CN109994622B - QLED device - Google Patents

QLED device Download PDF

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CN109994622B
CN109994622B CN201711473694.0A CN201711473694A CN109994622B CN 109994622 B CN109994622 B CN 109994622B CN 201711473694 A CN201711473694 A CN 201711473694A CN 109994622 B CN109994622 B CN 109994622B
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functional layer
composite functional
qled device
cathode
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CN109994622A (en
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李泽伟
曹蔚然
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TCL Technology Group Co Ltd
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00Organic light-emitting devices
    • H10K50/10OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/115OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00Constructional details relating to the organic devices covered by this subclass

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Abstract

The invention discloses a QLED device, which comprises a cathode, an anode and a lamination layer arranged between the cathode and the anode, wherein the lamination layer is formed by laminating a quantum dot light-emitting layer and a composite functional layer; the composite functional layer comprises a polymer and titanate nanorods dispersed in the polymer; wherein, the titanate nanorods are vertically arranged relative to the plane of the anode and/or the cathode.

Description

QLED device
Technical Field
The invention relates to the field of quantum dot light emitting devices, in particular to a QLED device and a preparation method thereof.
Background
In quantum dot light emitting diodes (QLEDs) and Organic Light Emitting Diodes (OLEDs), n-type metal oxides and organic materials are often used as electron transport layers and hole transport layers, respectively, to improve device efficiency. The use of n-type metal oxide semiconductors such as zinc oxide, titanium dioxide, etc. can significantly improve electron injection into the device. However, the Cd-based quantum dots have a deeper valence band energy level, and have a certain blocking effect on hole injection. In addition, electron mobility of electron transport materials such as zinc oxide and titanium dioxide is generally 10-3cm2V-1S-1In excess of the mobility of most organic hole transport materials.
In addition, the metal oxide semiconductor nanocrystal has a relatively large specific surface area, a large number of defects exist on the surface of the metal oxide semiconductor nanocrystal, the recombination efficiency of carriers of a light emitting layer can be influenced by the defect energy levels with obvious trap effects, and the surface defects are easy to adsorb water molecules and oxygen molecules in the environment, so that the service life of the device is reduced; in addition, the metal oxide semiconductor nanocrystal for preparing the QLED device is usually prepared by adopting a solution method with low cost and simple and convenient process, and the surface of the metal oxide semiconductor nanocrystal prepared by the solution method is easy to carry a large amount of hydroxyl, carboxyl and other dangling bonds, so that defect energy levels are also easy to introduce, and the luminous efficiency and the stability of the device are influenced.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a QLED device and a preparation method thereof, and aims to solve the problem of low luminous efficiency caused by unbalanced carriers in the conventional QLED device.
The technical scheme of the invention is as follows:
a QLED device comprises a cathode and an anode, and a laminated layer arranged between the cathode and the anode, wherein the laminated layer is formed by laminating a quantum dot light-emitting layer and a composite functional layer;
the composite functional layer comprises a polymer matrix and titanate nanorods dispersed in the polymer matrix;
wherein, the titanate nanorods are vertically arranged relative to the plane of the anode and/or the cathode.
The QLED device, wherein the composite functional layer is disposed adjacent to the anode, and the quantum dot light emitting layer is disposed adjacent to the cathode; the material of the polymer matrix is selected from polymers having hole transport properties.
The QLED device, wherein the polymer having hole transport properties is selected from one of poly (9, 9-dioctylfluorene-CO-N (4-butylphenyl) diphenylamine), polyvinylcarbazole, and N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine.
The QLED device is characterized in that the composite functional layer is arranged close to the cathode, and the quantum dot light-emitting layer is arranged close to the anode; the material of the polymer matrix is selected from polymers with electron transport properties.
The QLED device, wherein the polymer having an electron transport property is one selected from 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline, 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -triazole, and phenazopyridinium.
The QLED device is characterized in that the titanate nanorods are selected from one of barium titanate nanorods, strontium titanate nanorods, calcium titanate nanorods, bismuth titanate nanorods and dopants thereof.
The QLED device is characterized in that the titanate nanorods account for 20-40% of the volume fraction of the composite function layer.
