Light-emitting devices, display devices

Abstract

The light-emitting device (2) comprises a first layer (4), a second layer (6), a light-emitting element layer (8), a first adhesive layer (10), and a second adhesive layer (12). The light-emitting element layer is located between the first layer and the second layer and includes a light-emitting element. The first adhesive layer is located between the first layer and the light-emitting element layer, has a thickness of 10 μm or more and less than 25 μm, and a shear modulus of elasticity at 23 degrees Celsius of 4.0E+04 Pa or more and less than 1.0E+05 Pa. The second adhesive layer is located between the light-emitting element layer and the second layer, has a thickness greater than 0 μm and less than 15 μm, and a shear modulus of elasticity at 23 degrees Celsius of 1.0E+05 Pa or more.

Description

Technical Field

[0001] This invention relates to a light-emitting device having a light-emitting element, or a display device using the light-emitting device. Background Technology

[0002] Patent document 1 discloses a light-emitting device that uses a low-elasticity adhesive layer to bond multiple layers containing layers with light-emitting elements and suppresses the generation of defects such as cracks caused by bending.

[0003] Existing technical documents

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2017-126061 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the light-emitting device using a low-elasticity adhesive layer as described in Patent Document 1, there is a problem that it is difficult to increase the pencil hardness of the surface of the light-emitting device.

[0008] Solution for solving the problem

[0009] To address the aforementioned issues, one embodiment of the present invention relates to a light-emitting device comprising: a first layer; a second layer; a light-emitting element layer located between the first layer and the second layer and including a light-emitting element; a first adhesive layer located between the first layer and the light-emitting element layer, having a thickness of 10 μm or more and less than 25 μm, and a shear modulus at 23 degrees Celsius of 4.0E+04 Pa or more and less than 1.0E+05 Pa; and a second adhesive layer located between the light-emitting element layer and the second layer, having a thickness greater than 0 μm and less than 15 μm, and a shear modulus at 23 degrees Celsius of 1.0E+05 Pa or more.

[0010] Beneficial effects

[0011] According to one aspect of the present invention, a light-emitting device can be provided that ensures the pencil hardness of the surface while suppressing defects in the light-emitting element layer. Attached Figure Description

[0012] Figure 1 This is a schematic cross-sectional view of the light-emitting device according to Embodiment 1 of the present invention.

[0013] Figure 2 This is a schematic cross-sectional view of the light-emitting element layer according to Embodiment 1 of the present invention.

[0014] Figure 3This is a graph showing the relationship between the shear elastic modulus and the allowable deviation rate of the adhesive layer according to Embodiment 1 of the present invention.

[0015] Figure 4 This is a schematic cross-sectional view of the test sample involved in Embodiment 1 of the present invention.

[0016] Figure 5 This is a schematic cross-sectional view of the light-emitting device according to Embodiment 2 of the present invention.

[0017] Figure 6 This is a schematic cross-sectional view of the light-emitting device according to Embodiment 3 of the present invention. Detailed Implementation

[0018] [Implementation Method 1]

[0019] Figure 1 This is a schematic cross-sectional view showing the light-emitting device 2 according to this embodiment. Furthermore, it includes... Figure 1 The figures included in this instruction manual are schematic diagrams and do not show the specific scale of each component. First, refer to... Figure 1 The specific structure of the light-emitting device 2 involved in this embodiment will be described.

[0020] The light-emitting device 2 according to this embodiment includes: a window film 4 as a first layer, a back film 6 as a second layer, and a light-emitting element layer 8 having a light-emitting element described in detail later. The light-emitting element layer 8 is located between the window film 4 and the back film 6. In addition, the light-emitting device 2 has a first adhesive layer 10 located between the window film 4 and the light-emitting element layer 8, and also has a second adhesive layer 12 located between the back film 6 and the light-emitting element layer 8.

[0021] In this embodiment, the light-emitting device 2 has an optical layer 14 between the light-emitting element layer 8 and the first adhesive layer 10, and a third adhesive layer 16 between the light-emitting element layer 8 and the optical layer 14. Furthermore, the light-emitting device 2 has a touch panel layer 18 between the light-emitting element layer 8 and the third adhesive layer 16, and a fourth adhesive layer 20 between the light-emitting element layer 8 and the touch panel layer 18.

[0022] Therefore, as Figure 1 As shown, the light-emitting device 2 comprises, sequentially stacked from the back film 6 side, a light-emitting element layer 8, a touch panel layer 18, an optical layer 14, and a window film 4. Furthermore, a first adhesive layer 10 bonds the window film 4 and the optical layer 14. A second adhesive layer 12 bonds the back film 6 and the light-emitting element layer 8. A third adhesive layer 16 bonds the optical layer 14 and the touch panel layer 18. A fourth adhesive layer 20 bonds the light-emitting element layer 8 and the touch panel layer 18.

[0023] Next, each layer of the light-emitting device 2 according to this embodiment will be described in more detail.

[0024] The window film 4 is a light-transmitting thin film formed on the display surface side of the light-emitting device 2. Therefore, in this embodiment, light from the light-emitting element included in the light-emitting element layer 8, which will be described in detail later, is extracted from the light-emitting element layer 8 to the window film 4 side.

[0025] Window film 4 can also be a film such as PET film formed on the display surface of conventional light-emitting devices. Alternatively, the light-emitting device 2 can also use a glass cover sheet thin enough to be flexible to replace window film 4. Furthermore, such as... Figure 1 As shown, the window film 4 has a thickness dW.

