Display device, method for manufacturing display device, and apparatus for manufacturing display device

Abstract

The display device (1) has a hole transport layer (6C) shared by a plurality of sub-pixels (2R / 2G / 2B) between the anode (4) and the light-emitting layer (8R / 8G / 8B), and a separate hole transport layer (6P) is separately provided for each of the plurality of sub-pixels between the shared hole transport layer and the light-emitting layer. The shared hole transport layer is formed using a first hole transport layer material. The first separate hole transport layer (6B) of the sub-pixel (2B) of the first color is formed using a second hole transport layer material. The second separate hole transport layer (6R / 6G) of the sub-pixel (2R / 2G) of the second color is formed using a mixed material of the first hole transport layer material and the second hole transport layer material.

Description

Technical Field

[0001] The present invention relates to a display device having a light-emitting element. Background Art

[0002] Patent Document 1 describes a display device including a light-emitting element including a hole transport layer shared by sub-pixels.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-157225 Summary of the Invention

[0006] Technical problems to be solved by the present invention

[0007] In the light-emitting element described in Patent Document 1, holes injected into a sub-pixel are transported to other sub-pixels via a hole transport layer shared by the sub-pixels, causing a problem of so-called crosstalk in which undriven sub-pixels light up.

[0008] Technical solutions to technical problems

[0009] In order to solve the above problems, the display device of the present invention has multiple sub-pixels that emit light of different colors from each other, and the display device includes: a light-emitting layer, which is set for each of the multiple sub-pixels and emits light of the color corresponding to the sub-pixel; and a cathode and an anode respectively located on one side and the other side of the light-emitting layer, between the anode and the light-emitting layer, the multiple sub-pixels commonly have a common hole transport layer, and between the common hole transport layer and the light-emitting layer, each of the multiple sub-pixels has a separate hole transport layer, and the common hole transport layer is composed of a first hole transport layer material; the first separate hole transport layer possessed by the sub-pixel of the first color among the multiple sub-pixels is composed of a second hole transport layer material different from the first hole transport layer material, and the second separate hole transport layer possessed by the sub-pixel of the second color different from the first color is composed of a mixed material of the first hole transport layer material and the second hole transport layer material.

[0010] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a display device, wherein the display device includes a plurality of sub-pixels that emit light of different colors from each other, and the display device is stacked and includes: a light-emitting layer provided for each of the plurality of sub-pixels to emit light of a color corresponding to the sub-pixel; and a cathode and an anode respectively located on one side and the other side of the light-emitting layer. The method for manufacturing the display device includes a hole transport layer forming step for forming a common hole transport layer between the anode shared by the plurality of sub-pixels and the light-emitting layer, and for each of the plurality of sub-pixels, a separate hole transport layer is separately formed between the common hole transport layer and the light-emitting layer. In the hole transport layer forming step, the common hole transport layer is formed by evaporation of a first hole transport layer material, a first separate hole transport layer for a sub-pixel of a first color among the plurality of sub-pixels is formed by evaporation of a second hole transport layer material different from the first hole transport layer material, and a second separate hole transport layer for a sub-pixel of a second color different from the first color is formed by co-evaporation of the first hole transport layer material and the second hole transport layer material.

[0011] In order to solve the above-mentioned problem, the present invention provides a manufacturing device for a display device, wherein the display device has a plurality of sub-pixels that emit light of different colors from each other, and the display device is stacked and comprises: a light-emitting layer, which is arranged for each sub-pixel of the plurality of sub-pixels and emits light of a color corresponding to the sub-pixel; and a cathode and an anode respectively located on one side and the other side of the light-emitting layer. The manufacturing device of the display device includes a vapor deposition device, which is used to form a common hole transport layer between the anode shared by the plurality of sub-pixels and the light-emitting layer, and to form a separate hole transport layer between the common hole transport layer and the light-emitting layer for each sub-pixel in the plurality of sub-pixels. The vapor deposition device forms the common hole transport layer by vapor deposition of a first hole transport layer material, forms a first separate hole transport layer possessed by a sub-pixel of a first color among the plurality of sub-pixels by vapor deposition of a second hole transport layer material different from the first hole transport layer material, and forms a second separate hole transport layer possessed by a sub-pixel of a second color different from the first color by co-evaporation of the first hole transport layer material and the second hole transport layer material.

[0012] Beneficial effects

[0013] According to the present invention, a display device with reduced crosstalk can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 and 2 are a schematic top view and a schematic cross-sectional view of a display device according to a first embodiment of the present invention.

[0015] Figure 2 These are a schematic top view and a schematic cross-sectional view of a comparative display device.

[0016] Figure 3 This is a graph showing the relationship between the voltage applied to the light-emitting element and the current density of the current flowing through the light-emitting element in the display device according to the first embodiment of the present invention and the comparative embodiment.

[0017] Figure 4 It is a schematic cross-sectional view of a display device according to a second embodiment of the present invention.

[0018] Figure 5 It is a schematic cross-sectional view of a display device according to a third embodiment of the present invention.

[0019] Figure 6 It is a schematic cross-sectional view of a display device according to a fourth embodiment of the present invention.

