CN114447237A - A kind of quantum dot light-emitting diode and preparation method thereof - Google Patents

Abstract

The invention discloses a quantum dot light-emitting diode and a preparation method thereof, wherein the quantum dot light-emitting diode comprises a cathode, an anode and a quantum dot light-emitting layer arranged between the cathode and the anode, and the quantum dot light-emitting layer material comprises lead quantum dots and a block polymer coated on the surfaces of the lead quantum dots. The invention introduces a block polymer to modify the surface of the lead quantum dot, thereby forming a coating layer consisting of the block polymer on the surface of the lead quantum dot. On one hand, the block polymer is beneficial to the stability of the lead quantum dots, weakens the clusters of the lead quantum dots, reduces the energy transfer of the Dexter between the lead quantum dots and reduces the energy loss; on the other hand, the hydrophobicity of the block polymer and the coating structure thereof can weaken the erosion of water and oxygen, and the luminous efficiency and the service life of the quantum dot light-emitting diode are improved.

Description

A kind of quantum dot light-emitting diode and preparation method thereof

technical field

The invention relates to the field of quantum dots, in particular to a quantum dot light-emitting diode and a preparation method thereof.

Background technique

In recent years, with the rapid development of display technology, quantum dot light-emitting diodes (QLEDs) using semiconductor quantum dots (QDs) materials as light-emitting layers have received extensive attention. Quantum dot light-emitting diodes have good characteristics such as high color purity, high luminous efficiency, adjustable luminous color, and stable devices, which make them have wide application prospects in flat panel display, solid-state lighting and other fields.

The QLEDs currently studied usually adopt a sandwich structure, and the device includes an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode. Among them, the quantum dot light-emitting layer is formed by a layer of nanoparticles. The current problem is: if the concentration of nanoparticles is too low, a dense layer of quantum dots cannot be formed, that is, holes appear, which will lead to the occurrence of leakage current; If the concentration of nanoparticles is too high, the accumulation of nanoparticles will occur, that is, clusters will be formed, which will lead to Dexter energy transfer (Dexter energy transfer belongs to non-radiative energy transfer) and reduce the luminous efficiency of the device; in addition, water and oxygen Erosion of the quantum dot light-emitting layer will destroy the stability of the quantum dots, resulting in a decrease in the luminous efficiency and service life of the device.

Therefore, the existing technology still needs to be improved.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a quantum dot light emitting diode and a preparation method thereof, aiming at solving the problem of low luminous efficiency of the existing quantum dot light emitting diode.

The technical scheme of the present invention is as follows:

A quantum dot light-emitting diode, comprising a cathode, an anode, and a quantum dot light-emitting layer disposed between the cathode and the anode, wherein the quantum dot light-emitting layer material includes lead-based quantum dots and a lead-based quantum dot coated on the lead It is a block polymer on the surface of quantum dots.

A preparation method of a quantum dot light-emitting diode, comprising the steps of:

Provide anode substrate;

A quantum dot light-emitting layer is prepared on the surface of the anode substrate, and the material of the quantum dot light-emitting layer includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots;

A cathode is prepared on the surface of the quantum dot light-emitting layer to obtain the quantum dot light-emitting diode;

Alternatively, a cathode substrate is provided;

A quantum dot light-emitting layer is prepared on the surface of the cathode substrate, and the material of the quantum dot light-emitting layer includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots;

An anode is prepared on the surface of the quantum dot light-emitting layer to prepare the quantum dot light-emitting diode.

Beneficial effects: The quantum dot light-emitting diode provided by the present invention includes a quantum dot light-emitting layer disposed between the cathode and the anode, and the quantum dot light-emitting layer includes lead-based quantum dots and blocks coated on the surface of the lead-based quantum dots polymer. In the present invention, a block polymer is introduced into the lead-based quantum dots to modify the surface of the quantum dot nanoparticles, so that a coating layer composed of the block polymer is formed on the surface of the lead-based quantum dots . On the one hand, the block polymer is beneficial to the stability of lead-based quantum dots, weakens the clusters of lead-based quantum dots, reduces the Dexter energy transfer between lead-based quantum dots, and reduces energy loss, thereby effectively improving The luminous efficiency of the quantum dot light-emitting diode; on the other hand, the hydrophobicity of the block polymer and the existence of the coating layer structure can reduce the erosion of water and oxygen, which can affect the luminous efficiency and service life of the quantum dot light-emitting diode. Both improved.

