Fabrication methods and light-emitting devices

Abstract

This application discloses a method for fabricating a light-emitting device and the light-emitting device itself. The method for fabricating the light-emitting device includes the following steps: providing a substrate; forming a first film layer on the substrate, the first film layer being formed from a first solution including a first solvent; forming a barrier layer on the first film layer, the barrier layer being formed from a barrier solvent orthogonal to the first solvent; forming a second film layer on the barrier layer, the second film layer being formed from a second solution including a second solvent orthogonal to the barrier solvent; wherein, before forming the second film layer, the barrier solvent at least partially covers the first film layer. This application improves the performance of the light-emitting device.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a method for preparing a light-emitting device and the light-emitting device itself. Background Technology

[0002] Quantum dot light-emitting diodes (QLEDs) and organic light-emitting diodes (OLEDs) are a new type of self-emissive display technology with advantages such as fast response speed, low power consumption, wide color gamut, and tunable wavelength.

[0003] In the film structure of QLED / OLED devices, except for the cathode which requires vacuum evaporation, other film layers can be fabricated using solution processing. However, a drawback of solution processing is the risk of the upper solution dissolving the lower film layer during the fabrication of adjacent film layers. To address this issue, existing technologies typically employ orthogonal solvent methods (where the solvents used to fabricate adjacent film layers are immiscible) to prepare film layers other than the cathode. However, when the solvents used for adjacent film layers in the device structure are not orthogonal, the risk of the upper solution dissolving the lower film layer arises, affecting the individual properties of the adjacent film layers and consequently impacting the overall performance of the device. Summary of the Invention

[0004] This application provides a method for preparing a light-emitting device and a light-emitting device in order to solve the problem in the prior art where the upper solution dissolves the lower film layer during the preparation of adjacent film layers when the device is prepared by solution processing.

[0005] This application provides a method for fabricating a light-emitting device, characterized by comprising the following steps:

[0006] Provide a substrate;

[0007] A first film layer is formed on the substrate, the first film layer being formed from a first solution, the first solution comprising a first solvent;

[0008] A barrier layer is formed on the first film layer, the barrier layer being formed of a barrier solvent, and the barrier solvent being orthogonal to the first solvent;

[0009] A second film layer is formed on the barrier layer, the second film layer being formed from a second solution comprising a second solvent orthogonal to the barrier solvent; wherein, prior to the formation of the second film layer, the barrier solvent at least partially covers the first film layer.

[0010] Optionally, in some embodiments of this application, the barrier solvent completely covers the first film layer before the second film layer is formed.

[0011] Optionally, in some embodiments of this application, the first solvent and the second solvent are miscible.

[0012] Optionally, in some embodiments of this application, the polarity of the first solvent is the same as that of the second solvent and opposite to that of the barrier solvent.

[0013] Optionally, in some embodiments of this application, the first solvent is the same as the second solvent.

[0014] Optionally, in some embodiments of this application, the boiling point of the barrier solvent is higher than or equal to the boiling point of the second solvent.

[0015] Optionally, in some embodiments of this application, the first film layer is a first electron transport layer, the first solution includes a first solute which is a first electron transport material, the second film layer is a second electron transport layer, the second solution includes a second solute which is a second electron transport material.

[0016] Optionally, in some embodiments of this application, the first film layer is a first light-emitting layer, the first solution includes a first solute, the first solute is a first quantum dot light-emitting material, the second film layer is a second light-emitting layer, the second solution includes a second solute, the second solute is a second quantum dot light-emitting material, and the second quantum dot light-emitting material is the same as the first quantum dot light-emitting material.

[0017] Optionally, in some embodiments of this application, the concentration of the first solute in the first solution is between 6 mg / mL and 8 mg / mL; and / or

[0018] The concentration of the second solute in the second solution is between 6 mg / mL and 8 mg / mL.

[0019] Optionally, in some embodiments of this application, the first film layer is a hole transport layer, the first solution includes a first solute which is a hole transport material, the second film layer is a light-emitting layer, and the second solution includes a second solute which is a quantum dot light-emitting material.

[0020] Optionally, in some embodiments of this application, the first film layer is a hole transport layer, the second film layer is a light-emitting layer, the barrier layer is a first barrier layer, the barrier solvent is a first barrier solvent, and after the step of forming the second film layer on the barrier layer, the following step is further included:

[0021] A first electron transport layer is formed on the light-emitting layer, the first electron transport layer being formed from a third solution, the third solution comprising a third solvent;

[0022] A second barrier layer is formed on the first electron transport layer. The second barrier layer is formed by a second barrier solvent, and the second barrier solvent is orthogonal to the third solvent.

[0023] A second electron transport layer is formed on the second barrier layer, the second electron transport layer being formed from a fourth solution comprising a fourth solvent, the fourth solvent being orthogonal to the second barrier solvent; prior to the formation of the second electron transport layer, the second barrier solvent at least partially covers the first electron transport layer;

[0024] Wherein, the second barrier solvent is the same as the second solvent.

[0025] This application also provides a light-emitting device, which is prepared by the method for preparing a light-emitting device as described in any of the foregoing embodiments.

[0026] Compared to the existing methods for fabricating light-emitting devices, in the method provided in this application, after forming a first film layer on a substrate, a barrier layer formed by a barrier solvent is first formed on the first film layer. The barrier solvent is orthogonal to the first solvent in the first solution. When a second film layer is formed on the barrier layer, since the second solvent in the second solution is also orthogonal to the barrier solvent, the barrier layer can effectively prevent the second solution from eroding the first film layer, thereby ensuring the performance of the first and second film layers and improving the performance of the light-emitting device. Attached Figure Description

[0027] 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.

[0028] Figure 1 This is a schematic flowchart of the fabrication method of the light-emitting device provided in this application.