[0020] Figure 7 It is a block diagram of an apparatus for manufacturing a display device according to each embodiment of the present invention. DETAILED DESCRIPTION

[0021] [First embodiment]

[0022] Figure 1 (a) is a schematic plan view of the display device 1 according to this embodiment. Figure 1 (b) is Figure 1 (a) is a cross-sectional view taken along line AA.

[0023] like Figure 1 As shown in (a), the display device 1 of this embodiment includes a display area DA that facilitates display and a frame area NA surrounding the display area DA. The frame area NA may also include a terminal T to which a signal for driving a light-emitting element of the display device 1 described in detail later is input.

[0024] like Figure 1 As shown in (b), the display device 1 of this embodiment includes a light-emitting element layer 2 and an array substrate 3 at a position overlapping the display area DA when viewed from above. The display device 1 has a structure in which various layers of the light-emitting element layer 2 are stacked on an array substrate 3 on which TFTs (Thin Film Transistors) (not shown) are formed. In this specification, the direction from the light-emitting element layer 2 toward the array substrate 3 of the display device 1 is referred to as the "downward direction," and the direction from the array substrate 3 toward the light-emitting element layer 2 of the display device 1 is referred to as the "upward direction."

[0025] The light-emitting element layer 2 includes a hole transport layer 6, a light-emitting layer 8, an electron transport layer 10, and a cathode 12, stacked in order from the bottom layer on the anode 4. The anode 4 of the light-emitting element layer 2 formed on the upper layer of the array substrate 3 is electrically connected to the TFT of the array substrate 3. In this embodiment, the hole transport layer 6 includes a common hole transport layer 6C and an individual hole transport layer 6P.

[0026] Here, the anode 4, the individual hole transport layer 6P, and the light-emitting layer 8 are each separated by a bank 14. Specifically, in this embodiment, the anode 4 is separated by the bank 14 into a first anode 4R, a second anode 4G, and a third anode 4B. Furthermore, the individual hole transport layer 6P is separated by the bank 14 into a first hole transport layer 6R (second individual hole transport layer / third individual hole transport layer), a second hole transport layer 6G (second individual hole transport layer / third individual hole transport layer), and a third hole transport layer 6B (first individual hole transport layer). Furthermore, the light-emitting layer 8 is separated by the bank 14 into a first light-emitting layer 8R, a second light-emitting layer 8G, and a third light-emitting layer 8B. Furthermore, the common hole transport layer 6C, the electron transport layer 10, and the cathode 12 are not separated by the bank 14 but are formed in common.

[0027] In this embodiment, the light-emitting element layer 2 includes a first light-emitting element 2R, a second light-emitting element 2G, and a third light-emitting element 2B as a plurality of light-emitting elements. The first light-emitting element 2R is composed of a first anode 4R, a common hole transport layer 6C, a first hole transport layer 6R, a first light-emitting layer 8R, an electron transport layer 10, and a cathode 12. In addition, the second light-emitting element 2G is composed of a second anode 4G, a common hole transport layer 6C, a second hole transport layer 6G, a second light-emitting layer 8G, an electron transport layer 10, and a cathode 12. Furthermore, the third light-emitting element 2B is composed of a third anode 4B, a common hole transport layer 6C, a third hole transport layer 6B, a third light-emitting layer 8B, an electron transport layer 10, and a cathode 12. Therefore, the anode 4, the individual hole transport layer 6P, and the light-emitting layer 8 are formed separately in the first light-emitting element 2R, the second light-emitting element 2G, and the third light-emitting element 2B, respectively.

[0028] In this embodiment, first light-emitting layer 8R, second light-emitting layer 8G, and third light-emitting layer 8B emit red, green, and blue light, respectively. That is, first light-emitting element 2R, second light-emitting element 2G, and third light-emitting element 2B are light-emitting elements that emit red, green, and blue light, respectively, each of different colors.

[0029] That is, the first light-emitting element 2R, the second light-emitting element 2G, and the third light-emitting element 2B respectively constitute a plurality of sub-pixels of red (second color / third color), green (second color / third color), and blue (first color) in the display device 1. Furthermore, each of the red, green, and blue sub-pixels includes a light-emitting layer 8 that emits light of the corresponding color.

[0030] Here, blue light refers to light having a central emission wavelength in a wavelength band between 400 nm and 500 nm. Furthermore, green light refers to light having a central emission wavelength in a wavelength band between 500 nm and 600 nm. Furthermore, red light refers to light having a central emission wavelength in a wavelength band between 600 nm and 780 nm.

[0031] The anode 4 and cathode 12 contain conductive materials and are electrically connected to the shared hole transport layer 6C and electron transport layer 10, respectively. In this embodiment, the cathode 12, which is the electrode closest to the display surface of the display device 1, is a semi-transparent electrode. For example, ITO, IZO, AZO, or GZO can be used, and the film can be formed by sputtering. In addition, in this embodiment, the anode 4 contains a metal material. As the metal material, Al, Cu, Au, or Ag, which has a high reflectivity for visible light, is preferred.

