Display device and display apparatus

Abstract

The present application relates to a display device and a display apparatus. The display device comprises an anode, a functional layer, and a cathode. The functional layer comprises a plurality of light-emitting unit layers comprising light-emitting layers and auxiliary layers. A first light-emitting unit layer is arranged on the side close to the anode, and a second light-emitting unit layer is arranged on the side close to the cathode. The distance between the light-emitting layer in the first light-emitting unit layer and the anode and the distance between the light-emitting layer in the second light-emitting unit layer and the cathode meet a specific mathematical relationship, so that the characteristics of the display device can be improved.

Description

Display devices and display apparatus Technical Field

[0001] This application relates to the field of display technology, and in particular to a display device and display apparatus. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have achieved rapid development and widespread application due to their self-emissive properties, high contrast, wider viewing angle, and faster response speed.

[0003] Tandem OLED refers to an OLED where each pixel's light-emitting diodes are connected in a series, and the brightness of each pixel is adjusted by controlling the current. This series connection effectively controls the brightness of each pixel in the OLED display, achieving full-color display and offering the advantage of high brightness. However, tandem OLED technology suffers from poor display device characteristics. Summary of the Invention

[0004] This application provides a display device and display apparatus that can solve the problem of poor characteristics in tandem organic electroluminescent devices. The technical solution is as follows:

[0005] A display device, comprising:

[0006] An anode, a functional layer, and a cathode are sequentially arranged along a first direction;

[0007] The functional layer includes several light-emitting unit layers containing light-emitting layers and auxiliary layers, wherein the first light-emitting unit layer is disposed near the anode, and the second light-emitting unit layer is disposed near the cathode; wherein...

[0008] The auxiliary layer located in the first light-emitting unit layer is the first auxiliary layer and the light-emitting layer is the first light-emitting layer. The first auxiliary layer and the first light-emitting layer are stacked sequentially on the anode along the first direction. The auxiliary layer located in the second light-emitting unit layer is the second auxiliary layer and the light-emitting layer is the second light-emitting layer. The second auxiliary layer and the second light-emitting layer are stacked sequentially on the cathode along a direction opposite to the first direction.

[0009] The thickness of the first light-emitting layer is H1, and the thickness of the first auxiliary layer is L1;

[0010] The thickness of the second light-emitting layer is H2, and the thickness of the second auxiliary layer is L2. L1 and L2 satisfy the following:

[0011]

[0012] L1+L2>H+H2,

[0013]

[0014] Wherein, λ is the peak wavelength of the emission spectrum of the first or second emitting layer.

[0015] In one embodiment, the functional layer includes a red light-emitting area, a green light-emitting area, and a blue light-emitting area;

[0016] The first light-emitting layer includes a first red light-emitting layer, a first green light-emitting layer, and a first blue light-emitting layer arranged sequentially along the second direction;

[0017] The second light-emitting layer includes a second red light-emitting layer, a second green light-emitting layer, and a second blue light-emitting layer arranged sequentially along a second direction; wherein,

[0018] The first red emitting layer and the second red emitting layer are both located in the red emitting area, the first green emitting layer and the second green emitting layer are both located in the green emitting area, and the first blue emitting layer and the second blue emitting layer are both located in the blue emitting area.

[0019] In one embodiment, the light-emitting unit layer further includes an auxiliary light-emitting layer corresponding to the number of light-emitting layers, wherein,

[0020] The auxiliary light-emitting layer located within the first light-emitting unit layer is a first auxiliary light-emitting layer. The first auxiliary light-emitting layer is located between the first light-emitting layer and the first auxiliary layer. The thickness of the first auxiliary light-emitting layer is C1, and L1 and L2 satisfy:

[0021]

[0022] In one embodiment, the auxiliary light-emitting layer is configured as a single-layer structure; or

[0023] The auxiliary light-emitting layer is configured as a multi-layer structure.

[0024] In one embodiment, the first auxiliary light-emitting layer includes a first sub-auxiliary light-emitting layer, a second sub-auxiliary light-emitting layer, and a third sub-auxiliary light-emitting layer; wherein,

[0025] The first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer each use one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer individually, and the auxiliary light-emitting layers used by the first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer are different; and / or

[0026] In one embodiment, the first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer share at least one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer; and / or

[0027] The first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer share at least one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer between each pair.

[0028] In one embodiment, the thickness of the first red emitting layer is R1, the thickness of the second red emitting layer is R2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the red emitting region is E1. L1 and L2 satisfy:

[0029] E1+L1+L2>R1+R2; and / or

[0030] The thickness of the first blue emitting layer is B1, the thickness of the second blue emitting layer is B2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the blue emitting region is E2. L1 and L2 satisfy the following:

[0031] E2+L1+L2>B1+B2; and / or

[0032] The thickness of the first green emitting layer is G1, the thickness of the second green emitting layer is G2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the green emitting region is E3. L1 and L2 satisfy the following:

[0033] E3+L1+L2>G1+G2.

[0034] In one embodiment, the auxiliary light-emitting layer includes at least one hole-transporting material.

[0035] In one embodiment, the relationship between the light-emitting layer and the auxiliary light-emitting layer satisfies:

[0036]

[0037] in, This represents the lowest triplet energy of the hole transport material in the auxiliary light-emitting layer. This represents the lowest triplet energy of the luminescent material in the luminescent layer.

[0038] In one embodiment, the difference between the lowest triplet energy of the hole transport material in the auxiliary light-emitting layer and the lowest triplet energy of the light-emitting material in the light-emitting layer is greater than 0.1 eV.

[0039] In one embodiment, the molecules of the hole-transporting material of the auxiliary light-emitting layer satisfy the following:

[0040] -5.4eV <HOMO1<5.9eV,

[0041] HOMO1 represents the highest occupied molecular orbital energy level of the material molecule.

[0042] In one embodiment, the auxiliary light-emitting layer further comprises at least one light-emitting material, and the light-emitting material contains boron or at least one metal element.

[0043] In one embodiment, when the auxiliary light-emitting layer contains a light-emitting material, the thickness of the first red light-emitting layer is R1+E1, and L1 and L2 satisfy:

[0044] L1+L2>R1+E1+R2.

[0045] In one embodiment, when the auxiliary light-emitting layer contains a luminescent material, the thickness of the first blue light-emitting layer is B1+E2, and L1 and L2 satisfy:

[0046] L1+L2>B1+E2+B2.

[0047] In one embodiment, when the auxiliary light-emitting layer contains a luminescent material, the thickness of the first green light-emitting layer is G1+E3, and L1 and L2 satisfy:

[0048] L1+L2>G1+E3+G2.

[0049] In one embodiment, the first auxiliary layer includes a hole injection layer, and the second auxiliary layer includes an electron injection layer;

[0050] Several of the light-emitting unit layers share the electron injection layer and the hole injection layer.

[0051] In one embodiment, the light-emitting unit layer includes a hole transport layer and an electron transport layer, with the light-emitting layer located between the hole transport layer and the electron transport layer; wherein,

[0052] The hole transport layer includes a first hole transport layer and a second hole transport layer, and the electron transport layer includes a first electron transport layer and a second electron transport layer; wherein...

[0053] The first hole transport layer is located within the first auxiliary layer, and the second electron transport layer is located within the second auxiliary layer.

[0054] In one embodiment, the auxiliary layer further includes a hole blocking layer located between the light-emitting layer and the electron transport layer;

[0055] The hole blocking layer includes a first hole blocking layer and a second hole blocking layer; the first hole blocking layer is located between the first light-emitting layer and the first electron transport layer, and the second hole blocking layer is located between the second light-emitting layer and the second electron transport layer.

[0056] In one embodiment, the functional layer further includes a charge generation layer located between the light-emitting unit layers, and the charge generation layer is a single-layer structure or a multi-layer structure.

[0057] In one embodiment, the first light-emitting layer comprises a first host material and a first object material, and the second light-emitting layer comprises a second host material and a second object material; wherein,

[0058] The first object material includes at least one of fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials; and / or

[0059] The second guest material includes at least one of fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials.

[0060] In one embodiment, when the materials contained in the first light-emitting layer and the second light-emitting layer are different, the difference in the emission spectral peak value of the light-emitting materials in the first guest material and the second guest material is less than 5 nm.

