 and n2) at a regular distance d with a unit pitch. By this repetition, the enhancement layer may form a so-called Dielectric Bragg Reflector (DBR) Resonance Cavity. The enhancement layer does not perfectly reflect 100% of the light. The enhancement layer is configured to have a high reflectivity of 70 to 99%, while also having a semi-transparent characteristic that transmits some light. As an example, if the enhancement layer is designed to have a slightly lower reflectivity in the direction in which light is transmitted, that is, in the upward direction in FIG. 3, some of the wavelengths satisfying the resonance condition may be emitted upward.

[0057] Ultimately, light of a certain wavelength is amplified through resonance by the improvement layer, thereby obtaining light with increased brightness.

[0058] Meanwhile, in one embodiment of the present disclosure, the improvement layer can be formed by selectively applying an E-Beam deposition process, a coating process, a CVD method, or the like.

[0059] FIG. 4 is a diagram illustrating a wavelength range amplified by an improvement layer in one embodiment of the present disclosure.

[0060] Referring to Fig. 4, by selecting the refractive indices n1 and n2 of the first and second layers of the improvement layer and appropriately controlling the distance d, an optical mirror structure without a physical mirror can be formed to resonantly amplify only the emission wavelength of OLED, etc.

[0061] FIG. 5 is a diagram illustrating a conceptual diagram of an improvement layer in another embodiment of the present disclosure.

[0062] Referring to FIG. 5, in another embodiment of the present disclosure, the effect of a multi-refractive dielectric can be implemented through a twisted structure of liquid crystal molecules.

[0063] In this embodiment, the improvement layer can obtain a multilayer dielectric effect through the twisted structure of liquid crystal molecules. The improvement layer is a chiral liquid crystal (Chiral Liquid Crystal (CLC) layer.

[0064] Can be included. Mesogenic molecules such as liquid crystals have birefringence properties, with two refractive index values ​​of n1 and n2 in a single molecular structure. Therefore, by inducing a chiral structure of a birefringent molecule, a multilayer dielectric effect can be exerted in which the refractive dielectrics of n1 and n2 are repeated every ½ of the rotation period (pitch: p) from the perspective of light.

[0065] FIG. 6 is a diagram illustrating the pitch of liquid crystal molecules in an improvement layer in another embodiment of the present disclosure.

[0066] Referring to FIG. 6, the liquid crystal molecules within the improvement layer can reflect light of different wavelengths depending on the length of the spiral rotation structure.

[0067] Specifically, when the length of the helical rotation structure of a birefringent molecule changes, the reflected wavelength may change according to the de Vries condition Δλ = Δn p (Δλ: wavelength range of the selectively reflected expression color, Δn: difference in refractive index (n1-n2), p: rotation pitch repetition length).

[0068] Meanwhile, the rotational force per unit thickness of the enhancement layer (d / p: d is the unit thickness of the chiral LC helical structure, p: the helical rotational twist repetition period of the CLC molecule) increases as the temperature increases. Therefore, by inducing a temperature change, the helical rotational twist repetition period of the CLC molecule can be controlled, and ultimately, the wavelength of the amplified light can be controlled.

[0069] Figure 7 is a graph showing the change in pitch of a chiral liquid crystal according to temperature.

[0070] Referring to Figure 7, chiral liquid crystals have high viscosity in the smectic phase and low viscosity in the nematic phase. As the temperature increases, the chiral liquid crystal transitions to the nematic phase, lowering its viscosity and increasing its rotational force per unit length. Therefore, as the temperature increases, the pitch length of the chiral liquid crystal shortens.

[0071] Conversely, as the temperature decreases, the chiral liquid crystal undergoes a phase transition from the nematic phase to the smectic phase, and the pitch of the helical structure becomes longer.

[0072] Ultimately, chiral liquid crystals can control the De Vires condition Δλ = Δn·p (Δλ: wavelength range of the selectively reflected color expression, Δn: difference in refractive index (n1-n2), p: rotational pitch repetition length) by temperature change.

[0073] Figure 8 is a graph showing the wavelength of light amplified in a chiral liquid crystal depending on temperature.

[0074] Referring to Fig. 8, the improvement layer can induce an effect of shortening the rotational pitch p in a CLC layer of unit thickness d at high temperatures. When a change in the direction of temperature increase (ΔT) is applied, the rotational length of the CLC liquid crystal is directly controlled through the continuous strengthening phenomenon of the rotational force of d / p. Ultimately, as the temperature increases, the improvement layer tends to adjust the selective reflection wavelength of the De Vries condition toward the blue wavelength side.