[0032] The light emitting layer 8 emits light by generating recombination between holes transported from the anode 4 and electrons transported from the cathode 12. In this embodiment, the light emitting layer 8 may be made of an organic fluorescent material, a phosphorescent material, or a semiconductor nanoparticle (quantum dot) material.

[0033] The hole transport layer 6 is a layer that transports charges from the anode 4 to the light-emitting layer 8. The hole transport layer 6 may also have the function of blocking the transport of electrons from the cathode 12. The common hole transport layer 6C in the hole transport layer 6 is electrically connected to the first hole transport layer 6R, the second hole transport layer 6G, and the third hole transport layer 6B. Furthermore, the first hole transport layer 6R, the second hole transport layer 6G, and the third hole transport layer 6B are electrically connected to the first light-emitting layer 8R, the second light-emitting layer 8G, and the third light-emitting layer 8B, respectively.

[0034] In the present embodiment, the common hole transport layer 6C is formed using a first hole transport layer material. In addition, the third hole transport layer 6B included in the third light-emitting element 2B that constitutes the blue sub-pixel is formed using a second hole transport layer material different from the first hole transport layer material. Further, the first hole transport layer 6R included in the first light-emitting element 2R that constitutes the red sub-pixel is formed using a mixed material of the first hole transport layer material and the second hole transport layer material. Moreover, the second hole transport layer 6G included in the second light-emitting element 2G that constitutes the green sub-pixel is formed using the same first hole transport layer material as the common hole transport layer 6C. The mixing ratio of the second hole transport layer material in the first hole transport layer 6R is 10% or more and 50% or less with respect to the whole of the first hole transport layer 6R.

[0035] In the present embodiment, the energy level of the highest occupied orbital of the first hole transport layer material, that is, the absolute value of HOMO, is smaller than the absolute value of HOMO of the second hole transport layer material. Let the absolute value of HOMO of the first hole transport layer material be HOMO1 (eV), and let the absolute value of HOMO of the second hole transport layer material be HOMO2 (eV). In this case, in the present embodiment, HOMO1 + 0.2 eV < HOMO2...(1) holds.

[0036] In the present embodiment, the first hole transport layer material is, for example, α-NPD (HOMO: -5.40 eV) or TAPC (HOMO: -5.43 eV). In addition, the second hole transport layer material is, for example, TCTA (HOMO: -5.83 eV), mCP (HOMO: -5.90 eV), or mCBP (HOMO: -6.00 eV).

[0037] In the present embodiment, considering the efficiency of hole transport from the anode to the light-emitting layer, as the material of the common hole transport layer 6C, it is preferable to use the first hole transport layer material with a high hole mobility. In addition, generally, the absolute value of HOMO of the material of the third light-emitting layer 8B that emits blue is larger than the absolute value of HOMO of the materials of the first light-emitting layer 8R that emits red and the second light-emitting layer 8G that emits green. Therefore, considering the efficiency of hole injection into the third hole transport layer 6B, as the material of the third hole transport layer 6B, it is preferable to use the second hole transport layer material with an absolute value of HOMO larger than that of the first hole transport layer material.

[0038] The electron transport layer 10 is a layer that transports electrons from the cathode 12 to the light-emitting layer 8. The electron transport layer 10 may also have a function of blocking the transport of holes from the anode 4.

[0039] The hole transport layer 6, light-emitting layer 8, and electron transport layer 10 can be formed by conventionally known methods, for example, by vapor deposition using a vapor deposition mask. Specifically, in this embodiment, the common hole transport layer 6C and the second hole transport layer 6G are formed by vapor deposition of a first hole transport layer material, and the third hole transport layer 6B is formed by vapor deposition of a second hole transport layer material. Furthermore, in this embodiment, the first hole transport layer 6R is formed by co-evaporation of the first hole transport layer material and the second hole transport layer material.

[0040] In addition, in this embodiment, the display device 1 may also include a hole injection layer and an electron injection layer between the anode 4 and the hole transport layer 6, and between the cathode 12 and the electron transport layer 10, to assist in injecting charges from the electrodes into the charge transport layer. The hole injection layer and the electron injection layer can be formed by the same method as the hole transport layer 6 and the electron transport layer 10.

[0041] In addition, in this embodiment, the thickness of the hole transport layer 6P and the light emitting layer 8 may be different depending on the light emitting element. Figure 1 As shown in (b), in this embodiment, the thicknesses of the first hole transport layer 6R, the second hole transport layer 6G, and the third hole transport layer 6B decrease in order. This allows the distance between the light-emitting layer 8 and the anode 4 (reflective electrode) to be adjusted for each sub-pixel, enabling optical settings tailored to each sub-pixel.

[0042] In addition, Figure 1 In (b), for the sake of simplicity, the total thickness of the hole transport layer 6P and the light-emitting layer 8 is shown as the same thickness in the first light-emitting element 2R, the second light-emitting element 2G, and the third light-emitting element 2B. Figure 2 、 Figure 4 、 Figure 5 and Figure 6 In FIG. 1 , the total thickness of the hole transport layer 6P and the light-emitting layer 8 is expressed as the same thickness for all elements, regardless of the light-emitting element.