A QLED device comprises a cathode, an anode and a laminated layer arranged between the cathode and the anode, wherein the laminated layer is formed by sequentially laminating a first composite functional layer, a quantum dot light-emitting layer and a second composite functional layer, and the first composite functional layer is arranged close to the anode; the second composite functional layer is arranged close to the cathode;
the first composite functional layer and the second composite functional layer comprise a polymer matrix and titanate nanorods dispersed in the polymer matrix;
wherein, the titanate nanorods are vertically arranged relative to the plane of the anode and/or the cathode.
The QLED device is characterized in that the material of the polymer matrix in the first composite functional layer is selected from polymers with hole transport characteristics, and the volume fraction of titanate nanorods in the composite functional layer is 20-40%.
The QLED device is characterized in that the material of the polymer matrix in the second composite functional layer is selected from polymers with electron transport characteristics, and the volume fraction of titanate nanorods in the composite functional layer is 20-40%.
Has the advantages that: in the composite functional layer, the titanate nanorods can reduce the injection barrier of current carriers by an internal electric field arranged after being polarized by an external electric field, and the balance between electrons and holes in a QLED device is facilitated, so that the luminous efficiency of the QLED device is improved. In addition, an interface with a certain area exists between the titanate nanorods and the polymer material, space charge polarization can be generated at the interface under the action of an external electric field, a large amount of dipole moment is accumulated, great help is also provided for reducing the potential barrier of carriers between the transmission layer and the quantum dot light emitting layer, and the balance between electrons and holes in the QLED device is further realized, so that the light emitting efficiency of the QLED device is improved.
Drawings
Fig. 1 is a schematic structural diagram of a QLED device according to a preferred embodiment of the present invention.
Fig. 2 is a schematic structural diagram of another preferred embodiment of a QLED device according to the present invention.
Fig. 3 is a schematic structural diagram of a QLED device according to another preferred embodiment of the present invention.
Detailed Description
The invention provides a QLED device and a preparation method thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The composite functional layer can be used as a hole transport layer and applied to various existing QLED device structures. Specifically, fig. 1 is a schematic structural diagram of a QLED device according to a preferred embodiment of the present invention, and as shown in fig. 1, a positive QLED device is taken as an example in the embodiment of the present invention, the QLED device sequentially includes, from bottom to top, an anode substrate 10, a hole injection layer 11, a composite functional layer 12, a quantum dot light emitting layer 13, an electronic functional layer 14, and a cathode layer 15, where the composite functional layer 12 includes a polymer matrix and titanate nanorods dispersed in the polymer matrix, and the titanate nanorods are vertically arranged with respect to a plane where the anode substrate 10 and/or the cathode layer 15 are located.
In the embodiment of the present invention, the composite functional layer 12 serves as a hole transport layer of the QLED device. According to the invention, by using the dipole moment effect of the titanate nanorods in the composite function layer and the space charge effect in the composite material, the potential barrier of carriers between the hole injection layer and the quantum dot light emitting layer can be reduced, so that the number of holes and electrons injected into the quantum dots is closer, the effect of balancing the carriers is achieved, and the performance and the service life of the QLED device are improved. In addition, compared with a composite material (such as Au/TFB composite material and MWCNT/TFB composite material) which improves hole injection by improving the conductivity of a hole transport layer by adding a conductive material, the titanate used in the invention is an insulating material, and can prevent the deterioration of the device performance caused by too high leakage current.
Preferably, the titanate nanorod is composed of titanate which is a titanic acid compound having ferroelectricity, preferably one selected from barium titanate, strontium titanate, calcium titanate, bismuth titanate and their dopants (such as barium strontium titanate, sodium bismuth titanate, etc.). In other words, the titanate nanorods are selected from one of barium titanate nanorods, strontium titanate nanorods, calcium titanate nanorods, bismuth titanate nanorods, and dopants thereof.
