Display device and display panel

Abstract

This disclosure provides a display device and a display panel. The display panel includes: an anode; a cathode, disposed opposite to the anode, wherein one of the anode and the cathode is a reflective electrode and the other is a transmissive electrode; and a first light-emitting unit disposed between the anode and the cathode, the first light-emitting unit including a first hole transport layer, a first electron transport layer, and a first light-emitting structure, the first hole transport layer being disposed opposite to the first electron transport layer, and the first light-emitting structure being disposed between the first hole transport layer and the first electron transport layer; the first light-emitting structure including a red light-emitting layer and a first blue light-emitting layer. This disclosure can improve the luminous intensity.

Description

Technical Field

[0001] This disclosure relates to the field of display technology, and more particularly to a display device and a display panel. Background Technology

[0002] OLED (Organic Light Emitting Diode) displays have become a highly competitive and promising type of display device due to their advantages such as all-solid-state structure, self-illumination, fast response speed, high brightness, wide viewing angle, and flexible display capabilities. However, current OLED displays suffer from relatively weak luminous intensity. Summary of the Invention

[0003] The purpose of this disclosure is to provide a display device and display panel that can improve luminous intensity.

[0004] According to one aspect of this disclosure, a display panel is provided, comprising:

[0005] anode;

[0006] A cathode is disposed opposite to the anode, wherein one of the anode and the cathode is a reflective electrode and the other is a transmission electrode;

[0007] A first light-emitting unit is disposed between the anode and the cathode. The first light-emitting unit includes a first hole transport layer, a first electron transport layer, and a first light-emitting structure. The first hole transport layer and the first electron transport layer are disposed opposite to each other. The first light-emitting structure is disposed between the first hole transport layer and the first electron transport layer. The first light-emitting structure includes a red light-emitting layer and a first blue light-emitting layer.

[0008] Furthermore, the first light-emitting structure also includes:

[0009] A charge carrier transport layer is disposed on the side of the red light-emitting layer facing the first blue light-emitting layer, and the first blue light-emitting layer is disposed on the side of the charge carrier transport layer facing away from the red light-emitting layer.

[0010] Furthermore, the thickness of the carrier transport layer is 2nm-30nm.

[0011] Furthermore, the red light-emitting layer is disposed on the side of the first blue light-emitting layer facing the anode, and the hole transport rate of the carrier transport layer is greater than the electron transport rate; or, the red light-emitting layer is disposed on the side of the first blue light-emitting layer away from the anode, and the hole transport rate of the carrier transport layer is less than the electron transport rate.

[0012] Furthermore, the red luminescent layer comprises a host material and a guest material, wherein the guest material comprises a fluorescent material.

[0013] Furthermore, the guest material includes one or more of the following: redene, Nile red, ethidium bromide, ruthenium chloride hexahydrate of terpyridine, and coumarin compounds.

[0014] Furthermore, the mass ratio of the guest material to the host material in the red luminescent layer is 2%-10%.

[0015] Furthermore, the red light-emitting layer is disposed on the side of the first blue light-emitting layer facing the reflective electrode;

[0016] The distance between the red emitting layer and the reflective electrode is 190nm-210nm, and / or the distance between the first blue emitting layer and the reflective electrode is 192nm-240nm.

[0017] Furthermore, the red light-emitting layer is disposed on the side of the first blue light-emitting layer that faces away from the reflective electrode;

[0018] The distance between the red emitting layer and the reflective electrode is 350nm-370nm, and / or the distance between the first blue emitting layer and the reflective electrode is 320nm-368nm.

[0019] Furthermore, the display panel also includes:

[0020] A first charge generation layer is disposed on one side of the first light-emitting unit in the thickness direction of the display panel;

[0021] The second light-emitting unit is disposed between the anode and the cathode, and is located on the side of the first charge generation layer opposite to the first light-emitting unit. The second light-emitting unit is capable of emitting green light.

[0022] Furthermore, the second light-emitting unit is disposed on the side of the first light-emitting unit facing the reflective electrode.

[0023] Furthermore, the second light-emitting unit includes a green light-emitting layer, and the distance between the green light-emitting layer and the reflective electrode is 135nm-155nm.

[0024] Furthermore, the display panel also includes:

[0025] The second charge generation layer is disposed on the side of the second light-emitting unit that is opposite to the first charge generation layer;

[0026] The third light-emitting unit is disposed between the anode and the cathode, and is located on the side of the second charge generation layer opposite to the second light-emitting unit. The third light-emitting unit is capable of emitting blue light.

