A display device

Abstract

The present invention discloses a display device, comprising: a substrate and a light-emitting electrochemical cell device located on the substrate; the light-emitting electrochemical cell device comprises: a first electrode, a second electrode and a light-emitting layer located between the first electrode and the second electrode. The light-emitting layer adopts an ion-conducting delayed fluorescent material. The ion-conducting delayed fluorescent material is used as the light-emitting layer, which has both high exciton utilization and high luminous efficiency of the delayed fluorescent material and ion-conducting characteristics. The conduction of anions and cations in the ion-conducting delayed fluorescent material is conducive to the injection of carriers, so that the turn-on voltage is reduced.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a display device. Background Art

[0002] The light-emitting electrochemical cell (LEC) is developed based on the organic light-emitting diode (OLED). It has a sandwich structure similar to that of OLED devices, but its structure is simpler than that of OLED devices. It has broad application prospects in the field of low-cost and large-area displays.

[0003] At present, the luminescent materials used in LEC mainly include ionic transition metal complexes or polymers. Among them, polymer luminescent materials are difficult to prepare and purify, and the luminescent efficiency is relatively low; while ionic transition metal complex materials have high luminescent efficiency, but contain heavy metal elements and have high material costs, which restricts the industrialization of light-emitting devices. Summary of the invention

[0004] In some embodiments of the present invention, the light-emitting layer in the light-emitting electrochemical cell device adopts an ion-conducting delayed fluorescent material. The ion-conducting delayed fluorescent material has both high exciton utilization and high luminescence efficiency of delayed fluorescent materials and ion-conducting properties, which is beneficial to the injection of carriers and reduces the turn-on voltage.

[0005] In some embodiments of the present invention, the molecular structure of the ion-conducting delayed fluorescent material is [n1Cz·A][n2PF6 - ]; wherein Cz represents a carbazole group, n1 represents the number of carbazole groups, A represents an electron-withdrawing group, PF6 - represents hexafluorophosphate ions, and n2 represents the number of hexafluorophosphate ions. By changing the number of anions and cations in the molecule, the ion conduction capacity of the molecular system is regulated, thereby optimizing the ion transmission capacity of the LEC device.

[0006] In some embodiments of the present invention, the electron withdrawing group is any one of a thioxanthone group, a dibenzothiophene-s,s-dioxide group, a triazine group, a thioxanthene tetraoxide group, an oxadiazole group, and a triphenylboron group.

[0007] In some embodiments of the present invention, the light-emitting layer includes: a red light-emitting layer, a green light-emitting layer, a blue light-emitting layer and a white light-emitting layer.

[0008] In some embodiments of the present invention, the ion-conducting delayed fluorescent material used in the red light-emitting layer is [n1Cz·Anthraquinone][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0009] In some embodiments of the present invention, the ion-conducting delayed fluorescent material used in the red light-emitting layer is [n1Cz·Diboraanthracene][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0010] In some embodiments of the present invention, the ion-conducting delayed fluorescent material used in the blue light-emitting layer is [n1Cz·Benzoyl][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0011] In some embodiments of the present invention, the material of the white light-emitting layer is a mixture of the materials used in the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer.

[0012] In some embodiments of the present invention, the white light-emitting layer includes a stacked red sub-light-emitting layer, a green sub-light-emitting layer and a blue sub-light-emitting layer; the red sub-light-emitting layer uses an ion-conducting delayed fluorescent material that emits red light, the green sub-light-emitting layer uses an ion-conducting delayed fluorescent material that emits green light, and the blue sub-light-emitting layer uses an ion-conducting delayed fluorescent material that emits blue light.

[0013] In some embodiments of the present invention, the light-emitting electrochemical cell device further includes a hole injection layer for improving the hole injection capability of the device, increasing the stability of the device, and thus extending the service life.

[0014] In some embodiments of the present invention, the light-emitting electrochemical cell device further comprises a hole transport layer for improving hole transport capability. The hole transport layer also has the function of blocking electrons, which can balance the transmission of intercepted current carriers and help improve device efficiency.