Titanate has unique ferroelectricity under the nanometer size, dipole moment can be formed inside the material under the action of an external electric field, for example, barium titanate is taken as an example, the crystal of a barium titanate nanorod has a tetragonal phase perovskite structure, and Ti in the structure has a tetragonal phase perovskite structure4+(titanium ion) in O2-(oxygen ion) oxygen octahedron center, Ba2+The (barium ions) are in the gaps surrounded by eight oxygen octahedrons, and Ti is in the gap under the action of an external electric field4+The ion displacement polarization is generated along the electric field direction, a dipole moment is formed inside the crystal, and even if the electric field is cancelled, a certain inner electric field can be still maintained inside the barium titanate crystal, so that the injection barrier of carriers can be reduced by the inner electric field formed by the titanate nanorods after the polarization by the outer electric field, the balance between electrons and holes in the QLED device is favorably realized, and the luminous efficiency of the QLED device is improved. In addition, an interface with a certain area exists between the titanate nanorods and the polymer material, space charge polarization can be generated at the interface under the action of an external electric field, a large amount of dipole moment is accumulated, great help is also provided for reducing the potential barrier of carriers between the transmission layer and the quantum dot light emitting layer, and the balance between electrons and holes in the QLED device is further realized, so that the light emitting efficiency of the QLED device is improved.
Preferably, the volume fraction of the titanate nanorods in the composite functional layer is 20-40%. The volume fraction of the titanate nanorods is too low to obviously improve the effect of carrier injection efficiency, and the too high volume fraction of the titanate nanorods easily causes a large number of defects to be introduced into a composite functional layer, thereby not only affecting the film forming effect, but also causing the electrical performance of a device to deteriorate. It is to be understood that under the basic idea of the invention, the invention can also be dispersed in the polymer matrix by adding auxiliary materials such as dispersants, conductive fillers, anti-settling agents, etc. A dispersing agent can be added into the polymer matrix to improve the dispersing effect of the titanate nanorods in the polymer; other conductive fillers can be added to reduce the conductivity of the polymer matrix and improve the mobility of carriers; an anti-settling agent can be added to prevent the titanate nanorods from coagulation.
Preferably, the material of the polymer matrix in the composite functional layer is selected from polymers with hole transport properties, which may be, but not limited to, one of poly (9, 9-dioctylfluorene-CO-N (4-butylphenyl) diphenylamine) (TFB), Polyvinylcarbazole (PVK), N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine (NPB).
Specifically, as shown in fig. 2, in the embodiment of the invention, a positive-type QLED device is taken as an example, the QLED device includes, in order from bottom to top, an anode substrate 20, a hole function layer 21, a quantum dot light-emitting layer 22, a composite function layer 23, an electronic function layer 24, and a cathode layer 25, where the composite function layer 23 includes a polymer matrix and titanate nanorods dispersed in the polymer matrix, and the titanate nanorods are vertically arranged with respect to a plane where the anode substrate 20 and/or the cathode layer 25 are located.
In this embodiment, the composite functional layer 23 is an interface buffer layer. The interfacial buffer layer mainly plays two roles: a buffer energy band is introduced between the electronic function layer and the quantum dot luminescent layer under the action of dipole moment of titanate in the buffer layer and the action of space charge in the composite material, so that electrons can be injected into the quantum dot luminescent layer at lower voltage, and the efficiency and the service life of a device are improved; the quantum dot luminescent layer material and the electronic functional layer are blocked, and the defect state introduced by the interface is reduced, so that the exciton quenching effect caused by the defect state is relieved.
Preferably, the composite functional layer is disposed near the cathode, and the polymer matrix material in the composite functional layer is selected from polymers having electron transport properties, which may be, but not limited to, one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline, 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -triazole, and phenazopyridinium beryllium, and the like.
Preferably, the titanate nanorods are composed of titanate, which is a titanic acid compound having ferroelectricity, preferably one selected from barium titanate, strontium titanate, calcium titanate, bismuth titanate and their dopants (such as barium strontium titanate, bismuth sodium titanate, etc.). In other words, the titanate nanorods are selected from one of barium titanate nanorods, strontium titanate nanorods, calcium titanate nanorods, bismuth titanate nanorods, and dopants thereof.
Preferably, the volume fraction of the titanate nanorods in the composite functional layer is 20-40%. The volume fraction of the titanate nanorods is too low to obviously improve the effect of carrier injection efficiency, and the too high volume fraction of the titanate nanorods easily causes a large number of defects to be introduced into a composite functional layer, thereby not only affecting the film forming effect, but also causing the electrical performance of a device to deteriorate. It is to be understood that under the basic idea of the invention, the invention can also be dispersed in the polymer matrix by adding auxiliary materials such as dispersants, conductive fillers, anti-settling agents, etc. A dispersing agent can be added into the polymer matrix to improve the dispersing effect of the titanate nanorods in the polymer; other conductive fillers can be added to reduce the conductivity of the polymer matrix and improve the mobility of carriers; an anti-settling agent can be added to prevent the titanate nanorods from coagulation.