[0027] Furthermore, the second light-emitting unit is disposed on the side of the first light-emitting unit facing the reflective electrode, and the third light-emitting unit is disposed on the side of the second light-emitting unit facing the reflective electrode.

[0028] Furthermore, the second light-emitting unit includes a green light-emitting layer, the distance between the green light-emitting layer and the reflective electrode being 135nm-155nm; and / or

[0029] The third light-emitting unit includes a second blue light-emitting layer, and the distance between the second blue light-emitting layer and the reflective electrode is 100nm-120nm.

[0030] According to one aspect of this disclosure, a display device is provided, including the aforementioned display panel.

[0031] The display device and display panel disclosed herein have a first light-emitting structure disposed between a first hole transport layer and a first electron transport layer. The first light-emitting structure includes a red light-emitting layer and a first blue light-emitting layer. Thus, the red light-emitting layer and the first blue light-emitting layer are disposed between the first hole transport layer and the first electron transport layer, that is, the red light-emitting layer and the first blue light-emitting layer are located in one light-emitting unit. This allows the positions of the red light-emitting layer and the first blue light-emitting layer of this disclosure to be adjusted synchronously. At the same time, since the maximum gain front cavity length of red light is close to that of blue light, this disclosure can synchronously adjust the luminous intensity of red light and the luminous intensity of blue light to improve the luminous intensity and luminous efficiency of the display panel, and is also conducive to achieving a high color gamut. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a display panel in related technologies.

[0033] Figure 2 This is another schematic diagram of a display panel in related technologies.

[0034] Figure 3 This is a schematic diagram showing the relationship between the front cavity length and intensity of light.

[0035] Figure 4 This is a schematic diagram of a display panel according to an embodiment of the present disclosure.

[0036] Figure 5 This is a schematic diagram of carrier transport in a display panel according to an embodiment of the present disclosure.

[0037] Figure 6 This is a schematic diagram of the light-emitting principle of the display panel according to an embodiment of the present disclosure.

[0038] Figure 7 The images show the emission spectra of the comparative and example samples collected at a current density of 30 J.

[0039] Figure 8 This is a graph showing the change in CIE(x,y) of the device as a function of the device brightness for the scale and embodiment.

[0040] Figure 9 This is a graph showing the device efficiency versus the current density of the device in the comparative and embodiment examples.

[0041] Explanation of reference numerals in the attached figures: 1. Anode; 3. Third light-emitting unit; 301. Third hole injection layer; 302. Third hole transport layer; 303. Third electron blocking layer; 304. Second blue light-emitting layer; 305. Third hole blocking layer; 306. Third electron transport layer; 4. Second light-emitting unit; 401. Second hole injection layer; 402. Second hole transport layer; 403. Second electron blocking layer; 404. Green light-emitting layer; 405. Second hole blocking layer; 406. Second electron transport layer; 5. Second charge generation layer; 6. ... 7. Charge generation layer; 701. First light-emitting unit; 702. First hole injection layer; 703. First hole transport layer; 704. First electron blocking layer; 705. Red light-emitting layer; 706. Charge carrier transport layer; 707. First blue light-emitting layer; 708. First hole blocking layer; 709. First electron transport layer; 7000. First electron injection layer; 8. Cathode; 9. Charge carrier functional layer; 10. First light-emitting layer; 11. Second light-emitting layer; 1101. First sub-light-emitting layer; 1102. Second sub-light-emitting layer; 12. Third light-emitting layer. Detailed Implementation

[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0043] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. Unless otherwise defined, the technical or scientific terms used in this disclosure should be understood in their ordinary sense by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure and the claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “a” or “one,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. “A plurality” or “several” indicates two or more. Unless otherwise stated, the terms “front,” “rear,” “lower,” and / or “upper,” and similar terms are for ease of description only and are not limited to a location or spatial orientation. The terms “comprising,” “including,” and similar terms mean that the elements or objects preceding “comprising,” encompass the elements or objects listed following “comprising,” and their equivalents, and do not exclude other elements or objects. The terms “connected,” “linked,” and similar terms are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect. The singular forms “a,” “the,” and “the” used in this disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. 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 of the associated listed items.