[0026] The back film 6 is the outermost film formed on the opposite side of the display surface of the light-emitting device 2, and it may also have light-shielding properties. However, the back film 6 may also have light transmittance. In this case, the light-emitting device 2 may also be a double-sided light-emitting device in which light from the light-emitting element layer 8 is also extracted from the light-emitting element layer 8 on the back film 6 side.

[0027] The back film 6 can also be a thin film, such as a PET film, formed on the back of a conventionally known light-emitting device. Alternatively, the light-emitting device 2 can also use a glass substrate thin enough to be flexible instead of the back film 6. Furthermore, such as... Figure 1 As shown, the back film 6 has a thickness of dB.

[0028] Reference Figure 2 The light-emitting element layer 8 will be described in more detail. Figure 2 This is a schematic cross-sectional view showing the light-emitting element layer 8 according to this embodiment. Figure 2 As shown, the light-emitting element layer 8 has a structure in which light-emitting elements 24 are mounted on the array substrate 22. For example, the light-emitting element 24 is formed by sequentially stacking a cathode 26, an electron transport layer 28, a light-emitting layer 30, a hole transport layer 32, and an anode 34 from the array substrate 22 side. Furthermore, as... Figure 2 As shown, the light-emitting element layer 8 may also have a sealing layer 35, which contains an organic or inorganic sealing material that seals the light-emitting element 24.

[0029] The cathode 26 can be driven by a driving circuit (not shown) including TFTs formed on the array substrate 22, or a certain potential can be applied to the anode 34. In this case, by driving the cathode 26, electrons are injected from the cathode 26 into the light-emitting layer 30 via the electron transport layer 28, and holes are injected from the anode 34 into the light-emitting layer 30 via the hole transport layer 32.

[0030] The light-emitting layer 30 has a light-emitting body that emits light through the recombination of injected electrons and holes. Thus, light from the light-emitting body in the light-emitting layer 30 is obtained from the light-emitting element layer 8. For example, when the light-emitting element layer 8 has an anode 34 on the display surface side of the light-emitting device 2, it is preferable that the anode 34 is transmissive and the cathode 26 is reflective.

[0031] The array substrate 22 can also be formed by conventional methods, such as sputtering, to form the electrodes of the TFT (Thin Film Transistor).

[0032] The cathode 26 and anode 34 can also be obtained by forming a film of metallic material using methods such as sputtering. The electron transport layer 28 and the hole transport layer 32 can also be formed by forming films of electron transport materials and hole transport materials using conventionally known methods such as photolithography, coating, or evaporation.

[0033] The light-emitting layer 30, as a light emitter, can also be a conventionally known light emitter, such as a fluorescent material, a phosphorescent material, or a quantum dot material, which generates light through the recombination of electrons and holes in the light-emitting layer 30. For example, if the light-emitting layer 30 is an organic light-emitting material, such as an organic fluorescent material or an organic phosphorescent material, the light-emitting element 24 can also be an OLED (Organic Light-Emitting Diode) element. Alternatively, if the light-emitting layer 30 is a quantum dot material, the light-emitting element 24 can also be a QLED (Quantum dot Light-Emitting Diode) element. The light-emitting layer 30 can also be formed by film deposition using conventionally known methods such as photolithography, coating, or evaporation of a material containing the light emitter.

[0034] The sealing layer 35 can also be formed by film formation based on conventionally known methods, such as coating or vapor deposition of sealing materials.

[0035] Furthermore, the array substrate 22 may have multiple driving circuits, and the light-emitting element 24 may have multiple cathodes 26. Additionally, each cathode 26 may be driven individually by the driving circuit of the array substrate 22. Furthermore, the light-emitting layer 30 may also have multiple light-emitting layers emitting different colors of light for each cathode 26. In this case, the light-emitting device 2 may also constitute a display device.

[0036] In addition, such as Figure 1 As shown, the light-emitting element layer 8 has a thickness dE.

[0037] The optical layer 14 can also be an anti-reflective layer that allows light from the light-emitting element layer 8 to pass through, and blocks light so that external light incident on the light-emitting device 2 from the window film 4 side and reflected inside the light-emitting device 2 will not re-emit to the outside of the light-emitting device 2. For example, the optical layer 14 can also have a circularly polarized light film, which can be formed by bonding a linearly polarized film and a λ / 4 phase difference film.

[0038] The optical layer 14 can also be formed using existing, known methods for forming polarizing plates. Additionally, as... Figure 1 As shown, the optical layer 14 has a thickness dL.

[0039] The touch panel layer 18 is, for example, a touch panel that senses the presence or absence of contact by a human finger or the like on the outer surface of the window film 4 side of the light-emitting device 2, as well as the contact position. The touch panel layer 18 can also perform the aforementioned sensing using conventionally known methods, including electrostatic capacitance and film resistance methods. The touch panel layer 18 can also be formed using conventionally known methods, including the formation of each electrode of the touch panel using sputtering. Furthermore, as... Figure 1 As shown, the touch panel layer 18 has a thickness dT.

[0040] The first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 are all soft and light-transmitting adhesive materials. However, when light from the light-emitting element layer 8 is only extracted from the window film 4 side of the light-emitting device 2, the second adhesive layer 12 may also have light-shielding or light-reflecting properties.

[0041] The first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 can, for example, be conventionally known adhesive materials with flexibility and light transmittance, including an OCA (Optical Clear Adhesive: OCA) film. The first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 can be formed by conventionally known methods, such as heating for degassing after pasting the OCA film and curing by ultraviolet irradiation. Alternatively, the first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 can also be formed, for example, by applying an adhesive material and pasting the two layers to be bonded, and then drying the adhesive material by heating or curing it by ultraviolet irradiation.