[0061] In one embodiment, both the first host material and the second host material are electronic host materials, wherein the electronic host material is selected from triazine materials or thermally activated delayed fluorescence materials with electron transport characteristics.

[0062] In one embodiment, a microcavity is formed between the cathode and the anode, the microcavity including a red sub-microcavity located in the red emitting region, a green sub-microcavity located in the green emitting region, and a blue microcavity located in the blue emitting region;

[0063] The number of film layers located between the anode and cathode, corresponding to any color sub-microcavity, is d, and the optical thickness of d film layers is L, where L satisfies:

[0064]

[0065] Where, n i Let r be the refractive index of the i-th film layer among the d film layers. i Let λ be the thickness of the i-th film layer, k be a natural number, and λ be the target spectral peak wavelength. The phase shift caused by the reflection of the target light in the anode layer.

[0066] In one embodiment, the target spectral peak wavelength range within the red luminescent region is 615 nm to 640 nm; and / or

[0067] The target spectral peak wavelength range within the green luminescent region is 515nm to 540nm; and / or

[0068] The target spectral peak wavelength range within the blue luminescent region is 450 nm to 470 nm.

[0069] To address the aforementioned technical problems, this application further provides a display device, comprising:

[0070] An anode, a functional layer, and a cathode are sequentially arranged along a first direction;

[0071] The functional layer includes a light-emitting unit layer containing an independent light-emitting layer;

[0072] The thickness of the independent light-emitting layer is H3, and the thickness from the independent light-emitting layer to the cathode is L3, where L3 satisfies:

[0073]

[0074] Where λ is the peak wavelength of the emission spectrum of the independent emitting layer.

[0075] To address the aforementioned technical problems, this application provides another display device that utilizes the display device described in any of the above embodiments.

[0076] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0077] As can be seen from the above embodiments, the display device of this application includes an anode, a functional layer, and a cathode. The functional layer includes a plurality of light-emitting unit layers containing light-emitting layers and auxiliary layers, wherein the first light-emitting unit layer is disposed near the anode, and the second light-emitting unit layer is disposed near the cathode. This application improves the characteristics of the display device by setting the distance between the light-emitting layer in the first light-emitting unit layer and the anode, and the distance between the light-emitting layer in the second light-emitting unit layer and the cathode, so that the two satisfy a specific mathematical relationship.

[0078] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0079] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0080] Figure 1 is a schematic diagram of the structure of a display device in one embodiment of this application.

[0081] Figure 2 is a schematic diagram of another structure of the display device in one embodiment of this application.

[0082] Figure 3 is another structural schematic diagram of the display device in one embodiment of this application.

[0083] Figures 4A-4F are partial structural schematic diagrams of a display device in one embodiment of this application.

[0084] Figure 5 is a schematic diagram of another structure of the display device in one embodiment of this application.

[0085] Figure 6 is a schematic diagram of another structure of the display device in one embodiment of this application.

[0086] Figure 7 is a schematic diagram of another structure of the display device in one embodiment of this application.

[0087] Explanation of reference numerals in the attached figures:

[0088] 1. Substrate; 2. Anode; 3. Functional layer; 4. Cathode; 5. Optical cover layer; 6. Encapsulation layer.

[0089] 31. First light-emitting unit layer.

[0090] 310, First light-emitting layer; 3100, First red light-emitting layer; 3101, First green light-emitting layer; 3102, First blue light-emitting layer; 311, First auxiliary layer; 3110, Hole injection layer; 3111, First hole transport layer; 3112, Transparent conductive layer; 312, First auxiliary light-emitting layer; 3120, First sub-auxiliary light-emitting layer; 3121, Second sub-auxiliary light-emitting layer; 3122, Third sub-auxiliary light-emitting layer; 313, First hole blocking layer; 314, First electron transport layer.

[0091] 32. Second light-emitting unit layer.

[0092] 320. Second light-emitting layer; 3200. Second red light-emitting layer; 3201. Second green light-emitting layer; 3202. Second blue light-emitting layer; 321. Second auxiliary layer; 3210. Electron injection layer; 3211. Second electron transport layer; 322. Second hole transport layer; 323. Second auxiliary light-emitting layer; 324. Second hole blocking layer.

[0093] 33. Charge generation layer; 330. First charge generation layer; 331. Second charge generation layer.

[0094] a) Red emitting area; b) Green emitting area; c) Blue emitting area; X) First direction; Y) Second direction. Detailed Implementation

[0095] There are currently two main OLED mass production technologies: one provides a full-color display solution through individual R / G / B light-emitting units, and the other provides a full-color solution through color conversion or color filtering. For the latter, there are currently two mainstream methods, as illustrated in Figure 1 below:

[0096] The first approach uses a series-connected bottom-emitting white OLED device as the light source, achieving R / G / B full-color display through a color filter (CF) placed on the other side of the transparent substrate 1. This approach has already achieved mass production in OLED TVs. However, due to the limitations of the filter itself, the saturation is not high. The bottom-emitting device structure also makes it difficult to improve brightness at a normal viewing angle. If a top-emitting structure is used, there are problems with increased process complexity and excessive light loss in certain wavelengths.

[0097] The second method involves using a top-emitting blue OLED with a series structure to excite a QD color conversion layer (CC) placed above the cathode 4 to achieve full-color display. The biggest problem with this approach is that due to the light conversion efficiency of the CC itself, the color purity of the G / R pixels is low, requiring matching with a corresponding CF. This approach also has drawbacks in terms of manufacturing process and power consumption.

[0098] This application provides a display device in which, during the manufacturing process, the distance between the light-emitting layer closest to the anode 2 and the light-emitting layer closest to the cathode 4 is adjusted so that the values ​​of the two distances always satisfy a specific mathematical relationship. This can greatly optimize the characteristics of the display device, improve the brightness at the viewing angle and the purity of monochromatic color, and thus improve the light emission effect of the display device.

[0099] Specifically, referring to FIG1, the display device includes an anode 2, a functional layer 3, and a cathode 4 arranged sequentially along a first direction. The functional layer 3 includes several light-emitting unit layers containing light-emitting layers and auxiliary layers, for example, a first light-emitting unit layer 31 is arranged near the anode 2 and a second light-emitting unit layer 32 is arranged near the cathode 4.

[0100] The auxiliary layer located in the first light-emitting unit layer 31 is the first auxiliary layer 311, and the light-emitting layer is the first light-emitting layer 310. The first auxiliary layer 311 and the first light-emitting layer 310 are stacked sequentially on the anode 2 along the first direction. The auxiliary layer located in the second light-emitting unit layer 32 is the second auxiliary layer 321, and the light-emitting layer is the second light-emitting layer 320. The second auxiliary layer 321 and the second light-emitting layer 320 are stacked sequentially on the cathode 4 along a direction opposite to the first direction.

[0101] The thickness of the first light-emitting layer 310 is H1, and the thickness of the first auxiliary layer 311 is L1.

[0102] The thickness of the second light-emitting layer 320 is H2, and the thickness of the second auxiliary layer 321 is L2. L1 and L2 satisfy the following:

[0103]

[0104] L1 + L2 > H + H2,

[0105]

[0106] λ is the peak wavelength of the emission spectrum of the emitting layer.

[0107] In some embodiments, the display device can also be a single-light-emitting device. That is, the functional layer 3 contains only one light-emitting unit layer, i.e., there is only one light-emitting layer between the cathode 4 and the anode 2. To distinguish it from other light-emitting layers, it can be called an independent light-emitting layer.

[0108] In this embodiment, the organic light-emitting device comprises, sequentially along a first direction, a hole injection layer, a hole transport layer, an independent light-emitting layer, an electron transport layer, an electron injection layer, and a cathode on a substrate 1. Let the thickness of the independent light-emitting layer be H3, and the distance between the independent light-emitting layer and the cathode 4 be L3. It should be noted that L3 can also be understood as the sum of the thicknesses of the electron transport layer and the electron injection layer. L3 and H3 satisfy:

[0109]

[0110] Where λ is the peak wavelength of the emission spectrum of the independent emitting layer.

[0111] As can be seen from the above, when the display device is a single light-emitting device, the distance between the light-emitting layer and the cathode 4 still satisfies the above formula.