[0044] Among related technologies, white OLED devices include 1-Stack WOLED, Tandem WOLED, and 3-Stack WOLED. Figure 1 as well as Figure 2 A schematic diagram of a 3Stack WOLED structure is shown, which includes an anode 1, a first light-emitting layer 10, a second light-emitting layer 11, a third light-emitting layer 12, a carrier functional layer 9, and a cathode 8. The anode 1 is a reflective electrode, and the cathode 8 is a transmissive electrode; the anode 1 and cathode 8 form a microcavity. The carrier functional layer 9 may include an electron transport layer, a hole transport layer, etc. The first light-emitting layer 10 and the third light-emitting layer 12 can be blue light-emitting layers. Figure 1 In this context, the second light-emitting layer 11 is a yellow light-emitting layer; Figure 2In this design, the second light-emitting layer 11 includes a first sub-light-emitting layer 1101 and a second sub-light-emitting layer 1102. The first sub-light-emitting layer 1101 can be a green light-emitting layer, and the second sub-light-emitting layer 1102 can be a red light-emitting layer. Based on the intrinsic properties of excitons, the stability of the blue light-emitting layer using phosphorescent materials is poor; therefore, fluorescent materials are used for the blue light-emitting layer. Simultaneously, to ensure the brightness and efficiency of the white light device, both the green and red light-emitting layers use phosphorescent materials. The excitons in the red and green light-emitting layers using phosphorescent materials are triplet excitons. Triplet excitons have a long lifetime and long diffusion distance. When the operating current of the device differs or the device ages, the device is prone to significant color shift. The luminescence of the green light-emitting layer is the main contributor to the efficiency and brightness of the white light device. Figure 2 In the structure shown, the emission of light from the red light-emitting layer requires the transfer of some energy from the green light-emitting layer to the red light-emitting layer. This conversion process results in a significant energy loss for the device, and the emission of light from the red light-emitting layer contributes little to the device efficiency, causing the device efficiency to fall short of the ideal level.

[0045] Furthermore, the distance between the emitting layer and the reflecting electrode (the front cavity length of the microcavity) periodically affects the wavelength gain amplitude. This disclosure simplifies the blue light spectrum to single-wavelength emission at 460 nm, the green light spectrum to single-wavelength emission at 530 nm, and the red light spectrum to single-wavelength emission at 620 nm. For example... Figure 3 As shown in part a, the intensity of blue light with a wavelength of 460nm is highest at a front cavity length of (110nm ± n*115nm); Figure 3 As shown in part b, the green light with a wavelength of 530nm has the highest intensity at a front cavity length of (145nm ± n*130nm); Figure 3 As shown in part c, red light with a wavelength of 620nm has its highest intensity at a front cavity length of (40nm ± n * 160nm), where n is a positive integer greater than or equal to 1. For each color of light, the front cavity length corresponding to the highest intensity point can be called the maximum gain front cavity length. Therefore, the maximum gain front cavity length for blue light can be 110nm, 225nm, or 340nm; for green light, it can be 145nm, 275nm, or 405nm; and for red light, it can be 200nm, 360nm, or 520nm. Figure 2 In the structure shown, the red and blue light-emitting layers are located in almost the same position, which makes it impossible to adjust the intensity of red and blue light emission simultaneously. Red and blue light cannot be emitted at the same frequency, and the target requirements of high efficiency and high color gamut cannot be achieved at the same time.

[0046] like Figure 4As shown, this disclosure provides a display panel. The display panel may include an anode 1, a cathode 8, and a first light-emitting unit 7, wherein:

[0047] The cathode 8 is disposed opposite to the anode 1. One of the anode 1 and the cathode 8 is a reflective electrode, and the other is a transmissive electrode. The first light-emitting unit 7 is disposed between the anode 1 and the cathode 8. The first light-emitting unit 7 includes a first hole transport layer 702, a first electron transport layer 708, and a first light-emitting structure. The first hole transport layer 702 and the first electron transport layer 708 are disposed opposite to each other, and the first light-emitting structure is disposed between the first hole transport layer 702 and the first electron transport layer 708. The first light-emitting structure includes a red light-emitting layer 704 and a first blue light-emitting layer 706.

[0048] The display panel of this embodiment has a first light-emitting structure disposed between a first hole transport layer 702 and a first electron transport layer 708. The first light-emitting structure includes a red light-emitting layer 704 and a first blue light-emitting layer 706. Thus, the red light-emitting layer 704 and the first blue light-emitting layer 706 are disposed between the first hole transport layer 702 and the first electron transport layer 708, that is, the red light-emitting layer 704 and the first blue light-emitting layer 706 are located in one light-emitting unit. This allows the positions of the red light-emitting layer 704 and the first blue light-emitting layer 706 to be adjusted synchronously. At the same time, since the maximum gain front cavity length of red light is close to that of blue light, this embodiment can synchronously adjust the luminous intensity of red light and the luminous intensity of blue light to improve the luminous intensity and luminous efficiency of the display panel, and is also conducive to achieving a high color gamut.