[0043] In addition, if Figure 1 As shown in (b), in this embodiment, the thicknesses of the first light-emitting layer 8R, the second light-emitting layer 8G, and the third light-emitting layer 8B are increased in sequence. Figure 1 As shown in (b), the total thickness of the hole transport layer 6P and the light-emitting layer 8 can be substantially constant depending on the light-emitting element. However, this is not limiting, and the total thickness of the hole transport layer 6P and the light-emitting layer 8 can also vary depending on the light-emitting element, as long as it does not hinder the formation of the common electron transport layer 10 on the light-emitting layer 8.

[0044] Figure 2 is a comparison method of the display device with Figure 1 (b) corresponds to the cross-sectional view. The display device of the comparative embodiment differs from the display device 1 of the present embodiment only in the material used for the first hole transport layer 6R. In the comparative embodiment, the first hole transport layer 6R is formed using the same first hole transport layer material as the common hole transport layer 6C of the display device 1 of the present embodiment.

[0045] Figure 3 This is a graph showing the relationship between the voltage applied to a light-emitting element of a display device and the current density of the current flowing through the light-emitting element. Figure 3 The horizontal axis represents the voltage (V) applied to a light-emitting element of a certain sub-pixel constituting the display device, and the vertical axis represents the current density (mA / cm 2 ).

[0046] exist Figure 3 In the graph of "B" shown by the solid line, the voltage applied to the third light-emitting element 2B and the current density of the current flowing in the third light-emitting element 2B to which the voltage is applied are shown in the present embodiment and the comparative embodiment. Figure 3 In the graph of “R-0%” indicated by a dashed line, in the comparative embodiment, the voltage applied to the first light-emitting element 2R and the current density of the current flowing through the first light-emitting element 2R to which the voltage is applied are shown.

[0047] Generally, a light-emitting element having a light-emitting layer that emits red or green light has a higher charge injection efficiency than a light-emitting element having a light-emitting layer that emits blue light. Consequently, the current density of the current flowing when the same voltage is applied also becomes higher. Figure 3 As shown, when a voltage of 2 V is applied to the first light-emitting element 2R and the third light-emitting element 2B in the comparative embodiment, the current density of the current flowing through the first light-emitting element 2R is approximately 100 times greater than the current density of the current flowing through the third light-emitting element 2B.

[0048] Therefore, in Figure 2 In the embodiment, as shown by the arrow h+ indicating the movement of holes, when the third light-emitting element 2B is driven, the holes injected from the third anode 4B into the common hole transport layer 6C may reach the first hole transport layer 6R via the common hole transport layer 6C having high hole mobility. In the comparative embodiment, the first hole transport layer 6R is formed using the same first hole transport layer material as the common hole transport layer 6C having high hole mobility.

[0049] Therefore, there is a possibility that holes from the third anode 4B may recombine with electrons from the cathode 12, which is a common electrode, in the first light-emitting layer 8R via the common hole transport layer 6C and the first hole transport layer 6R, causing the first light-emitting element 2R to emit light. Therefore, in the comparative embodiment, there is a possibility that so-called crosstalk may occur, where light emission from the first light-emitting element 2R, which is different from the third light-emitting element 2B being driven, may occur.

[0050] On the other hand, Figure 3 In the graphs of "R-10%" and "R-30%" shown by the dashed and intermittent lines, respectively, represent the voltage applied to the first light-emitting element 2R and the current density of the current flowing through the first light-emitting element 2R when the voltage is applied. The "R-10%" and "R-30%" graphs indicate that the first hole transport layer 6R of the first light-emitting element 2R contains 10% or 30% of the second hole transport layer material, respectively.

[0051] When the first hole transport layer 6R in this embodiment contains 10% of the second hole transport layer material, the current density of the current flowing through the first light emitting element 2R applied with a voltage of 2 V is reduced to about 1 / 2 compared to the first light emitting element 2R of the comparative embodiment.

[0052] That is, the difference in ease of current flow between the first light-emitting element 2R and the third light-emitting element 2B in this embodiment is smaller than that in the comparative embodiment. This is because the first hole transport layer 6R in this embodiment includes a portion of the second hole transport layer material, resulting in a lower hole mobility in the first hole transport layer 6R, compared to the first hole transport layer 6R in the comparative embodiment.

[0053] Therefore, in this embodiment, when a voltage is applied to the third light-emitting element 2B, the first light-emitting element 2R, through which current easily flows via the shared hole transport layer 6C and the first hole transport layer 6R, can be driven less frequently. In other words, the display device 1 of this embodiment can reduce crosstalk from the blue sub-pixel to the red sub-pixel. This effect is particularly pronounced when a material with high hole mobility is used for the shared hole transport layer 6C.

[0054] Furthermore, when the first hole transport layer 6R in this embodiment includes 30% of the second hole transport layer material, the current density of the current flowing through the first light-emitting element 2R under an applied voltage of 2 V is reduced to approximately 1 / 10 compared to the first light-emitting element 2R in the comparative embodiment. In other words, the difference in the ease of current flow between the first light-emitting element 2R and the third light-emitting element 2B in this embodiment is further reduced compared to the comparative embodiment.