[0042] The first adhesive layer 10 is a relatively soft and thick adhesive layer. Specifically, as... Figure 1As shown, the first adhesive layer 10 has a thickness d1, which is 10 μm or more and 25 μm or less. Furthermore, the shear modulus of the first adhesive layer at 23°C is 4.0E+04 Pa or more and less than 1.0E+05 Pa. Additionally, the shear modulus of the first adhesive layer at -20°C is 4.0E+04 Pa or more and less than 5.0E+05 Pa.

[0043] The second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 are relatively hard and thin adhesive layers. Specifically, as... Figure 1 As shown, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 have thicknesses d2, d3, and d4, respectively, where d2, d3, and d4 are thicker than 0 μm and less than 15 μm. Furthermore, the shear modulus of the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 at 23 degrees Celsius is 1.0E+05 Pa or more. Additionally, the shear modulus of the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 at -20 degrees Celsius is 1.0E+06 Pa or more.

[0044] Furthermore, in this specification, 23 degrees Celsius will sometimes be designated as room temperature. Additionally, in this specification, adhesive layers with a shear modulus less than 1.0E+05 Pa at room temperature will sometimes be designated as soft adhesive layers. Similarly, in this specification, adhesive layers with a shear modulus of 1.0E+05 Pa or more at room temperature will sometimes be designated as hard adhesive layers. As described above, the adhesive layer comprising the first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 tends to have an increased shear modulus at low temperatures compared to room temperature.

[0045] Furthermore, the thickness and shear modulus of the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 may be different from each other, or they may be equal to each other.

[0046] Here, refer to Figure 3 Explain the relationship between the elastic modulus of the adhesive layer and the allowable deviation rate of the adhesive layer. Figure 3 This is a graph showing the relationship between the shear modulus of the adhesive layer and the allowable deviation rate. Figure 3 In the chart, the horizontal axis represents the shear modulus, and the vertical axis represents the allowable deviation rate of the adhesive layer having that shear modulus. Additionally, Figure 3 The chart is a single logarithmic chart with only the horizontal axis as a logarithmic scale. Additionally, the unit for shear modulus is Pa.

[0047] Here, the so-called tolerance rate of the adhesive layer refers to a parameter that is expressed as a ratio to the thickness of the adhesive layer, which is the maximum distance of the deviation absorbed by the adhesive layer of a certain thickness in the direction orthogonal to the thickness direction, i.e., in the planar direction.

[0048] exist Figure 3 In the chart, the circular markers represent the measured values ​​of shear modulus and permissible deviation rate at room temperature, i.e., 23 degrees Celsius, while the triangular markers represent the measured values ​​of shear modulus and permissible deviation rate at -10 degrees Celsius.

[0049] exist Figure 3 As shown in the charts, supplemented by solid lines, for adhesive layers at room temperature with a shear modulus below approximately 1.0E+06 Pa, the lower the shear modulus, the higher the allowable deviation rate. In particular, Figure 3 As shown by the dashed line in the chart, the adhesive layer with a shear modulus of 1.0E+05 Pa at room temperature has a tolerance rate of 75%. Therefore, at room temperature, adhesive layers with a shear modulus of less than 1.0E+05 Pa absorb deviations in the direction orthogonal to the thickness direction that accompany bending better.

[0050] exist Figure 3 In the charts, as indicated by the dashed lines, for adhesive layers at -10°C with a shear modulus below approximately 1.0E+06 Pa, the lower the shear modulus, the higher the allowable deviation rate. Specifically, Figure 3 As shown by the dotted line in the chart, at -10 degrees Celsius, the adhesive layer with a shear modulus of 5.0E+05 Pa has a tolerance rate of 50%. Therefore, at low temperatures, adhesive layers with a shear modulus less than 5.0E+05 Pa absorb deviations in the direction orthogonal to the thickness direction that accompany bending better.

[0051] In addition, such as Figure 3 As shown in the chart, at -10 degrees Celsius, when the shear modulus of the adhesive layer is approximately 1.0E+06 Pa or higher, changes in the shear modulus have little contribution to changes in the tolerance rate. In other words, when the shear modulus of the adhesive layer is 1.0E+06 Pa or higher, it is difficult to produce a decrease in the tolerance rate of the adhesive layer that accompanies the increase in the shear modulus of the adhesive layer.

[0052] The light-emitting device 2 according to this embodiment includes a first adhesive layer 10 with a thickness of 10 μm or more and a shear modulus of elasticity of less than 1.0E+05 Pa at 23 degrees Celsius. In other words, the first adhesive layer 10 has a relatively high tolerance rate and a relatively thick thickness.

[0053] Therefore, the first adhesive layer 10 better absorbs deviations between the two bonded layers in the direction orthogonal to the thickness direction, in other words, in the planar direction of the light-emitting device 2.

[0054] Typically, in light-emitting devices having a light-emitting element layer or a touch panel layer, deviations in the planar direction of the light-emitting device are transmitted to the light-emitting element layer or touch panel layer, easily causing defects such as cracks. However, when the light-emitting device has a layer that absorbs deviations in the planar direction, these deviations are less likely to be transmitted to the light-emitting element layer or touch panel layer.

[0055] Therefore, the light-emitting element layer 8 and touch panel layer 18 of the light-emitting device 2 having the first adhesive layer 10 have improved resistance to bending and the like, and can suppress the generation of defects in the light-emitting element layer 8 and touch panel layer 18.

[0056] Furthermore, even at low temperatures, the shear modulus of the first adhesive layer 10 is less than 5.0E+05 Pa. Therefore, the light-emitting device 2 can ensure resistance to bending and other defects even at low temperatures, thus suppressing the occurrence of defects.

