Quantum dot device and preparation method thereof

Abstract

The invention provides a quantum dot device and a preparation method of the quantum dot device. The quantum dot device comprises an electron transport layer and a strong n-type layer, wherein an adhesion layer is further arranged between the electron transport layer and the strong n-type layer, and the adhesion layer is used for enhancing the adhesion between the electron transport layer and the strong n-type layer. According to the preparation method of the quantum dot device, the following effective effects can be brought by spin coating of the adhesion layer: 1, a layer of hydroxyl (the adhesion layer is a polyethoxy ethyleneimine solution) is formed on the surface of the electron transport layer C60, so that the growth of the tin oxide layer is facilitated; due to the property of the adhesion layer, the mechanical strength and the tensile property of the whole film can be improved, and the adhesiveness of the film is also improved. And later preparation and production of the device are facilitated.

Description

Technical Field

[0001] The present application relates to the field of infrared detection technology, and in particular to a quantum dot device and a method for preparing the quantum dot device. Background Art

[0002] Infrared light is a form of electromagnetic radiation that is ubiquitous in natural and artificial environments. Infrared imaging technology has greater application potential in emerging fields such as intelligent sensing, machine vision, and autonomous driving. However, infrared light cannot be directly perceived by the naked eye. Therefore, infrared photodetectors were invented to detect infrared light, and photoactive materials play a vital role in this process, among which semiconductor materials are usually used. Commercial infrared photodetectors are usually made of traditional narrow-bandgap bulk inorganic semiconductors (such as InSb, Ge, HgCdTe, InGaAs). However, bulk semiconductor materials are quite limited. First, they are usually grown under extreme temperature and vacuum conditions, which is very costly. Second, the epitaxial growth method commonly used is epitaxial growth on a lattice-matched crystal substrate, which makes this type of infrared photodetector expensive, inflexible, and limited. Therefore, there is an urgent need for alternative materials for infrared detectors with small size, low dark current, and low energy consumption.

[0003] Compared with traditional bulk semiconductors, infrared quantum dots have the advantages of easy processing, good flexibility and photostability, and high absorption coefficient. Colloidal photodetectors have the advantages of adjustable corresponding bands, excellent detection performance, low price, and process compatibility. They have shown great potential to replace silicon-based pixel arrays and achieve full coverage imaging in the short-wave infrared band.

[0004] However, the interlayer adhesion in existing quantum dot devices is weak, which slightly reduces the performance of infrared detectors.

[0005] Application Contents

[0006] In view of the above problems, the present application provides a quantum dot device and a method for preparing the quantum dot device.

[0007] In a first aspect, a quantum dot device is provided, the quantum dot device comprising: an electron transport layer and a strong n-type layer;

[0008] Wherein, an adhesion layer is further included between the electron transport layer and the strong n-type layer, and the adhesion layer is used to enhance the adhesion between the electron transport layer and the strong n-type layer.

[0009] Wherein, the adhesive layer material is polyethoxyethyleneimine.

[0010] Wherein, the quantum dot device further comprises:

[0011] bottom electrode layer;

[0012] An electron blocking layer, disposed on the bottom electrode layer;

[0013] A p-type layer is disposed on a side of the electron blocking layer away from the bottom electrode layer;

[0014] The active layer is arranged on the side of the p-type layer away from the bottom electrode layer; wherein the electron transport layer is arranged on the side of the active layer away from the bottom electrode layer; and the strong n-type layer is arranged on the side of the electron transport layer away from the bottom electrode layer;

[0015] The top electrode layer is arranged on a side of the strong n-type layer away from the bottom electrode layer.

[0016] Wherein, the materials of the top electrode layer and the bottom electrode layer are indium tin oxide;

[0017] The material of the electron blocking layer is NiOX;

[0018] The material of the p-type layer is PbS;

[0019] The material of the electron transport layer is C 60 ;

[0020] The material of the strong n-type layer is SnO2.

[0021] In a second aspect, the present application provides a method for preparing a quantum dot device, comprising:

[0022] preparing an electron transport layer;

[0023] preparing an adhesion layer on the electron transport layer, wherein the adhesion layer is used to enhance adhesion between the electron transport layer and the strong n-type layer;

[0024] A strong n-type layer is prepared on the side of the adhesion layer away from the electron transport layer.

[0025] Wherein, the step of preparing an adhesion layer on the electron transport layer comprises:

[0026] The polyethoxyethyleneimine solution was spin-coated on the electron transport layer to prepare an adhesion layer on the electron transport layer.