[0029] Figure 2 This is a schematic diagram of the process structure of the fabrication method of the light-emitting device provided in the first embodiment of this application.

[0030] Figure 3 This is a schematic flowchart of the fabrication method of the light-emitting device provided in the second embodiment of this application.

[0031] Figure 4This is a schematic flowchart of the fabrication method of the light-emitting device provided in the third embodiment of this application.

[0032] Figure 5 This is a schematic flowchart of the fabrication method of the light-emitting device provided in the fourth embodiment of this application.

[0033] Figure 6 This is a schematic diagram of the structure of the light-emitting device provided in this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0035] It should be noted that the light-emitting device in this application can be a QLED device or an OLED device. The following embodiments of this application are only described using the structure of a QLED device as an example, but are not limited thereto.

[0036] It should be noted that the term "orthogonal" as used in this application refers to two solvents that are insoluble in each other.

[0037] This application provides a method for fabricating a light-emitting device and the light-emitting device itself, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0038] Please refer to Figure 1 This application provides a method for fabricating a light-emitting device, which includes the following steps:

[0039] Step B1: Provide a substrate;

[0040] Step B2: Form a first film layer on the substrate, the first film layer being formed from a first solution, the first solution comprising a first solvent;

[0041] Step B3: Form a barrier layer on the first film layer, the barrier layer being formed of a barrier solvent, the barrier solvent being orthogonal to the first solvent;

[0042] Step B4: Form a second film layer on the barrier layer, the second film layer being formed from a second solution comprising a second solvent, the second solvent being orthogonal to the barrier solvent; wherein, prior to the formation of the second film layer, the barrier solvent at least partially covers the first film layer.

[0043] Therefore, in the method for fabricating the light-emitting device provided in this application, after forming a first film layer on the substrate, a barrier layer formed by a barrier solvent is first formed on the first film layer. The barrier solvent is orthogonal to the first solvent in the first solution. Then, when a second film layer is formed on the barrier layer, since the second solvent in the second solution is also orthogonal to the barrier solvent, the barrier layer can effectively prevent the second solution from eroding the first film layer, thereby ensuring the performance of the first film layer and the second film layer respectively, and thus improving the overall performance of the light-emitting device.

[0044] The fabrication method of the light-emitting device provided in this application will be described in detail below.

[0045] Please refer to Figure 2 The first embodiment of this application provides a method for fabricating a light-emitting device 10, which includes the following steps:

[0046] Step B11: Provide a substrate 101 and form a first electrode 102 on the substrate 101, such as... Figure 2 As shown in (a) in the figure.

[0047] Specifically, the substrate 101 is a substrate, which can be a glass substrate, a quartz sheet, etc.

[0048] The first electrode 102 can be an anode. The anode material can include one or more conductive metals or alloys composed of conductive metals such as Mo, Al, Ti, Nd, or Cu; or one or more conductive oxides such as indium gallium zinc oxide (IGZO), indium zinc tin oxide (IZTO), indium gallium zinc tin oxide (IGZTO), indium tin oxide (ITO), indium zinc oxide (IZO), indium aluminum zinc oxide (IAZO), indium gallium tin oxide (IGTO), or antimony tin oxide (ATO); or, the anode material can also be materials with good conductivity such as silver nanowires or graphene. This application does not specifically limit the anode material.

[0049] Specifically, the anode can be a three-layer conductive structure of ITO / Ag / ITO, a two-layer conductive structure of Ag / ITO, Al / WOx or Ag / IZO, or a single-layer conductive structure.

[0050] Step B12: A first film layer is formed on the first electrode 102. The first film layer is a hole transport layer 103. The hole transport layer 103 is formed by a first solution, which includes a first solute and a first solvent. The first solute is a hole transport material.

[0051] Specifically, the hole transport material can be selected from one or more of the following: polytriphenylamine, 9,9-dioctylfluorene / N-(4-sec-butylphenyl)-diphenylamine alternating copolymer (TFB), N,N′-bis(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), poly-3-hexylthiophene (P3HT), polyvinylcarbazole (PVK), or 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA). The first solvent can include organic solvents such as chlorobenzene and dichlorobenzene. It should be noted that this application does not limit the type of the first solvent; as long as it can dissolve the hole transport material, it is within the scope of protection of this application.

[0052] In this embodiment, the hole transport material is TFB, the first solvent is chlorobenzene, and the first solution is a TFB solution. The specific method for forming the hole transport layer 103 on the first electrode 102 is as follows:

[0053] First, TFB is dissolved in chlorobenzene to prepare a TFB solution of a certain concentration, such as a TFB solution with a concentration between 4 mg / mL and 10 mg / mL. The concentration can be 4 mg / mL, 5 mg / mL, 6 mg / mL, 8 mg / mL, or 10 mg / mL, etc.

[0054] Next, the TFB solution is spin-coated onto the first electrode 102 at a rotation speed of 2000 r / min to 4000 r / min. The rotation speed can be 2000 r / min, 2500 r / min, 3000 r / min, 3500 r / min, or 4000 r / min, etc. Furthermore, the spin-coating time of the TFB solution is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0055] Finally, the TFB solution is dried by heating to remove chlorobenzene, thereby forming the TFB layer, which is the hole transport layer 103. Figure 2 As shown in (b), the hole transport layer 103 plays the role of transporting holes.

[0056] Step B13: Form a barrier layer 103a on the hole transport layer 103, such as Figure 2 As shown in (c) in the figure. The barrier layer 103a is formed of a barrier solvent, which is orthogonal to the first solvent.

[0057] The barrier solvent has a polarity opposite to that of the first solvent. Specifically, the barrier solvent may include one or more of methanol, ethanol, propanol, or butanol. In some embodiments, to avoid residue of the barrier solvent during subsequent drying, a barrier solvent with a low boiling point may be used. In other embodiments, the boiling point of the barrier solvent may also be higher than 100 degrees Celsius to prevent premature evaporation and failure of the barrier solvent.