[0112] In some embodiments, referring to FIG1, the display device is formed on substrate 1. Substrate 1 may be a flexible substrate. The materials of the flexible substrate include, but are not limited to, PET (Polyethylene Terephthalate), PI (Polyimide), etc.

[0113] In some embodiments, substrate 1 may be a rigid substrate. The material of the rigid substrate includes, but is not limited to, glass, quartz, or plastic.

[0114] In some embodiments, the anode 2 can be made of a material with a high work function. For bottom-emitting OLEDs, the anode 2 can be made of a transparent oxide material, such as indium tin oxide (ITO) or indium zinc oxide (IZO). For top-emitting OLEDs, the anode 2 can be a composite structure of metal and transparent oxide, such as Ag / ITO or Ag / IZO. The thickness of the transparent oxide in the anode 2 can be approximately 5 nm to 20 nm, resulting in an average reflectance of the anode 2 greater than 85% in the visible light region.

[0115] Furthermore, the anode 2 can be a single-layer structure or a multi-layer structure.

[0116] In some implementations, the cathode 4 can be made of a metallic material. For top-emitting OLEDs, formed by a vapor deposition process, the metallic material can be magnesium (Mg), silver (Ag), or aluminum (Al), or an alloy material, such as a Mg:Ag alloy.

[0117] Preferably, the Mg:Ag ratio can be adjusted between approximately 3:7 and 1:9. Preferably, the thickness of the cathode 4 is in the range of 10 nm to 20 nm, so that the average transmittance of the cathode 4 at a wavelength of 530 nm is approximately 45% to 60%.

[0118] For bottom-emitting OLEDs, the cathode 4 can be made of magnesium (Mg), silver (Ag), aluminum (Al), or a magnesium-silver alloy. The thickness of the cathode 4 is greater than 80 nm, which gives the cathode 4 good reflectivity.

[0119] Furthermore, the cathode 4 can be a single-layer structure or a multi-layer structure.

[0120] In some embodiments, referring to FIG2, functional layer 3 includes a red light-emitting area a, a blue light-emitting area c, and a green light-emitting area b. The first light-emitting layer 310 includes a first red light-emitting layer 3100, a first green light-emitting layer 3101, and a first blue light-emitting layer 3102 arranged sequentially along a second direction. The second light-emitting layer 320 includes a second red light-emitting layer 3200, a second green light-emitting layer 3201, and a second blue light-emitting layer 3202 arranged sequentially along a second direction.

[0121] The first red luminescent layer 3100 and the second red luminescent layer 3200 are both located in the red luminescent region a, the first blue luminescent layer 3102 and the second blue luminescent layer 3202 are both located in the blue luminescent region c, and the first green luminescent layer 3101 and the second green luminescent layer 3201 are both located in the green luminescent region b.

[0122] In some embodiments, referring to FIG3, the light-emitting unit layer further includes an auxiliary light-emitting layer corresponding to the number of light-emitting layers. For the first light-emitting unit layer 31, the first auxiliary light-emitting layer 312 is located between the first light-emitting layer 310 and the first auxiliary layer 311, and the thickness of the first auxiliary light-emitting layer 312 is C1, and L1 and L2 satisfy:

[0123] (L1+C1)+L2>H1+H2.

[0124] In some embodiments, the auxiliary light-emitting layer is configured as a single-layer structure. The auxiliary light-emitting layer is configured as a multi-layer structure. The first auxiliary light-emitting layer 312 includes a first sub-auxiliary light-emitting layer 3120, a second sub-auxiliary light-emitting layer 3121, and a third sub-auxiliary light-emitting layer 3122.

[0125] For example, referring to FIG5, the first sub-auxiliary light-emitting layer 3120, the second sub-auxiliary light-emitting layer 3121 and the third sub-auxiliary light-emitting layer 3122 can be a common layer formed of a material.

[0126] In some embodiments, the first red light-emitting layer 3100, the first blue light-emitting layer 3102, and the first green light-emitting layer 3101 correspond to one of the first sub-auxiliary light-emitting layer 3120, the second sub-auxiliary light-emitting layer 3121, and the third sub-auxiliary light-emitting layer 3122, respectively, and the auxiliary light-emitting layers used by the first red light-emitting layer 3100, the first blue light-emitting layer 3102, and the first green light-emitting layer 3101 are different.

[0127] Preferably, the first sub-auxiliary light-emitting layer 3120 is used to assist the first red light-emitting layer 3100 in emitting light; for ease of understanding, it is referred to as the first red auxiliary light-emitting layer. The second sub-auxiliary light-emitting layer 3121 is used to assist the first green light-emitting layer 3101 in emitting light; it is referred to as the first green auxiliary light-emitting layer. The third sub-auxiliary light-emitting layer 3122 is used to assist the first blue light-emitting layer 3102 in emitting light; it is referred to as the first blue auxiliary light-emitting layer.

[0128] In one embodiment, referring to FIG3, the first red auxiliary light-emitting layer, the first green light-emitting layer 3101, and the first blue auxiliary light-emitting layer of the display device are all single-layer structures.

[0129] In one embodiment, referring to FIG4A, the first red auxiliary light-emitting layer and the first blue auxiliary light-emitting layer of the display device are both configured as single-layer structures, and the first green auxiliary light-emitting layer is configured as a double-layer structure.

[0130] Specifically, as shown in the figure, the first green auxiliary light-emitting layer includes a first sub-green auxiliary light-emitting layer 3121a and a second sub-green auxiliary light-emitting layer 3121b.

[0131] In one embodiment, referring to FIG4B, the first blue auxiliary light-emitting layer of the display device is configured as a single-layer structure, and the first red auxiliary light-emitting layer and the first green auxiliary light-emitting layer are both configured as double-layer structures.

[0132] Specifically, as shown in the figure, the first red auxiliary light-emitting layer includes a first sub-red-green auxiliary light-emitting layer 3120a and a second sub-red auxiliary light-emitting layer 3120b. The first green auxiliary light-emitting layer is the same as described above and will not be repeated here.

[0133] In one embodiment, referring to FIG4C, the first green auxiliary light-emitting layer and the first blue auxiliary light-emitting layer of the display device are configured as a single-layer structure, and the first red auxiliary light-emitting layer is configured as a double-layer structure.

[0134] Specifically, the double-layer structure of the first red auxiliary light-emitting layer is the same as described above, and will not be repeated here.

[0135] In some embodiments, the first red light-emitting layer 3100, the first blue light-emitting layer 3102, and the first green light-emitting layer 3101 share at least one of the first sub-auxiliary light-emitting layer 3120, the second sub-auxiliary light-emitting layer 3121, and the third sub-auxiliary light-emitting layer 3122.

[0136] In one embodiment, referring to FIG4D, the first red light-emitting layer 3100 uses a first red auxiliary light-emitting layer independently, and the first green light-emitting layer 3101 uses an independent layer.

[0137] The first green auxiliary light-emitting layer, and both the first red auxiliary light-emitting layer and the first green auxiliary light-emitting layer are single-layer structures.

[0138] The first green light-emitting layer 3101 and the first blue light-emitting layer 3102 share a first blue auxiliary light-emitting layer, and the first blue auxiliary light-emitting layer is a single-layer structure. It should be noted that within the green light-emitting region b, the first blue auxiliary light-emitting layer and the first green auxiliary light-emitting layer are stacked sequentially along the second direction Y.

[0139] The diameter of the first stepped hole is smaller than the diameter of the compression spring, and equal to or greater than the diameter of the connecting end of the slider 220. It should be noted that the connecting end of the slider 220 is the end that is connected to the transmission assembly 23.

[0140] In one embodiment, referring to FIG4E, the first red light-emitting layer 3100 independently uses a first red auxiliary light-emitting layer, the first blue light-emitting layer 3102 independently uses a first blue auxiliary light-emitting layer, and both the first red auxiliary light-emitting layer and the first blue auxiliary light-emitting layer are single-layer structures.

[0141] The first red luminescent layer 3100 and the first green luminescent layer 3101 share a first green auxiliary luminescent layer, and the first green auxiliary luminescent layer is a single-layer structure. It should be noted that within the green luminescent region b, the first green auxiliary luminescent layer and the first red auxiliary luminescent layer are stacked sequentially along the second direction Y.