[0049] The following is a detailed description of each part of the display panel according to the embodiments of this disclosure:

[0050] like Figure 4 As shown, the anode 1 and cathode 8 are disposed opposite to each other. The anode 1 can be a reflective electrode, and the cathode 8 can be a transmissive electrode, thereby forming a microcavity between the anode 1 and the cathode 8 to improve the light emission intensity of the light-emitting unit. In other embodiments of this disclosure, the anode 1 can be a transmissive electrode, and the cathode 8 can be a reflective electrode. The transmissive electrode can be a semi-transmissive / semi-reflective electrode, but this disclosure does not impose any particular limitation on this. For example, the anode 1 is a reflective electrode and can be composed of a stacked Ag metal layer and an ITO layer, the thickness of which can be 1000 angstroms, and the thickness of which can be 100-150 angstroms; the cathode 8 is a transmissive electrode and is a Mg / Ag electrode, the thickness of which can be 100-150 angstroms.

[0051] The display panel disclosed herein may further include a driving backplane. The anode 1 may be disposed on the driving backplane. The driving backplane may include a substrate and a driving circuit layer. The substrate may be a rigid substrate. The rigid substrate may be a glass substrate or a PMMA (Polymethyl methacrylate) substrate, etc. Alternatively, the substrate may be a flexible substrate. The flexible substrate may be a PET (Polyethylene terephthalate) substrate, a PEN (Polyethylene naphthalate dimethyl methacrylate) substrate, or a PI (Polyimide) substrate. The driving circuit layer may be disposed on the substrate. The driving circuit layer may include multiple driving transistors. The driving transistor may be a thin-film transistor, but the embodiments disclosed herein are not limited to this. The thin-film transistor may be a top-gate type thin-film transistor; of course, the thin-film transistor may also be a bottom-gate type thin-film transistor. Taking a top-gate type thin-film transistor as an example, the driving circuit layer may include an active layer, a gate insulating layer, a gate electrode, an interlayer insulating layer, a source electrode, and a drain electrode. The active layer can be disposed on the substrate. The gate insulating layer can be disposed on the substrate and cover the active layer. The gate electrode can be disposed on the side of the gate insulating layer away from the substrate. The interlayer insulating layer can be disposed on the gate insulating layer and cover the gate electrode. The source and drain electrodes can be disposed on the interlayer insulating layer and connected to the active layer via vias passing through the interlayer insulating layer and the gate insulating layer. Furthermore, the driving backplane can also include a planarization layer. The planarization layer can be disposed on the surface of the driving circuit layer opposite to the substrate and cover the source and drain electrodes of the driving transistor. The anode 1 can be disposed on the planarization layer and connected to the source or drain electrode of the driving transistor via a via passing through the planarization layer.

[0052] The first light-emitting unit 7 can be disposed on the side of the anode 1 facing away from the substrate. The first light-emitting unit 7 includes a first hole transport layer 702, a first electron transport layer 708, and a first light-emitting structure. The first hole transport layer 702 is disposed on the side of the anode 1 facing away from the substrate, the first light-emitting structure is disposed on the side of the first hole transport layer 702 facing away from the anode 1, and the first electron transport layer 708 is disposed on the side of the first light-emitting structure facing away from the anode 1. The first light-emitting unit 7 may also include a first hole injection layer 701, a first electron blocking layer 703, a first electron injection layer 709, and a first hole blocking layer 707. The first hole injection layer 701 can be disposed between the first hole transport layer 702 and the anode 1, the first electron blocking layer 703 can be disposed between the first hole transport layer 702 and the first light-emitting structure, the first electron injection layer 709 can be disposed between the first electron transport layer 708 and the cathode 8, and the first hole blocking layer 707 can be disposed between the first electron transport layer 708 and the first light-emitting structure.

[0053] The first light-emitting structure includes a red light-emitting layer 704 and a first blue light-emitting layer 706. The red light-emitting layer 704 can be disposed on the side of the first blue light-emitting layer 706 facing the anode 1, or it can be disposed on the side of the first blue light-emitting layer 706 facing away from the anode 1. Taking the red light-emitting layer 704 disposed on the side of the first blue light-emitting layer 706 facing the anode 1 and the anode 1 being a reflective electrode as an example, the distance between the red light-emitting layer 704 and the reflective electrode can be 190nm-210nm, such as 190nm, 195nm, 200nm, 205nm, 210nm, etc.; the distance between the first blue light-emitting layer 706 and the reflective electrode can be 192nm-240nm, such as 192nm, 210nm, 220nm, 225nm, 240nm, etc. Taking the example of a red light-emitting layer 704 disposed on the side of the first blue light-emitting layer 706 facing away from the anode 1 and the anode 1 being a reflective electrode, the distance between the red light-emitting layer 704 and the reflective electrode can be 350nm-370nm, such as 350nm, 355nm, 360nm, 365nm, 370nm, etc.; the distance between the first blue light-emitting layer 706 and the reflective electrode can be 320nm-368nm, such as 320nm, 330nm, 340nm, 350nm, 360nm, 368nm, etc.