[0057] On the other hand, the light-emitting device 2 according to this embodiment includes a second adhesive layer 12, a third adhesive layer 16, and a fourth adhesive layer 20 with a thickness of 15 μm or less and a shear modulus of elasticity of 1.0E+05 Pa or more at 23 degrees Celsius. In other words, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 have relatively high shear modulus of elasticity and relatively thin thickness.

[0058] Generally, in light-emitting devices with a layered structure, those with thinner layers and high elastic modulus tend to have a higher pencil hardness on their outermost surface. Therefore, the pencil hardness of the outermost surface of the light-emitting device 2, having a second adhesive layer 12, a third adhesive layer 16, and a fourth adhesive layer 20, is increased. Furthermore, at low temperatures, the shear modulus of the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 is 1.0E+06 Pa or higher, further increasing the pencil hardness of the outermost surface of the light-emitting device 2.

[0059] Furthermore, as described above, when the shear modulus of the adhesive layer is 1.0E+06 Pa or higher, it is difficult to cause a decrease in the allowable deviation rate of the adhesive layer along with the increase in the shear modulus. Therefore, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 have a smaller impact on the resistance of the light-emitting device 2 to bending, etc. This is also the case when the shear modulus of the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 increases at low temperatures.

[0060] Furthermore, the thickness of the first adhesive layer 10 is less than 25 μm, and its shear modulus at 23 degrees Celsius is greater than or equal to 4.0E+04 Pa. Therefore, the first adhesive layer 10 has a relatively small impact on the pencil hardness of the light-emitting device 2.

[0061] Therefore, the light-emitting device 2, which has a first adhesive layer 10, a second adhesive layer 12, a third adhesive layer 16 and a fourth adhesive layer 20, not only suppresses the occurrence of defects on the light-emitting element layer 8 and the touch panel layer 18, but also ensures the surface hardness of a pencil.

[0062] Furthermore, in this embodiment, the light-emitting device 2 only needs to have a first adhesive layer 10 on one side of the light-emitting element layer 8 and a second adhesive layer 12 on the opposite side of the first adhesive layer 10 in the thickness direction. The light-emitting device 2 with this structure effectively suppresses damage to the light-emitting element layer 8 while ensuring the surface's pencil hardness.

[0063] As described above, in this embodiment, the light-emitting device 2 can also be used to construct the display device. This not only suppresses defects in the light-emitting element layer 8 and the touch panel layer 11, but also ensures the surface's pencil hardness, enabling a foldable screen display device with superior reliability or higher performance.

[0064] Next, refer to Figure 1 and Figure 4 The positions of the light-emitting element layer 8 and the touch panel layer 18 in the light-emitting device 2 are described in detail.

[0065] Figure 4 This is a schematic cross-sectional view of test sample 36 used to verify the effect of the distance between the center position of the total thickness of the laminated structure and the center position of a specific layer on the deviation in the planar direction of the laminated structure caused by the specific layer when the laminated structure is bent.

[0066] The test sample 36 has a test layer 42 between an upper layer 38 with a thickness dS1 and a lower layer 40 with a thickness dS2. Furthermore, the upper layer 38, the lower layer 40, and the test layer 42 are all bonded together by a test adhesive layer 44 with a thickness dS4. Therefore, the total thickness dS0 of the test sample 36 is dS1 + dS2 + dS3 + 2dS4. Additionally, each layer of the test sample 36 contains a flexible, bendable material.

[0067] The end face of one side is carved here, as in Figure 4 As shown, the test sample 36 has a center position HSA of its total thickness. In other words, the test sample 36 has a center position HAS that is half the total thickness dS0 of the test sample 36, i.e., dS0 / 2, at a distance from one end face of the test sample 36 in the thickness direction.

[0068] Likewise, if Figure 4 As shown, the test layer 42 has a center position HSB in the thickness direction. In other words, the test layer 42 has a center position HSB at a distance of half the thickness of the test layer 42, i.e., dS3 / 2, from one end face in the thickness direction of the test layer 42.

[0069] Here, the distance between the center position HSA of the test sample 36 and the center position HSB of the test layer 42 is set as dS5. In this case, the distance dS5 is expressed, for example, as |dS0 / 2-(dS2+dS4+dS3 / 2)|=|(dS1-dS2) / 2|. That is, by changing the thickness of the upper layer 38 and the lower layer 40, the distance between the center positions HSA and HSB can be changed.

[0070] In addition, when (dS1-dS2) / 2 is positive, the center position HSA is located 38 layers above the center position HSB. When (dS1-dS2) / 2 is negative, the center position HSA is located 40 layers below the center position HSB.

[0071] Here, the test layer 42 of the test sample 36 is used as the aforementioned light-emitting element layer 8 or touch panel layer 18. Multiple test samples 36 with varying thicknesses of the upper layer 38 and lower layer 40 are manufactured, and an experiment is conducted to bend each test sample 36. This experiment is carried out by bending each test sample 36 10,000 times in a low-temperature environment of -10 degrees Celsius to form a teardrop shape.

[0072] In this experiment, the thickness dS4 of the test adhesive layer 44 was set to 15 μm, the thickness of the light-emitting element layer 8 was set to 30 μm, and the thickness of the touch panel layer 18 was set to 10 μm. Furthermore, the shear modulus of the test adhesive layer 44 was set to 2.5E+0.5 Pa. Therefore, the test adhesive layer 44, like the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20, is a thinner adhesive layer with a high shear modulus.

[0073] After bending each test sample 36, check whether the light-emitting element layer 8 or touch panel layer 18 of each test sample 36 is working properly. The results of this inspection are summarized in Table 1 below.