[0142] In some embodiments, the first red light-emitting layer 3100, the first blue light-emitting layer 3102, and the first green light-emitting layer 3101 share at least one of the first sub-auxiliary light-emitting layer 3120, the second sub-auxiliary light-emitting layer 3121, and the third sub-auxiliary light-emitting layer 3122.

[0143] In one embodiment, referring to FIG4F, the first red light-emitting layer 3100 independently uses a first red auxiliary light-emitting layer, and the first red auxiliary light-emitting layer is a single-layer structure.

[0144] The first red light-emitting layer 3100 and the first green light-emitting layer 3101 share the first green auxiliary light-emitting layer, and the first green auxiliary light-emitting layer is a single-layer structure.

[0145] The first red light-emitting layer 3100, the first green light-emitting layer 3101, and the first blue light-emitting layer 3102 share a first blue auxiliary light-emitting layer. Furthermore, the first blue auxiliary light-emitting layer is a single-layer structure.

[0146] In some embodiments, the thickness of the first red emitting layer 3100 is R1, the thickness of the second red emitting layer 3200 is R2, and the sum of the thicknesses of the first sub-auxiliary emitting layer 3120, the second sub-auxiliary emitting layer 3121, and the third sub-auxiliary emitting layer 3122 located in the red emitting region a is E1. L1 and L2 satisfy:

[0147] E1+L1+L2>R1+R2.

[0148] The thickness of the first blue emitting layer 3102 is B1, the thickness of the second blue emitting layer 3202 is B2, and the sum of the thicknesses of the first sub-auxiliary emitting layer 3120, the second sub-auxiliary emitting layer 3121, and the third sub-auxiliary emitting layer 3122 located in the blue emitting region c is E2. L1 and L2 satisfy:

[0149] E2+L1+L2>B1+B2.

[0150] The thickness of the first green luminescent layer 3101 is G1, the thickness of the second green luminescent layer 3201 is G2, and the sum of the thicknesses of the first sub-auxiliary luminescent layer 3120, the second sub-auxiliary luminescent layer 3121, and the third sub-auxiliary luminescent layer 3122 located in the green luminescent region b is E3. L1 and L2 satisfy:

[0151] E3+L1+L2>G1+G2.

[0152] In some embodiments, the auxiliary light-emitting layer includes at least one hole-transporting material. Preferably, the hole-transporting material includes, but is not limited to, carbazole or aniline materials.

[0153] In some implementations, the relationship between the light-emitting layer and the auxiliary light-emitting layer satisfies:

[0154]

[0155] in, This represents the lowest triplet energy of the hole-transporting material in the auxiliary light-emitting layer. This represents the lowest triplet energy of the luminescent material in the luminescent layer.

[0156] In some implementations, the difference between the lowest triplet energy of the hole transport material in the auxiliary light-emitting layer and the lowest triplet energy of the light-emitting material in the light-emitting layer is greater than 0.1 eV.

[0157] In some implementations, the molecules of the hole-transporting material in the auxiliary light-emitting layer satisfy the following:

[0158] --5.4eV <HOMO1<5.9eV,

[0159] HOMO1 represents the highest occupied molecular orbital energy level of the material molecule.

[0160] In some embodiments, the auxiliary light-emitting layer further comprises at least one light-emitting material, and the light-emitting material contains boron or at least one metal element.

[0161] In some embodiments, when the auxiliary light-emitting layer contains a light-emitting material, the thickness of the first red light-emitting layer 3100 is R1+E1, and L1 and L2 satisfy:

[0162] L1+L2>R1+E1+R2,

[0163] In some embodiments, when the auxiliary light-emitting layer contains a luminescent material, the thickness of the first blue light-emitting layer 3102 is B1+E2, and L1 and L2 satisfy:

[0164] L1+L2>B1+E2+B2,

[0165] In some embodiments, when the auxiliary light-emitting layer contains a luminescent material, the thickness of the first green light-emitting layer 3101 is G1+E3, and L1 and L2 satisfy:

[0166] L1+L2>G1+E3+G2.

[0167] In some embodiments, the first auxiliary layer 311 includes a hole injection layer 3110, and the second auxiliary layer 321 includes an electron injection layer 3210. Several light-emitting unit layers share the electron injection layer 3210 and the hole injection layer 3110.

[0168] By way of example, the hole injection layer 3110 includes a hole transport material, and the hole transport material is doped with a P-type dopant. Preferably, the P-type dopant includes, but is not limited to, manganese trioxide or F4TCNQ. Preferably, the doping ratio is less than 5%. Preferably, the thickness of the hole injection layer 3110 is no more than 10 nm.

[0169] For example, the electron injection layer 3210 is formed by a vapor deposition process. Materials include, but are not limited to, LiF (lithium fluoride), LiQ (8-hydroxyquinoline lithium), Yb (ytterbium), or Ca (calcium). Preferably, the thickness of the electron injection layer 3210 ranges from 0.5 nm to 2 nm.

[0170] In some embodiments, the light-emitting unit layer includes a hole transport layer and an electron transport layer, with the light-emitting layer located between the hole transport layer and the electron transport layer.

[0171] Referring to Figure 5, the hole transport layer includes a first hole transport layer 3111 and a second hole transport layer 322, and the electron transport layer includes a first electron transport layer 314 and a second electron transport layer 3211. The first hole transport layer 3111 is located within the first auxiliary layer 311, and the second electron transport layer 3211 is located within the second auxiliary layer 321.

[0172] For example, the hole transport layer is formed of a pure hole transport material. Preferably, the hole transport layer is prepared by vapor deposition of a carbazole-based material. Preferably, the highest occupied orbital (HOMO) energy level of the material of the hole transport layer is in the range of -5.2 eV to -5.6 eV.

[0173] For example, the electron transport layer is prepared by blending quinoline lithium with thiophene, imidazole, or azazine derivatives. Preferably, the proportion of quinoline lithium ranges from 30% to 70%.

[0174] In one embodiment, the thickness of the first electron transport layer 314 is 0.

[0175] In one embodiment, the thickness of the second hole transport layer 322 ranges from 15 to 50 nm.

[0176] In some embodiments, the auxiliary layer further includes a hole blocking layer located between the light-emitting layer and the electron transport layer. The hole blocking layer includes a first hole blocking layer 313 and a second hole blocking layer 324. The first hole blocking layer 313 is located between the first light-emitting layer 310 and the first electron transport layer 314, and the second hole blocking layer 324 is located between the second light-emitting layer 320 and the second electron transport layer 3211.

[0177] For example, the hole blocking layer may be made of materials including, but not limited to, triazine or azazine materials. Preferably, the thickness of the hole blocking layer is less than 10 nm.

[0178] In one embodiment, the absolute HOMO value of the hole blocking layer material is greater than the absolute HOMO value of the host material of the light-emitting layer. Preferably, the absolute HOMO value of the hole blocking layer material is 0.2 eV higher than the absolute HOMO value of the host material of the light-emitting layer.

[0179] For example, the energy level (TI) of the triplet excited state of the material contained in the first hole blocking layer 313 is greater than the energy level (TI) of the triplet excited state of the light-emitting material contained in the first light-emitting layer 310. Preferably, the TI of the material in the first hole blocking layer 313 is 0.2 eV higher than the TI of the light-emitting material contained in the first light-emitting layer 310.

[0180] For example, the Ti of the material contained in the second hole blocking layer 324 is greater than the Ti of the light-emitting material contained in the second light-emitting layer 320. Preferably, the Ti of the material in the second hole blocking layer 324 is 0.2 eV higher than the Ti of the light-emitting material contained in the first light-emitting layer 310.

[0181] In some embodiments, the first light-emitting layer 310 comprises a first host material and a first guest material, and the second light-emitting layer 320 comprises a second host material and a second guest material. The first guest material comprises at least one material selected from fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials. The second guest material comprises at least one material selected from fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials.

[0182] For example, the first and second host materials can be a single host material or a PN-mixed host material. These include, but are not limited to, anthracene derivatives and carbazole derivatives.

[0183] For example, fluorescent materials include, but are not limited to, pyrene-based, condensed carbazole-based, or boron-containing materials.

[0184] For example, phosphorescent materials include, but are not limited to, metal complexes such as iridium (Ir) and platinum (Pt).

[0185] In some embodiments, when the materials contained in the first light-emitting layer 310 and the second light-emitting layer 320 are different, the difference in the emission spectral peak value of the light-emitting materials in the first guest material and the second guest material is less than 5 nm.