[0055] Therefore, in this embodiment, the crosstalk can be reduced more effectively when the first hole transport layer 6R includes 30% of the second hole transport layer material as compared to when the first hole transport layer 6R includes 10% of the second hole transport layer material as a whole.

[0056] In this embodiment, the above-mentioned effects can be fully achieved by making the first hole transport layer 6R contain at least 10% of the second hole transport layer material. Furthermore, to ensure the efficiency of hole injection in the first light-emitting element 2R, the first hole transport layer 6R preferably contains no more than 50% of the second hole transport layer material.

[0057] That is, when the first hole transport layer 6R contains more than 50% of the second hole transport layer material, the luminance of the first light-emitting element 2R decreases as the content of the second hole transport layer material increases. Therefore, by setting the content of the second hole transport layer material in the first hole transport layer 6R to less than 50% of the total, the above-mentioned crosstalk can be effectively reduced, and a high-luminance second light-emitting element 2R can be easily formed.

[0058] In this embodiment, the common hole transport layer 6C may be composed only of the first hole transport layer material, and similarly, the third hole transport layer 6B may be composed only of the second hole transport layer material. This can more effectively reduce the crosstalk described above.

[0059] In this embodiment, the absolute value of the HOMO of the first hole transport layer material is smaller than the absolute value of the HOMO of the second hole transport layer material, satisfying the above-mentioned formula (1). This effectively reduces the ease with which current flows in the first light-emitting element 2R, thereby more effectively reducing the above-mentioned crosstalk.

[0060] Compared to existing display devices, the display device 1 of this embodiment does not require a new layer structure. Therefore, compared to existing display devices, the display device 1 of this embodiment can reduce the increase in total film thickness. In addition, the first hole transport layer 6R is obtained by co-evaporating the first hole transport layer material used for the common hole transport layer 6C and the second hole transport layer material used for the third hole transport layer 6B. Therefore, there is no need to prepare the material of the first hole transport layer 6R separately. Therefore, the display device 1 of this embodiment can be manufactured while reducing the production cycle time and the increase in manufacturing costs.

[0061] [Second embodiment]

[0062] Figure 4 The display device 1 of this embodiment is Figure 1The display device 1 of this embodiment is different from the display device 1 of the previous embodiment in configuration only in that the materials of the first hole transport layer 6R and the second hole transport layer 6G are different.

[0063] In this embodiment, similar to the common hole transport layer 6C, the first hole transport layer 6R is formed using a first hole transport layer material. Meanwhile, the second hole transport layer 6G is formed using a mixture of the first hole transport layer material and the second hole transport layer material. The mixing ratio of the second hole transport layer material in the second hole transport layer 6G is 10% or more and 50% or less relative to the overall material.

[0064] That is, in the second hole transport layer 6G, the mixing ratio of the second hole transport layer material is set to 10% to 50%, similar to the first hole transport layer 6R in the first embodiment. This effectively reduces the above-mentioned crosstalk and easily forms a high-brightness second light-emitting element 2G.

[0065] In addition, the current density and applied voltage characteristics of the second hole transport layer 6G when the mixing ratio of the second hole transport layer material is set to 10% or 30% of the total are similar to those of the second hole transport layer 6G. Figure 3 The characteristics indicated by "R-10%" and "R-30%" are the same.

[0066] In this embodiment, based on the same principle as described above, when a voltage is applied to the third light-emitting element 2B, the transfer of charge via the shared hole transport layer 6C to the second light-emitting element 2G, through which current easily flows, can be reduced. In other words, the display device 1 according to this embodiment can reduce crosstalk from the blue sub-pixel to the green sub-pixel.

[0067] [Third embodiment]

[0068] Figure 5 The display device 1 of this embodiment is Figure 1 (b) corresponds to the cross-sectional view. The display device 1 of this embodiment differs from the display device 1 of the previous embodiment in that the material of the first hole transport layer 6R is different. Furthermore, the display device 1 of this embodiment differs from the display device 1 of the previous embodiment in that the thicknesses of the first hole transport layer 6R, the second hole transport layer 6G, the first light-emitting layer 8R, and the second light-emitting layer 8G are different. Other than the above, the display device 1 of this embodiment has the same configuration as the display device 1 of the previous embodiment.

[0069] In this embodiment, the first hole transport layer 6R is formed of a mixture of a first hole transport layer material and a second hole transport layer material. The mixing ratio of the second hole transport layer material in the first hole transport layer 6R is 10% to 50% relative to the entire first hole transport layer 6R.

[0070] Furthermore, in this embodiment, if Figure 5 As shown, the first hole transport layer 6R and the second hole transport layer 6G have the same thickness, and the first light-emitting layer 8R and the second light-emitting layer 8G have the same thickness. For example, the first hole transport layer 6R and the second hole transport layer 6G may have the same thickness d6. Furthermore, the first light-emitting layer 8R and the second light-emitting layer 8G may have the same thickness d8. In this case, by making the mixing ratio of the second hole transport layer material in the first hole transport layer 6R and the second hole transport layer 6G the same, the first hole transport layer 6R and the second hole transport layer 6G can be formed simultaneously by the above-mentioned co-evaporation.