[0015] In some embodiments of the present invention, the hole injection layer, the hole transport layer and the light emitting layer are made by a solution method. The solution method can effectively control the production cost and has a high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings introduced below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a cross-sectional structure of a display device provided by an embodiment of the present invention;

[0018] Figure 2 One of the cross-sectional structural schematic diagrams of the light-emitting electrochemical cell device provided in an embodiment of the present invention;

[0019] Figure 3 The second schematic diagram of the cross-sectional structure of the light-emitting electrochemical cell device provided in an embodiment of the present invention;

[0020] Figure 4 The third schematic diagram of the cross-sectional structure of the light-emitting electrochemical cell device provided in an embodiment of the present invention;

[0021] Figure 5 The present invention provides a flowchart of a method for manufacturing a display device according to an embodiment of the present invention.

[0022] Among them, 11 is a substrate, 12 is a light-emitting electrochemical cell, 121 is a first electrode, 122 is a second electrode, 123 is a light-emitting layer, 124 is a hole injection layer, and 125 is a hole transport layer. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described below with reference to the accompanying drawings and examples. However, the exemplary embodiments can be implemented in various forms and should not be understood as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concepts of the exemplary embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in the present invention are all explained using the accompanying drawings as examples, but changes can be made as needed, and the changes made are all included in the scope of protection of the present invention. The drawings of the present invention are only used to illustrate the relative position relationship and do not represent the true proportions.

[0024] LEC is developed based on OLED and has a sandwich structure similar to OLED devices.

[0025] The light-emitting layer of LEC contains a large number of mobile anions and cations, and has ionic conductivity. Its luminescence mechanism utilizes the chemical doping effect of the luminescent material. When LEC is working, the anions and cations move to the positive and negative electrodes respectively, and finally form a pin junction, while the carriers diffuse from the positive and negative electrodes to the inside of the light-emitting layer and finally recombine to form excitons, which radiate light.

[0026] Compared with traditional OLED devices, LEC devices are insensitive to the work function of the electrode, and stable metals such as aluminum, gold, and silver can be used as the cathode of the device; LEC devices are insensitive to the thickness of the light-emitting layer, which simplifies the device preparation process; LEC devices have a simple structure and do not require an additional charge injection layer; LEC devices have a low turn-on voltage; LEC's luminescence behavior is independent of the direction of the electric field, and it emits light under both positive and negative bias voltages. Therefore, LEC has a broad application prospect in the field of low-cost, large-area displays.

[0027] Figure 1 A schematic cross-sectional structure diagram of a display device provided by an embodiment of the present invention.

[0028] Reference Figure 1 The display device includes a base substrate 11 and a light-emitting electrochemical cell device 12 located on the base substrate.

[0029] The base substrate 11 is generally located at the bottom of the display device, and is used to support and carry all components in the display device. The shape of the base substrate 11 is adapted to the shape of the display device. Currently, display devices used in fields such as televisions or mobile terminals are all rectangular, so the base substrate 11 can also be set to a rectangular shape; in addition, if the display device is used in special-shaped display devices such as smart watches, the base substrate can also be set to a circular shape or the like, which is not limited here.

[0030] The display device in the embodiment of the present invention can be a rigid display device or a flexible display device. The base substrate 11 of the rigid display device can be made of a rigid material such as glass, while the base substrate 11 of the flexible display device can be made of a flexible material such as polyimide (PI).

[0031] Before making quantum dot light-emitting diodes on the base substrate 11, it is also necessary to make a driving circuit on the base substrate. Usually, a thin film manufacturing process can be used to form a thin film transistor array on the base substrate 11 to form a driving circuit. After the driving circuit is electrically connected to the LEC device, the light emission of the LEC device can be controlled. In the embodiment of the present invention, the LEC device can be driven by a passive driving method or an active driving method.

[0032] The light-emitting electrochemical cell device 12 is located on the substrate 11. Each light-emitting electrochemical cell device 12 serves as a sub-pixel unit, and each light-emitting electrochemical cell device 12 has the same structure. After the LEC device is electrically connected to the driving circuit, the light emission control of the sub-pixel unit can be achieved by controlling the electrical signal of the driving circuit.