[0058] It should be noted that the type of barrier solvent can be selected according to the actual application requirements. As long as the first solvent and the barrier solvent are orthogonal, they are all within the protection scope of this application.

[0059] In this embodiment, the barrier solvent is ethanol. Specifically, a certain amount of ethanol is spin-coated onto the hole transport layer 103 at a rotation speed of 3000 r / min to 5000 r / min to form an ethanol layer. The aforementioned rotation speed can be 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min, or 5000 r / min, etc. Furthermore, the spin-coating time of the ethanol is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0060] It should be noted that the membrane formed by ethanol needs to completely cover the hole transport layer 103. The specific amount of ethanol can be selected according to the actual situation, and this application does not limit it.

[0061] Step B14: A second film layer is formed on the barrier layer 103a. The second film layer is a light-emitting layer 104. The light-emitting layer 104 is formed by a second solution. The second solution includes a second solute and a second solvent. The second solute is a quantum dot light-emitting material. The second solvent is orthogonal to the barrier solvent.

[0062] Prior to the formation of the light-emitting layer 104, the barrier solvent at least partially covers the hole transport layer 103. In this embodiment, the barrier solvent completely covers the hole transport layer 103, thereby minimizing the possibility of the second solution dissolving the hole transport layer 103.

[0063] Specifically, the quantum dot luminescent material may include one or more of cadmium-based quantum dots, indium phosphide, zinc selenide, or perovskite quantum dots. The second solvent is miscible with the first solvent, and the polarity of the second solvent is the same as that of the first solvent and opposite to that of the barrier solvent. The second solvent may include one or more of butane, pentane, hexane, heptane, or octane. It should be noted that this application does not limit the type of the second solvent; any solvent capable of dissolving the quantum dot luminescent material is within the scope of protection of this application.

[0064] In this embodiment, the second solvent is n-octane, and the second solution is a quantum dot solution. The specific method for forming the light-emitting layer 104 on the barrier layer 103a is as follows:

[0065] First, the quantum dot luminescent material is dissolved in n-octane to prepare a quantum dot solution of a certain concentration, such as a quantum dot solution with a concentration between 6 mg / mL and 12 mg / mL. The concentration can be 6 mg / mL, 8 mg / mL, 10 mg / mL, 11 mg / mL, or 12 mg / mL, etc.

[0066] Next, the quantum dot solution is spin-coated onto the barrier layer 103a at a rotation speed of 3000 r / min to 5000 r / min. The aforementioned rotation speed can be 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min, or 5000 r / min, etc. Furthermore, the spin-coating time of the quantum dot solution is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0067] Finally, the quantum dot solution is dried by heating to remove n-octane, thereby forming the luminescent layer 104. Figure 2 As shown in (d) in the figure.

[0068] Understandably, in existing spin-coating processes, the solvent (e.g., chlorobenzene) used to dissolve the hole transport material (e.g., TFB) during hole transport layer preparation and the solvent (e.g., n-octane) used to dissolve the quantum dot luminescent material in the emissive layer are miscible. After the TFB layer is formed, when the quantum dot solution is spin-coated onto the TFB layer, some of the quantum dot solution penetrates into the TFB layer, causing the TFB in the TFB layer to disperse into the quantum dot solution. Therefore, in the final TFB layer and emissive layer, the TFB layer will be doped with quantum dot luminescent material, and the emissive layer will be doped with TFB, thus affecting the performance of both the hole transport layer and the emissive layer.

[0069] In this embodiment, after the TFB layer is formed, a barrier layer 103a (ethanol layer) is pre-coated onto the TFB layer. Since the solvent used in the TFB layer formation process is insoluble in ethanol, and the solvent (n-octane) in the quantum dot solution is insoluble in ethanol when the quantum dot solution is spin-coated, the ethanol layer effectively prevents the quantum dot solution from penetrating the interior of the TFB layer. This significantly reduces the doping probability between the solute in the final TFB layer and the light-emitting layer 104, thereby ensuring that the functions of the hole transport layer 103 and the light-emitting layer 104 remain unaffected.

[0070] Furthermore, comparative experiments revealed that during the fabrication of the hole transport layer 103 and the light-emitting layer 104: without the use of a barrier solvent, the sum of the thicknesses of the final TFB layer and the light-emitting layer 104 was between 30 nm and 40 nm, with a total thickness of 40 nm in one specific experiment; with the use of a barrier solvent, the sum of the thicknesses of the final TFB layer and the light-emitting layer 104 was between 40 nm and 50 nm, with a total thickness of 43 nm in one specific experiment. That is, the sum of the thicknesses of the TFB layer and the light-emitting layer 104 significantly increased after using a barrier solvent. Therefore, by using a barrier solvent, the doping probability between solutes during the fabrication of the TFB layer and the light-emitting layer 104 can be significantly reduced, thereby contributing to improved device performance.

[0071] It should be noted that, in some embodiments, in order to further increase the doping probability between solutes during the preparation of hole transport layer 103 and light-emitting layer 104, the boiling point of the barrier solvent is higher than that of the second solvent, so that during the removal of the second solvent, the hole transport material in hole transport layer 103 is prevented from being dispersed into the second solvent due to the barrier solvent evaporating before the second solvent.

[0072] Following step B14, the method further includes the step of sequentially forming an electron transport layer 105, a cathode 106, and a light extraction layer 107 on the light-emitting layer 104, such as... Figure 2 As shown in (e) in the figure. The materials and preparation methods of the electron transport layer 105, cathode 106 and light extraction layer 107 can be referred to the prior art, and will not be described in detail here.

[0073] Please refer to Figure 3 The second embodiment of this application provides a method for fabricating a light-emitting device 20, which includes the following steps:

[0074] Step B21: Provide a substrate 201, and sequentially form a first electrode 202, a hole transport layer 203, and a light-emitting layer 204 on the substrate 201, such as... Figure 3 As shown in (a) in the figure.