Specifically, fig. 3 is a schematic structural diagram of a QLED device according to another preferred embodiment of the present invention, as shown in fig. 3, a positive QLED device is taken as an example in the embodiment of the present invention, the QLED device includes, in order from bottom to top, an anode substrate 30, a hole injection layer 31, an electron blocking layer 32, a first composite functional layer 33, a quantum dot light emitting layer 34, a second composite functional layer 35, an electronic functional layer 36, and a cathode layer 37, where the first composite functional layer 33 includes a polymer matrix and titanate nanorods dispersed in the polymer matrix, and the titanate nanorods are vertically arranged with respect to a plane where the anode substrate and/or the cathode layer are located; the second composite functional layer 35 includes a polymer matrix and titanate nanorods dispersed in the polymer matrix, and the titanate nanorods are vertically aligned with respect to a plane in which the anode substrate 30 and/or the cathode layer 37 are located. For more details on titanate nanorods and composite functional layers, see above, they are not repeated here.
Preferably, the first composite functional layer is disposed adjacent to the anode, the first composite functional layer 33 serves as a hole transport layer, and the polymer matrix material in the first composite functional layer is selected from a polymer having a hole transport property, which may be, but not limited to, one of 4,4',4 ″ -tris (carbazol-9-yl) triphenylamine (TCTA), N ' -bis (1-naphthyl) N, N ' -diphenyl- (1,1' -biphenyl) -4,4' -diamine (NPBX).
Preferably, when the second composite functional layer is disposed near the cathode and the second composite functional layer 35 serves as an interface buffer layer, the polymer matrix material in the second composite functional layer is selected from polymers having electron transport properties, which may be, but not limited to, 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (BCP), 4, 7-diphenyl-1, 10-phenanthroline (Bphen), 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -Triazole (TAZ), and phenazopyridinium beryllium (be) (pp)2) One kind of (1).
According to the invention, the first composite functional layer is used as a hole transport layer, the dipole moment effect of the medium titanate nanorods of the first composite functional layer and the space charge effect in the composite material can reduce the potential barrier of carriers between the hole injection layer and the quantum dot light emitting layer, so that the number of holes and electrons injected into the quantum dots is closer, the effect of balancing the carriers is achieved, and the performance and the service life of the QLED device are improved. In addition, compared with a composite material (such as Au/TFB composite material and MWCNT/TFB composite material) which improves hole injection by improving the conductivity of a hole transport layer by adding a conductive material, the titanate used in the invention is an insulating material, and can prevent the deterioration of the device performance caused by too high leakage current. The invention adds a second composite function layer between the electronic function layer and the quantum dot luminescent layer, and the second composite function layer is used as an interface buffer layer and mainly plays two roles: a buffer energy band is introduced between the electronic function layer and the quantum dot luminescent layer under the action of dipole moment of titanate in the buffer layer and the action of space charge in the composite material, so that electrons can be injected into the quantum dot luminescent layer at lower voltage, and the efficiency and the service life of a device are improved; the quantum dot luminescent layer material and the electronic functional layer are blocked, and the defect state introduced by the interface is reduced, so that the exciton quenching effect caused by the defect state is relieved.
In the invention, the first composite functional layer is arranged close to the anode, and means that other conventional layer structures can be formed between the anode and the first composite layer in a stacking mode. Similarly, in the present invention, the second composite functional layer is disposed close to the cathode, which means that other conventional layer structures can be formed by stacking between the cathode and the second composite layer.
Based on the above quantum dot light emitting diode, in combination with the specific embodiment of the present invention, there is also provided a method for manufacturing a QLED device, where the method includes a step of preparing a first composite functional layer, and the step of preparing the first composite functional layer includes:
providing a solution comprising a first polymer and titanate nanorods;
depositing the solution on a substrate;
arranging titanate nanorods in the solution along a direction vertical to the plane of the substrate under the action of an electric field;
and volatilizing the solvent through annealing treatment to obtain the first composite functional layer.
The material of the first composite functional layer is prepared by blending a first polymer and titanate nanorods. Wherein the temperature of the annealing treatment is 60-100 ℃, and the time of the annealing treatment is 20-40 min.