Description of drawings

FIG. 1 is a schematic structural diagram of a preferred embodiment of a positive structure quantum dot light emitting diode according to the present invention.

FIG. 2 is a schematic structural diagram of a preferred embodiment of an inversion structure quantum dot light emitting diode according to the present invention.

3 is a flow chart of a preferred embodiment of a method for manufacturing a positive-type quantum dot light-emitting diode according to the present invention.

FIG. 4 is a flow chart of a preferred embodiment of a method for fabricating a quantum dot light-emitting diode with an inversion structure according to the present invention.

Detailed ways

The present invention provides a quantum dot light-emitting diode and a preparation method thereof. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Existing quantum dot light-emitting diodes usually lead to Dexter energy transfer due to the accumulation of quantum dot materials, which reduces the luminous efficiency of quantum dot light-emitting diodes, and the erosion of water and oxygen molecules easily destroys the stability of quantum dots, further reducing quantum dot light-emitting diodes. luminous efficiency and service life.

Based on the problems existing in the prior art, an embodiment of the present invention provides a quantum dot light-emitting diode, which includes a cathode, an anode, and a quantum dot light-emitting layer disposed between the cathode and the anode. The quantum dot light-emitting layer material is It includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots.

In this example, a block polymer is introduced to modify the surface of the lead-based quantum dots, so that a coating layer composed of the block polymer is formed on the surface of the lead-based quantum dots. On the one hand, the block polymer is beneficial to the stability of lead-based quantum dots, weakens the clusters of lead-based quantum dots, reduces the Dexter energy transfer between lead-based quantum dots, and reduces energy loss, thereby effectively improving The luminous efficiency of quantum dot light-emitting diodes; on the other hand, the hydrophobicity of the block polymer and the existence of the coating layer structure can reduce the erosion of water and oxygen, which can affect the luminous efficiency and service life of quantum dot light-emitting diodes Both improved.

In some embodiments, the lead-based quantum dots specifically bind to the block polymer. The specific binding refers to the binding process in which a certain ligand that can be competitively blocked by the corresponding substance interacts with a specific structural site in vitro or in vivo, such as between an antigen and an antibody or between a receptor and a ligand. combination. In this embodiment, the block polymer can specifically bind to the lead-based quantum dots, because the block polymer contains lone electrons, and the block polymer is connected to the lead-based quantum dots through the lone electrons. The empty electron orbits of lead ions in the lead-based quantum dots are matched to form a stable bond, and then a coating layer composed of block polymers is obtained on the surface of the lead-based quantum dots.

所述铅系量子点为硫化铅、硒化铅和碲化铅中的一种或多种，但不限于此。本实施例中，当所述嵌段聚合物为聚苯乙烯-聚(4-乙烯嘧啶)，所述铅系量子点为硫化铅时，所述聚苯乙烯-聚(4-乙烯嘧啶)通过聚(4-乙烯嘧啶)中氮原子的孤电子匹配所述硫化铅中铅离子的空电子轨道，使得聚苯乙烯-聚(4-乙烯嘧啶)与硫化铅二者形成稳定的结合；另外P4VP均聚物还可与硫化铅量子点表面陷阱态结合使之钝化；从而在硫化铅量子点的表面得到一层由聚苯乙烯-聚(4-乙烯嘧啶)组成的包覆层。所述包覆层的存在一是有利于硫化铅量子点的稳定性，减少所述硫化铅量子点的团簇，使得较高浓度的硫化铅量子点分布均匀，从而较少能量损耗；二是所述包覆层可以起到隔绝水氧的作用，所述包覆层中聚苯乙烯的疏水性加上包覆层结构，可以有效减弱水氧分子对量子点的侵蚀，从而提升量子点发光二极管的发光效率和使用寿命。In some embodiments, the block polymer is polystyrene-poly(4-vinylpyrimidine), poly-4-methylstyrene-poly(4-vinylpyrimidine), and poly-3-methylstyrene-polyethylene One or more of (4-vinyl pyrimidine), but not limited thereto, wherein, the molecular structural formula of the polystyrene-poly (4-vinyl pyrimidine) is:

The lead-based quantum dots are one or more of lead sulfide, lead selenide and lead telluride, but are not limited thereto. In this embodiment, when the block polymer is polystyrene-poly(4-vinylpyrimidine) and the lead-based quantum dots are lead sulfide, the polystyrene-poly(4-vinylpyrimidine) passes through The lone electron of the nitrogen atom in the poly(4-vinylpyrimidine) matches the empty electron orbit of the lead ion in the lead sulfide, so that the polystyrene-poly(4-vinylpyrimidine) and the lead sulfide form a stable combination; in addition, P4VP The homopolymer can also be combined with the surface trap states of lead sulfide quantum dots to passivate them; thus, a coating layer composed of polystyrene-poly(4-vinylpyrimidine) is obtained on the surface of lead sulfide quantum dots. The existence of the coating layer is conducive to the stability of the lead sulfide quantum dots, reducing the clusters of the lead sulfide quantum dots, so that the higher concentration lead sulfide quantum dots are evenly distributed, thereby reducing energy loss; The coating layer can play the role of isolating water and oxygen. The hydrophobicity of polystyrene in the coating layer and the coating layer structure can effectively reduce the erosion of water and oxygen molecules on the quantum dots, thereby enhancing the luminescence of quantum dots. Luminous efficiency and service life of diodes.

In some embodiments, the quantum dot light-emitting layer has a thickness of 10-60 nm.

In some embodiments, a quantum dot light-emitting diode is provided, which includes a cathode, an anode, and a quantum dot light-emitting layer disposed between the cathode and the anode, and an electronic functional layer is disposed between the cathode and the quantum dot light-emitting layer , a hole functional layer is arranged between the anode and the quantum dot light-emitting layer, wherein the quantum dot light-emitting layer material includes lead-based quantum dots and a block polymer coated on the surface of the lead-based quantum dots; The electron functional layer is one or more of a hole blocking layer, an electron injection layer and an electron transport layer, and the hole functional layer is one or more of an electron blocking layer, a hole injection layer and a hole transport layer. Various, but not limited to this.

In some specific embodiments, a quantum dot light-emitting diode with a positive structure is provided, as shown in FIG. 1 , which includes an anode disposed on the surface of the substrate, a hole injection layer disposed on the surface of the anode, and a hole disposed on the surface of the anode. A hole transport layer on the surface of the injection layer, a quantum dot light-emitting layer provided on the surface of the hole transport layer, an electron transport layer provided on the surface of the quantum dot light-emitting layer, and a cathode provided on the surface of the electron transport layer, wherein the quantum dots The point light-emitting layer material includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots.

In some embodiments, a quantum dot light-emitting diode with an inversion structure is also provided, as shown in FIG. 2 , which includes a cathode disposed on the surface of the substrate, an electron transport layer disposed on the surface of the cathode, and an electron transport layer disposed on the surface of the electron transport layer. The quantum dot light-emitting layer, the hole transport layer provided on the surface of the quantum dot light-emitting layer, the hole injection layer provided on the surface of the hole transport layer, and the anode provided on the surface of the hole injection layer, wherein the quantum dot light-emitting layer The material includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots.

In various embodiments of the present invention, the material of each functional layer is a common material in the field, such as:

In some embodiments, the substrate may be a rigid substrate (glass) or a flexible substrate.

In some embodiments, the anode may be ITO, FTO, or ZTO.

In some embodiments, the hole injection layer material may be water-soluble PEDOT:PSS, or may be other materials with good hole injection properties, such as NiO, MoO ₃ , WO ₃ or V ₂ O ₅ .

In some specific embodiments, the hole injection layer material is PEDOT:PSS, and its thickness is 10-100 nm.

In some embodiments, the hole transport layer material may be commonly used poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), poly(N ,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine)(Poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N -Phenyl-1,4-phenylenediamine) (PFB), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazole) ) biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), One or more of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), which can also be Other high-performance hole transport materials, such as MoO ₃ , WoO ₃ , NiO, CuO, V2O5, CuS, etc.

In some specific embodiments, the hole transport layer has a thickness of 1-100 nm.