[0075] Specifically, the substrate 201 is a substrate, which can be a glass substrate, a quartz sheet, etc.

[0076] The first electrode 202 can be an anode. The anode material can include one or more conductive metals or alloys composed of conductive metals such as Mo, Al, Ti, Nd, or Cu; or one or more conductive oxides such as indium gallium zinc oxide (IGZO), indium zinc tin oxide (IZTO), indium gallium zinc tin oxide (IGZTO), indium tin oxide (ITO), indium zinc oxide (IZO), indium aluminum zinc oxide (IAZO), indium gallium tin oxide (IGTO), or antimony tin oxide (ATO); or, the anode material can also be materials with good conductivity such as silver nanowires or graphene. This application does not specifically limit the anode material.

[0077] Specifically, the anode can be a three-layer conductive structure of ITO / Ag / ITO, a two-layer conductive structure of Ag / ITO, Al / WOx or Ag / IZO, or a single-layer conductive structure.

[0078] The hole transport layer 203 can be made of one or more of the following: polytriphenylamine, 9,9-dioctylfluorene / N-(4-sec-butylphenyl)-diphenylamine alternating copolymer (TFB), N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), poly-3-hexylthiophene (P3HT), polyvinylcarbazole (PVK), or 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA).

[0079] The material of the light-emitting layer 204 can be a quantum dot light-emitting material, such as one or more of cadmium-based quantum dots, indium phosphide, zinc selenide, or perovskite quantum dots.

[0080] Step B22: A first film layer is formed on the light-emitting layer 204. The first film layer is a first electron transport layer 205. The first electron transport layer 205 is formed by a first solution, which includes a first solute and a first solvent. The first solute is a first electron transport material.

[0081] Specifically, the first electron transport material may include zinc oxide and / or titanium oxide doped with at least one of magnesium, aluminum, yttrium, or scandium. The first solvent may include one or more organic solvents such as methanol, ethanol, propanol, or butanol. It should be noted that this application does not limit the type of the first solvent; as long as it can dissolve the first electron transport material, it is within the scope of protection of this application.

[0082] In this embodiment, the first electron transport material is zinc magnesium oxide (ZnMgO), the first solvent is ethanol, and the first solution is a ZnMgO solution. The specific method for forming the first electron transport layer 205 on the light-emitting layer 204 is as follows:

[0083] First, dissolve ZnMgO in ethanol to prepare a ZnMgO solution of a certain concentration, such as a ZnMgO solution with a concentration between 15 mg / mL and 25 mg / mL. The concentration can be 15 mg / mL, 18 mg / mL, 20 mg / mL, 22 mg / mL, or 25 mg / mL, etc.

[0084] Next, the ZnMgO solution is spin-coated onto the luminescent layer 204 at a rotation speed of 4000 r / min to 6000 r / min. The aforementioned rotation speed can be 4000 r / min, 4500 r / min, 5000 r / min, 5500 r / min, or 6000 r / min, etc. Furthermore, the spin-coating time of the ZnMgO solution is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0085] Finally, since ethanol is volatile, after the ZnMgO solution is formed on the luminescent layer 204, the ethanol in the ZnMgO solution will evaporate after a short time, thus forming a ZnMgO layer, which is the first electron transport layer 205. Figure 3 As shown in (b), the first electron transport layer 205 not only transports electrons but also improves the efficiency of the device.

[0086] Step B23: Form a barrier layer 205a on the first electron transport layer 205, such as Figure 3 As shown in (c) in the diagram. The barrier layer 205a is formed of a barrier solvent, which is orthogonal to the first solvent.

[0087] The barrier solvent has a polarity opposite to that of the first solvent. Specifically, the barrier solvent may include one or more of butane, pentane, hexane, heptane, or octane. In some embodiments, to avoid residue of the barrier solvent during subsequent drying, a barrier solvent with a low boiling point may be used. In other embodiments, the boiling point of the barrier solvent may also be higher than 100 degrees Celsius to prevent premature evaporation and failure of the barrier solvent.

[0088] It should be noted that the type of barrier solvent can be selected according to the actual application requirements. As long as the first solvent and the barrier solvent are orthogonal, they are all within the protection scope of this application.

[0089] In this embodiment, the barrier solvent is n-octane. Specifically, a certain amount of n-octane is spin-coated onto the first electron transport layer 205 at a rotation speed of 4000 r / min to 6000 r / min to form an n-octane layer. The aforementioned rotation speed can be 4000 r / min, 4500 r / min, 5000 r / min, 5500 r / min, or 6000 r / min, etc. Furthermore, the spin-coating time for n-octane is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0090] It should be noted that the film formed by n-octane needs to completely cover the first electron transport layer 205. The specific amount of n-octane can be selected according to the actual situation, and this application does not limit it.

[0091] Step B24: A second film layer is formed on the barrier layer 205a. The second film layer is a second electron transport layer 206. The second electron transport layer 206 is formed by a second solution. The second solution includes a second solute and a second solvent. The second solute is a second electron transport material. The second solvent is orthogonal to the barrier solvent.

[0092] Prior to the formation of the second electron transport layer 206, the barrier solvent at least partially covers the first electron transport layer 205. In this embodiment, the barrier solvent completely covers the first electron transport layer 205, thereby minimizing the possibility of the second solution dissolving the first electron transport layer 205.

[0093] The second electron transport material differs from the first electron transport material. Specifically, the second electron transport material may include either zinc oxide or titanium oxide.

[0094] The second solvent is miscible with the first solvent, and the polarity of the second solvent is the same as that of the first solvent. The second solvent may include one or more organic solvents such as methanol, ethanol, propanol, or butanol. To reduce the impact on the film layer, the second solvent is the same as the first solvent.

