Hole transfer structure of quantum dot light emitting diode, diode using the same and manufacturing method of the same

Abstract

A hole transport structure of a quantum dot light-emitting diode according to the present invention comprises a hole injection layer, an excess electron removal layer stacked on one side of the hole injection layer, an ohmic contact induction layer stacked on one side of the excess electron removal layer, and a hole transport layer stacked on one side of the ohmic contact induction layer, wherein the excess electron removal layer removes excess electrons generated at the interface between the hole injection layer and the ohmic contact induction layer.

Description

Technology Field

[0001] The present invention relates to a hole transport structure for quantum dots (QDs), a diode using the same, and a method for manufacturing the same. Background Technology

[0002] Quantum dot light-emitting diodes (QDs) possess the characteristic of allowing holes from the anode and electrons from the cathode to move into the quantum dot light-emitting layer. Consequently, excitons are formed in the layer through the interaction between holes and the cathode, and the final light emission occurs through this energy release. In particular, quantum dot light-emitting diodes offer various advantages, such as high luminous efficiency and high color clarity.

[0003] On the other hand, quantum dot light-emitting diodes have the problem that hole injection imbalance is easily induced, resulting in a relatively short usage time during which optimal performance can be maintained. Prior art literature

[0004] Korean Published Patent No. 10-2018-0060441 The problem to be solved

[0005] As part of solving the aforementioned problem, the present invention aims to provide a hole transport structure for a quantum dot light-emitting diode capable of minimizing various factors that cause performance degradation of the quantum dot light-emitting diode, such as carrier injection imbalance, a diode using the same, and a method for manufacturing the same. means of solving the problem

[0006] A hole transport structure of a quantum dot light-emitting diode according to the present invention comprises a hole injection layer, an excess electron removal layer stacked on one side of the hole injection layer, an ohmic contact induction layer stacked on one side of the excess electron removal layer, and a hole transport layer stacked on one side of the ohmic contact induction layer, wherein the excess electron removal layer removes excess electrons generated at the interface between the hole injection layer and the ohmic contact induction layer.

[0007] In addition, the excess electron removal layer is characterized by comprising at least one selected from the group including molybdenum oxide, vanadium oxide, and tungsten oxide.

[0008] In addition, the resistance contact inducing layer is characterized by having a higher HOMO (Highest Occupied Molecular Orbital) energy level than the hole transport layer.

[0009] In addition, the resistance contact inducing layer is characterized by comprising poly(n-vinylcarbazole).

[0010] In addition, the resistance contact inducing layer is characterized by being doped with phosphomolybdic acid.

[0011] In addition, the above-mentioned phosphomolybdic acid is characterized by being doped to 10 wt% to 40 wt%.

[0012] In addition, the resistance contact inducing layer is characterized by having a thickness of 1 nm to 5 nm.

[0013] In addition, the thickness ratio of the excess electron removal layer and the resistance contact induction layer is characterized as being 1:0.7 to 1.5.

[0014] In addition, the quantum dot light-emitting diode according to the present invention can be manufactured using the above-mentioned moving structure.

[0015] In addition, the method for manufacturing a quantum dot light-emitting diode according to the present invention is characterized by comprising: a hole injection layer forming step in which a hole injection layer is deposited; an excess electron removal layer forming step in which an excess electron removal layer is stacked on one side of the hole injection layer; an induction layer forming step in which a resistance contact induction layer is stacked on one side of the excess electron removal layer; and a hole transport layer forming step in which a hole transport layer is stacked on one side of the resistance contact induction layer. Effects of the invention

[0016] According to the hole transport structure of the present invention, a resistance contact inducing layer is provided between the hole injection layer and the hole transport layer. At this time, just as a Schottky junction is converted into a resistance contact, the resistance contact inducing layer lowers the energy barrier between the hole injection layer and the hole transport layer.

[0017] Therefore, due to the aforementioned resistance contact effect, the stagnation of holes transported to the quantum dot is minimized, thereby further improving the efficiency and lifespan of the diode.

[0018] In addition, the resistance contact inducing layer can be manufactured inexpensively and easily through a relatively simple solution-based process, such as coating.