In some embodiments, the electron transport layer material is selected from materials with good electron transport properties, which can be but not limited to n-type ZnO, TiO ₂ , Fe ₂ O ₃ , Ta ₂ O ₃ , AlZnO, ZnSnO, etc. one or more.

In some specific embodiments, the material of the electron transport layer is n-type ZnO with a thickness of 60-120 nm.

In some embodiments, the cathode may be Au, Ag, Al, Cu, Mo, or alloys thereof.

In some embodiments, a method for preparing a positive structure quantum dot light-emitting diode is also provided, as shown in FIG. 3 , which includes the steps:

S10. Provide an anode substrate, and prepare a hole transport layer on the anode substrate;

S20, mixing the lead-based quantum dot solution with the block polymer solution, so that the block polymer is coated on the surface of the lead-based quantum dots to prepare a composite material solution;

S30, depositing the composite material solution on the surface of the hole transport layer to prepare a quantum dot light-emitting layer;

S40, preparing an electron transport layer on the surface of the quantum dot light-emitting layer;

S50, preparing a cathode on the surface of the electron transport layer to prepare the quantum dot light-emitting diode.

In each embodiment of the present invention, the preparation method of each layer may be a chemical method or a physical method, wherein the chemical method includes but is not limited to chemical vapor deposition method, continuous ion layer adsorption and reaction method, anodization method, electrolytic deposition method, co-precipitation method One or more of; physical methods include but are not limited to solution methods (such as spin coating, printing, blade coating, dip-pulling, immersion, spraying, roll coating, casting, slot coating method or strip coating method, etc.), evaporation method (such as thermal evaporation method, electron beam evaporation method, magnetron sputtering method or multi-arc ion coating method, etc.), deposition method (such as physical vapor deposition method) , atomic layer deposition, pulsed laser deposition, etc.) one or more.

In some embodiments, a preparation method of an inversion structure quantum dot light-emitting diode is also provided, as shown in FIG. 4 , which includes the steps:

S100. Provide a cathode substrate, and prepare an electron transport layer on the cathode substrate;

S200, mixing the lead-based quantum dot solution with the block polymer solution, so that the block polymer coats the surface of the lead-based quantum dots to prepare a composite material solution;

S300, depositing the composite material solution on the surface of the electron transport layer to prepare a quantum dot light-emitting layer;

S400, preparing a hole transport layer on the surface of the quantum dot light-emitting layer;

S500, an anode is prepared on the surface of the hole transport layer to prepare the quantum dot light-emitting diode.

The preparation method of a quantum dot light-emitting diode of the present invention will be further explained below through specific examples:

Example 1

First, the patterned ITO substrate was placed in acetone, washing solution, deionized water and isopropanol in order for ultrasonic cleaning, and each step of ultrasonics lasted for about 15 minutes. After the ultrasonic wave is completed, the ITO is placed in a clean oven to dry for use. After the ITO substrate is dried, the surface of the ITO is treated with ultraviolet-ozone for 5 minutes to further remove the organic matter attached to the surface of the ITO and improve the work function of the ITO;

Then, a hole injection layer PEDOT:PSS was deposited on the ITO substrate processed in the previous step, the thickness of this layer was 30 nm, and the substrate was heated on a heating table at 150 ° C for 30 minutes to remove moisture. done in air;

Next, place the dried substrate coated with the hole injection layer in a nitrogen atmosphere, deposit a layer of hole transport layer material TFB, the thickness of this layer is 30nm, and place the substrate on a heating table at 150°C for heating. 30 minutes to remove solvent;

PS-P4VP was prepared into 2mg/ml chloroform solution, and then 1ml of the solution was added to 9ml of lead sulfide quantum dot toluene solution to obtain modified lead sulfide quantum dots, dried to obtain powder, and then the powder was dissolved in toluene The desired modified quantum dot solution is obtained. After the sheet treated in the previous step was cooled, the modified quantum dot solution was spin-coated on the hole transport layer, and then placed in a vacuum of 1 × 10 ^-3 Pa for 2 hours with a thickness of about 20 nm to obtain quantum dots. point light-emitting layer;

Subsequently, a layer of ZnO electron transport layer is deposited on the surface of the quantum dot light-emitting layer, and after the deposition is completed, the wafer is placed on a heating table at 80°C for 30 minutes, and its thickness is 30nm;

Finally, the wafers on which each functional layer has been deposited are placed in an evaporation chamber, and a layer of 100 nm silver is thermally evaporated through a mask as a cathode, and the device preparation is completed.