[0095] In this embodiment, the second electron transport material is zinc magnesium oxide (ZnO), the second solvent is ethanol, and the second solution is a ZnO solution. The specific method for forming the second electron transport layer 206 on the barrier layer 205a is as follows:

[0096] First, dissolve ZnO in ethanol to prepare a ZnO solution of a certain concentration, such as a ZnO solution with a concentration between 15 mg / mL and 25 mg / mL. The concentration can be 15 mg / mL, 18 mg / mL, 20 mg / mL, 22 mg / mL, or 25 mg / mL, etc.

[0097] Next, the ZnO solution is spin-coated onto the barrier layer 205a at a rotation speed of 4000 r / min to 6000 r / min. The aforementioned rotation speed can be 4000 r / min, 4500 r / min, 5000 r / min, 5500 r / min, or 6000 r / min, etc. Furthermore, the spin-coating time of the ZnO solution is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0098] Finally, since ethanol is volatile, after the ZnO solution is formed on the barrier layer 205a, the ethanol in the ZnO solution will evaporate after a short time, thus forming a ZnO layer, which is the second electron transport layer 206. Figure 3 As shown in (d) in the figure. Since ZnO is a wide bandgap material, it can improve the electron mobility. The second electron transport layer 206 can improve the device lifetime while transporting electrons due to its high mobility.

[0099] Understandably, in existing technologies, adjacent ZnMgO and ZnO layers are typically used as electron transport composite films to improve the overall performance of devices. However, in spin-coating processes, if the solvents used to dissolve ZnMgO during ZnMgO layer preparation and ZnO during ZnO layer preparation are solvents of the same polarity, or even the same solvent, when the ZnO solution is spin-coated onto the ZnMgO layer after its formation, some of the ZnO solution will penetrate into the ZnMgO layer, causing the ZnMgO in the ZnMgO layer to disperse into the ZnO solution. Consequently, in the final ZnMgO and ZnO layers, the ZnMgO layer will be doped with ZnO, and the ZnO layer will be doped with ZnMgO, thus affecting the individual properties of the ZnMgO and ZnO layers.

[0100] In this embodiment, after the ZnMgO layer is formed, a barrier layer 205a (n-octane layer) is spin-coated onto the ZnMgO layer beforehand. Since the solvent used in the ZnMgO layer formation process is insoluble in n-octane, and the solvent (ethanol) in the ZnO solution is also insoluble in n-octane when spin-coating the ZnO solution, the n-octane layer effectively prevents the ZnO solution from penetrating the interior of the ZnMgO layer. This significantly reduces the doping probability between the solutes in the final ZnMgO and ZnO layers, thereby ensuring the respective performance of the ZnMgO and ZnO layers as electron transport films.

[0101] Furthermore, comparative experiments revealed that during the preparation of the ZnMgO and ZnO layers: without the use of a barrier solvent, the sum of the thicknesses of the final ZnMgO and ZnO layers was between 20 nm and 30 nm, with a total thickness of 30 nm in one specific experiment; with the use of a barrier solvent, the sum of the thicknesses of the final ZnMgO and ZnO layers was between 30 nm and 40 nm, with a total thickness of 50 nm in one specific experiment. That is, the sum of the thicknesses of the ZnMgO and ZnO layers significantly increased after using a barrier solvent. Therefore, the use of a barrier solvent reduces the doping probability between solutes during the preparation of the ZnMgO and ZnO layers, thereby improving the device performance.

[0102] It should be noted that, in some embodiments, in order to further increase the doping probability between solutes during the preparation of the first electron transport layer 205 and the second electron transport layer 206, the boiling point of the barrier solvent is higher than that of the second solvent, so that during the removal of the second solvent, the first electron transport material in the first electron transport layer 205 is prevented from being dispersed into the second solvent due to the barrier solvent evaporating before the second solvent.

[0103] Following step B24, the method further includes the step of sequentially forming a cathode 207 and a light extraction layer 208 on the second electron transport layer 206, such as... Figure 3 As shown in (e) in the figure. The materials and preparation methods of the cathode 207 and the light extraction layer 208 can be referred to the existing technology, and will not be described in detail here.

[0104] Please refer to Figure 4 The third embodiment of this application provides a method for fabricating a light-emitting device 30, which includes the following steps:

[0105] Step B31: Provide a substrate 301, and sequentially form a first electrode 302 and a hole transport layer 303 on the substrate 301, such as... Figure 4 As shown in (a) in the figure.

[0106] Specifically, substrate 301 is a substrate, which can be a glass substrate, quartz sheet, etc.

[0107] The first electrode 302 can be an anode. The anode material can include one or more conductive metals or alloys composed of conductive metals such as Mo, Al, Ti, Nd, or Cu; or one or more conductive oxides such as indium gallium zinc oxide (IGZO), indium zinc tin oxide (IZTO), indium gallium zinc tin oxide (IGZTO), indium tin oxide (ITO), indium zinc oxide (IZO), indium aluminum zinc oxide (IAZO), indium gallium tin oxide (IGTO), or antimony tin oxide (ATO); or, the anode material can also be materials with good conductivity such as silver nanowires or graphene. This application does not specifically limit the anode material.

[0108] Specifically, the anode can be a three-layer conductive structure of ITO / Ag / ITO, a two-layer conductive structure of Ag / ITO, Al / WOx or Ag / IZO, or a single-layer conductive structure.

[0109] The hole transport layer 303 can be made of one or more of the following: polytriphenylamine, 9,9-dioctylfluorene / N-(4-sec-butylphenyl)-diphenylamine alternating copolymer (TFB), N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), poly-3-hexylthiophene (P3HT), polyvinylcarbazole (PVK), or 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA).