[0054] The aforementioned red luminescent layer 704 may include a host material and a guest material. The guest material of the red luminescent layer 704 may include a fluorescent material. Specifically, the fluorescent material may include one or more of the following: rubber, nilored, ethidium bromide, ruthenium chloride hexahydrate (CAS No.: 50525-27-4), and coumarin compounds, but this disclosure does not specifically limit this. The host material of the red luminescent layer 704 may be a metal chelate compound, a bis(styrene) derivative, an aromatic amine derivative, a dibenzofuran derivative, or other types of materials, but this disclosure is not limited thereto. In other embodiments of this disclosure, the red luminescent layer 704 may include a dual host material, comprising an N-type and a P-type host material. Furthermore, the mass ratio of the guest material to the host material in the red luminescent layer 704 may be 2%-10%, for example, 2%, 5%, 7%, 8%, 10%, etc.

[0055] The first blue emitting layer 706 described above may be doped with fluorescent materials. The fluorescent materials doped in the first blue emitting layer 706 may include 4,4′-bis(9-carbazole)biphenyl (CPB), and may also include dihydroethidium, etc. The first blue emitting layer 706 may also contain dual host materials, namely, N-type and P-type host materials. The P-type material is selected from one or more of triarylamine derivatives, carbazole derivatives, fused carbazole derivatives, carbazole triphenylene derivatives, and dibenzofuran and benzofuran-dibenzofuran derivatives; the N-type material is selected from one or more of triazine derivatives, pyrimidine derivatives, diazaphosphacyclopentadiene derivatives, indolocarbazole derivatives substituted with electron-deficient heteroaromatic groups, and indocarbazole derivatives substituted with electron-deficient heteroaromatic groups.

[0056] From the perspective of device stability, compared to the phosphorescent triplet excitons with millisecond-level lifetimes, the fluorescent singlet excitons in the red emitting layer 704 and the first blue emitting layer 706 have very short nanosecond-picosecond-level lifetimes and short exciton diffusion distances. This makes the recombination emitting centers of the red emitting layer 704 and the first blue emitting layer 706 very stable under high and low current densities. As a result, the device CIE(x,y) remains stable under high and low currents and before and after device aging.

[0057] The first light-emitting structure of this embodiment may further include a carrier transport layer 705. This carrier transport layer 705 may be disposed on the surface of the red light-emitting layer 704 facing the first blue light-emitting layer 706, and the first blue light-emitting layer 706 may be disposed on the surface of the carrier transport layer 705 facing away from the red light-emitting layer 704. Taking the red light-emitting layer 704 disposed on the side of the first blue light-emitting layer 706 facing the anode 1 as an example, the hole transport rate of this carrier transport layer 705 is greater than the electron transport rate, meaning the carrier transport layer 705 mainly functions as a "hole transport layer." Taking the red light-emitting layer 704 disposed on the side of the first blue light-emitting layer 706 facing away from the anode 1 as an example, the hole transport rate of this carrier transport layer 705 is less than the electron transport rate, meaning the carrier transport layer 705 mainly functions as an "electron transport layer." The thickness of the carrier transport layer 705 can be 2nm-30nm. Furthermore, the thickness of the carrier transport layer 705 can be 2nm-20nm, such as 2nm, 9nm, 15nm, 18nm, 20nm, etc.