[0186] This configuration ensures that the materials of the first luminescent layer 310 and the second luminescent layer 320 corresponding to each color have a certain similarity in their emission spectra, producing similar color effects. This allows the luminescent layers of different colors to be more matched and coordinated when emitting light, thereby improving the overall luminous effect and visual experience.

[0187] In some embodiments, both the first host material and the second host material are electronic host materials, which are selected from triazine materials or thermally activated delayed fluorescence materials with electron transport characteristics.

[0188] Specifically, thermally activated delayed fluorescence (TEF) materials can be polycarbazole-based materials, such as 4CzIPN. TEF materials generally have a DA structure, and their S1-T1 ratio is less than 0.3 eV. Here, S1 represents the energy level of the excited singlet state of the material.

[0189] In some embodiments, the functional layer 3 further includes a charge generation layer 33, which is located between the light-emitting unit layers and is a single-layer structure or a multi-layer structure.

[0190] For example, referring to FIG5, the charge generating layer 33 includes a first charge generating layer 330 and a second charge generating layer 331. The first charge generating layer 330 and the second charge generating layer 331 are arranged sequentially along a first direction X.

[0191] In one embodiment, the first charge-generating layer 330 comprises an electron transport material. Preferably, the electron transport material is doped with a low-function metal. Preferably, the low-function metal includes, but is not limited to, LiF, Yb, Ca, etc. Preferably, the doping ratio of the low-function metal is less than 5%.

[0192] In one embodiment, the second charge-generating layer 331 comprises a hole transport material. Preferably, the hole transport material is doped with a p-type dopant. Preferably, the p-type dopant content is less than 5%.

[0193] In some embodiments, continuing to refer to FIG5, the display device further includes an optical cover layer 5. The optical cover layer 5 is formed on the cathode layer 4.

[0194] For example, the optical coating layer 5 comprises a high-refractive-index organic material. Preferably, the optical coating layer 5 has a wavelength of 530 nm and a refractive index greater than 1.9. Preferably, the thickness of the optical coating layer 5 is less than 100 nm.

[0195] In some embodiments, continuing to refer to FIG5, the display device further includes an encapsulation layer 6. Preferably, the encapsulation layer 6 employs either frame encapsulation or thin-film encapsulation.

[0196] In some embodiments, functional layer 3 includes multiple light-emitting unit layers. The multiple light-emitting units are connected in series. A charge-generating layer 33 is disposed between each pair of the multiple light-emitting unit layers. Referring to FIG6, the cathode 4 and anode 2 further include an Nth light-emitting unit layer 3N, which includes a 3a light-emitting layer and a 3b auxiliary light-emitting layer.

[0197] In some embodiments, referring to FIG7, the first auxiliary layer further includes a transparent conductive layer 3112.

[0198] In some embodiments, a microcavity is formed between the cathode 4 and the anode 2, the microcavity including a red sub-microcavity located in the red light-emitting region a, a green sub-microcavity located in the green light-emitting region b, and a blue sub-microcavity located in the blue light-emitting region c.

[0199] The number of film layers located between anode 2 and cathode 4, corresponding to any color sub-microcavity, is d, and the optical thickness of d film layers is L, where L satisfies:

[0200]

[0201] Where, n i Let r be the refractive index of the i-th film layer out of d film layers. i Let λ be the thickness of the i-th film layer, k be a natural number, and λ be the target spectral peak wavelength. The phase shift is caused by the reflection of the target light in the anode layer 2.

[0202] In some embodiments, the target spectral peak wavelength range within the red emitting region a is 615 nm to 640 nm. The target spectral peak wavelength range within the green emitting region b is 515 nm to 540 nm. The target spectral peak wavelength range within the blue emitting region c is 450 nm to 470 nm.

[0203] Based on the device structure proposed in this case, cavity length design and reasonable positioning of the light-emitting layer within the overall film layer are required to ensure luminous efficacy. The inventors of this disclosure have verified the voltage, efficiency, and lifespan of the display device disclosed herein.

[0204] Verification Example 1: Includes Comparative Example 1 and Example 1.

[0205] Comparative Example 1 is a typical single-layer display device. It includes an anode, a transparent conductive layer, a hole injection layer, an electron blocking layer, an independent light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode, which are stacked sequentially.

[0206] The thickness of each film layer corresponding to the light-emitting area in the display device of Comparative Example 1 is shown in Table 1-1 below. Table 1-1

[0207] In Comparative Example 1 above, the red luminescent layer in the red luminescent region includes a red host material and a red phosphorescent guest material, with the red phosphorescent guest material accounting for 5% of the mass; the green luminescent layer in the green luminescent region includes a green host material and a green phosphorescent guest material, with the green phosphorescent guest material accounting for 5% of the mass; and the blue luminescent layer in the blue luminescent region includes a blue fluorescent host material and a fluorescent guest material (emission peak wavelength of 400 nm), with the fluorescent guest material accounting for 1% of the mass.

[0208] Embodiment 1 illustrates the display device involved in this application. Referring to FIG7, it includes a red light-emitting region a, a green light-emitting region b, and a blue light-emitting region c arranged sequentially along the second direction Y. It includes an anode 2, a transparent conductive layer 3112, a hole injection layer 3110, a first hole transport layer 3111, a first auxiliary light-emitting layer 312, a first light-emitting layer 310, a semiconductor layer, a second light-emitting layer 320, a second hole blocking layer 324, a second electron transport layer 3211, an electron injection layer 3210, and a cathode 4, which are arranged sequentially along the first direction X.

[0209] It should be noted that, continuing to refer to Figure 7, the semiconductor layer includes a first hole-blocking layer 313, a first electron transport layer 314, a first charge-generating layer 330, a second charge-generating layer 331, a second hole transport layer 322, and a second auxiliary light-emitting layer 323, sequentially disposed along the first direction X. Since the thickness parameters of each film layer in the semiconductor layer do not affect the calculation of the mathematical relationships involved in the display device of this application, the thicknesses of the above-mentioned film layers will not be elaborated upon in the table below for ease of reading and understanding.

[0210] Furthermore, the thickness of the aforementioned film layer can be determined according to different needs in actual production.

[0211] The thickness of each film layer corresponding to each light-emitting region in the display device of Example 1 is shown in Table 1-2 below. Table 1-2

[0212] In the above embodiment 1, the red emitting layer (i.e., the first red emitting layer and the second red emitting layer) in the red emitting region includes a red host material and a red phosphorescent guest material, and the mass percentage of the red phosphorescent guest material is 2%; the green emitting layer (i.e., the first green emitting layer and the second green emitting layer) in the green emitting region includes a green phosphorescent host material and a green Ir (iridium) phosphorescent guest material, and the mass percentage of the green phosphorescent guest material is 1%; the blue emitting layer (i.e., the first blue emitting layer and the second blue emitting layer) in the blue emitting region includes a blue fluorescent host material and a fluorescent guest material (emission peak wavelength is 400 nm), and the mass percentage of the fluorescent guest material is 1%.

[0213] In both Comparative Example 1 and Example 1, the P-type doping ratio of the hole injection layer was 3%. The cathode layer 4 was made of a magnesium-silver alloy, with a magnesium to silver mass ratio of 1:9.

[0214] The comparison results of various parameters of the devices in Comparative Example 1 and Example 1 are shown in Table 1-3 below. Table 1-3

[0215] As can be seen from Tables 1-3 above, after the first light-emitting layer 310 and the second light-emitting layer 320 in the display device of Embodiment 1 are connected in series, and the distance between the first light-emitting layer 310 and the anode 2 (i.e., the sum of the thickness L1 of the first auxiliary layer and the thickness C1 of the first auxiliary light-emitting layer) and the distance between the second light-emitting layer 320 and the cathode 4 (i.e., the thickness L2 of the second auxiliary layer) satisfy a specific mathematical relationship, compared with Comparative Example 1, under similar coordinates and brightness conditions, the efficiency and lifespan of the display device of Embodiment 1 are improved by several times.

[0216] Verification Example 2: Includes Comparative Example 1 and Example 2.

[0217] The specific settings for Comparative Example 1 are as described above. The structure of the display device in Example 2 is the same as that in Example 1, and can be referred to above, so it will not be repeated here.