[0110] Step B32: A first film layer is formed on the hole transport layer 303. The first film layer is a first light-emitting layer 304. The first light-emitting layer 304 is formed by a first solution, which includes a first solute and a first solvent. The first solute is a first quantum dot light-emitting material.

[0111] Specifically, the first quantum dot luminescent material may include one or more of cadmium-based quantum dots, indium phosphide, zinc selenide, or perovskite quantum dots. The first solvent may include one or more of butane, pentane, hexane, heptane, or octane. It should be noted that this application does not limit the type of the first solvent; as long as it can dissolve the first quantum dot luminescent material, it is within the scope of protection of this application.

[0112] In this embodiment, the concentration of the first solute in the first solution is between 6 mg / mL and 8 mg / mL. Specifically, the first solvent is n-octane, and the first solution is a first quantum dot solution. The specific method for forming the first light-emitting layer 304 on the hole transport layer 303 is as follows:

[0113] First, the first quantum dot luminescent material is dissolved in n-octane to prepare a first quantum dot solution of a certain concentration, such as a first quantum dot solution with a concentration between 6 mg / mL and 8 mg / mL. The concentration can be 6 mg / mL, 6.5 mg / mL, 7 mg / mL, 7.5 mg / mL, or 8 mg / mL, etc.

[0114] Next, the first quantum dot solution is spin-coated onto the hole transport layer 303 at a rotation speed of 3000 r / min to 5000 r / min. The aforementioned rotation speed can be 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min, or 5000 r / min, etc. Furthermore, the spin-coating time of the first quantum dot solution is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0115] Finally, the first quantum dot solution is dried by heating to remove n-octane, thereby forming the first light-emitting layer 304. Figure 4 As shown in (b) of the diagram.

[0116] Step B33: Form a barrier layer 304a on the first light-emitting layer 304, such as Figure 4 As shown in (c) in the diagram. The barrier layer 304a is formed of a barrier solvent, which is orthogonal to the first solvent.

[0117] The barrier solvent has a polarity opposite to that of the first solvent. Specifically, the barrier solvent may include one or more of methanol, ethanol, propanol, or butanol. In some embodiments, to avoid residue of the barrier solvent during subsequent drying, a barrier solvent with a low boiling point may be used. In other embodiments, the boiling point of the barrier solvent may also be higher than 100 degrees Celsius to prevent premature evaporation and failure of the barrier solvent.

[0118] It should be noted that the type of barrier solvent can be selected according to the actual application requirements. As long as the first solvent and the barrier solvent are orthogonal, they are all within the protection scope of this application.

[0119] In this embodiment, the barrier solvent is ethanol. Specifically, a certain amount of ethanol is spin-coated onto the first light-emitting layer 304 at a rotation speed of 3000 r / min to 5000 r / min to form an ethanol layer. The aforementioned rotation speed can be 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min, or 5000 r / min, etc. Furthermore, the spin-coating time of the ethanol is between 20 s and 40 s, such as 20 s, 25 s, 30 s, 35 s, or 40 s.

[0120] It should be noted that the film layer formed by ethanol needs to completely cover the first light-emitting layer 304. The specific amount of ethanol can be selected according to the actual situation, and this application does not limit it.

[0121] Step B34: A second film layer is formed on the barrier layer 304a. The second film layer is the second light-emitting layer 305. The second light-emitting layer 305 is formed by a second solution. The second solution includes a second solute and a second solvent. The second solute is the second quantum dot light-emitting material. The second solvent is orthogonal to the barrier solvent.

[0122] Before the second light-emitting layer 305 is formed, the barrier solvent at least partially covers the first light-emitting layer 304. In this embodiment, the barrier solvent completely covers the first light-emitting layer 304, thereby minimizing the possibility of the second solution dissolving the first light-emitting layer 304.

[0123] The concentration of the second solute in the second solution is between 6 mg / mL and 8 mg / mL. Specifically, the second solution is a second quantum dot solution, and the second quantum dot luminescent material is the same as the first quantum dot luminescent material. The second solvent is the same as the first solvent. It should be noted that the spin-coating method for the second quantum dot solution can refer to the description of the first quantum dot solution in step B33, and will not be repeated here.

[0124] Finally, the second quantum dot solution is dried by heating to remove n-octane, thereby forming the second luminescent layer 305. Figure 4 As shown in (d) in the figure.

[0125] Understandably, in existing technologies, high-concentration quantum dot solutions are typically spin-coated to achieve the effect of a double-layer quantum dot luminescent layer. However, the above method results in an irregular arrangement of quantum dots in the formed quantum dot luminescent layer.

[0126] To address the aforementioned technical problems, this embodiment uses low-concentration first quantum dot solutions (6 mg / mL-8 mg / mL) and second quantum dot solutions (6 mg / mL-8 mg / mL) to form the first light-emitting layer 304 and the second light-emitting layer 305, respectively. During the preparation of the first and second light-emitting layers 304 and 305, after the formation of the first light-emitting layer 304, a barrier solvent is spin-coated onto it. During the subsequent spin-coating of the second quantum dot solution, since the barrier solvent is orthogonal to the second solvent in the second quantum dot solution, the barrier solvent can prevent the second quantum dot solution from eroding the first light-emitting layer 304. Therefore, the probability of solute doping between the first and second light-emitting layers 304 and 305 is reduced, thereby improving the regularity of the quantum dot arrangement in the first and second light-emitting layers 304 and 305, thus improving the efficiency of carrier transport and enhancing the overall performance of the device.

[0127] Following step B34, the method further includes the step of sequentially forming an electron transport layer 306, a cathode 307, and a light extraction layer 308 on the second light-emitting layer 305, such as... Figure 4 As shown in (e) in the figure. The materials and preparation methods of the electron transport layer 306, cathode 307 and light extraction layer 308 can be referred to the prior art, and will not be described in detail here.