[0033] Figure 2 This is one of the schematic cross-sectional structure diagrams of the light-emitting electrochemical cell device provided in an embodiment of the present invention.

[0034] Reference Figure 2 The light-emitting electrochemical cell device includes a first electrode 121 and a second electrode 122 facing each other, and a light-emitting layer 123 sandwiched therebetween.

[0035] The first electrode 121 is located on the base substrate 11 and is electrically connected to the driving circuit on the base substrate 11 .

[0036] The first electrode 121 is usually used as an anode. The area of ​​each anode defines the light emitting area of ​​the LEC device, that is, the opening area of ​​the sub-pixel. The size of the anode can be determined according to the design and resolution of the display device, and is not limited here. The shape of the anode can usually be set to a rectangle. The material used for the anode is indium tin oxide (ITO) and the like.

[0037] The second electrode 122 is located on a side of the first electrode 121 away from the base substrate 11 .

[0038] The second electrode 122 is usually used as a cathode, which is disposed opposite to the bottom anode. When an electrical signal is applied, an electric field is generated between the cathode and the anode.

[0039] The cathode can usually be set on the whole surface, and there is no need to distinguish each sub-pixel and set it separately. The shape of the cathode is adapted to the shape of the substrate 11, and can usually be set to a rectangle. The size of the cathode is determined by the occupied area of ​​all LEC devices, and the cathode covers all LEC devices. The material used for the cathode is silver Ag, aluminum Al or copper Au, etc.

[0040] The light emitting layer 123 is located between the first electrode 121 and the second electrode 122 .

[0041] The pattern of the first electrode 121 on the base substrate 11 is usually a mutually discrete pattern. After the first electrode 121 is formed, a pixel defining layer is formed at the gap between the first electrodes 121 to define the position of the sub-pixel. Since different sub-pixel units may have different luminous colors, the luminous layer 123 is only located on the surface of the first electrode 121.

[0042] The light-emitting layer 123 in the embodiment of the present invention adopts an ion-conducting delayed fluorescent material. The delayed fluorescent material is a new type of fluorescent material, and its luminescence mechanism is different from the traditional first-generation fluorescent material (singlet radiative luminescence) and the second-generation phosphorescent material (triplet radiative luminescence). When the energy gap difference between the S1 state (the first singlet excited state) and the T1 state (the first triplet excited state) is very small (<0.1eV), the triplet exciton can effectively cross into the singlet state and complete the singlet radiative luminescence, that is, emit fluorescence. Due to the crossing effect of the triplet exciton, the exciton utilization rate of the delayed fluorescent material can reach 100%, thereby significantly improving the luminous efficiency of the luminescent material. In addition, the delayed fluorescent material is a pure organic material and does not contain precious metals, so the cost is low, and the preparation of low-cost and high-efficiency luminescent materials can be achieved.

[0043] The embodiment of the present invention introduces anion and cation groups on the basis of the traditional delayed fluorescent material and finally prepares an ion-conducting delayed fluorescent material. This material has both the high exciton utilization rate and high luminous efficiency of the delayed fluorescent material and the ion-conducting property, and can be used as a light-emitting layer in the LEC device. The conduction of anions and cations in the ion-conducting delayed fluorescent material is conducive to the injection of carriers, so that the turn-on voltage is reduced.

[0044] In the embodiment of the present invention, the molecular structure of the ion-conducting delayed fluorescent material is [n1Cz·A][n2PF6 - ]; wherein Cz represents a carbazole group, n1 represents the number of carbazole groups, A represents an electron-withdrawing group, PF6 - represents hexafluorophosphate ion, and n2 represents the number of hexafluorophosphate ions.

[0045] As a delayed fluorescent material, Cz·A has high exciton utilization and high luminescence efficiency. The carbazole group Cz is an electron-donating group, and A is an electron-withdrawing group, so that a covalent bond is formed between the two.

[0046] The electron withdrawing group A may be any one of a thioxanthone group, a dibenzothiophene-s,s-dioxide group, a triazine group, a thioxanthene tetraoxide group, an oxadiazole group, and a triphenylboron group.