Specifically, the preparation method of the QLED device of the present invention includes the steps of:
s10, depositing a hole injection layer 11 on the surface of the anode substrate 10;
s20, depositing a composite functional layer 12 on the surface of the hole injection layer 11;
s30, depositing a quantum dot light-emitting layer 13 on the surface of the composite functional layer 12;
s40, depositing an electronic function layer 14 on the surface of the quantum dot light-emitting layer 13;
s50, depositing a cathode layer 15 on the surface of the electronic function layer 14 to obtain the QLED device.
Specifically, when the quantum dot light emitting diode device as illustrated in fig. 1 is manufactured, the composite functional layer 12 in step S20 may be manufactured by using a solution method, which may be, but is not limited to, one of a spin coating method, a printing method, a blade coating method, a dip-coating method, a dipping method, a spray coating method, a roll coating method, a casting method, a slit coating method, and a stripe coating method. After the deposition of the composite functional layer 12 is completed, titanate nanorods are arranged in a direction perpendicular to the substrate plane through electrical induction, and finally, the solvent is volatilized through annealing treatment such as annealing at 80 ℃ for 30min, so that the preparation of the composite functional layer 12 is completed.
Specifically, the preparation method of the QLED device of the present invention includes the steps of:
s10', sequentially depositing a hole injection layer 31 and a hole transport layer 32 on the surface of the anode substrate 30;
s20', depositing a first composite function layer 33 on the surface of the hole transport layer 32;
s30', depositing a quantum dot light-emitting layer 34 on the surface of the first composite functional layer 33;
s40', depositing a second composite function layer 35 on the surface of the quantum dot light-emitting layer 34;
s50' depositing an electronic functional layer 36 on the surface of the second composite functional layer 35;
s60', depositing a cathode layer 37 on the surface of the electronic function layer 36 to obtain the QLED device.
Further, in the present invention, the deposition method of each layer may be a chemical method or a physical method, wherein the chemical method includes, but is not limited to, one or more of a chemical vapor deposition method, a successive ionic layer adsorption and reaction method, an anodic oxidation method, an electrolytic deposition method, and a coprecipitation method; the physical method includes, but is not limited to, one or more of spin coating, printing, knife coating, dip coating, dipping, spraying, roll coating, casting, slit coating, bar coating, thermal evaporation, electron beam evaporation, magnetron sputtering, multi-arc ion coating, physical vapor deposition, atomic layer deposition, and pulsed laser deposition.
The present invention will be described in detail below with reference to examples.
Example 1
The preparation steps of the QLED device of this example are as follows:
1. deposition of PEDOT on a substrate containing an ITO anode: a PSS hole injection layer;
2. depositing a first composite functional layer consisting of TFB and barium titanate nanorods on the hole injection layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent, thereby completing the preparation of the first composite functional layer;
3. depositing a CdSeCdS quantum dot light-emitting layer on the first composite functional layer;
4. depositing a ZnO electron transmission layer on the quantum dot light-emitting layer;
5. and manufacturing a cathode Al on the electron transport layer, and packaging to obtain the QLED device with the positive structure.
Example 2
The preparation steps of the QLED device of this example are as follows:
1. sequentially depositing PEDOT: a PSS hole injection layer and a TFB hole transport layer;
2. preparing a first composite functional layer consisting of TCTA and barium titanate nanorods on the hole transport layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent so as to finish the preparation of the first composite functional layer;
3. depositing a CdSeCdS quantum dot light-emitting layer on the first composite functional layer;
4. preparing a second composite functional layer consisting of TPBi and barium titanate nanorods on the quantum dot light-emitting layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent so as to finish the preparation of the second composite functional layer;
5. depositing an electron transport layer ZnO on the second composite functional layer;
6. and manufacturing a cathode Al on the electron transport layer, and packaging to obtain the QLED device with the positive structure.
Example 3
The preparation steps of the QLED device of this example are as follows:
1. depositing a ZnO electron transport layer on a substrate containing an ITO cathode;
2. depositing a CdSeCdS quantum dot light-emitting layer on the electron transport layer;
3. depositing a first composite functional layer consisting of TFB and barium titanate nanorods on the quantum dot light-emitting layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent, thereby completing the preparation of the first composite functional layer;
4. depositing a layer of PEDOT: a PSS hole injection layer;
5. and manufacturing an anode Al on the hole injection layer, and packaging to obtain the QLED device with the inverted structure.