[0075] FIG. 9 is a diagram illustrating an example of a molecular structure included in an improvement layer in another embodiment of the present disclosure.

[0076] Referring to FIG. 9, the improvement layer can be formed of a material that includes a molecular structure capable of forming a UV-curable chain, which constitutes a selective reflection layer of a chiral liquid crystal layer (chiral LC). The material constituting the improvement layer can include, for example, a monoacrylate or diacrylate molecular material having one or two acrylate reactive groups capable of being cured by UV. At this time, the molecular material has a bonding structure "R" composed of all various birefringences, and the molecule of R can include any one of all other reactive bonding structures, including a phenyl group, a heagonal group, a methyl group, an ester group, and an ether group.

[0077] FIGS. 10a, 10b, 10c and 10d are conceptual diagrams illustrating a process for forming an improvement layer in a high-efficiency light-emitting display device according to another embodiment of the present disclosure.

[0078] A display according to the present disclosure can be manufactured by creating subpixels, creating an encapsulation layer (200), and then forming an enhancement layer. The enhancement layer can be created by forming a black bank in an R / G / B subpixel and then curing a chiral liquid crystal layer with an adjusted pitch in each subpixel.

[0079] Referring to FIG. 10a, the third improvement layer (430) can be cured at a first temperature so as to have a short pitch to amplify blue light.

[0080] Referring to FIG. 10b, the second enhancement layer (420) can be cured at a second temperature so as to have an intermediate pitch to amplify green light.

[0081] Referring to FIG. 10c, the first improvement layer (410) can be cured at a third temperature so as to have the longest pitch to amplify red light.

[0082] At this time, the ink for forming the first improvement layer (410), the second improvement layer (420), and the third improvement layer (430) may be of the same material. However, each improvement layer may be protected by UV after being adjusted to a predetermined temperature so as to control the pitch of the chiral liquid crystal. At this time, the third improvement layer (430) that amplifies blue light may be cured after being adjusted to the highest temperature. Next, the second improvement layer (420) that amplifies green light may be cured after being adjusted to a lower temperature than the third improvement layer (430). Finally, the first improvement layer (410) that amplifies red light may be cured after being adjusted to the lowest temperature.

[0083] Referring to Fig. 10d, the rotational twist pitch of the chiral liquid crystals within each enhancement layer can be maintained in a fixed state. Of course, when adjusted to room temperature or operating temperature, the change in pitch according to temperature can be considered, and the chiral liquid crystal pitch can be determined by pre-compensation.

[0084] Meanwhile, although not shown, an additional protective layer covering the improvement layer and bank may be provided. This protective layer may be composed of an organic film. Furthermore, the protective layer may be composed of transparent glass, photoacrylic, or other materials.

[0085] Figure 11 is a drawing illustrating the concept of forming an improvement layer using a photolithography process.

[0086] Referring to FIG. 11, in the present disclosure, each enhancement layer can be formed in a geometric pattern on a number of pixels. The enhancement layer controls and coats a material constituting a selective reflection layer of a chiral LC into a molecular structure capable of forming a chain in a photocurable (UV Curable) form, and when only the portions where blue selective reflection is desired (red pixels and green pixels) are exposed through an exposure mask, a Curable CLC layer for blue selective amplification can be formed only in the selective portions. Afterwards, the areas where UV curing is not formed due to blocking of the mask pattern are washed away through a Develop process, thereby forming a Chiral LC Cavity corresponding to the color of the desired portion.

[0087] In addition, each improvement layer can be formed through a UV curing structure and a UV curing pattern using a desired MASK. At this time, by inducing a pitch change state according to temperature and controlling the pitch, an amplification Chiral LC Cavity for each of R / G / B can be formed.

[0088] FIG. 12 is a conceptual diagram illustrating a modified example of the pattern of the improvement layer in another embodiment of the present disclosure.

[0089] Referring to Fig. 12, the improvement layer can be generated by changing the temperature of one element to change several pitch lengths and fixing the memory by MASK patterning only the desired position. Therefore, the generated display device can form Cavity chiral structures of various colors at once when recovered to the operating condition temperature of room temperature. In addition, the direction in which the first improvement layer (410), the second improvement layer (420), and the third improvement layer (430) are arranged can be changed to generate the improvement layer, and the improvement layer can be formed in a desired shape depending on the size of the subpixel.

[0090] FIG. 13 is a plan view illustrating multiple pixels in another embodiment of the present disclosure.