[0047] In the embodiment of the present invention, anions and cations are introduced into the delayed fluorescent material, and the delayed fluorescent material is transformed into an ionic compound through a chemical reaction, which has ion conductivity and is used as a light-emitting layer of an LEC device.

[0048] In the above-mentioned general structure formula of the ion-conducting delayed fluorescent material, the carbazole group acts as an electron-donating group and an electron-withdrawing group to jointly regulate the band gap of the molecule. Where n1 represents the number of carbazole groups in the molecule. The change in the number of carbazole groups in the molecule can change the molecular band gap and its HOMO and LUMO energy levels. Therefore, the molecular properties can be regulated by changing the number of carbazole groups.

[0049] By changing the number of anions and cations in the molecule, the ion conduction ability of the molecular system can be regulated, thereby optimizing the ion transmission capacity of the LEC device.

[0050] In the embodiment of the present invention, the LEC device can be used to emit light of different colors. Accordingly, the LEC device is divided into a red LEC device, a green LEC device and a blue LEC device. Every three red, green and blue LEC devices constitute a pixel unit. By controlling the light emitting brightness of the red, green and blue LEC devices in each pixel unit, image display can be achieved.

[0051] The light-emitting layer in the red LEC device is a red light-emitting layer, the light-emitting layer in the green LEC device is a green light-emitting layer, and the light-emitting layer in the blue LEC device is a blue light-emitting layer. The light-emitting layers of different colors use different ion-conducting delayed fluorescent materials.

[0052] For example, the molecular structure of the ion-conducting delayed fluorescent material used in the red light-emitting layer is [n1Cz·Anthraquinone][n2PF6 - ], n1 can take different values ​​so that the molecule includes different numbers of carbazole groups, thereby making the number of anions and cations carried by the molecule different.

[0053] When n1=2, the ion-conducting delayed fluorescent material used for the red light-emitting conductor can be any of the following:

[0054]

[0055] When n1=4, the ion-conducting delayed fluorescent material used for the red light-emitting conductor can be any of the following:

[0056]

[0057] When n1=6, the ion-conducting delayed fluorescent material used for the red light-emitting conductor can be any of the following:

[0058]

[0059] In addition, n1 may also take other values. The embodiment of the present invention is only used to illustrate the materials used for the red light-emitting layer, and does not limit the specific value of n1, nor does it limit the red light-emitting layer to use other ion-conducting delayed fluorescent materials.

[0060] The molecular structure of the ion-conducting delayed fluorescent material used in the green light-emitting layer is [n1Cz·Diboraanthracene][n2PF6 - ], n1 can take different values ​​so that the molecule includes different numbers of carbazole groups, thereby making the number of anions and cations carried by the molecule different.

[0061] When n1=2, the ion-conducting delayed fluorescent material used for the green light-emitting conductor can be any of the following:

[0062]

[0063] When n1=4, the ion-conducting delayed fluorescent material used for the green light-emitting conductor can be any of the following:

[0064]

[0065] When n1=6, the ion-conducting delayed fluorescent material used for the green light-emitting conductor can be any of the following:

[0066]

[0067]

[0068] In addition, n1 may also take other values. The embodiment of the present invention is only used to illustrate the materials used in the green light-emitting layer, and does not limit the specific value of n1, nor does it limit the green light-emitting layer to use other ion-conducting delayed fluorescent materials.

[0069] The molecular structure of the ion-conducting delayed fluorescent material used in the blue light-emitting layer is [n1Cz·Benzoyl][n2PF6 - ], n1 can take different values ​​so that the molecule includes different numbers of carbazole groups, thereby making the number of anions and cations carried by the molecule different.

[0070] When n1=2, the ion-conducting delayed fluorescent material used for the blue light-emitting conductor can be any of the following:

[0071]

[0072] When n1=4, the ion-conducting delayed fluorescent material used for the blue light-emitting conductor can be any of the following:

[0073]

[0074] When n1=6, the ion-conducting delayed fluorescent material used for the blue light-emitting conductor can be any of the following:

[0075]

[0076] In addition, n1 may also take other values. The embodiment of the present invention is only used to illustrate the materials used for the blue light-emitting layer, and does not limit the specific value of n1, nor does it limit the blue light-emitting layer to use other ion-conducting delayed fluorescent materials.