[0128] Please refer to Figure 5 The fourth embodiment of this application provides a method for fabricating a light-emitting device 40, which includes the following steps:

[0129] Step B41: Provide a substrate 401, and form a first electrode 402 on the substrate 401, such as... Figure 5 As shown in (a) in the figure.

[0130] Specifically, substrate 401 is a substrate, which can be a glass substrate, a quartz sheet, etc.

[0131] The first electrode 402 can be an anode. The anode material can include one or more of conductive metals or alloys composed of conductive metals such as Mo, Al, Ti, Nd, or Cu, or one or more of conductive oxides such as indium gallium zinc oxide (IGZO), indium zinc tin oxide (IZTO), indium gallium zinc tin oxide (IGZTO), indium tin oxide (ITO), indium zinc oxide (IZO), indium aluminum zinc oxide (IAZO), indium gallium tin oxide (IGTO), or antimony tin oxide (ATO). Alternatively, the anode material can also be a material with good conductivity such as silver nanowires or graphene.

[0132] Specifically, the anode can be a three-layer conductive structure of ITO / Ag / ITO, a two-layer conductive structure of Ag / ITO, Al / WOx or Ag / IZO, or a single-layer conductive structure.

[0133] Step B42: A first film layer is formed on the first electrode 402. The first film layer is a hole transport layer 403, such as... Figure 5 As shown in (b) above. The hole transport layer 403 is formed of a first solution, which includes a first solute and a first solvent, wherein the first solute is a hole transport material.

[0134] The hole transport layer 403 can be made of one or more of the following: polytriphenylamine, 9,9-dioctylfluorene / N-(4-sec-butylphenyl)-diphenylamine alternating copolymer (TFB), N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), poly-3-hexylthiophene (P3HT), polyvinylcarbazole (PVK), or 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA). The first solvent can include organic solvents such as chlorobenzene and dichlorobenzene.

[0135] In this embodiment, the hole transport material is TFB, the first solvent is chlorobenzene, and the first solution is a TFB solution.

[0136] Step B43: Form a first barrier layer 403a on the hole transport layer 403, such as Figure 5 As shown in (c) in the figure. The first barrier layer 403a is formed of a first barrier solvent, and the first barrier solvent is orthogonal to the first solvent.

[0137] The first barrier solvent has the opposite polarity to the first solvent. Specifically, the first barrier solvent may include one or more of methanol, ethanol, propanol, or butanol. In some embodiments, to avoid residue of the first barrier solvent during subsequent drying, a first barrier solvent with a low boiling point may be used. In other embodiments, the boiling point of the first barrier solvent may also be higher than 100 degrees Celsius to prevent premature evaporation and failure of the first barrier solvent.

[0138] In this embodiment, the first barrier solvent is ethanol.

[0139] Step B44: A second film layer is formed on the first barrier layer 403a. The second film layer is a light-emitting layer 404, as shown below. Figure 5 As shown in (d) in the figure. The light-emitting layer 404 is formed by a second solution, which includes a second solute and a second solvent. The second solute is a quantum dot light-emitting material, and the second solvent is orthogonal to the first barrier solvent.

[0140] In this embodiment, before the light-emitting layer 404 is formed, the first barrier solvent at least partially covers the hole transport layer 403. In this embodiment, the first barrier solvent completely covers the hole transport layer 403, thereby minimizing the possibility of the second solution dissolving the hole transport layer 403.

[0141] Specifically, the quantum dot luminescent material may include one or more of cadmium-based quantum dots, indium phosphide, zinc selenide, or perovskite quantum dots. The second solvent is miscible with the first solvent, and the polarity of the second solvent is the same as that of the first solvent and opposite to that of the first barrier solvent. The second solvent may include one or more of butane, pentane, hexane, heptane, or octane.

[0142] In this embodiment, the second solvent is n-octane, and the second solution is a quantum dot solution.

[0143] The light-emitting layer 404 may include a first light-emitting layer and a second light-emitting layer sequentially formed on the hole transport layer 403. It should be noted that the preparation methods of the first and second light-emitting layers in this embodiment can refer to the description of the preparation methods of the first light-emitting layer 304 and the second light-emitting layer 305 in the light-emitting device 30 provided in the third embodiment of this application, and will not be repeated here.

[0144] Step B45: Form a first electron transport layer 405 on the light-emitting layer 404, such as... Figure 5 As shown in (e) in the figure. The first electron transport layer 405 is formed by a third solution, which includes a third solute and a third solvent, wherein the third solute is the first electron transport material.

[0145] Specifically, the first electron transport material may include zinc oxide and / or titanium oxide doped with at least one of magnesium, aluminum, yttrium, or scandium. The third solvent may include one or more organic solvents such as methanol, ethanol, propanol, or butanol.

[0146] In this embodiment, the first electron transport material is zinc magnesium oxide (ZnMgO), the third solvent is ethanol, and the third solution is a ZnMgO solution.

[0147] Step B46: Form a second barrier layer 405a on the first electron transport layer 405, such as Figure 5As shown in (f) above, the second barrier layer 405a is formed of a second barrier solvent, which is orthogonal to the third solvent and is identical to the second solvent. The polarity of the second barrier solvent is opposite to that of the third solvent. Specifically, the second barrier solvent may include one or more of butane, pentane, hexane, heptane, or octane. In some embodiments, to avoid residue of the second barrier solvent during subsequent drying, a second barrier solvent with a low boiling point can be used. In other embodiments, the boiling point of the second barrier solvent may also be higher than 100 degrees Celsius to prevent premature evaporation and failure.

[0148] In this embodiment, the second barrier solvent is n-octane.

[0149] Therefore, in this embodiment, the first barrier solvent and the third solvent are the same, both being ethanol. The second barrier solvent and the second solvent are the same, both being n-octane. By using the same solvent as that used in the fabrication of the light-emitting device film as the barrier solvent (first barrier solvent / second barrier solvent), the impact of barrier solvent residue on the performance of the light-emitting device can be reduced.