[0019] In addition, excess electrons generated at the hole injection and hole transport interfaces are efficiently absorbed and removed by the excess electron removal layer. Brief explanation of the drawing

[0020] FIG. 1 is a schematic diagram showing a quantum dot light-emitting diode according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a method for manufacturing a quantum dot light-emitting diode according to an embodiment of the present invention. Figure 3 is a graph showing the results of a voltage-current density comparison between an embodiment of the present invention and comparative examples. Figure 4 is a graph showing the results of a comparison of current density-external quantum efficiency between the embodiments and comparative examples of the present invention. Specific details for implementing the invention

[0021] Prior to a detailed description of the present invention, specific details for implementing the invention are included in the embodiments and drawings described below. Additionally, identical reference numerals throughout the specification refer to identical components. Furthermore, singular expressions in this specification include plural forms unless specifically stated otherwise.

[0022] Hereinafter, with reference to the drawings, a hole transport structure of a quantum dot light-emitting diode according to the present invention, a diode using the same, and a method for manufacturing the same will be described.

[0023] FIG. 1 is a schematic diagram showing a quantum dot light-emitting diode according to an embodiment of the present invention. FIG. 2 is a flowchart showing a method for manufacturing a quantum dot light-emitting diode according to an embodiment of the present invention.

[0024] Referring to FIGS. 1 and 2, a quantum dot light-emitting diode (1000) according to an embodiment of the present invention comprises an anode (100), a hole transport structure (200), a light-emitting part (300), an electron transport structure (400), and a cathode (500). Additionally, a method for manufacturing a quantum dot light-emitting diode according to an embodiment of the present invention comprises an anode formation step (S100), a hole transport layer formation step (S200), a light-emitting layer formation step (S300), an electron transport layer formation step (S400), and a cathode formation step (S500). Here, the hole transport layer formation step (S200) corresponds to the hole transport structure (200) of the quantum dot light-emitting diode and the method for manufacturing the same according to the present invention.

[0025] First, the anode portion (100) is manufactured through the anode formation step (S100).

[0026] More specifically, to manufacture the anode (100), ITO (Indium tin oxide), FTO (fluorine-doped tin oxide), graphene, CNT, and various other materials may be used. Additionally, the anode (100) can be finally produced through various post-treatments such as ultrasonic cleaning and UV-O.

[0027] Next, through the hole transport layer formation step (S200), the hole transport structure (200) is stacked on one side of the anode (100).

[0028] Additionally, the hole transport layer formation step (S200) includes a hole injection layer formation step (S210), an excess electron removal layer formation step (S220), an induction layer formation step (S230), and a hole transport layer formation step (S240). Furthermore, the hole transport structure (200) includes a hole injection layer (210), an excess electron removal layer (220), a resistance contact induction layer (230), and a hole transport layer (240).

[0029] More specifically, first, through the hole injection layer formation step (S210), the hole injection layer (210) is laminated on one side of the anode (100).

[0030] At this time, the hole injection layer (210) can be manufactured from Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), Poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine, poly(N-vinylcarbazole) (PVK), polyaniline, polypyrrole, and various other materials.

[0031] In addition, the hole injection layer (210) can be laminated using various coating / printing methods. For example, spin coating, spray coating, dip coating, inkjet printing, gravure printing, and various other solution application methods may be utilized.

[0032] Additionally, the hole injection layer (210) may have a thickness of 5 nm to 65 nm.

[0033] Next, the excess electron removal layer (220) can be stacked through the excess electron removal layer formation step (S220). Here, the hole injection layer (210) and the excess electron removal layer (220) can be sequentially stacked from the anode to the cathode. Additionally, only one of the hole injection layer (210) and the excess electron removal layer (220) may be formed.

[0034] More specifically, the excess electron removal layer (220) can be made of molybdenum oxide, vanadium oxide, tungsten oxide, and various other materials. Preferably, molybdenum trioxide (MoO3) may be selected. Additionally, the vanadium oxide may be vanadium pentoxide.

[0035] Additionally, the excess electron removal layer (220) can be deposited by a deposition method. Additionally, the excess electron removal layer (220) can be deposited through a solution-based process.

[0036] Additionally, the excess electron removal layer (220) may have a thickness of 0.7 nm to 10 nm.