[0027] Wherein, before the step of spin coating the polyethoxyethyleneimine solution on the electron transport layer to prepare an adhesion layer on the electron transport layer, the method comprises:

[0028] The polyethoxyethyleneimine solution was diluted with isopropyl alcohol.

[0029] Wherein, the step of spin coating the polyethoxyethyleneimine solution on the electron transport layer to prepare an adhesion layer on the electron transport layer comprises:

[0030] A polyethoxyethyleneimine solution was spin-coated on the electron transport layer and annealed in a nitrogen atmosphere to prepare an adhesion layer on the electron transport layer.

[0031] Wherein, the method further comprises:

[0032] preparing a bottom electrode layer;

[0033] preparing an electron blocking layer on the bottom electrode layer;

[0034] Prepare a P-type layer on a surface of the electron blocking layer away from the bottom electrode layer;

[0035] Prepare the active layer on a surface of the P-type layer away from the bottom electrode layer;

[0036] Preparing the electron transport layer comprises:

[0037] The electron transport layer is prepared on a surface of the active layer away from the bottom electrode layer;

[0038] After preparing a strong n-type layer on a side of the adhesion layer away from the electron transport layer, the method further comprises:

[0039] A top electrode layer is prepared on a surface of the strong n-type layer away from the bottom electrode layer.

[0040] Wherein, the materials of the top electrode layer and the bottom electrode layer are indium tin oxide;

[0041] The material of the electron blocking layer is NiOX;

[0042] The material of the p-type layer is PbS;

[0043] The material of the electron transport layer is C 60 ;

[0044] The material of the strong n-type layer is SnO2.

[0045] The method for preparing the quantum dot device of the present application can bring the following effective effects by spin coating a layer of adhesion layer: 1. 60 The formation of a layer of hydroxyl groups on the surface (the adhesion layer is a polyethoxyethyleneimine solution) is conducive to the growth of the tin oxide layer. Due to the properties of the adhesion layer itself, the mechanical strength and tensile properties of the entire film can be improved, and the adhesion of the film is also increased. This is beneficial to the later preparation and production of the device.

[0046] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0048] Figure 1 It is a schematic structural diagram of an embodiment of the quantum dot device of the present application;

[0049] Figure 2 It is a schematic flow chart of an embodiment of a method for preparing a quantum dot device of the present application;

[0050] Figure 3 It is a schematic flow chart of another embodiment of the method for preparing a quantum dot device of the present application. DETAILED DESCRIPTION

[0051] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0052] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0053] The quantum dot device of the present application is described in detail below with reference to the accompanying drawings.

[0054] See first Figure 1 , Figure 1This is a structural schematic diagram of an embodiment of a quantum dot device of the present application. The quantum dot device specifically includes: an electron transport layer 115 and a strong n-type layer 116, wherein between the electron transport layer 115 and the strong n-type layer 116 there is also an adhesion layer 118, and the adhesion layer 118 is used to enhance the adhesion between the electron transport layer 115 and the strong n-type layer 116.

[0055] In one embodiment, the adhesive layer material is polyethoxyethyleneimine.

[0056] Specifically, the quantum dot device includes: a bottom electrode layer 111, an electron blocking layer 112, a p-type layer 113, an active layer 114, an electron transport layer 115, an adhesion layer 118, a strong n-type layer 116, and a top electrode layer 117. The electron blocking layer 112 is disposed on the bottom electrode layer 111; the p-type layer 113 is disposed on a side of the electron blocking layer 112 away from the bottom electrode layer 111; the active layer 114 is disposed on a side of the p-type layer 113 away from the bottom electrode layer 111; the electron transport layer 115 is disposed on a side of the active layer 114 away from the bottom electrode layer 111; the strong n-type layer 116 is disposed on a side of the electron transport layer 115 away from the bottom electrode layer 111; and the top electrode layer 117 is disposed on a side of the strong n-type layer 116 away from the bottom electrode layer 111.

[0057] The material of the bottom electrode layer 111 is the same as that of the top electrode layer 117 , both of which are indium tin oxide thin films.

[0058] The material of the strong n-type layer 116 is SnO 2 .

[0059] The material of the electron transport layer 115 is C 60 .

[0060] The material of the p-type layer 113 is PbS.

[0061] The material of the electron blocking layer 112 is NiOX.