[0074] [Table 1]

[0075]

[0076] The “Displacement” column in Table 1 represents the displacement of each test sample 36 from the center position HSA of the total thickness to the center position HSB of the test layer 42. Specifically, it represents the value of (dS1-dS2) / 2 for each test sample 36. Therefore, the absolute value of the “displacement” is equivalent to the distance dS5 between the center position HSA of the test sample 36 and the center position HSB of the test layer 42.

[0077] Table 1 shows the evaluation when the test layer 42 is set as the light-emitting element layer 8 in the "Light-emitting element layer" column, and the evaluation when the test layer 42 is set as the touch panel layer 18 in the "Touch panel layer" column. After the above experiment, the evaluation is set to 0 for the case where the light-emitting element layer 8 or the touch panel layer 18 works normally, and X for the case where it does not work.

[0078] As shown in Table 1, if the distance dS5 between the center positions HSA and HSB is less than 35 μm, both the light-emitting element layer 8 and the touch panel layer 18 will function normally even after the test sample 36 is bent. Furthermore, as clearly stated in Table 1, this does not depend on the vertical relationship between the center positions HSA and HSB.

[0079] Here, refer again Figure 1 The light-emitting element layer 8 has a center position HE in the thickness direction. In other words, the light-emitting element layer 8 has a center position HE that is half the thickness of the light-emitting element layer 8, i.e., dE / 2, at a distance from one end face of the light-emitting element layer 8 in the thickness direction.

[0080] Similarly, as Figure 1 As shown, the touch panel layer 18 has a center position HT in the thickness direction. In other words, the touch panel layer 18 has a center position HT at a distance of half the thickness of the touch panel layer 18, i.e., dT / 2, from one end face of the touch panel layer 18 in the thickness direction.

[0081] Here, the total thickness of the layers bonded by the hard adhesive layer, in other words, the layers bonded by the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20, from the back film 6 to the optical layer 14, is defined as d0. That is, the thickness d0 is dB+d2+dE+d4+dT+d3+dL.

[0082] Furthermore, the center position in the thickness direction from the back film 6 to the optical layer 14 is set as H0. In other words, the center position H0 is the position where the distance from the end face of the back film 6, the outermost surface of the light-emitting device 2, or the end face of the optical layer 14 from the window film 4 is half the total thickness from the back film 6 to the optical layer 14, i.e., d0 / 2.

[0083] Here, the distance between the center position HE and the center position H0 is set as d5. Here, d5 is represented, for example, as |d0 / 2 - (dB + d2 + dE / 2)|. Furthermore, the distance between the center position HT and the center position H0 is set as d6. Here, d6 is represented, for example, as |d0 / 2 - (dL + d3 + dT / 2)|. Additionally, the distance between the center position HE and the center position HT is set as d7. Here, d7 is represented as dE / 2 + d4 + dT / 2.

[0084] As the experimental results related to the bending of test sample 36 summarized in Table 1 are clear, the distance d5 is preferably 0 μm or more and 35 μm or less. If the distance d5 is within this range, the adverse effects on the light-emitting element layer 8 caused by the bending of the light-emitting device 2 can be suppressed. Similarly, the distance d6 is preferably 0 μm or more and 35 μm or less. If the distance d6 is within this range, the adverse effects on the touch panel layer 18 caused by the bending of the light-emitting device 2 can be suppressed.

[0085] Furthermore, when the distances d5 and d6 are within the aforementioned ranges, the distance d7 is preferably thicker than 0 μm and less than 35 μm. In this way, since the light-emitting element layer 8 and the touch panel layer 18 are positioned close to each other, it is possible to suppress any adverse effects on both the light-emitting element layer 8 and the touch panel layer 18 caused by the bending of the light-emitting device 2.

[0086] Furthermore, the aforementioned thickness d0 does not include the thickness of the window film 4 and the first adhesive layer 10. However, as described above, the first adhesive layer 10, being relatively thick and having a low shear modulus, significantly absorbs deviations in the planar direction of the light-emitting device 2. Therefore, deviations in the planar direction of the light-emitting device 2 caused by the bending of the light-emitting device 2 due to the thickness of the window film 4 and the first adhesive layer 10 are largely absorbed by the first adhesive layer 10 and are less likely to be transmitted to the back film 6 side than those caused by the first adhesive layer 10.

[0087] Therefore, from the viewpoint of reducing the adverse effects on the light-emitting element layer 8 and the touch panel layer 18, when discussing the position of the light-emitting element layer 8 and the touch panel layer 18 on the light-emitting device 2, the thickness of the window film 4 and the first adhesive layer 10 can be excluded from the discussion.

[0088] According to the above embodiments, the light-emitting devices involved in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were manufactured respectively.

[0089] The light-emitting devices in each embodiment and comparative example have the same configuration as the light-emitting device 2 and the materials of each adhesive layer according to this embodiment. In particular, in the light-emitting devices in each embodiment and comparative example, dW is 90 μm, dB is 50 μm, dE is 30 μm, dL is 50 μm, and dT is 10 μm. In addition, in the light-emitting devices in each embodiment and comparative example, d1 is 25 μm, and d2, d3, and d4 are all 15 μm.

[0090] Here, Table 2 below shows the materials used for the first adhesive layer 10, the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 of the light-emitting devices involved in each embodiment and comparative example. In addition, the shear modulus of adhesives A, B, C, and D, which are the materials of the adhesive layers listed in Table 2, are shown in Table 3 below.