[0071] However, in this embodiment, the present invention is not limited thereto, and the first hole transport layer 6R and the second hole transport layer 6G may have different film thicknesses. Furthermore, the mixing ratios of the second hole transport layer materials in the first hole transport layer 6R and the second hole transport layer 6G may also be different.

[0072] In this embodiment, based on the same principle as described above, when a voltage is applied to the third light-emitting element 2B, the transfer of charge via the shared hole transport layer 6C to the first light-emitting element 2R and the second light-emitting element 2G, through which current easily flows, can be reduced. In other words, the display device 1 of this embodiment can reduce crosstalk from the blue sub-pixel to the red and green sub-pixels.

[0073] [Fourth embodiment]

[0074] Figure 6 The display device 1 of this embodiment is Figure 1 The display device 1 of this embodiment is different from the display device 1 of the previous embodiment in that a fourth hole transport layer 6Ra (fourth separate hole transport layer) is further provided between the anode 4 and the first hole transport layer 6R.

[0075] The fourth hole transport layer 6Ra is in contact with and electrically connected to the common hole transport layer 6C and the first hole transport layer 6R. Like the common hole transport layer 6C, the fourth hole transport layer 6Ra is made of the material of the first hole transport layer. Figure 6 As shown, the total thickness of the first hole transport layer 6R and the fourth hole transport layer 6Ra may have the same thickness d6 as the thickness of the second hole transport layer 6G.

[0076] In this embodiment, there is almost no obstacle to hole transport from the common hole transport layer 6C to the fourth hole transport layer 6Ra. Therefore, in this embodiment, the efficiency of hole transport from the first anode 4R to the first light-emitting layer 8R in the first light-emitting element 2R can be improved while maintaining the effect of reducing crosstalk to the red sub-pixel.

[0077] The display device 1 of each embodiment is not particularly limited as long as it includes a display panel having a flexible, bendable display element. The display element includes a display element whose brightness and transmittance are controlled by current and a display element whose brightness and transmittance are controlled by voltage.

[0078] For example, the display device 1 of each embodiment described above may include an OLED (Organic Light Emitting Diode) as a current-controlled display element. In this case, the display device 1 of each embodiment described above may also be an organic EL (Electro Luminescence) display.

[0079] Alternatively, the display device 1 of each of the above embodiments may include an inorganic light-emitting diode as a current-controlled display element. In this case, the display device 1 of each of the above embodiments may also be a QLED (Quantum dot Light Emitting Diode) EL display such as an inorganic EL display.

[0080] In addition, as a voltage-controlled display element, there are liquid crystal display elements and the like.

[0081] Figure 7 This is a block diagram showing a display device manufacturing apparatus 50 used in the manufacturing process of the display device 1 in each of the above embodiments. The display device manufacturing apparatus 50 includes a controller 52, a vapor deposition apparatus 54, and a film forming apparatus 56. The controller 52 can also control the vapor deposition apparatus 54 and the film forming apparatus 56.

[0082] The evaporation device 54 may also form at least a portion of each layer of the display device 1, including the hole transport layer 6, by evaporation. In each of the above-described embodiments, the evaporation device 54 may also form a single hole transport layer 6P composed of a mixed material of the first hole transport layer material and the second hole transport layer material by co-evaporation of the first hole transport layer material and the second hole transport layer material. The film forming device 56 may also perform film formation of each layer of the display device 1 that is not formed by the evaporation device 54.

[0083] 〔Summarize〕

[0084] A display device of form 1 has multiple sub-pixels that emit light of different colors from each other, and the display device includes: a light-emitting layer, which is provided for each of the multiple sub-pixels and emits light of a color corresponding to the sub-pixel; and a cathode and an anode respectively located on one side and the other side of the light-emitting layer, wherein the multiple sub-pixels commonly have a common hole transport layer between the anode and the light-emitting layer, and each of the multiple sub-pixels has a separate hole transport layer between the common hole transport layer and the light-emitting layer, and the common hole transport layer is composed of a first hole transport layer material; the first separate hole transport layer possessed by the sub-pixel of the first color among the multiple sub-pixels is composed of a second hole transport layer material different from the first hole transport layer material, and the second separate hole transport layer possessed by the sub-pixel of the second color different from the first color is composed of a mixed material of the first hole transport layer material and the second hole transport layer material.

[0085] In the second aspect, the common hole transport layer is composed only of the first hole transport layer material, and the first individual hole transport layer is composed only of the second hole transport layer material.

[0086] In the third aspect, the absolute value of the energy level of the highest occupied molecular orbital of the first hole transport layer material is smaller than the absolute value of the energy level of the highest occupied molecular orbital of the second hole transport layer material.

[0087] In the fourth embodiment, when the absolute value of the energy level of the highest occupied molecular orbital of the first hole transport layer material is set to HOMO1 (eV), and the absolute value of the energy level of the highest occupied molecular orbital of the second hole transport layer material is set to HOMO2 (eV), HOMO1+0.2eV is satisfied. <HOMO2。

[0088] In the fifth aspect, in the second single hole transport layer, the mixing ratio of the second hole transport layer material is 10% or more and 50% or less of the entire material.

[0089] In form six, the first color is blue and the second color is red.