[0062] The electron blocking layer 112 is of p-type, the active layer 114 is of i-type, and the electron transport layer 115 is of n-type.

[0063] The active layer 114 is a PbS quantum dot layer, which can absorb the energy of photons under 1550nm light irradiation and generate optical signals. The electron blocking layer 112, the p-type layer 113, the active layer 114, the electron transport layer 115, and the strong n-type layer 116 form an ohmic contact between the bottom electrode layer 111 and the top electrode layer 117. Among them, the electron blocking layer 112, the p-type layer 113, the active layer 114, the electron transport layer 115, and the strong n-type layer 116 form a pin structure as a whole. Under 1550nm light irradiation, the active layer 114 will generate electrons and vacancies, and the electrons will go along the electron transport layer 115 to the strong n-type layer 116; the vacancies will reach the p-type layer 113. The electron blocking layer 112 prevents electrons from traveling back from the active layer 114 to the p-type layer 113. The p-type layer 113 forms a pn junction (light-emitting diode structure) with the strong n-type layer 116. The p-type layer 113 generates carriers. As the bias voltage increases, the built-in potential of the initial built-in electric field begins to change. When the p-type layer 113 is completely depleted, the photocurrent is maximum. The net photocurrent is obtained by subtracting the initial dark current from the photocurrent. The optical signal per unit area is the responsivity of 1550nm light.

[0064] In the quantum dot device of the present application, an adhesion layer 118 is arranged between the electron transport layer 115 and the strong n-type layer 116. The adhesion layer 118 is used to enhance the adhesion between the electron transport layer 115 and the strong n-type layer 116, thereby improving the device performance. Experiments have shown that under the scheme of the present application, the dark current and external quantum efficiency of the quantum dot device are improved.

[0065] See also Figure 2 , Figure 2 The flowchart of one embodiment of the method for preparing a quantum dot device of the present application specifically includes:

[0066] Step S11: preparing an electron transport layer.

[0067] The material of the electron transport layer is C 60 .

[0068] Step S12: preparing an adhesion layer on the electron transport layer, wherein the adhesion layer is used to enhance adhesion between the electron transport layer and the strong n-type layer.

[0069] Step S13: preparing a strong n-type layer on a side of the adhesion layer away from the electron transport layer.

[0070] In one embodiment, please combine Figure 3 , Figure 3 1 is a flow chart of another embodiment of the method for preparing a quantum dot device of the present application. In this embodiment, before step S11, the method includes:

[0071] Step S21: preparing a bottom electrode layer.

[0072] In one embodiment, the bottom electrode layer material is indium tin oxide. Specifically, a magnetron sputtering method is used to sputter an indium tin oxide film on a substrate, and a laser etching / photolithography / nanoimprinting process is used to pattern the indium tin oxide film to form a bottom electrode layer. After the bottom electrode layer is prepared, the bottom electrode layer can be further cleaned, for example, using pure water, ethanol, or N,N-dimethylformamide solution DMF to clean the bottom electrode layer.

[0073] Step S22: preparing an electron blocking layer on the bottom electrode layer.

[0074] The material of the electron blocking layer is NiOx. The electron blocking layer is prepared by vacuum magnetron sputtering of a NiO-Li target on the bottom electrode layer. The target material is a Li-doped NiOx target. Specifically, the distance between the target and the substrate is set to 80 cm, and the RF mode sputtering is adopted. Argon gas is introduced to make the chamber pressure about 2.0 Pa, the sputtering power is 100-200 W, and the sputtering time is 10-30 min. A NiOx film of about 20 nm thickness is obtained, thereby forming an electron blocking layer.

[0075] Step S23: preparing a P-type layer on a surface of the electron blocking layer away from the bottom electrode layer.

[0076] The P-type layer material is PbS. In one embodiment, the operation is carried out in a fume hood, and the EDT solution is spin-coated, and the spin-coating parameters are set as follows: the spin-coating speed is 2500-5000 r / s, the acceleration is 500-2000 r / s, and the spin-coating time is 10-30s, so as to obtain a PbS-EDT film with a thickness of about 20nm, thereby preparing the P-type layer.

[0077] Step S24: preparing the active layer on a surface of the P-type layer away from the bottom electrode layer.

[0078] In one embodiment, the active layer precursor may be spin-coated on a surface of the P-type layer away from the bottom electrode layer by spin coating, thereby forming the active layer. The active layer material is PbS quantum dots.