[0218] The thickness of each film layer corresponding to each light-emitting region in the display device of Example 2 is shown in Table 2-1 below. Table 2-1

[0219] Compared to Example 1, in Example 2, the host and guest materials of the red and blue luminescent layers are the same, and the mass ratio of the luminescent materials is also consistent. However, in Example 2, the green luminescent layer in the green luminescent region is replaced with a luminescent layer with TADF-sensitized fluorescence properties.

[0220] Specifically, the green luminescent layers in Example 2 are all multi-layered structures. Preferably, the green luminescent layer has a two-layer structure. The host material of the first layer is a hole-type host material, and the guest material is an iridium-based phosphorescent guest material, with the mass percentage of the green phosphorescent material being 1.2%. The thickness of the first layer is set to 5 nm.

[0221] The second layer is a ternary TADF-sensitized luminescence system consisting of a hole-based host material, an electronic host material with TADF properties, and a boron-containing fluorescent guest material, with the three materials having a mass ratio of 60%, 39%, and 1%, respectively. The thickness of the second layer is set to 30 nm.

[0222] Similar to Comparative Example 1 and Example 1, the P-type doping ratio of the hole injection layer in Example 2 is 3%. The cathode layer is made of a magnesium-silver alloy, and the mass ratio of magnesium to silver in the magnesium-silver alloy is 1:9.

[0223] The comparison results of various parameters of the devices in Comparative Example 1 and Example 2 are shown in Table 2-2 below. Table 2-2

[0224] As shown in Table 2-2 above, the display device of Embodiment 2 connects the first light-emitting layer 310 and the second light-emitting layer 320 in series, and the first and second light-emitting layers adopt a TADF system. Applying the mathematical relationship between the distance between the first light-emitting layer 310 and the anode 0 (i.e., the sum of the thickness L1 of the first auxiliary layer and the thickness C1 of the first auxiliary light-emitting layer) and the distance between the second light-emitting layer 320 and the cathode 4 (i.e., the thickness L2 of the second auxiliary layer) as defined in this application, compared with Comparative Example 1, under similar coordinates and brightness conditions, the efficiency and lifespan of the display device of Embodiment 2 are also improved several times. Therefore, the display device of this application is applicable to the TADF system and can greatly improve the performance of the display device.

[0225] Verification Example 3: Comparative Example 2 and Example 1.

[0226] The specific settings for Example 1 are as described above, and will not be repeated here.

[0227] The structure of the display device in Comparative Example 2 is the same as the film layer structure of the display device in Example 1, and will not be described in detail here.

[0228] The thickness of each film layer corresponding to each light-emitting region in the display device of Comparative Example 2 is shown in Table 3-1 below. Table 3-1

[0229] The selection of host and guest materials for the red, green, and blue luminescent layers in Comparative Example 2, as well as the mass ratio of each luminescent material, are the same as in Example 1. Further details are omitted here. Also, as with Comparative Example 2 and Example 1, the P-type doping ratio of the hole injection layer in Comparative Example 2 is 3%. The cathode layer is made of a magnesium-silver alloy, with a magnesium to silver mass ratio of 1:9.

[0230] By comparing Tables 1-2 and 3-1, it can be seen that Comparative Example 2 increases the distance between the second light-emitting layer and the cathode compared to Example 1.

[0231] Specifically, in Embodiment 1, referring to Figure 7 and Tables 1-2, the distance between the second light-emitting layer 320 and the cathode 4 (i.e., the thickness L2 of the second auxiliary layer) is: the thickness of the second hole blocking layer 324 (5nm) + the thickness of the second electron transport layer 3211 (35nm) + the thickness of the electron injection layer 3210 (1nm) = 41nm;

[0232] In Comparative Example 2, referring to Table 3-1, the distance between the second light-emitting layer and the cathode is: the thickness of the second hole blocking layer (5nm) + the thickness of the second electron transport layer (45nm) + the thickness of the electron injection layer (1nm) = 51nm.

[0233] It should be noted that in Comparative Example 2, while increasing the thickness of the second electron transport layer, the thickness of the second hole transport layer needs to be reduced. Furthermore, the increase and reduction in thickness must be proportional. In this embodiment, if the thickness of the second electron transport layer increases by 10 nm, then the thickness of the second hole transport layer needs to be reduced by 10 nm.

[0234] The comparison results of various parameters of the devices in Comparative Example 2 and Example 1 are shown in Table 3-2 below. Table 3-2

[0235] As can be seen from Table 3-2 above, although the distance L2 between the second light-emitting layer and the cathode is increased, the distance between the first light-emitting layer and the anode and the distance between the second light-emitting layer and the cathode in Comparative Example 2 satisfy the same mathematical relationship as the corresponding two distance parameters in Example 1.

[0236] However, since L2 is inversely proportional to μ (the formula for calculating μ is given above), the larger L2 is, the smaller μ is. In Comparative Example 2, continuing to refer to Table 3-2 above, the μ values ​​in the green and blue emitting regions are 6.81 and 6.98, respectively, neither of which falls within the range of μ > 7 as defined in this application.

[0237] Therefore, compared to Example 1, the efficiency of Comparative Example 2 is significantly reduced, resulting in a substantial increase in voltage at the same brightness, which affects the performance of the display device and also significantly reduces its lifespan.

[0238] Verification Example 4: Comparative Example 3 and Example 1.

[0239] The specific settings for Example 1 are as described above, and will not be repeated here.

[0240] The structure of the display device in Comparative Example 3 is the same as the film layer structure of the display device in Example 1, and will not be described in detail here.

[0241] The thickness of each film layer corresponding to each light-emitting region in the display device of Comparative Example 3 is shown in Table 4-1 below. Table 4-1

[0242] The selection of host and guest materials for the red, green, and blue luminescent layers in Comparative Example 3, as well as the mass ratio of each luminescent material, are the same as in Example 1. Further details are omitted here. Also, as in Example 1, the P-type doping ratio of the hole injection layer in Comparative Example 2 is 3%. The cathode layer is made of a magnesium-silver alloy, with a magnesium to silver mass ratio of 1:9.

[0243] By comparing Tables 1-2 and 4-1, it can be seen that Comparative Example 3 increases the distance between the first light-emitting layer and the anode compared to Example 1.

[0244] Specifically, take the film layer in the red luminescent region as an example.

[0245] In Embodiment 1, referring to Figure 7 and Tables 1-2, the distance between the first light-emitting layer 310 and the anode 2 (i.e., the sum of the thickness L1 of the first auxiliary layer and the thickness C1 of the first auxiliary light-emitting layer) = the thickness of the transparent conductive layer 3112 (8nm) + the thickness of the hole injection layer 3110 (10nm) + the thickness of the first hole transport layer 3111 (15nm) + the thickness of the first auxiliary light-emitting layer 312 (28nm) = 61nm.

[0246] In Comparative Example 3, referring to Table 4-1, the distance between the first light-emitting layer and the anode = the thickness of the transparent conductive layer (8nm) + the thickness of the hole injection layer (10nm) + the thickness of the first hole transport layer (30nm) + the thickness of the first auxiliary light-emitting layer (28nm) = 76nm.

[0247] It should be noted that in Comparative Example 3, while increasing the thickness of the first hole transport layer, the thickness of the second hole transport layer needs to be reduced. Furthermore, the increase and reduction in thickness must be the same. In this embodiment, if the thickness of the first hole transport layer increases by 15 nm, then the thickness of the second hole transport layer needs to be reduced by 15 nm.

[0248] The comparison results of various parameters of the devices in Comparative Example 3 and Example 1 are shown in Table 4-2 below. Table 4-2

[0249] As shown in Table 4-2 above, in order to improve the lifespan of the display device, the distance between the first light-emitting layer and the anode in the red light-emitting area of ​​the display device in Comparative Example 3 was increased (which can be understood as increasing the thickness of the auxiliary layer L2).

[0250] However, Comparative Example 3 fails to satisfy the specific mathematical relationship between the distance L2 from the first light-emitting layer to the anode and the distance L1 from the second light-emitting layer to the cathode as required in this application. Specifically, The two do not match Mathematical formulas.

[0251] Therefore, continuing to refer to Table 4-2 above, compared with Example 1, Comparative Example 3 shows a significant decrease in the efficiency of the display device, and the voltage also increases relatively for the same brightness.