[0037] Next, through the induction layer formation step (S230), the resistance contact (Ohmic contact) induction layer (230) is laminated on one side of the hole injection layer (210).

[0038] More specifically, the resistance contact inducing layer (230) can be laminated using various coating / printing methods. For example, spin coating, spray coating, dip coating, inkjet printing, gravure printing, and various other solution application methods may be utilized.

[0039] Additionally, the resistance contact inducing layer (230) may have a higher HOMO (Highest Occupied Molecular Orbital) energy level than the hole transport layer (240) described later. For example, the resistance contact inducing layer (230) may be formed from a material including poly(N-vinylcarbazole) (PVK). Furthermore, preferably, the PVK may be doped with phosphomolybdic acid (PMA).

[0040] In addition, the doping concentration of the PMA may be 5 wt% to 70 wt%. Preferably, the doping concentration of the PMA may be 10 wt% to 40 wt%. More preferably, the doping concentration of the PMA may be 30 wt%.

[0041] Here, the thickness ratio of the excess electron removal layer (220) and the resistance contact induction layer (230) may be 1:0.5 to 3. More preferably, the thickness ratio of the excess electron removal layer (220) and the resistance contact induction layer (230) may be 1:0.7 to 1.5.

[0042] In addition, VCBP, DV-CBP, etc. can be used to manufacture the resistance contact induction layer (230).

[0043] Additionally, the thickness of the resistance contact inducing layer (230) may be 0.7 nm to 12 nm. Preferably, the thickness of the resistance contact inducing layer (230) may be 1 nm to 7 nm. More preferably, the thickness of the resistance contact inducing layer (230) may be 1 nm to 5 nm.

[0044] Next, through the hole transport layer formation step (S240), the hole transport layer (240) is stacked on one side of the hole transport structure (200).

[0045] More specifically, the hole transport layer (240) can be manufactured from poly(N-vinylcarbazole) (PVK), N,N'-Bis(naphthalen-1-yl)-N,N'-bis(4-vinyl-phenyl)benzidine (VNPB), TAPC, TCTA, NPB, and various other materials. Additionally, the hole transport layer (240) can be laminated using various coating / printing methods. For example, spin coating, spray coating, dip coating, inkjet printing, gravure printing, and various other solution application methods may be utilized.

[0046] In addition, the thickness of the hole transport layer (240) may be 10 nm to 40 nm.

[0047] In addition, the hole transport layer (240) can be manufactured as a multilayer, not just a single layer.

[0048] Next, through the light-emitting layer formation step (S300), the light-emitting part (300) is laminated on one side of the hole transport layer (240).

[0049] More specifically, the light-emitting part (300) forms a quantum dot layer. Additionally, the light-emitting part (300) may include a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, and a Group IV compound. In addition, the light emitting part 300 includes CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, GaN, GaP, GaAs, It can be manufactured from GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, InZnP, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and various other materials.

[0050] Additionally, the light-emitting part (300) can be laminated using various coating / printing methods. For example, spin coating, spray coating, dip coating, inkjet printing, gravure printing, and various other solution application methods may be utilized. Additionally, the thickness of the light-emitting part (300) may be 5 nm to 30 nm.

[0051] Next, the electron transport structure (400) is stacked on one side of the light-emitting part (300) through the electron transport layer formation step (S400). Additionally, the electron transport structure (400) may include an electron transport layer (410) and an electron injection layer (420) in the order from the positive electrode to the negative electrode.

[0052] In addition, the electron transfer structure (400) can be manufactured from ZnO or various other materials. In addition, the electron transfer structure (400) can be laminated using various coating / printing methods. For example, spin coating, spray coating, dip coating, inkjet printing, gravure printing, and various other solution application methods may be utilized.

[0053] In addition, the thickness of the electron transport structure (400) may be 7 nm to 50 nm.

[0054] Next, through the cathode formation step (S500), the cathode portion (500) is laminated on one side of the electron transport structure (400). Additionally, the thickness of the cathode portion (500) may be 15 nm to 120 nm.

[0055] In addition, the cathode (500) may include silver, gold, copper, platinum, iridium, lithium, aluminum, magnesium, tin, and various other materials. In addition, the cathode (500) may be laminated through a deposition process.