To sum up, the quantum dot light-emitting diode provided by the present invention includes a quantum dot light-emitting layer disposed between the cathode and the anode, and the quantum dot light-emitting layer includes lead-based quantum dots and a lead-based quantum dot coated on the surface of the lead-based quantum dot. block polymer. In the present invention, a block polymer is introduced into the lead-based quantum dots to modify the surface of the quantum dot nanoparticles, so that a coating layer composed of the block polymer is formed on the surface of the lead-based quantum dots . On the one hand, the block polymer is beneficial to the stability of lead-based quantum dots, weakens the clusters of lead-based quantum dots, reduces the Dexter energy transfer between lead-based quantum dots, and reduces energy loss, thereby effectively improving the performance of the lead-based quantum dots. The luminous efficiency of quantum dot light-emitting diodes; on the other hand, the hydrophobicity of the block polymer and the existence of the coating layer structure can reduce the erosion of water and oxygen, which can affect the luminous efficiency and service life of quantum dot light-emitting diodes Both improved.

It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. a quantum dot light-emitting diode, comprising a cathode, an anode and a quantum dot light-emitting layer arranged between the cathode and the anode, wherein the quantum dot light-emitting layer material comprises lead-based quantum dots and a coating A block polymer on the surface of the lead-based quantum dots. 2 . The quantum dot light-emitting diode according to claim 1 , wherein the quantum dot light-emitting layer material is composed of lead-based quantum dots and a block polymer coated on the surface of the lead-based quantum dots. 3 . 3 . The quantum dot light-emitting diode according to claim 1 , wherein the block polymer specifically binds to the lead-based quantum dots. 4 . 4 . The quantum dot light-emitting diode according to claim 1 , wherein the block polymer contains lone electrons, and the block polymer passes through the lone electrons and lead ions in the lead-based quantum dots. 5 . Empty electron orbital matching binding. 5. The quantum dot light-emitting diode according to claim 1, wherein the block polymer is polystyrene-poly(4-vinylpyrimidine), poly-4-methylstyrene-poly(4-ethylene) pyrimidine) and one or more of poly-3-methylstyrene-poly(4-vinylpyrimidine). 6 . The quantum dot light-emitting diode according to claim 1 , wherein the lead-based quantum dots are one or more of lead sulfide, lead selenide and lead telluride. 7 . 7 . The quantum dot light-emitting diode according to claim 1 , wherein the quantum dot light-emitting layer has a thickness of 10-60 nm. 8 . 8. A method for preparing a quantum dot light-emitting diode, comprising the steps of: Provide anode substrate; A quantum dot light-emitting layer is prepared on the surface of the anode substrate, and the material of the quantum dot light-emitting layer includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots; A cathode is prepared on the surface of the quantum dot light-emitting layer to obtain the quantum dot light-emitting diode; Alternatively, a cathode substrate is provided; A quantum dot light-emitting layer is prepared on the surface of the cathode substrate, and the material of the quantum dot light-emitting layer includes lead-based quantum dots and block polymers coated on the surface of the lead-based quantum dots; An anode is prepared on the surface of the quantum dot light-emitting layer to prepare the quantum dot light-emitting diode. 9 . The method for preparing a quantum dot light-emitting diode according to claim 8 , wherein the block polymer is specifically bound to the lead-based quantum dots. 10 . 10. The method for preparing a quantum dot light-emitting diode according to claim 8, wherein the step of preparing the quantum dot light-emitting layer on the surface of the anode substrate comprises: Mixing the lead-based quantum dot solution with the block polymer solution to coat the block polymer on the surface of the lead-based quantum dots to prepare a composite material solution; Depositing the composite material solution on the surface of the anode substrate to prepare a quantum dot light-emitting layer; Alternatively, the step of preparing the quantum dot light-emitting layer on the surface of the cathode substrate includes: Mixing the lead-based quantum dot solution with the block polymer solution to coat the block polymer on the surface of the lead-based quantum dots to prepare a composite material solution; The composite material solution is deposited on the surface of the cathode substrate to prepare a quantum dot light-emitting layer.

Images