[0058] Taking the red light-emitting layer 704 disposed on the side of the first blue light-emitting layer 706 facing the anode 1 as an example, the concentration curve of holes transmitted in the display panel is as follows: Figure 5 As shown by curve Y2, along the direction from the carrier transport layer 705 to the first blue light-emitting layer 706, the concentration of holes gradually decreases; the concentration curve of electrons transported in the display panel is as follows: Figure 5 As shown by curve Y1, the electron concentration gradually decreases along the direction from the first blue emitting layer 706 to the carrier transport layer 705. Figure 5 It can be seen that the hole concentration in the carrier transport layer 705 is greater than the electron concentration, indicating that the hole transport rate in the carrier transport layer 705 is greater than the electron transport rate; at the same time, the hole concentration decreases rapidly in the first blue emitting layer 706, indicating that the recombination process of holes and electrons mainly occurs in the first blue emitting layer 706. Figure 6 As shown, holes and electrons recombine in the first blue emitting layer 706, generating singlet (S1) excitons and triplet (T1) excitons. The first blue emitting layer 706 is doped with fluorescent material. Triplet (T1) excitons can only dissipate heat energy non-radiatively, while singlet (S1) excitons can transition to the ground state to emit light radiatively. Furthermore, in... Figure 6 In the process, some of the energy generated in the first blue luminescent layer 706 can be transferred to the red luminescent layer 704, so that singlet (S1) excitons and triplet (T1) excitons are formed in the red luminescent layer 704. The singlet (S1) excitons can transition to the ground state to emit light.

[0059] The display panel of this embodiment may further include a first charge generation layer 6 and a second light-emitting unit 4. The first charge generation layer 6 is disposed on one side of the first light-emitting unit 7 in the thickness direction of the display panel. For example, the first charge generation layer 6 may be disposed on the side of the first hole injection layer 701 facing away from the first light-emitting structure, that is, the first charge generation layer 6 is disposed on the side of the first light-emitting unit 7 facing the anode 1. The second light-emitting unit 4 is disposed between the anode 1 and the cathode 8, and is located on the side of the first charge generation layer 6 facing away from the first light-emitting unit 7, that is, the second light-emitting unit 4 may be disposed on the side of the first light-emitting unit 7 facing the anode 1. The second light-emitting unit 4 may include a second electron transport layer 406, a second light-emitting structure, a second hole transport layer 402, and a second hole injection layer 401. The second electron transport layer 406 can be disposed on the side of the first charge generation layer 6 facing away from the first hole injection layer 701. The second light-emitting structure can be disposed on the side of the second electron transport layer 406 facing away from the first charge generation layer 6. The second hole transport layer 402 can be disposed on the side of the second light-emitting structure facing away from the first charge generation layer 6. The second hole injection layer 401 can be disposed on the side of the second hole transport layer 402 facing away from the first charge generation layer 6. Of course, the second light-emitting unit 4 can include a second electron blocking layer 403 and a second hole blocking layer 405. The second electron blocking layer 403 can be disposed between the second hole transport layer 402 and the second light-emitting structure. The second hole blocking layer 405 can be disposed between the second electron transport layer 406 and the second light-emitting structure. The second light-emitting unit 4 can emit green light; that is, the second light-emitting structure can include a green light-emitting layer 404. Of course, the second light-emitting unit 4 can also emit light of other colors. The electrons required for the second light-emitting unit 4 to emit light can be injected from the first charge generation layer 6. Taking the second light-emitting unit 4 located on the side of the first light-emitting unit 7 facing the reflective electrode as an example, the distance between the green light-emitting layer 404 and the reflective electrode can be 135nm-155nm, such as 135nm, 138nm, 140nm, 145nm, 150nm, 155nm, etc. The green light-emitting layer 404 can be doped with phosphorescent materials, such as tris(2-phenylpyridine)iridium, Ir(ppy)3 (CAS No.: 94928-86-6), etc.

[0060] The display panel disclosed herein may further include a second charge generation layer 5 and a third light-emitting unit 3. The second charge generation layer 5 may be disposed on the side of the second light-emitting unit 4 facing away from the first charge generation layer 6. Specifically, the second charge generation layer 5 may be disposed on the side of the second hole injection layer 401 facing away from the first charge generation layer 6. The third light-emitting unit 3 may be disposed between the anode 1 and the cathode 8, and located on the side of the second charge generation layer 5 facing away from the second light-emitting unit 4. The third light-emitting unit 3 may include a third electron transport layer 306, a third light-emitting structure, a third hole transport layer 302, and a third hole injection layer 301. The third electron transport layer 306 may be disposed on the side of the second charge generation layer 5 facing away from the second hole injection layer 401, the third light-emitting structure may be disposed on the side of the third electron transport layer 306 facing away from the second charge generation layer 5, the third hole transport layer 302 may be disposed on the side of the third light-emitting structure facing away from the second charge generation layer 5, and the third hole injection layer 301 may be disposed on the side of the third hole transport layer 302 facing away from the second charge generation layer 5. Of course, the third light-emitting unit 3 may include a third electron blocking layer 303 and a third hole blocking layer 305. The third electron blocking layer 303 may be disposed between the third hole transport layer 302 and the third light-emitting structure. The third hole blocking layer 305 may be disposed between the third electron transport layer 306 and the third light-emitting structure. The third light-emitting unit 3 can emit blue light, that is, the third light-emitting structure may include a second blue light-emitting layer 304. Of course, the third light-emitting unit 3 may also emit light of other colors. The electrons required for the third light-emitting unit 3 to emit light can be injected by the second charge generation layer 5. Taking the third light-emitting unit 3 disposed on the side of the second light-emitting unit 4 facing the reflective electrode as an example, the distance between the second blue light-emitting layer 304 and the reflective electrode is 100nm-120nm, such as 100nm, 105nm, 108nm, 110nm, 115nm, 120nm, etc. The second blue emitting layer 304 can be doped with a fluorescent material, such as 4,4′-bis(9-carbazole)biphenyl (CPB), or it can be dihydroethidium, etc. The fluorescent material doped in the second blue emitting layer 304 can be the same as the fluorescent material doped in the first blue emitting layer 706, or it can be different. The main material of the second blue emitting layer 304 can be the same as the main material of the first blue emitting layer 706, or it can be different.