[0090] In form seven, the first color is blue and the second color is green.

[0091] In the eighth aspect, the plurality of sub-pixels further include sub-pixels of a third color, and the third color is green.

[0092] In aspect 9, the plurality of sub-pixels further include sub-pixels of a third color, and the third color is red.

[0093] In the tenth aspect, the third single hole transport layer included in the third color sub-pixel is formed using the first hole transport layer material.

[0094] In the eleventh aspect, the third single hole transport layer included in the sub-pixel of the third color is formed using the mixed material.

[0095] In the twelfth aspect, in the third single hole transport layer, the mixing ratio of the second hole transport layer material is 10% or more and 50% or less of the entire material.

[0096] In the thirteenth aspect, the thickness of the second individual hole transport layer is the same as the thickness of the third individual hole transport layer.

[0097] In the fourteenth aspect, the sub-pixel of the second color further includes a fourth individual hole transport layer between the second individual hole transport layer and the common hole transport layer, and the fourth individual hole transport layer is formed using the first hole transport layer material.

[0098] In the fifteenth aspect, the single hole transport layer formed using the mixed material is in contact with the light-emitting layer.

[0099] In a method for manufacturing a display device of form sixteen, the display device includes a plurality of sub-pixels that emit light of different colors from each other, and the display device is stacked and includes: a light-emitting layer, which is provided for each of the plurality of sub-pixels and emits light of a color corresponding to the sub-pixel; and a cathode and an anode, which are respectively located on one side and the other side of the light-emitting layer. The method for manufacturing the display device includes a hole transport layer forming step, forming a common hole transport layer between the anode and the light-emitting layer, which is shared by the plurality of sub-pixels, and forming a separate hole transport layer between the common hole transport layer and the light-emitting layer for each of the plurality of sub-pixels. In the hole transport layer forming step, the common hole transport layer is formed by evaporation of a first hole transport layer material, a first separate hole transport layer for a sub-pixel of a first color among the plurality of sub-pixels is formed by evaporation of a second hole transport layer material different from the first hole transport layer material, and a second separate hole transport layer for a sub-pixel of a second color different from the first color is formed by co-evaporation of the first hole transport layer material and the second hole transport layer material.

[0100] In a manufacturing device of form seventeen, the display device has a plurality of sub-pixels that emit light of different colors from each other, and the display device is stacked and has: a light-emitting layer, which is arranged for each sub-pixel of the plurality of sub-pixels and emits light of a color corresponding to the sub-pixel; and a cathode and an anode respectively located on one side and the other side of the light-emitting layer. The manufacturing device of the display device includes a vapor deposition device, which is used to form a common hole transport layer between the anode and the light-emitting layer shared by the plurality of sub-pixels, and to form a separate hole transport layer between the common hole transport layer and the light-emitting layer for each sub-pixel in the plurality of sub-pixels. The vapor deposition device forms the common hole transport layer by vapor deposition of a first hole transport layer material, forms a first separate hole transport layer possessed by a sub-pixel of a first color among the plurality of sub-pixels by vapor deposition of a second hole transport layer material different from the first hole transport layer material, and forms a second separate hole transport layer possessed by a sub-pixel of a second color different from the first color by co-evaporation of the first hole transport layer material and the second hole transport layer material.

[0101] The present invention is not limited to the above-described embodiments. Various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in the various embodiments.

[0102] Description of Reference Numerals

[0103] 1 Display device

[0104] 2 Light-emitting element layer

[0105] 2R / 2G / 2B First to third light-emitting elements

[0106] 4 Anode

[0107] 6 Hole transport layer

[0108] 6C shared hole transport layer

[0109] 6P single hole transport layer

[0110] 6R / 6G / 6B First hole transport layer to third hole transport layer

[0111] 6Ra fourth hole transport layer

[0112] 8. Luminescent layer

[0113] 8R / 8G / 8B First to third light-emitting layers

[0114] 12 cathode

[0115] 50. Manufacturing equipment for display devices

Claims

1. A display device comprising a plurality of sub-pixels emitting light of mutually different colors, The display device comprises: a light emitting layer provided for each of the plurality of sub-pixels and emitting light of a color corresponding to the sub-pixel; as well as a cathode and an anode located on one side and the other side of the light-emitting layer respectively, The display device is characterized in that: The plurality of sub-pixels are provided with a common hole transport layer between the anode and the light-emitting layer, and a separate hole transport layer is provided for each of the plurality of sub-pixels between the common hole transport layer and the light-emitting layer. The common hole transport layer is formed using only the first hole transport layer material. A first single hole transport layer of a sub-pixel of a first color among the plurality of sub-pixels is formed using only a second hole transport layer material different from the first hole transport layer material, and a second single hole transport layer of a sub-pixel of a second color different from the first color is formed using a mixed material of the first hole transport layer material and the second hole transport layer material. The hole mobility of the second hole transport layer material is lower than the hole mobility of the first hole transport layer material, A third separate hole transport layer included in a sub-pixel of a third color different from both the first color and the second color is formed using only the first hole transport layer material. The third individual hole transport layer is separated from the first individual hole transport layer and the second individual hole transport layer, The common hole transport layer is shared by the sub-pixels of the first color, the sub-pixels of the second color, and the sub-pixels of the third color. The third individual hole transport layer is a layer different from the common hole transport layer, A fourth individual hole transport layer is further provided between the second individual hole transport layer and the common hole transport layer, and the fourth individual hole transport layer is formed using the first hole transport layer material.