[0091] [Table 2]

[0092]

[0093] [Table 3]

[0094]

[0095] In Table 2, the column for "First Adhesive Layer (25 μm)" indicates the type of adhesive used in the first adhesive layer 10 of the light-emitting device according to each embodiment and comparative example. The column for "Second Adhesive Layer (15 μm)" indicates the type of adhesive used in the second adhesive layer 12 of the light-emitting device according to each embodiment and comparative example. The column for "Third Adhesive Layer (15 μm)" indicates the type of adhesive used in the third adhesive layer 16 of the light-emitting device according to each embodiment and comparative example. The column for "Fourth Adhesive Layer (15 μm)" indicates the type of adhesive used in the fourth adhesive layer 20 of the light-emitting device according to each embodiment and comparative example.

[0096] In Table 3, the "Room Temperature" column of "Elastic Modulus (Pa)" expresses the shear elastic modulus of each adhesive at 23 degrees Celsius in Pa. Additionally, the "Low Temperature" column of "Elastic Modulus (Pa)" expresses the shear elastic modulus of each adhesive at -20 degrees Celsius in Pa.

[0097] As shown in Table 3, adhesives A and B are soft adhesives used in adhesive layers, such as the first adhesive layer 10 in this embodiment, with a shear modulus of elasticity of less than 1.0E+05 Pa at room temperature. Adhesives C and D are hard adhesives used in hard adhesive layers, such as the second adhesive layer 12, the third adhesive layer 16, and the fourth adhesive layer 20 in this embodiment, with a shear modulus of elasticity of 1.0E+05 Pa or higher at room temperature.

[0098] For the light-emitting devices according to the various embodiments and comparative examples manufactured as described above, the pencil hardness and bending resistance of the outermost surface on the four sides of the window film were measured.

[0099] The pencil hardness of the outermost surface of the four sides of the window film was measured according to the scratch hardness test method of JIS K5600. However, when measuring the pencil hardness, the load applied to the tip of the pencil was 500g. In the above pencil hardness test, if a pencil with a hardness of 2H or higher caused a scratch on the outermost surface of the four sides of the window film, the evaluation was set to X. Conversely, if a pencil with a hardness of 2H or higher did not cause a scratch on the outermost surface of the four sides of the window film, the evaluation was set to 0.

[0100] In addition, the bending resistance of the light-emitting devices involved in each embodiment and comparative example was determined by performing bending tests at both room temperature and low temperature. The bending test at room temperature was performed by bending the light-emitting devices involved in each embodiment and comparative example 200,000 times at 23 degrees Celsius until they formed a teardrop shape. The bending test at low temperature was performed by bending the light-emitting devices involved in each embodiment and comparative example 10,000 times at -10 degrees Celsius until they formed a teardrop shape.

[0101] Following the aforementioned bending test, the bending resistance of the light-emitting devices in each embodiment and comparative example is evaluated based on whether defects such as cracks exist in the light-emitting element layer 8 and the touch panel layer 18. If a defect is found in either the light-emitting element layer 8 or the touch panel layer 18, the evaluation is set to X. If no defect is found in either the light-emitting element layer 8 or the touch panel layer 18, the evaluation is set to 0.

[0102] Regarding the light-emitting devices involved in each embodiment and comparative example, the evaluation of pencil hardness and bending resistance is shown in Table 4 below.

[0103] [Table 4]

[0104]

[0105] Table 4 shows the evaluation of the pencil hardness of the light-emitting devices involved in each embodiment and comparative example, together with the measured value of the pencil hardness of the outermost surface of the window film 4. The measured value of pencil hardness here represents the maximum hardness of a pencil that did not produce scratches on the outermost surface of the window film 4 after the aforementioned pencil hardness measurement test. Additionally, the "Room Temperature" column of "Bending Resistance" indicates the evaluation of the bending resistance of the light-emitting devices involved in each embodiment and comparative example after the aforementioned bending test at room temperature. The "Low Temperature" column of "Bending Resistance" indicates the evaluation of the bending resistance of the light-emitting devices involved in each embodiment and comparative example after the aforementioned bending test at low temperature.

[0106] As shown in Table 4, in the light-emitting device involved in Comparative Example 1, the pencil hardness was as low as 8B. In addition, in the light-emitting device involved in Comparative Example 2, although the pencil hardness was improved to 2B, it did not reach 2H, and the bending resistance was rated as × in both room temperature and low temperature environments.

[0107] This is because the adhesives used in the bonding layers of the light-emitting devices involved in each comparative example are adhesives A and B, which have lower shear moduli than those used in soft bonding layers, thus failing to adequately ensure pencil hardness. Furthermore, as can be seen from Table 4, as with the light-emitting device involved in Comparative Example 2, if only a portion of the bonding layer's shear modulus is slightly increased, it is sometimes impossible to ensure both pencil hardness and bending resistance.

[0108] On the other hand, the light-emitting device according to Example 1 achieves both a pencil hardness of 2H and bendability at room temperature. Furthermore, the light-emitting devices according to Examples 2 and 3 achieve both a pencil hardness of 3H and bendability at both room temperature and low temperature.

[0109] It is presumed that the light-emitting devices of the various embodiments can ensure pencil hardness because adhesives C and D, which are used in hard adhesive layers, are used in at least one layer of the adhesive layer, and the adhesive layer is formed relatively thin. Furthermore, it is presumed that the light-emitting devices of the various embodiments can maintain pencil hardness and ensure bending resistance because adhesive A, which is used in soft adhesive layers, is used in at least one layer of the remaining adhesive layer, and the adhesive layer is formed relatively thick.