[0061] The materials for the electron transport layer described above may include benzimidazole derivatives, oxadiazole derivatives, quinoxaline derivatives, or other electron transport materials, and this disclosure does not impose any specific limitations on them. The materials for the electron injection layer described above may include inorganic materials such as alkali metal sulfides and alkali metal halides, or may include complexes of alkali metals and organic compounds. The materials for the hole transport layer described above may include carbazole polymers, carbazole-linked triarylamine compounds, or other types of compounds. The materials for the hole injection layer described above may include benzidine derivatives, starburst-like arylamine compounds, phthalocyanine derivatives, or other materials.

[0062] Furthermore, the display panel of this disclosure embodiment may include a plurality of pixel units arranged in an array. Each pixel unit may include the aforementioned anode 1, cathode 8, first light-emitting unit 7, second light-emitting unit 4, and third light-emitting unit 3, i.e., the display panel is a white organic light-emitting diode (W-OLED) display panel. Each pixel unit may share a cathode 8, but this disclosure embodiment does not impose any special limitation on this. Each pixel unit may include its own anode 1, i.e., multiple pixel units do not share an anode 1. Further, the display panel may also include a color filter substrate disposed on the light-emitting side of the pixel unit to adjust the emitted light color of the pixel unit. Specifically, the color filter substrate may include a plurality of color resist blocks, which are disposed one-to-one on the light-emitting side of the plurality of pixel units. The plurality of color resist blocks may include red color resist blocks, blue color resist blocks, green color resist blocks, etc.

[0063] This disclosure also provides a display device. The display device may include the display panel described in any of the above embodiments. The display device may be a mobile phone, tablet computer, television, etc. Since the display panel included in the display device of this disclosure is the same as the display panel in the embodiments of the above-described display panels, and has the same beneficial effects, this disclosure will not repeat it here.

[0064] Performance testing

[0065] This disclosure Figure 2 The structure shown is used as a comparative example. Figure 4 The structure shown is an example, and performance tests were performed on the comparative example and the example. Each film layer was formed by thermal evaporation, and the vacuum degree of the cavity during thermal evaporation was 3×10⁻⁶. -6 Torr, evaporation rate maintained at The film thickness was measured using an XP-2 profilometer. To ensure the accuracy of the experimental results, the device was encapsulated. The encapsulation method used in the experiment was to cover the area to be encapsulated with a glass cover plate, then apply UV-curable adhesive around it, and irradiate it under a 265nm UV lamp for 20-25 minutes. During the above evaporation process, except for the cathode which used a metal cathode mask with an evaporation rate of 0.3nm / s, all other layers used open masks with an evaporation rate of 0.1nm / s; the light-emitting area of ​​the device was 2mm × 2mm.

[0066] Figure 7 The emission spectra of the comparative example and the embodiment are shown at a current density of 30J. It can be seen from the spectrum that, compared with the comparative example (line L2), the emission of red and green light in the embodiment (line L1) is significantly enhanced. That is to say, the intensity of red light and green light can be increased simultaneously.

[0067] Figure 8 The curves showing the change of CIE(x,y) of the device with the device brightness are shown. It can be seen that although the change in CIEx (line L6) of the embodiment is not much different from the change in CIEx (line L5) of the comparative example, the change in CIEy (line L4) of the embodiment is significantly smaller than the change in CIEy (line L3) of the comparative example, indicating that the color point stability of the embodiment is significantly improved compared with the white light device of the comparative example.