2. The display device according to claim 1, characterized in that An absolute value of an energy level of a highest occupied molecular orbital of the first hole transport layer material is smaller than an absolute value of an energy level of a highest occupied molecular orbital of the second hole transport layer material.

3. The display device according to claim 2, characterized in that When the absolute value of the energy level of the highest occupied molecular orbital of the first hole transport layer material is set to HOMO1 (eV), and the absolute value of the energy level of the highest occupied molecular orbital of the second hole transport layer material is set to HOMO2 (eV), HOMO1+0.2eV is satisfied. <HOMO2。 4. The display device according to claim 1, characterized in that In the second single hole transport layer, the mixing ratio of the second hole transport layer material is 10% or more and 50% or less of the entirety.

5. The display device according to claim 1, characterized in that The first color is blue and the second color is red.

6. The display device according to claim 1, characterized in that The first color is blue and the second color is green.

7. The display device according to claim 5, characterized in that The plurality of sub-pixels further include sub-pixels of a third color, and the third color is green.

8. The display device according to claim 6, characterized in that The plurality of sub-pixels further include sub-pixels of a third color, and the third color is red.

9. The display device according to claim 1, characterized in that: The film thickness of the second individual hole transport layer is the same as the film thickness of the third individual hole transport layer.

10. The display device according to claim 1, characterized in that The single hole transport layer formed using the mixed material is in contact with the light emitting layer.

11. A method for manufacturing a display device, the display device comprising a plurality of sub-pixels emitting light of mutually different colors, The display device is stacked and comprises: a light emitting layer, provided for each of the plurality of sub-pixels, and emitting light of a color corresponding to the sub-pixel; and a cathode and an anode located on one side and the other side of the light-emitting layer respectively, The manufacturing method of the display device is characterized in that: The manufacturing method of the display device comprises a hole transport layer forming step, forming a common hole transport layer between the anode and the light emitting layer shared by the plurality of sub-pixels, and forming a separate hole transport layer between the common hole transport layer and the light emitting layer for each of the plurality of sub-pixels. In the hole transport layer forming step, the common hole transport layer is formed by vapor-depositing only a first hole transport layer material, a first individual hole transport layer of a sub-pixel of a first color among the plurality of sub-pixels is formed by vapor-depositing only a second hole transport layer material different from the first hole transport layer material, and a second individual hole transport layer of a sub-pixel of a second color different from the first color is formed by co-evaporating the first hole transport layer material and the second hole transport layer material. The hole mobility of the second hole transport layer material is lower than the hole mobility of the first hole transport layer material, A third separate hole transport layer included in a sub-pixel of a third color different from both the first color and the second color is formed using only the first hole transport layer material. The third individual hole transport layer is separated from the first individual hole transport layer and the second individual hole transport layer, The common hole transport layer is shared by the sub-pixels of the first color, the sub-pixels of the second color, and the sub-pixels of the third color. The third individual hole transport layer is a layer different from the common hole transport layer, A fourth individual hole transport layer is further provided between the second individual hole transport layer and the common hole transport layer, and the fourth individual hole transport layer is formed using the first hole transport layer material.

12. A manufacturing apparatus for a display device, the display device comprising a plurality of sub-pixels emitting light of mutually different colors, The display device is stacked and comprises: a light emitting layer, provided for each of the plurality of sub-pixels, and emitting light of a color corresponding to the sub-pixel; and a cathode and an anode located on one side and the other side of the light-emitting layer respectively, The manufacturing device of the display device is characterized in that: The manufacturing device of the display device includes an evaporation device, which is used to form a common hole transport layer between the anode and the light-emitting layer shared by the plurality of sub-pixels, and to form a separate hole transport layer between the common hole transport layer and the light-emitting layer for each of the plurality of sub-pixels. The evaporation device forms the common hole transport layer by evaporating only a first hole transport layer material, forms a first individual hole transport layer for a sub-pixel of a first color among the plurality of sub-pixels by evaporating only a second hole transport layer material different from the first hole transport layer material, and forms a second individual hole transport layer for a sub-pixel of a second color different from the first color by co-evaporating the first hole transport layer material and the second hole transport layer material. The hole mobility of the second hole transport layer material is lower than the hole mobility of the first hole transport layer material, A third separate hole transport layer included in a sub-pixel of a third color different from both the first color and the second color is formed using only the first hole transport layer material. The third individual hole transport layer is separated from the first individual hole transport layer and the second individual hole transport layer, The common hole transport layer is shared by the sub-pixels of the first color, the sub-pixels of the second color, and the sub-pixels of the third color. The third individual hole transport layer is a layer different from the common hole transport layer, A fourth individual hole transport layer is further provided between the second individual hole transport layer and the common hole transport layer, and the fourth individual hole transport layer is formed using the first hole transport layer material.

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