[0056] [Example 1]

[0057] A diode according to the present embodiment was manufactured according to the above-described manufacturing method.

[0058] First, the anode portion (100) was manufactured through the anode formation step (S100).

[0059] More specifically, an ITO-coated glass was prepared. The glass was then washed with acetone, IPA, and Di-water for 15 minutes each. The washed and dried glass was then baked in an oven for 8 hours. The baked glass was then UV-O treated for 15 minutes.

[0060] Next, through the hole injection layer formation step (S210), a hole injection layer (210) with a thickness of 40 nm was laminated on one side of the anode (100).

[0061] More specifically, PEDOT:PSS was spin-coated at 4000 rpm for 30 seconds under room temperature and atmospheric conditions. Then, the coating was heat-treated on a hot plate at 150°C for 15 minutes.

[0062] Next, through the above-mentioned excess electron removal layer formation step (S220), an excess electron removal layer (220) is formed on one side of the hole injection layer (210).

[0063] More specifically, molybdenum trioxide was deposited to a thickness of 3 nm in a glove box under a nitrogen atmosphere. The deposited layer was then annealed at 200°C.

[0064] Next, through the above-mentioned induction layer formation step (S230), a resistance contact induction layer (230) is laminated on one side of the excess electron removal layer (220).

[0065] More specifically, a PVK solution doped with 30 wt% PMA was prepared. The doped solution was then spin-coated at 3000 rpm for 45 seconds. After spin-coating was completed, heat treatment was performed on a hot plate at a temperature of 150 ℃ for 15 minutes.

[0066] At this time, chlorobenzene, 1,2-dichloroethane, and acetonitrile were mixed in a ratio of 2:2:1 (v / v / v) to prepare the solvent for the corresponding PVK solution. The same solvent was subsequently used in other solution processes as well.

[0067] And, the thickness of the resistance contact inducing layer (230) was formed to be 3 nm.

[0068] Next, through the hole transport layer formation step (S240), two hole transport layers (240) using VNPB and PVK were stacked on one side of the resistance contact induction layer (230).

[0069] More specifically, the VNPB solution was spin-coated at 3000 rpm for 45 seconds. After spin-coating was completed, heat treatment was performed on a hot plate at a temperature of 150 ℃ for 15 minutes, followed by additional heat treatment at a temperature of 200 ℃ for 60 minutes. At this time, the thickness of the VNPB layer was formed to be 25 nm.

[0070] In addition, a PVK solution was spin-coated on one side of the VNPB layer at 3000 rpm for 45 seconds. After the spin coating was completed, heat treatment was performed on a hot plate at a temperature of 150 ℃ for 15 minutes. At this time, the thickness of the PVK layer was formed to be 5 nm.

[0071] Next, through the above-mentioned light-emitting layer formation step (S300), the light-emitting part (300) is laminated on one side of the hole transport layer (240).

[0072] More specifically, the InP solution was spin-coated at 3000 rpm for 45 seconds. After the spin coating was completed, vacuum drying was performed for 15 minutes. After vacuum drying, annealing was performed at 140°C for 30 minutes. At this time, the thickness of the light-emitting part (300) was formed to be 20 nm.

[0073] Next, through the electron transfer layer formation step (S400), an electron transfer structure (400) is laminated on one side of the light-emitting part (300).

[0074] More specifically, a ZnO nanoparticle solution was spin-coated at 2000 rpm for 45 seconds. After spin-coating was completed, annealing was performed at 180°C for 30 minutes. At this time, the thickness of the electron transfer structure (400) was formed to be 40 nm.

[0075] Next, through the cathode formation step (S500), a cathode portion (500) was laminated on one side of the electron transport structure (400). More specifically, silver (Ag) was deposited with a thickness of 80 nm.

[0076] [Comparative Example 1]

[0077] In this comparative example, the excess electron removal layer (220) and the resistance contact induction layer (230) are omitted compared to Example 1 described above.

[0078] [Comparative Example 2]

[0079] In this comparative example, the excess electron removal layer (220) compared to Example 1 described above has been omitted.

[0080] [Test Example 1]

[0081] Figure 3 is a graph showing the results of a voltage-current density comparison between an embodiment of the present invention and comparative examples.