[0077] In another embodiment of the present invention, the LEC device may also be a white LEC device. The output light of the white LEC device is white light, and full-color display can be achieved in combination with a color filter.

[0078] When a white LEC device is used in the display device, the light-emitting layer can be provided as a whole layer, and it is no longer necessary to provide each region where the first electrode 121 is located separately, thereby improving production efficiency.

[0079] The light-emitting layer in the white LEC device is a white light-emitting layer, which can be set as a single-layer structure or a stacked-layer structure.

[0080] The white light-emitting layer of the single-layer structure uses a mixture of the ion-conducting delayed fluorescent materials used in the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer.

[0081] The white light-emitting layer of the stacked structure is respectively provided with a red sub-light-emitting layer, a green sub-light-emitting layer and a blue sub-light-emitting layer from the bottom side to the top side, wherein the red sub-light-emitting layer can adopt the above-mentioned ion-conducting delayed fluorescent material emitting red light, the green sub-light-emitting layer can adopt the above-mentioned ion-conducting delayed fluorescent material emitting green light, and the blue sub-light-emitting layer can adopt the above-mentioned ion-conducting delayed fluorescent material emitting blue light.

[0082] The light-emitting layer in the embodiment of the present invention uses an ion-conducting delayed fluorescent material, which is usually an organic material and can be processed by a solution method, thereby improving the light-emitting efficiency and reducing the production cost.

[0083] Figure 3 The second schematic diagram of the cross-sectional structure of the light-emitting electrochemical cell device provided in an embodiment of the present invention.

[0084] Reference Figure 3 The light-emitting electrochemical cell device further includes a hole injection layer 124 .

[0085] The hole injection layer 124 is located on a side of the first electrode facing away from the substrate 11 .

[0086] The hole injection layer 124 may be disposed on the entire layer, or may be disposed only on the first electrode 121 .

[0087] The hole injection layer 124 is provided as a whole layer so as to provide holes for all LEC devices. The process of providing the hole injection layer 124 as a whole layer is also relatively simple.

[0088] However, only the holes injected into the first electrode 121 contribute to the light emission of the LEC device, so the hole injection layer 124 may be formed only on the first electrode 121 to save costs.

[0089] In the embodiment of the present invention, a hole injection layer 124 is disposed on the first electrode 121 , which can improve the hole injection capability of the device, increase the stability of the device, and thus prolong the service life.

[0090] The hole injection layer 124 is made of a polymer material and is manufactured by a solution method. For example, the hole injection layer 124 can be made of a material such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS).

[0091] Figure 4 The third schematic diagram of the cross-sectional structure of the light-emitting electrochemical cell device provided in an embodiment of the present invention.

[0092] Reference Figure 4 The light-emitting electrochemical cell device further includes a hole transport layer 125 .

[0093] The hole transport layer 125 is located on a side of the hole injection layer 124 away from the first electrode 121 .

[0094] The hole transport layer 125 may be provided as a whole layer, or may be provided only at a position corresponding to the first electrode 121 .

[0095] The hole transport layer 125 can improve the hole transport capability, which is beneficial for the carriers to be transported to the light emitting layer 123. At the same time, the hole transport layer 125 also has the function of blocking electrons, which can balance the transmission of carriers and is beneficial for improving the device efficiency.

[0096] The hole transport layer 125 is made of polymer material and is prepared by solution method. For example, the hole transport layer 125 can be made of polyvinyl carbazole (PVK), bis(4-phenyl)(4-butylphenyl)amine (TPD), poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB) and other materials.

[0097] In the embodiment of the present invention, the light-emitting layer and the functional layer in the LEC device can be manufactured by a solution method, which can effectively control the cost.

[0098] Figure 5The present invention provides a flowchart of a method for manufacturing a display device according to an embodiment of the present invention.

[0099] Reference Figure 5 , a method for manufacturing a display device, comprising:

[0100] S10, manufacturing a first electrode on a substrate;

[0101] S20, forming a hole injection layer on a side of the first electrode away from the substrate;

[0102] S30, forming a hole transport layer on a side of the hole injection layer away from the first electrode;

[0103] S40, forming a light-emitting layer on a side of the hole transport layer away from the hole injection layer;

[0104] S50, forming a second electrode on a side of the light-emitting layer away from the hole transport layer.