[0079] Combined with the above Figure 2 Step S11 of preparing the electron transport layer comprises:

[0080] Step S25: preparing the electron transport layer on a surface of the active layer away from the bottom electrode layer.

[0081] The material of the electron transport layer is C 60 The device with active layer is placed on the thermal evaporation instrument, and the film is deposited by thermal evaporation. The C 60, maintaining the evaporation rate at 0.1 angstroms per second, to prepare a C layer with a thickness of about 10-40 nm, for example, 15 nm. 60 , an electron transport layer is prepared.

[0082] Proceeding to step S12, an adhesion layer is prepared on the electron transport layer, wherein the adhesion layer is used to enhance adhesion between the electron transport layer and the strong n-type layer.

[0083] In one embodiment, a polyethoxyethyleneimine solution is spin-coated on the electron transport layer to prepare an adhesion layer on the electron transport layer.

[0084] In one embodiment, the polyethoxyethyleneimine solution is diluted with isopropanol, and the polyethoxyethyleneimine solution is spin-coated on the electron transport layer, thereby preparing an adhesion layer on the electron transport layer. Specifically, the stock solution of polyethoxyethyleneimine PEIE is diluted with isopropanol, for example, 20 ml of isopropanol solution is taken, 200 μL of PEIE solution is added thereto, and the PEIE solution is diluted to 1% of the original. Then 40 ml of isopropanol solution is taken, 1 mL of 1% PEIE solution is added thereto, and the solution is diluted to 0.025% of the PEIE stock solution.

[0085] The polyethoxyethyleneimine solution is spin coated on the electron transport layer and annealed in a nitrogen atmosphere to prepare an adhesion layer on the electron transport layer. Specifically, the quantum dot device is placed in the center of the spin coater, and then 80-150 μL of 0.025% PEIE is taken using a pipette and spin coated on the center of the device at a speed of 3000-6000 r / s, such as 5000 r / s, an acceleration of 2000-6000 r / s, such as 5000 r / s, and a spin coating time of 20-60s, such as 30s. After the spin coating is completed, the device is removed and annealed on a 100°C hot stage in a nitrogen atmosphere for 2-5 minutes to prepare the adhesion layer.

[0086] Next, the process proceeds to step S13 , in which a strong n-type layer is prepared on a side of the adhesion layer away from the electron transport layer.

[0087] The material of the strong n-type layer is SnO2, and the strong n-type layer is prepared by coating on a surface of the adhesion layer away from the bottom electrode layer by atomic layer deposition. Specifically, the film is coated by atomic layer deposition, tetrakis(dimethylamino)tin (TDMASn) is used as the tin source, water is used as the oxygen source, the tin source temperature is set to 60°C, the substrate temperature is set to 90°C, and the reaction is fully carried out as much as possible. After 250 cycles of growth, a SnO2 film with a thickness of about 40nm is obtained, and a strong n-type layer is prepared.

[0088] After the step S13 of preparing a strong n-type layer on a side of the adhesion layer away from the electron transport layer, the step further includes: step S26: preparing a top electrode layer on a surface of the strong n-type layer away from the bottom electrode layer.

[0089] The top electrode layer material is indium tin oxide. The top electrode is coated by magnetron sputtering, and the target material is indium-doped tin oxide. The sputtering power is 100w-200w, and the sputtering time is 10-30 minutes.

[0090] The method for preparing the quantum dot device of the present application can bring the following effective effects by spin coating a layer of adhesion layer: 1. 60 The formation of a layer of hydroxyl groups on the surface (the adhesion layer is a polyethoxyethyleneimine solution) is conducive to the growth of the tin oxide layer. Due to the properties of the adhesion layer itself, the mechanical strength and tensile properties of the entire film can be improved, and the adhesion of the film is also increased. This is beneficial to the later preparation and production of the device.

[0091] The algorithm and display provided herein are not inherently related to any particular computer, virtual system or other device. Various general purpose systems can also be used together with the teachings based on this. According to the above description, it is obvious that the structure required for constructing such systems. In addition, the application is not directed to any specific programming language either. It should be understood that various programming languages ​​can be utilized to realize the content of the application described herein, and the description of the specific language above is for the purpose of disclosing the best mode of implementation of the application.

[0092] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0093] Similarly, it should be understood that in order to streamline the present disclosure and assist in understanding one or more of the various aspects of the application, in the above description of exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof.