[0110] Furthermore, regarding the light-emitting devices involved in Embodiments 2 and 3, the aforementioned distances d5, d6, and d7 are all greater than 0 μm and less than 35 μm. Therefore, the light-emitting element layer 8 and touch panel layer 18 of the light-emitting devices involved in Embodiments 2 and 3 become structures that can further suppress deviations of each light-emitting device in the planar direction. Therefore, it is speculated that the light-emitting devices involved in Embodiments 2 and 3 have increased shear elastic modulus of each adhesive layer, and can maintain bending resistance even at low temperatures where it is easier to produce defects in the light-emitting element layer 8 and touch panel layer 18 due to bending.

[0111] [Implementation Method 2]

[0112] Figure 5 This is a schematic cross-sectional view showing the light-emitting device 2 according to this embodiment. Figure 5 As shown, the light-emitting device 2 according to this embodiment differs from the light-emitting device 2 according to the previous embodiment in that it does not have a touch panel layer 18. Therefore, the light-emitting device 2 according to this embodiment also does not have a fourth adhesive layer 20. In addition, the third adhesive layer 16 bonds the light-emitting element layer 8 and the optical layer 14.

[0113] In this embodiment, the touch panel can also be fabricated in the light-emitting element layer 8. In other words, in this embodiment, the light-emitting element layer 8 can have an embedded touch panel.

[0114] In addition to the points mentioned above, the light-emitting device 2 according to this embodiment may also have the same structure as the light-emitting device 2 according to the previous embodiment.

[0115] The light-emitting device 2 according to this embodiment is similar to the light-emitting device 2 according to the previous embodiment, wherein a first adhesive layer 10 with a relatively thick film thickness and a low shear elastic modulus at room temperature is provided between the window film 4 and the light-emitting element layer 8 and the optical layer 14. In addition, the light-emitting device 2 according to this embodiment has a second adhesive layer 12 with a relatively thin film thickness and a third adhesive layer 16 with a high shear elastic modulus at room temperature between the back film 6 and the light-emitting element layer 8, and between the light-emitting element layer 8 and the optical layer 14, respectively.

[0116] Therefore, the light-emitting device 2 in this embodiment, like the light-emitting device 2 in the previous embodiment, serves to suppress adverse effects on the light-emitting element layer 8 while ensuring the surface's pencil hardness.

[0117] In this embodiment, the total thickness d0 from the back film 6 to the optical layer 14 is dB+d2+dE+d3+dL. Furthermore, in this embodiment, the distance d5 between the center position HE and the center position H0 is also expressed, for example, as |d0 / 2-(dB+d2+dE / 2)|.

[0118] For the same reasons explained in the previous embodiments, in this embodiment, the distance d5 is preferably 0 μm or more and 35 μm or less. If the distance d5 is within this range, it is possible to suppress the adverse effects on the light-emitting element layer 8 caused by the bending of the light-emitting device 2.

[0119] [Implementation Method 3]

[0120] Figure 6 This is a schematic cross-sectional view showing the light-emitting device 2 according to this embodiment. Figure 6 As shown, the light-emitting device 2 of this embodiment differs from the light-emitting device 2 of Embodiment 1 in that it lacks the optical layer 14. Therefore, the light-emitting device 2 of this embodiment also lacks the third adhesive layer 16. In addition, the first adhesive layer 10 adheres the window film 4 and the touch panel layer 18.

[0121] In this embodiment, an optical layer can be fabricated in the light-emitting element layer 8. For example, the light-emitting element layer 8 may have a circularly polarized film with a linear polarizing film and a λ / 4 phase difference film stacked on it as an optical layer. Alternatively, the optical layer in the light-emitting element layer 8 may also be formed by coating a repeating alignment film and irradiating the alignment film with light.

[0122] Apart from the above aspects, the light-emitting device 2 involved in this embodiment may have the same configuration as the light-emitting device 2 in the above embodiments.

[0123] The light-emitting device 2 of this embodiment is the same as the light-emitting device 2 of the above embodiment, and has a first adhesive layer 10 with a relatively thick film thickness and a low shear elastic modulus at room temperature between the window film 4, the light-emitting element layer 8, and the touch panel layer 18. In addition, the light-emitting device 2 of this embodiment has a second adhesive layer 12 with a relatively thin film thickness and a fourth adhesive layer 20 with a high shear elastic modulus at room temperature between the back film 6 and the light-emitting element layer 8, and between the light-emitting element layer 8 and the touch panel layer 18, respectively.

[0124] Therefore, the light-emitting device 2 of this embodiment, like the light-emitting device 2 of the previous embodiment, not only suppresses the damage to the light-emitting element layer 8 and the touch panel layer 18, but also ensures the surface hardness of a pencil.

[0125] This disclosure is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical solutions disclosed in different embodiments are also included in the technical scope of this disclosure. Moreover, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0126] Explanation of reference numerals in the attached figures

[0127] 2. Light-emitting devices (display devices)

[0128] 4. Window film (first layer)

[0129] 6. Backing film (second layer)

[0130] 8. Light-emitting element layer

[0131] 10 First adhesive layer

[0132] 12 Second adhesive layer

[0133] 14 Optical Layer

[0134] 16 Third adhesive layer

[0135] 18 Touch panel layer

[0136] 20 Fourth adhesive layer

[0137] 24 Light-emitting elements

Claims

1. A light-emitting device, characterized in that, have: First layer; Second layer; A light-emitting element layer, located between the first layer and the second layer, includes a light-emitting element; The first adhesive layer is located between the first layer and the light-emitting element layer, with a thickness of more than 10 μm and less than 25 μm, and a shear elastic modulus at 23 degrees Celsius of more than 4.0E+04 Pa and less than 1.0E+05 Pa. The second adhesive layer, located between the light-emitting element layer and the second layer, has a thickness greater than 0 μm and less than 15 μm, and a shear modulus at 23 degrees Celsius greater than 1.0E+05 Pa. The first adhesive layer has a shear modulus of elasticity of more than 4.0E+04 Pa and less than 5.0E+05 Pa at -20 degrees Celsius. The second adhesive layer has a shear modulus of more than 1.0E+06 Pa at -20 degrees Celsius.