[0105] Among them, the hole injection layer, the hole transport layer and the light-emitting layer are all made by a solution method.

[0106] In the embodiment of the present invention, the LEC device is manufactured by a solution method, which includes an inkjet printing method, a spin coating method, a screen printing method or a roll-to-roll preparation process. The LEC device manufactured by the solution method can effectively control the production cost and has a high production efficiency.

[0107] Specifically, a pattern of a first electrode is formed on a base substrate on which a driving circuit is formed. The first electrode can be formed by an etching process, and the first electrode is made of indium tin oxide (ITO).

[0108] After the first electrode is prepared, the base substrate with the first electrode needs to be cleaned.

[0109] After cleaning the substrate with the first electrode, a hole injection layer is formed on the first electrode by a solution method. For example, the hole injection layer can be inkjet printed on the first electrode. The hole injection layer uses poly (3,4-ethylenedioxythiophene): poly (styrene sulfonic acid) (PEDOT:PSS) with a thickness of 10nm-40nm.

[0110] After forming the hole injection layer, the substrate is vacuum dried and baked, and then a hole transport layer is formed on the hole injection layer by a solution method. For example, the hole transport layer can be inkjet printed on the hole injection layer. The hole transport layer uses polybis(4-phenyl)(4-butylphenyl)amine (Poly-TPD) with a thickness of 10nm-40nm.

[0111] After forming the hole transport layer, the substrate is vacuum dried and baked, and then a light-emitting layer is formed on the hole transport layer by a solution method. The above-mentioned ion-conducting delayed fluorescent material is dissolved in a solvent to form a light-emitting ink, and then inkjet printing is used to form the light-emitting layer. The thickness of the light-emitting layer is 20nm-200nm.

[0112] The solvent used in the luminescent ink may be an organic solvent such as acetonitrile, chlorobenzene, dichlorobenzene, etc., which is not limited here.

[0113] In order to improve the ion conduction ability of the light-emitting layer, optimize the injection of carriers, and reduce the turn-on voltage, the embodiment of the present invention can add a certain amount of ionic liquid to the above-mentioned light-emitting ink and then inkjet print it to form a light-emitting layer. The added ionic liquid can be 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) and the like, which is not limited here. The doping ratio of the ionic liquid in the ion-conducting delayed fluorescent material ranges from 1% to 25%. According to different material systems, the optimal ratio is selected within this range, which is not limited here.

[0114] After the light-emitting layer is formed, the substrate is vacuum dried and baked, and then a second electrode is deposited on the light-emitting layer. The second electrode can be made of aluminum, silver, copper, etc., which is not limited here.

[0115] After the LEC device is prepared, the display device is packaged to complete the production of the display device.

[0116] According to the first invention concept, the light-emitting device of the display device in the embodiment of the present invention adopts a light-emitting electrochemical cell device. The LEC device is insensitive to the work function of the electrode, and stable metals such as aluminum, gold, and silver can be used as the cathode of the device; the LEC device is insensitive to the thickness of the light-emitting layer, which simplifies the device preparation process; the LEC device has a simple structure and does not require an additional charge injection layer; the LEC device has a low turn-on voltage; the light-emitting behavior of the LEC is independent of the direction of the electric field, and it emits light under both positive and negative bias voltages. Therefore, LEC has a broad application prospect in the field of low-cost and large-area displays.

[0117] According to the second invention concept, the light-emitting layer in the light-emitting electrochemical cell device adopts an ion-conducting delayed fluorescent material. The ion-conducting delayed fluorescent material has both high exciton utilization and high luminous efficiency of the delayed fluorescent material and ion-conducting characteristics. The conduction of anions and cations in the ion-conducting delayed fluorescent material is conducive to the injection of carriers, so that the turn-on voltage is reduced.