[0150] Step B47: Form a second electron transport layer 406 on the second barrier layer 405a, such as Figure 5 As shown in (g) in the figure. The second electron transport layer 406 is formed by a fourth solution, which includes a fourth solute and a fourth solvent. The fourth solute is the second electron transport material, and the fourth solvent is orthogonal to the second barrier solvent.

[0151] Prior to the formation of the second electron transport layer 406, the second barrier solvent at least partially covers the first electron transport layer 405. In this embodiment, the second barrier solvent completely covers the first electron transport layer 405, thereby minimizing the possibility of the fourth solution dissolving the first electron transport layer 405.

[0152] The second electron transport material differs from the first electron transport material. Specifically, the second electron transport material may include either zinc oxide or titanium oxide.

[0153] The fourth solvent has the same polarity as the third solvent. The fourth solvent may include one or more organic solvents such as methanol, ethanol, propanol, or butanol. To minimize its impact on device performance, the fourth solvent is the same as the third solvent.

[0154] In this embodiment, the second electron transport material is zinc magnesium oxide (ZnO), the fourth solvent is ethanol, and the fourth solution is a ZnO solution.

[0155] Following step B47, the method further includes the step of sequentially forming a cathode 407 and a light extraction layer 408 on the second electron transport layer 406, such as... Figure 5 As shown in (h) in the figure. The materials and preparation methods of the cathode 407 and the light extraction layer 408 can be referred to the existing technology, and will not be described in detail here.

[0156] Please refer to Figure 6 This application also provides a light-emitting device 50, which includes a substrate 501, a first electrode 502, a hole transport layer 503, a light-emitting layer 504, an electron transport layer 505, a cathode 506, and a light extraction layer 507 sequentially disposed therefrom. The light-emitting layer 405 may include a first light-emitting layer and a second light-emitting layer. The electron transport layer 505 may include a first electron transport layer and a second electron transport layer.

[0157] In addition, the light-emitting device 50 in this embodiment can be prepared by the light-emitting device preparation method described in any of the foregoing embodiments, and will not be repeated here.

[0158] The above provides a detailed description of the fabrication method and the light-emitting device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fabricating a light-emitting device, characterized in that, Includes the following steps: Provide a substrate; A first film layer is formed on the substrate, the first film layer being formed from a first solution, the first solution comprising a first solvent; A barrier layer is formed on the first film layer, the barrier layer being formed of a barrier solvent, and the barrier solvent being orthogonal to the first solvent; as well as A second film layer is formed on the barrier layer, the second film layer being formed from a second solution comprising a second solvent, the second solvent being orthogonal to the barrier solvent; wherein, prior to the formation of the second film layer, the barrier solvent at least partially covers the first film layer; the second film layer is dried while removing the second solvent and the barrier solvent; or, the second film layer is dried while sequentially removing the second solvent and the barrier solvent.

2. The method for preparing a light-emitting device according to claim 1, characterized in that, Before the second film layer is formed, the barrier solvent completely covers the first film layer.

3. The method for fabricating a light-emitting device according to claim 1, characterized in that, The first solvent and the second solvent are miscible.

4. The method for fabricating a light-emitting device according to claim 1, characterized in that, The polarity of the first solvent is the same as that of the second solvent, and opposite to that of the barrier solvent.

5. The method for fabricating a light-emitting device according to claim 4, characterized in that, The first solvent is the same as the second solvent.

6. The method for fabricating a light-emitting device according to claim 1, characterized in that, The boiling point of the barrier solvent is higher than or equal to the boiling point of the second solvent.

7. The method for preparing a light-emitting device according to claim 1, characterized in that, The first membrane layer is a first electron transport layer, the first solution includes a first solute which is a first electron transport material, the second membrane layer is a second electron transport layer, the second solution includes a second solute which is a second electron transport material.

8. The method for preparing a light-emitting device according to claim 1, characterized in that, The first film layer is a first light-emitting layer, the first solution includes a first solute, the first solute is a first quantum dot light-emitting material, the second film layer is a second light-emitting layer, the second solution includes a second solute, the second solute is a second quantum dot light-emitting material, and the second quantum dot light-emitting material is the same as the first quantum dot light-emitting material.

9. The method for preparing a light-emitting device according to claim 8, characterized in that, The concentration of the first solute in the first solution is between 6 mg / mL and 8 mg / mL; and / or The concentration of the second solute in the second solution is between 6 mg / mL and 8 mg / mL.

10. The method for fabricating a light-emitting device according to claim 1, characterized in that, The first film layer is a hole transport layer, the first solution includes a first solute, which is a hole transport material, the second film layer is a light-emitting layer, the second solution includes a second solute, which is a quantum dot light-emitting material.

11. The method for fabricating a light-emitting device according to claim 1, characterized in that, The first film layer is a hole transport layer, the second film layer is a light-emitting layer, the barrier layer is a first barrier layer, the barrier solvent is a first barrier solvent, and after the step of forming the second film layer on the barrier layer, the following steps are also included: A first electron transport layer is formed on the light-emitting layer, the first electron transport layer being formed from a third solution, the third solution comprising a third solvent; A second barrier layer is formed on the first electron transport layer. The second barrier layer is formed by a second barrier solvent, and the second barrier solvent is orthogonal to the third solvent. A second electron transport layer is formed on the second barrier layer, the second electron transport layer being formed from a fourth solution comprising a fourth solvent, the fourth solvent being orthogonal to the second barrier solvent; prior to the formation of the second electron transport layer, the second barrier solvent at least partially covers the first electron transport layer; Wherein, the second barrier solvent is the same as the second solvent.

12. A light-emitting device, characterized in that, The light-emitting device is prepared by the method for preparing a light-emitting device as described in any one of claims 1 to 11.

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