[0252] Verification Example 5: Comparative Example 4 and Example 1.

[0253] The specific settings for Example 1 are as described above, and will not be repeated here.

[0254] The structure of the display device in Comparative Example 4 is the same as the film layer structure of the display device in Example 1, and will not be described in detail here.

[0255] The thickness of each film layer corresponding to each light-emitting region in the display device of Comparative Example 4 is shown in Table 5-1 below. Table 5-1

[0256] The selection of host and guest materials for the red, green, and blue luminescent layers in Comparative Example 4, as well as the mass ratio of each luminescent material, are the same as in Example 1. Further details are omitted here. Also, as in Example 1, the P-type doping ratio of the hole injection layer in Comparative Example 2 is 3%. The cathode layer is made of a magnesium-silver alloy, with a magnesium to silver mass ratio of 1:9.

[0257] By comparing Tables 1-2 and 5-1, it can be seen that Comparative Example 4 reduces the distance between the second light-emitting layer and the cathode compared to Example 1.

[0258] In Example 1, referring to Figure 7 and Table 1-2, the distance between the second light-emitting layer 320 and the cathode 4 (i.e. the thickness L2 of the second auxiliary layer) is: the thickness of the second hole blocking layer 324 (5nm) + the thickness of the second electron transport layer 3211 (35nm) + the thickness of the electron injection layer 3210 (1nm) = 41nm;

[0259] In Comparative Example 4, the distance between the second light-emitting layer and the cathode is: the thickness of the second hole blocking layer (5nm) + the thickness of the second electron transport layer (25nm) + the thickness of the electron injection layer (1nm) = 31nm.

[0260] It should be noted that in Comparative Example 4, while reducing the thickness of the second electron transport layer, the thickness of the second hole transport layer needs to be increased. Furthermore, the reduction in thickness must be proportional to the increase in thickness. In this embodiment, if the thickness of the second electron transport layer is reduced by 10 nm, then the thickness of the second hole transport layer needs to be increased by 10 nm.

[0261] The comparison results of various parameters of the devices in Comparative Example 4 and Example 1 are shown in Table 5-2 below. Table 5-2

[0262] As shown in Table 5-2 above, in order to reduce the voltage and efficiency of the display device, the display device in Comparative Example 4 reduced the distance L2 between the second light-emitting layer and the cathode to satisfy the specific mathematical relationship between the distance between the first light-emitting layer and the anode and the distance between the second light-emitting layer and the cathode.

[0263] However, since L2 is inversely proportional to μ (the formula for calculating μ is given above), the smaller L2 is, the larger μ is. In Comparative Example 4, continuing to refer to Table 5-2 above, the μ values ​​in the red and blue emitting regions are 10.06 and 10.02, respectively, neither of which conforms to the numerical range of μ < 10 defined in this application. This results in a significant decrease in the lifespan of the display device in Comparative Example 4 compared to Example 1.

[0264] Verification Example 6: Comparative Example 5 and Example 2.

[0265] The specific settings for Example 2 are as described above, and will not be repeated here.

[0266] The structure of the display device in Comparative Example 5 is the same as the film layer structure of the display device in Example 2, and will not be described in detail here.

[0267] The thickness of each film layer corresponding to each light-emitting region in the display device of Comparative Example 5 is shown in Table 6-1 below. Table 6-1

[0268] The selection of host and guest materials for the red, green, and blue luminescent layers in Comparative Example 5, as well as the mass ratio of each luminescent material, are the same as in Example 2. Further details are omitted here. Also, as in Example 2, the P-type doping ratio of the hole injection layer in Comparative Example 5 is 3%. The cathode layer is made of a magnesium-silver alloy, with a magnesium to silver mass ratio of 1:9.

[0269] By comparing Table 2-1 and Table 6-1, it can be seen that Comparative Example 5 increased the distance between the first light-emitting layer and the anode compared to Example 2.

[0270] Specifically, take the film layer in the red luminescent region as an example.

[0271] In Embodiment 2, referring to Figure 7 and Table 2-1, the distance between the first light-emitting layer 310 and the anode 2 (i.e., the sum of the thickness L1 of the first auxiliary layer and the thickness C1 of the first auxiliary light-emitting layer) = the thickness of the transparent conductive layer 3112 (8nm) + the thickness of the hole injection layer 3110 (10nm) + the thickness of the first hole transport layer 3111 (15nm) + the thickness of the first auxiliary light-emitting layer 312 (34nm) = 67nm.

[0272] In Comparative Example 5, the distance between the first light-emitting layer and the anode is equal to the thickness of the transparent conductive layer (8nm) + the thickness of the hole injection layer (10nm) + the thickness of the first hole transport layer (25nm) + the thickness of the first auxiliary light-emitting layer (39nm) = 82nm.

[0273] It should be noted that in Comparative Example 5, while increasing the thickness of the first hole transport layer, the thickness of the second hole transport layer needs to be reduced. Furthermore, the increase and reduction in thickness must be the same. In this embodiment, if the thickness of the first hole transport layer increases by 10 nm, then the thickness of the second hole transport layer needs to be reduced by 10 nm.

[0274] Furthermore, Comparative Example 5 increased the thickness of the first auxiliary light-emitting film layer in the red and green light-emitting regions compared to Example 2.

[0275] Specifically, take the first auxiliary light-emitting layer in the red light-emitting area as an example.

[0276] In Example 2, the thickness C1 of the first auxiliary light-emitting layer 312 is 34 nm. In Comparative Example 5, the thickness C1 of the first auxiliary light-emitting layer is 39 nm.

[0277] It should be noted that while increasing the thickness of the first auxiliary light-emitting layer, the thickness of the second auxiliary light-emitting layer needs to be decreased. Furthermore, the increase and decrease in thickness must be proportional. In this embodiment, if the thickness of the first auxiliary light-emitting layer increases by 5 nm, then the thickness of the second auxiliary light-emitting layer needs to be decreased by 5 nm.

[0278] The comparison results of various parameters of the devices in Comparative Example 5 and Example 2 are shown in Table 6-2 below. Table 6-2

[0279] As shown in Table 6-2 above, in order to improve the lifespan of the display device, the distance between the first light-emitting layer and the anode in the red light-emitting area of ​​the display device in Comparative Example 6 was increased (which can be understood as increasing the thickness of the auxiliary layer L2).

[0280] However, Comparative Example 6 fails to satisfy the specific mathematical relationship between the distance L2 from the first light-emitting layer to the anode and the distance L1 from the second light-emitting layer to the cathode as required in this application. Specifically, The two do not match Mathematical formulas.

[0281] Therefore, continuing to refer to Table 6-2 above, compared with Example 1, Comparative Example 3 shows a significant decrease in the efficiency of the display device, and the voltage also increases relatively for the same brightness.

[0282] Based on the above verification examples one to six, this application limits the distance between the light-emitting layer and the anode in the first light-emitting unit layer and the distance between the light-emitting layer and the cathode in the second light-emitting unit layer, so that the two satisfy a specific mathematical relationship, thereby maximizing the display device's performance in terms of efficiency, voltage, and lifespan.

[0283] This application also provides a display device that uses the display device of any of the above embodiments.

[0284] Display devices include, but are not limited to, small and medium-sized electronic devices such as tablet computers, smartphones, wireless devices, head-mounted displays, car navigation units, cameras, central information displays (CIDs) provided in vehicles, watch-type electronic devices or other wearable devices, personal digital assistants (PDAs), portable multimedia players (PMPs), and game consoles, as well as medium and large-sized electronic devices such as televisions, external billboards, monitors, home appliances containing display screens, personal computers, and laptop computers. The electronic devices described above may represent simple examples of applications for display devices, and therefore those skilled in the art will recognize that other electronic devices may also be used without departing from the spirit and scope of this disclosure.

[0285] The terms "first," "second," and similar terms used in this application and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. "A plurality" or "several" means two or more. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more associated listed items.