[0068] Figure 9 The curves showing the change in device efficiency with the device's current density are shown. It can be seen that the white light efficiency of the embodiment (line L7) is higher than that of the comparative example (line L8).

[0069] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above with reference to a preferred embodiment, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A display panel, characterized in that, include: anode; A cathode is disposed opposite to the anode, wherein one of the anode and the cathode is a reflective electrode and the other is a transmissive electrode, and a microcavity is formed between the anode and the cathode; A first light-emitting unit is disposed between the anode and the cathode. The first light-emitting unit includes a first hole transport layer, a first electron transport layer and a first light-emitting structure. The first hole transport layer and the first electron transport layer are disposed opposite to each other, and the first light-emitting structure is disposed between the first hole transport layer and the first electron transport layer. The first light-emitting structure includes a red light-emitting layer and a first blue light-emitting layer; The first light-emitting structure further includes: A charge carrier transport layer is disposed on the side of the red light-emitting layer facing the first blue light-emitting layer, and the first blue light-emitting layer is disposed on the side of the charge carrier transport layer facing away from the red light-emitting layer; the charge carrier transport layer is disposed between the red light-emitting layer and the first blue light-emitting layer, and the charge carrier transport layer is in contact with both the red light-emitting layer and the first blue light-emitting layer; The display panel also includes: A first charge generation layer is disposed on one side of the first light-emitting unit in the thickness direction of the display panel; The second light-emitting unit is disposed between the anode and the cathode, and is located on the side of the first charge generation layer opposite to the first light-emitting unit. The second light-emitting unit is capable of emitting green light. The first charge generation layer is located between the first light-emitting unit and the second light-emitting unit. The second charge generation layer is disposed on the side of the second light-emitting unit that is opposite to the first charge generation layer; The third light-emitting unit is disposed between the anode and the cathode, and is located on the side of the second charge generation layer opposite to the second light-emitting unit. The third light-emitting unit is capable of emitting blue light, and the second charge generation layer is located between the second light-emitting unit and the third light-emitting unit.

2. The display panel according to claim 1, characterized in that, The thickness of the carrier transport layer is 2nm-30nm.

3. The display panel according to claim 1, characterized in that, The red light-emitting layer is disposed on the side of the first blue light-emitting layer facing the anode, and the hole transport rate of the carrier transport layer is greater than the electron transport rate; or, the red light-emitting layer is disposed on the side of the first blue light-emitting layer away from the anode, and the hole transport rate of the carrier transport layer is less than the electron transport rate.

4. The display panel according to claim 1, characterized in that, The red luminescent layer comprises a host material and a guest material, wherein the guest material includes a fluorescent material.

5. The display panel according to claim 4, characterized in that, The guest material includes one or more of the following: redene, Nile red, ethidium bromide, ruthenium chloride hexahydrate of terpyridine, and coumarin compounds.

6. The display panel according to claim 4, characterized in that, The mass ratio of the guest material to the host material in the red luminescent layer is 2%-10%.

7. The display panel according to claim 1, characterized in that, The red light-emitting layer is disposed on the side of the first blue light-emitting layer facing the reflective electrode; The distance between the red emitting layer and the reflective electrode is 190nm-210nm, and / or the distance between the first blue emitting layer and the reflective electrode is 192nm-240nm.

8. The display panel according to claim 1, characterized in that, The red light-emitting layer is disposed on the side of the first blue light-emitting layer that faces away from the reflective electrode; The distance between the red emitting layer and the reflective electrode is 350nm-370nm, and / or the distance between the first blue emitting layer and the reflective electrode is 320nm-368nm.

9. The display panel according to claim 1, characterized in that, The second light-emitting unit is located on the side of the first light-emitting unit facing the reflective electrode.

10. The display panel according to claim 9, characterized in that, The second light-emitting unit includes a green light-emitting layer, and the distance between the green light-emitting layer and the reflective electrode is 135nm-155nm.

11. The display panel according to claim 1, characterized in that, The second light-emitting unit is located on the side of the first light-emitting unit facing the reflective electrode, and the third light-emitting unit is located on the side of the second light-emitting unit facing the reflective electrode.

12. The display panel according to claim 11, characterized in that, The second light-emitting unit includes a green light-emitting layer, the distance between the green light-emitting layer and the reflective electrode being 135nm-155nm; and / or The third light-emitting unit includes a second blue light-emitting layer, and the distance between the second blue light-emitting layer and the reflective electrode is 100nm-120nm.

13. A display device, characterized in that, Includes the display panel as described in any one of claims 1-12.

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