[0091] Referring to Fig. 13, a display in which R / G / B are configured side-by-side can be provided according to the manufacturing method described with reference to Figs. 10 to 12. At this time, the light-emitting element can be an OLED, QD, a miro LED, and any other light-emitting element. According to the present disclosure, a display and lighting element based on light-emitting array pixels with significantly amplified light emission brightness can be provided by configuring an array amplifying element capable of amplifying R / G / B respectively on the outer side (upper side) of the light-emitting element.

[0092] The high-efficiency light-emitting display device according to the present invention described above can have the following effects.

[0093] First, it can improve the external quantum efficiency (EQE), which determines the final luminance of light-emitting devices such as white OLED and RGB OLED.

[0094] Secondly, the brightness of all light-emitting elements composed of red, green, and blue can be effectively amplified through Chiral Cavity amplification technology.

[0095] Third, by comprehensively implementing these effects, it will be possible to develop high-quality, high-efficiency, innovative display products using technologies such as QD color conversion OLED (QD-OLED) and QD-Micro LED.

Claims

1. Contains a light-emitting element layer, A high-efficiency light-emitting display device having a defined internal quantum efficiency of light and including an enhancement layer for improving the final external quantum efficiency.

2. In paragraph 1, The above improvement layer is a high-efficiency light-emitting display device including a nano-length cavity resonance structure.

3. In paragraph 2, A high-efficiency light-emitting display device comprising materials having different refractive indices to have a dielectric Bragg reflector effect, wherein the above-mentioned improvement layer is a dielectric Bragg reflector.

4. In paragraph 3, The above improvement layer is, A first dielectric layer having a refractive index of n1; It includes a second dielectric layer having a refractive index of n2, A high-efficiency light-emitting display device configured by repeatedly stacking the first dielectric layer and the second dielectric layer.

5. In paragraph 4, A high-efficiency light-emitting display device in which the first dielectric layer and the second dielectric layer are formed by any one of deposition, coating, and e-beam processes.

6. In paragraph 5, A high-efficiency light-emitting display device comprising a chiral liquid crystal having a refractive index of n1 and n2 depending on the rotation angle as a birefringent medium, wherein the above improvement layer is a birefringent medium.

7. In paragraph 6, The above improvement layer is, A high-efficiency light-emitting display device comprising a chiral liquid crystal having a rotation direction of the left and / or right.

8. In paragraph 2, The above light emitting element layer, A high-efficiency light-emitting display device comprising a light source configured to generate light having a wavelength within a range of 200 nm to 2000 nm.

9. In paragraph 2, A high-efficiency light-emitting display device in which the light-emitting element layer is configured to include one light-emitting element (single emission) or is configured by stacking two or more light-emitting elements (tandem emission).

10. In paragraph 2, The above improvement layer is a high-efficiency light-emitting display device in which the repetition cycle pitch length of the two dielectric repeating layers is determined according to the wavelength of the light generated from the light-emitting element layer.

11. In paragraph 10, A high-efficiency light-emitting display device comprising the above-mentioned improvement layer including chiral liquid crystals having the same pitch length or a plurality of different pitches.

12. In paragraph 12, A high-efficiency light-emitting display device including the chiral liquid crystal, wherein the improvement layer includes a bank so that the area can be divided by pixel of the light-emitting element, or the pixel boundary is divided by an organic or metal black matrix.

13. In paragraph 12, A high-efficiency light-emitting display device in which at least some of the areas defined by the banks include chiral liquid crystals of different pitches.

14. In paragraph 11, A high-efficiency light-emitting display device in which the above-mentioned improvement layer is formed using the above-mentioned chiral liquid crystal and a curable material.

15. In paragraph 14, A high-efficiency light-emitting display device in which the above improvement layer is configured to enable UV curing.

16. In paragraph 15, A high-efficiency light-emitting display device in which the above improvement layer is formed by curing into a predetermined pattern using a photolithography process.

17. In paragraph 2, A high-efficiency light-emitting display device comprising the above-mentioned improvement layer having a thickness of 1 mm or less.

18. In paragraph 2, The above light emitting element layer, A high-efficiency light-emitting display device composed of any one of organic, inorganic, organic-inorganic hybrid, quantum dot, perovskite, quantum nanowire, and organic light-emitting semiconductor.

19. In paragraph 2, The above improvement layer is a high-efficiency light-emitting display device configured so that the pitch length of the dielectric repeater and the wavelength of the light that is selectively reflected and resonated change depending on the temperature.

20. In paragraph 2, A high-efficiency light-emitting display device in which the above-mentioned improvement layer is composed of a geometric pattern.

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