Claims

1. A display device, characterized in that, include: An anode, a functional layer, and a cathode are sequentially arranged along a first direction; The functional layer includes several light-emitting unit layers containing light-emitting layers and auxiliary layers, wherein the first light-emitting unit layer is disposed near the anode, and the second light-emitting unit layer is disposed near the cathode; wherein... The auxiliary layer located in the first light-emitting unit layer is a first auxiliary layer and the light-emitting layer is a first light-emitting layer. The first auxiliary layer and the first light-emitting layer are stacked sequentially on the anode along the first direction. The auxiliary layer located in the second light-emitting unit layer is a second auxiliary layer and the light-emitting layer is a second light-emitting layer. The second auxiliary layer and the second light-emitting layer are stacked sequentially on the cathode along a direction opposite to the first direction. The thickness of the first light-emitting layer is H1, and the thickness of the first auxiliary layer is L1; The thickness of the second light-emitting layer is H2, and the thickness of the second auxiliary layer is L2; ​​L1 and L2 satisfy the following conditions; L1+L2>H1+H2, Wherein, λ is the peak wavelength of the emission spectrum of the first or second emitting layer.

2. The display device according to claim 1, characterized in that, The functional layer includes a red light-emitting area, a green light-emitting area, and a blue light-emitting area; The first light-emitting layer includes a first red light-emitting layer, a first green light-emitting layer, and a first blue light-emitting layer arranged sequentially along the second direction; The second light-emitting layer includes a second red light-emitting layer, a second green light-emitting layer, and a second blue light-emitting layer arranged sequentially along the second direction; wherein, The first red emitting layer and the second red emitting layer are both located in the red emitting area, the first green emitting layer and the second green emitting layer are both located in the green emitting area, and the first blue emitting layer and the second blue emitting layer are both located in the blue emitting area.

3. The display device according to claim 2, characterized in that, The light-emitting unit layer further includes auxiliary light-emitting layers corresponding to the number of light-emitting layers, wherein... The auxiliary light-emitting layer located within the first light-emitting unit layer is a first auxiliary light-emitting layer. The first auxiliary light-emitting layer is located between the first light-emitting layer and the first auxiliary layer. The thickness of the first auxiliary light-emitting layer is C1, and L1 and L2 satisfy:

4. The display device according to claim 3, characterized in that, The auxiliary light-emitting layer is configured as a single-layer structure; or The auxiliary light-emitting layer is configured as a multi-layer structure.

5. The display device according to claim 4, characterized in that, The first auxiliary light-emitting layer includes a first sub-auxiliary light-emitting layer, a second sub-auxiliary light-emitting layer, and a third sub-auxiliary light-emitting layer; wherein The first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer each use one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer individually, and the auxiliary light-emitting layers used by the first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer are different; and / or The first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer share at least one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer; and / or The first red light-emitting layer, the first blue light-emitting layer, and the first green light-emitting layer share at least one of the first sub-auxiliary light-emitting layer, the second sub-auxiliary light-emitting layer, and the third sub-auxiliary light-emitting layer between each pair.

6. The display device according to claim 5, characterized in that, The thickness of the first red emitting layer is R1, the thickness of the second red emitting layer is R2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the red emitting region is E1. L1 and L2 satisfy: and / or The thickness of the first blue emitting layer is B1, the thickness of the second blue emitting layer is B2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the blue emitting region is E2. L1 and L2 satisfy the following: and / or The thickness of the first green emitting layer is G1, the thickness of the second green emitting layer is G2, and the sum of the thicknesses of the first sub-auxiliary emitting layer, the second sub-auxiliary emitting layer, and the third sub-auxiliary emitting layer located in the green emitting region is E3. L1 and L2 satisfy the following:

7. The display device according to claim 6, characterized in that, The auxiliary light-emitting layer includes at least one hole-transporting material.

8. The display device according to claim 7, characterized in that, The relationship between the light-emitting layer and the auxiliary light-emitting layer satisfies: in, This represents the lowest triplet energy of the hole transport material in the auxiliary light-emitting layer. This represents the lowest triplet energy of the luminescent material in the luminescent layer.

9. The display device according to claim 8, characterized in that, The difference between the lowest triplet energy of the hole transport material in the auxiliary light-emitting layer and the lowest triplet energy of the light-emitting material in the light-emitting layer is greater than 0.1 eV.

10. The display device according to claim 9, characterized in that, The hole-transporting material of the auxiliary light-emitting layer satisfies the following molecular condition: -5.4 eV < HOMO1 < 5.9 eV HOMO1 represents the highest occupied molecular orbital energy level of the material molecule.

11. The display device according to claim 7, characterized in that, The auxiliary light-emitting layer further comprises at least one light-emitting material, and the light-emitting material contains boron or at least one metal element.

12. The display device according to claim 11, characterized in that, When the auxiliary light-emitting layer contains a light-emitting material, the thickness of the first red light-emitting layer is R1+E1, and L1 and L2 satisfy:

13. The display device according to claim 11, characterized in that, When the auxiliary light-emitting layer contains a light-emitting material, the thickness of the first blue light-emitting layer is B1+E2, and L1 and L2 satisfy:

14. The display device according to claim 11, characterized in that, When the auxiliary light-emitting layer contains a light-emitting material, the thickness of the first green light-emitting layer is G1+E3, and L1 and L2 satisfy:

15. The display device according to any one of claims 3-14, characterized in that, The first auxiliary layer includes a hole injection layer, and the second auxiliary layer includes an electron injection layer; Several of the light-emitting unit layers share the electron injection layer and the hole injection layer.

16. The display device according to claim 15, characterized in that, The light-emitting unit layer includes a hole transport layer and an electron transport layer, with the light-emitting layer located between the hole transport layer and the electron transport layer; wherein... The hole transport layer includes a first hole transport layer and a second hole transport layer, and the electron transport layer includes a first electron transport layer and a second electron transport layer; wherein... The first hole transport layer is located within the first auxiliary layer, and the second electron transport layer is located within the second auxiliary layer.

17. The display device according to claim 16, characterized in that, The auxiliary layer further includes a hole blocking layer, which is located between the light-emitting layer and the electron transport layer; The hole blocking layer includes a first hole blocking layer and a second hole blocking layer; the first hole blocking layer is located between the first light-emitting layer and the first electron transport layer, and the second hole blocking layer is located between the second light-emitting layer and the second electron transport layer.

18. The display device according to claim 15, characterized in that, The functional layer further includes a charge generation layer, which is located between the light-emitting unit layers, and the charge generation layer is a single-layer structure or a multi-layer structure.

19. The display device according to any one of claims 3-14, characterized in that, The first light-emitting layer comprises a first host material and a first object material, and the second light-emitting layer comprises a second host material and a second object material, wherein... The first guest material includes at least one of fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials; and / or The second guest material includes at least one of fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials.

20. The display device according to claim 19, characterized in that, When the materials contained in the first light-emitting layer and the second light-emitting layer are different, the difference in the emission spectral peak value of the light-emitting materials in the first guest material and the second guest material is less than 5 nm.

21. The display device according to claim 19, characterized in that, Both the first host material and the second host material are electronic host materials, and the electronic host material is selected from triazine materials or thermally activated delayed fluorescence materials with electron transport characteristics.

22. The display device according to any one of claims 3-14, characterized in that, A microcavity is formed between the cathode and the anode, the microcavity including a red sub-microcavity located in the red emitting region, a green sub-microcavity located in the green emitting region, and a blue microcavity located in the blue emitting region; The number of film layers located between the anode and cathode, corresponding to any color sub-microcavity, is d, and the optical thickness of d film layers is L, where L satisfies: Where, n i Let r be the refractive index of the i-th film layer among the d film layers. i Let λ be the thickness of the i-th film layer, k be a natural number, and λ be the target spectral peak wavelength. The phase shift caused by the reflection of the target light in the anode layer.

23. The display device according to claim 22, characterized in that, The target spectral peak wavelength range within the red luminescent region is 615 nm to 640 nm; and / or The target spectral peak wavelength range within the green luminescent region is 515nm to 540nm; and / or The target spectral peak wavelength range within the blue luminescent region is 450 nm to 470 nm.

24. A display device, characterized in that, include: An anode, a functional layer, and a cathode are sequentially arranged along a first direction; The functional layer includes a light-emitting unit layer containing an independent light-emitting layer; The thickness of the independent light-emitting layer is H3, and the thickness from the independent light-emitting layer to the cathode is L3, where L3 satisfies: Where λ is the peak wavelength of the emission spectrum of the independent emitting layer.

25. A display device, characterized in that, Includes the display device as described in any one of claims 1 to 24.

Images