2. The light-emitting device according to claim 1, characterized in that, Light from the light-emitting element is extracted from the light-emitting element layer toward the first layer side.

3. The light-emitting device according to claim 2, characterized in that, The first layer is a window film or a glass cover.

4. The light-emitting device according to claim 2 or 3, characterized in that, The second layer is a back film or a glass substrate.

5. A display device, characterized in that, The light-emitting device according to any one of claims 1 to 4 is used.

6. A light-emitting device, characterized in that, have: First layer; Second layer; A light-emitting element layer, located between the first layer and the second layer, includes a light-emitting element; The first adhesive layer is located between the first layer and the light-emitting element layer, with a thickness of more than 10 μm and less than 25 μm, and a shear elastic modulus at 23 degrees Celsius of more than 4.0E+04 Pa and less than 1.0E+05 Pa. The second adhesive layer, located between the light-emitting element layer and the second layer, has a thickness greater than 0 μm and less than 15 μm, and a shear modulus at 23 degrees Celsius greater than 1.0E+05 Pa. An optical layer is also provided between the light-emitting element layer and the first adhesive layer. A third adhesive layer is provided between the light-emitting element layer and the optical layer. The thickness of the third adhesive layer is greater than 0 μm and less than 15 μm, and the shear elastic modulus at 23 degrees Celsius is greater than 1.0E+05Pa.

7. The light-emitting device according to claim 6, characterized in that, The third adhesive layer has a shear modulus of elasticity of more than 1.0E+06 Pa at -20 degrees Celsius.

8. The light-emitting device according to claim 6 or 7, characterized in that, The distance from the center of the total thickness of the second layer to the optical layer to the center of the thickness of the light-emitting element layer is greater than 0 μm and less than 35 μm.

9. A display device, characterized in that, The light-emitting device according to any one of claims 6 to 8 is used.

10. A light-emitting device, characterized in that, have: First layer; Second layer; A light-emitting element layer, located between the first layer and the second layer, includes a light-emitting element; The first adhesive layer is located between the first layer and the light-emitting element layer, with a thickness of more than 10 μm and less than 25 μm, and a shear elastic modulus at 23 degrees Celsius of more than 4.0E+04 Pa and less than 1.0E+05 Pa. The second adhesive layer, located between the light-emitting element layer and the second layer, has a thickness greater than 0 μm and less than 15 μm, and a shear modulus at 23 degrees Celsius greater than 1.0E+05 Pa. A touch panel layer is also provided between the light-emitting element layer and the first adhesive layer. Between the light-emitting element layer and the touch panel layer, there is also a fourth adhesive layer with a thickness greater than 0 μm and less than 15 μm and a shear elastic modulus of more than 1.0E+05Pa at 23 degrees Celsius.

11. The light-emitting device according to claim 10, characterized in that, The shear modulus of the fourth adhesive layer at -20 degrees Celsius is above 1.0E+06Pa.

12. A display device, characterized in that, The light-emitting device described in claim 10 or 11 was used.

13. A light-emitting device, characterized in that, have: First layer; Second layer; A light-emitting element layer, located between the first layer and the second layer, includes a light-emitting element; The first adhesive layer is located between the first layer and the light-emitting element layer, with a thickness of more than 10 μm and less than 25 μm, and a shear elastic modulus at 23 degrees Celsius of more than 4.0E+04 Pa and less than 1.0E+05 Pa. The second adhesive layer, located between the light-emitting element layer and the second layer, has a thickness greater than 0 μm and less than 15 μm, and a shear modulus at 23 degrees Celsius greater than 1.0E+05 Pa. An optical layer is also provided between the light-emitting element layer and the first adhesive layer. Between the light-emitting element layer and the optical layer, there is also a third adhesive layer with a thickness greater than 0 μm and less than 15 μm, and a shear elastic modulus of more than 1.0E+05 Pa at 23 degrees Celsius. A touch panel layer is also provided between the light-emitting element layer and the third adhesive layer. Between the light-emitting element layer and the touch panel layer, there is also a fourth adhesive layer with a thickness greater than 0 μm and less than 15 μm and a shear elastic modulus of more than 1.0E+05Pa at 23 degrees Celsius.

14. The light-emitting device according to claim 13, characterized in that, The shear modulus of the third adhesive layer at -20 degrees Celsius is greater than 1.0E+06 Pa. The shear modulus of the fourth adhesive layer at -20 degrees Celsius is greater than 1.0E+06Pa.

15. The light-emitting device according to claim 13 or 14, characterized in that, The distance from the center of the total thickness of the second layer to the optical layer to the center of the thickness of the light-emitting element layer is greater than 0 μm and less than 35 μm.

16. The light-emitting device according to claim 13 or 14, characterized in that, The distance from the center of the total thickness of the second layer to the optical layer to the center of the thickness of the touch panel layer is greater than 0 μm and less than 35 μm.

17. The light-emitting device according to claim 15, characterized in that, The distance from the center of the thickness of the light-emitting element layer to the center of the thickness of the touch panel layer is longer than 0 μm and less than 35 μm.

18. A display device, characterized in that, The light-emitting device according to any one of claims 13 to 17 is used.

Images