[0094] Those skilled in the art will appreciate that the modules in the device in the embodiment can be adaptively changed and arranged in one or more devices different from the embodiment. The modules or units or components in the embodiment can be combined into one module or unit or component, and in addition they can be divided into multiple submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including abstracts and drawings) and all processes or units of any method or device disclosed in this manner can be combined in any combination. Unless otherwise explicitly stated, each feature disclosed in this specification (including accompanying abstracts and drawings) can be replaced by alternative features that provide the same, equivalent or similar purposes.

[0095] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present application and to form different embodiments.

[0096] It should be noted that the above embodiments illustrate the present application rather than limit the present application. Any reference symbol between brackets should not be constructed as a limitation to the present application. The word "comprising" does not exclude the existence of components or steps not listed in the present application. The word "one" or "an" before a component does not exclude the existence of multiple such components. The present application can be implemented by means of hardware including several different components and by means of a suitably programmed computer. In the embodiments in which several devices are listed, several of these devices can be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words can be interpreted as names.

Claims

1. A quantum dot device, characterized in that: The quantum dot device comprises: an electron transport layer and a strong n-type layer; Wherein, an adhesion layer is further included between the electron transport layer and the strong n-type layer, and the adhesion layer is used to enhance the adhesion between the electron transport layer and the strong n-type layer. 2 . The quantum dot device according to claim 1 , wherein the adhesion layer material is polyethoxyethyleneimine.

3. The quantum dot device according to claim 1, characterized in that: The quantum dot device further comprises: bottom electrode layer; An electron blocking layer, disposed on the bottom electrode layer; A p-type layer is disposed on a side of the electron blocking layer away from the bottom electrode layer; The active layer is arranged on the side of the p-type layer away from the bottom electrode layer; wherein the electron transport layer is arranged on the side of the active layer away from the bottom electrode layer; and the strong n-type layer is arranged on the side of the electron transport layer away from the bottom electrode layer; The top electrode layer is arranged on a side of the strong n-type layer away from the bottom electrode layer.

4. The quantum dot device according to claim 3, characterized in that: The top electrode layer and the bottom electrode layer are made of indium tin oxide; The material of the electron blocking layer is NiOX; The material of the p-type layer is PbS; The material of the electron transport layer is C 60 ; The material of the strong n-type layer is SnO2.

5. A method for preparing a quantum dot device, characterized in that: include: preparing an electron transport layer; preparing an adhesion layer on the electron transport layer, wherein the adhesion layer is used to enhance adhesion between the electron transport layer and the strong n-type layer; A strong n-type layer is prepared on the side of the adhesion layer away from the electron transport layer.

6. The method for preparing a quantum dot device according to claim 5, characterized in that: The step of preparing an adhesion layer on the electron transport layer comprises: The polyethoxyethyleneimine solution was spin-coated on the electron transport layer to prepare an adhesion layer on the electron transport layer.

7. The method for preparing a quantum dot device according to claim 6, characterized in that: Before the step of spin coating the polyethoxyethyleneimine solution on the electron transport layer to prepare an adhesion layer on the electron transport layer, the method comprises: The polyethoxyethyleneimine solution was diluted with isopropyl alcohol.

8. The method for preparing a quantum dot device according to claim 6, characterized in that: The step of spin coating the polyethoxyethyleneimine solution on the electron transport layer to prepare an adhesion layer on the electron transport layer comprises: A polyethoxyethyleneimine solution was spin-coated on the electron transport layer and annealed in a nitrogen atmosphere to prepare an adhesion layer on the electron transport layer.

9. The method for preparing a quantum dot device according to claim 5, characterized in that: The method further comprises: preparing a bottom electrode layer; preparing an electron blocking layer on the bottom electrode layer; Prepare a P-type layer on a surface of the electron blocking layer away from the bottom electrode layer; Prepare the active layer on a surface of the P-type layer away from the bottom electrode layer; Preparing the electron transport layer comprises: The electron transport layer is prepared on a surface of the active layer away from the bottom electrode layer; After preparing a strong n-type layer on a side of the adhesion layer away from the electron transport layer, the method further comprises: A top electrode layer is prepared on a surface of the strong n-type layer away from the bottom electrode layer.

10. The method for preparing a quantum dot device according to claim 9, characterized in that: The top electrode layer and the bottom electrode layer are made of indium tin oxide; The material of the electron blocking layer is NiOX; The material of the p-type layer is PbS; The material of the electron transport layer is C 60 ; The material of the strong n-type layer is SnO2.

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