Example 4
The preparation steps of the QLED device of this example are as follows:
1. depositing a ZnO electron transport layer on a substrate containing an ITO cathode;
2. preparing a first composite functional layer consisting of TPBi and barium titanate nanorods on the electron transport layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent so as to finish the preparation of the first composite functional layer;
3. depositing a CdSeCdS quantum dot light-emitting layer on the first composite functional layer;
4. preparing a second composite functional layer consisting of TCTA and barium titanate nanorods on the quantum dot light-emitting layer, arranging the barium titanate nanorods along a direction vertical to the plane of the substrate through electric induction, and finally annealing at 80 ℃ for 30min to volatilize the solvent so as to finish the preparation of the second composite functional layer;
5. and sequentially depositing a TFB hole transport layer and PEDOT on the second composite functional layer: a PSS hole injection layer;
6. and manufacturing an anode Al on the hole injection layer, and packaging to obtain the QLED device with the inverted structure.
In summary, in the composite functional layer of the present invention, the internal electric field formed by the titanate nanorods after being polarized by the external electric field can reduce the injection barrier of the carriers, which is beneficial to realizing the balance between electrons and holes in the QLED device, thereby improving the light emitting efficiency of the QLED device. In addition, an interface with a certain area exists between the titanate nanorods and the polymer material, space charge polarization can be generated at the interface under the action of an external electric field, a large amount of dipole moment is accumulated, great help is also provided for reducing the potential barrier of carriers between the transmission layer and the quantum dot light emitting layer, and the balance between electrons and holes in the QLED device is further realized, so that the light emitting efficiency of the QLED device is improved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (10)

1. A QLED device is characterized by comprising a cathode, an anode and a laminated layer arranged between the cathode and the anode, wherein the laminated layer is formed by laminating a quantum dot light-emitting layer and a composite functional layer;
the composite functional layer comprises a polymer matrix and titanate nanorods dispersed in the polymer matrix;
wherein, the titanate nanorods are vertically arranged relative to the plane of the anode and/or the cathode.
2. A QLED device according to claim 1, wherein the composite functional layer is disposed adjacent an anode and the quantum dot light emitting layer is disposed adjacent a cathode; the material of the polymer matrix is selected from polymers having hole transport properties.
3. A QLED device according to claim 2, wherein the polymer with hole transporting properties is selected from one of poly (9, 9-dioctylfluorene-CO-N (4-butylphenyl) diphenylamine), polyvinylcarbazole and N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine.
4. A QLED device according to claim 1, wherein the composite functional layer is disposed adjacent to a cathode and the quantum dot light emitting layer is disposed adjacent to an anode; the material of the polymer matrix is selected from polymers with electron transport properties.
5. The QLED device according to claim 4, wherein the polymer having electron transport properties is one selected from the group consisting of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline, 3- (4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -triazole and phenazopyridinium beryllium.
6. The QLED device of any of claims 1-5, wherein the titanate nanorods are selected from one of barium titanate nanorods, strontium titanate nanorods, calcium titanate nanorods, bismuth titanate nanorods, and their dopants.
7. The QLED device of any of claims 1 to 5, wherein the titanate nanorods comprise 20-40% volume fraction of the composite functional layer.
8. A QLED device is characterized by comprising a cathode, an anode and a lamination layer arranged between the cathode and the anode, wherein the lamination layer is formed by sequentially laminating a first composite functional layer, a quantum dot light-emitting layer and a second composite functional layer, and the first composite functional layer is arranged close to the anode; the second composite functional layer is arranged close to the cathode;
the first composite functional layer and the second composite functional layer comprise a polymer matrix and titanate nanorods dispersed in the polymer matrix;
wherein, the titanate nanorods are vertically arranged relative to the plane of the anode and/or the cathode.
9. The QLED device of claim 8, wherein the material of the polymer matrix in the first composite functional layer is selected from polymers with hole transport properties, and the volume fraction of the titanate nanorods in the composite functional layer is 20-40%.
10. The QLED device of claim 8, wherein the material of the polymer matrix in the second composite functional layer is selected from polymers with electron transport properties, and the volume fraction of the titanate nanorods in the composite functional layer is 20-40%.
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