[0082] Referring further to FIG. 3, it was confirmed that the current density in the negative voltage region did not differ significantly in the comparison results between the comparative examples. In other words, it was confirmed that the leakage current reduction effect was not pronounced solely by the presence or absence of the resistance contact induction layer (230).

[0083] However, when both the excess electron removal layer (220) and the resistance contact induction layer (230) are provided as in Example 1, a significantly superior effect of reducing leakage current at a negative voltage level compared to comparative examples was confirmed. More specifically, according to Example 1, it was analyzed that the energy injection barrier at the hole injection and hole transport interface is lowered, and at the same time, excess electrons generated at the hole injection and hole transport interface are absorbed and removed.

[0084] [Test Example 2]

[0085] Figure 4 is a graph showing the results of a comparison of current density-external quantum efficiency between the embodiments and comparative examples of the present invention.

[0086] Referring further to FIG. 4, it was confirmed that a significant difference in external quantum efficiency (EQE) occurs depending on the presence or absence of at least one of the excess electron removal layer (220) and the resistance contact induction layer (230).

[0087] More specifically, it was analyzed that a high energy barrier, such as a Schottky contact, is formed depending on the presence or absence of the resistance contact induction layer (230). In addition, as with the analysis of Test Example 1, it was analyzed that the absorption and removal efficiency of excess electrons generated at the hole injection and hole transport interfaces differs depending on the presence or absence of the excess electron removal layer (220).

[0088] As described above, the main technical concept of the present invention is to provide a hole transport structure for a quantum dot light-emitting diode, a diode utilizing the same, and a method for manufacturing the same. Furthermore, the embodiments described above with reference to the drawings are merely partial embodiments, and the scope of the present invention should be determined based on the patent claims. In addition, the scope of the present invention extends to various equivalent embodiments that can be derived. Explanation of the symbols

[0089] 1000 : Quantum dot light-emitting diode according to the present invention 100 : Positive side 200 : Hole transfer structure 210: Hole injection layer 210: Hole injection layer 220: Excess electron removal layer 230: Resistance contact inducing layer 240 : Hole transport layer 300 : Light-emitting part 400: Electron transport structure 410: Electron transport layer 420: Electron injection layer 500 : Cathode

Claims

Claim 1 A hole transport structure of a quantum dot light-emitting diode comprising: a hole injection layer; an excess electron removal layer stacked on one side of the hole injection layer; a resistance contact (Ohmic contact) inducing layer stacked on one side of the excess electron removal layer; and a hole transport layer stacked on one side of the resistance contact inducing layer, wherein the excess electron removal layer removes excess electrons generated at the interface between the hole injection layer and the resistance contact inducing layer, wherein the excess electron removal layer has a thickness of 3 nm and comprises molybdenum trioxide, wherein the resistance contact inducing layer has a thickness of 3 nm and comprises poly(n-vinylcarbazole) doped with 30 wt% phosphomolybdic acid, and wherein the hole transport layer comprises a VNPB layer having a thickness of 25 nm; and a PVK layer coated on one side of the VNPB layer with a thickness of 5 nm. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 Quantum dot light-emitting diode using a hole transport structure of a quantum dot light-emitting diode according to claim 1. Claim 10 A method for manufacturing a hole transport structure of a quantum dot light-emitting diode, comprising: a hole injection layer forming step in which a hole injection layer is deposited; an excess electron removal layer forming step in which an excess electron removal layer is stacked on one side of the hole injection layer; an induction layer forming step in which a resistance contact induction layer is stacked on one side of the excess electron removal layer; and a hole transport layer forming step in which a hole transport layer is stacked on one side of the resistance contact induction layer, wherein in the excess electron removal layer forming step, molybdenum trioxide is stacked to a thickness of 3 nm to form the excess electron removal layer, and in the induction layer forming step, poly(n-vinylcarbazole) doped with 30 wt% phosphomolybdic acid is stacked to a thickness of 3 nm to form the resistance contact induction layer, and wherein the hole transport layer forming step comprises: a step of forming a VNPB layer having a thickness of 25 nm; and a step of coating a PVK layer with a thickness of 5 nm on one side of the VNPB layer.

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