[0118] According to the third invention concept, the molecular structure of the ion-conducting delayed fluorescent material is [n1Cz·A][n2PF6 -]; wherein Cz represents a carbazole group, n1 represents the number of carbazole groups, and A represents an electron-withdrawing group. The electron-withdrawing group can be any one of a thioxanthone group, a dibenzothiophene-s,s-dioxide group, a triazine group, a thioxanthene tetraoxide group, an oxadiazole group, and a triphenylborane group. PF6 - represents hexafluorophosphate ions, and n2 represents the number of hexafluorophosphate ions. The carbazole group acts as an electron-donating group and an electron-withdrawing group to regulate the band gap of the molecule. By changing the number of anions and cations in the molecule, the ion conduction ability of the molecular system is regulated, thereby optimizing the ion transmission ability of the LEC device.

[0119] According to the fourth invention, the light-emitting layer can be divided into a red light-emitting layer, a green light-emitting layer, a blue light-emitting layer and a white light-emitting layer. The red light-emitting layer, the green light-emitting layer and the blue light-emitting layer can be used as sub-pixels to achieve full-color display. The white light-emitting layer can be used in conjunction with a color filter to achieve full-color display.

[0120] According to the fifth inventive concept, the white light-emitting layer can adopt a mixture of the ion-conducting delayed fluorescent materials adopted by the red light-emitting layer, the green light-emitting layer and the blue light-emitting layer; or the white light-emitting layer can include a red sub-light-emitting layer, a green sub-light-emitting layer and a blue sub-light-emitting layer of a stacked structure; wherein the red sub-light-emitting layer adopts an ion-conducting delayed fluorescent material that emits red light, the green sub-light-emitting layer adopts an ion-conducting delayed fluorescent material that emits green light, and the blue sub-light-emitting layer adopts an ion-conducting delayed fluorescent material that emits blue light.

[0121] According to the fifth invention, the ion-conducting delayed fluorescent material used in the red light-emitting layer is [n1Cz·Anthraquinone][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0122] According to the sixth invention, the ion-conducting delayed fluorescent material used in the red light-emitting layer is [n1Cz·Diboraanthracene][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0123] According to the seventh invention, the ion-conducting delayed fluorescent material used in the blue light-emitting layer is [n1Cz·Benzoyl][n2PF6 - ]; wherein n1 represents the number of carbazole groups, and n2 represents the number of hexafluorophosphate ions.

[0124] According to the eighth invention concept, the light-emitting electrochemical cell device further comprises a hole injection layer located on the side of the first electrode away from the substrate. The hole injection layer can enhance the hole injection capability of the device, increase the stability of the device, and extend the service life.

[0125] According to the ninth invention concept, the light-emitting electrochemical cell device also includes a hole transport layer located on the side of the hole injection layer away from the first electrode. The arrangement of the hole transport layer can improve the hole transport capacity and at the same time has the function of blocking electrons, which can balance the transmission of intercepted current carriers and is beneficial to improving the device efficiency.

[0126] According to the tenth invention concept, the hole injection layer, the hole transport layer and the light emitting layer are made by a solution method. The solution method can effectively control the production cost and has a high production efficiency.

[0127] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0128] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A display device, characterized in that: include: The substrate has supporting and bearing functions; A light-emitting electrochemical cell device is located on the substrate; The light-emitting electrochemical cell device comprises: A first electrode is located on the substrate; A second electrode is located on a side of the first electrode away from the substrate; A light-emitting layer is located between the first electrode and the second electrode; the light-emitting layer is made of ion-conducting delayed fluorescent material; The light-emitting layer includes: a red light-emitting layer, a green light-emitting layer, a blue light-emitting layer and a white light-emitting layer; The material of the red light-emitting layer is any one of the following: The material of the green light-emitting layer is any one of the following: The material of the blue light-emitting layer is any one of the following:

2. The display device according to claim 1, wherein: The light-emitting electrochemical cell device also includes: The hole injection layer is located on a side of the first electrode away from the substrate.

3. The display device according to claim 2, wherein: The light-emitting electrochemical cell device also includes: The hole transport layer is located on a side of the hole injection layer away from the first electrode.

4. The display device according to claim 3, characterized in that The hole injection layer, the hole transport layer and the light emitting layer are made by a solution method.

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