A method for manufacturing a photodetector and a photodetector

Abstract

The application provides a preparation method of a photoelectric detector and the photoelectric detector. The preparation method of the photoelectric detector comprises the following steps: preparing a quantum dot solution, quantum dots in the quantum dot solution are wrapped by halogen; preparing a quantum dot dispersant by using a 2,6-bis(aminomethyl)pyridine ligand; adding the quantum dot solution into the quantum dot dispersant to obtain an active layer precursor; and preparing an active layer based on the active layer precursor, so as to prepare the photoelectric detector. The quantum dot dispersant prepared by introducing the 2,6-bis(aminomethyl)pyridine ligand into the active layer can effectively passivate surface defects of quantum dots in the quantum dot solution which are not sufficiently passivated by halogen ligands, so that exposed crystal surface defects of PbS CQDs are better passivated, and the photoelectric performance of the photoelectric detector is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of infrared detection, and in particular to a preparation method of a photoelectric detector and the photoelectric detector. BACKGROUND

[0002] Infrared light is a form of electromagnetic radiation, 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, people have invented infrared photoelectric detectors to detect infrared light, and optically active materials play a crucial role in this process, among which semiconductor materials are commonly used. Commercial infrared photoelectric detectors are usually made of traditional narrow-bandgap bulk inorganic semiconductors such as InSb, Ge, HgCdTe, and 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 commonly used epitaxial growth method is epitaxial growth on a lattice-matched crystal substrate, which makes this type of infrared photoelectric detector expensive, inflexible, and limited. Therefore, there is an urgent need for infrared detector replacement materials that are small in size, have low dark current, and consume less energy.

[0003] Compared with traditional bulk semiconductors, infrared quantum dots have advantages such as easy processing, good flexibility and light stability, and high absorption coefficient. Colloidal photoelectric detectors have great potential to replace silicon-based pixel arrays and achieve full coverage imaging in the short-wave infrared band due to their corresponding waveband tunability, excellent detection performance, low cost, and process compatibility.

[0004] Currently, the most reported PbS CQD image sensor in China has a photosensitive wavelength band below 1.3 μm, and the functionality and advantages of infrared imaging are limited, so there is an urgent need to develop PbS CQD materials that can detect wavelengths up to the near-infrared II region (1.3-1.7 μm). Due to quantum confinement effects, redshift of the detection wavelength corresponds to larger size CQD. As the size of the quantum dots increases, the proportion of crystal faces increases, and the existing ligands in the system are difficult to effectively passivate the crystal faces, resulting in an increase in CQD defect sources, including an increase in dangling bonds, water and oxygen adsorption, and particle agglomeration.

[0005] Application Content

[0006] In view of the above problems, the present application provides a preparation method of a photoelectric detector and the photoelectric detector.

[0007] In a first aspect, a preparation method of a photoelectric detector is provided, comprising:

[0008] Preparation of a quantum dot solution, the quantum dots in the quantum dot solution are wrapped by halogen;

[0009] Preparation of quantum dot dispersant by using 2,6-bis(aminomethyl)pyridine ligand;

[0010] Adding the quantum dot solution into the quantum dot dispersant to obtain an active layer precursor;

[0011] Preparation of an active layer based on the active layer precursor, thereby preparing the photodetector.

[0012] The step of preparing the quantum dot solution comprises:

[0013] Preparation of an initial quantum dot solution, wherein the quantum dots in the initial quantum dot solution are wrapped by oleic acid ligand;

[0014] Preparation of a ligand solution;

[0015] Mixing the initial quantum dot solution and the ligand solution to perform ligand exchange, thereby obtaining the quantum dot solution, wherein the quantum dots in the quantum dot solution are wrapped by halogen.

[0016] The step of preparing the initial quantum dot solution comprises:

[0017] Synthesis of zinc sulfide quantum dots by using thioacetamide and zinc stearate;

[0018] Cation exchange by using lead chloride and the zinc sulfide quantum dots, control of the reaction time of the lead chloride and the zinc sulfide quantum dots, and addition of the zinc sulfide quantum dots into n-octane, thereby obtaining the initial quantum dot solution.

[0019] The step of preparing the ligand solution comprises:

[0020] Mixing PbI2 and PbBr2 with N,N-dimethylformamide solution to obtain the ligand solution.

[0021] The step of mixing the initial quantum dot solution and the ligand solution to perform ligand exchange, thereby obtaining the quantum dot solution, comprises:

[0022] Filtering and mixing the initial quantum dot solution and the ligand solution according to a preset ratio, fully oscillating, and performing ligand exchange;

[0023] Removing the upper solution, adding n-octane, mixing and oscillating, and removing the upper liquid;

[0024] Centrifuging the lower solution, removing the solvent, and obtaining the quantum dot solution.

[0025] The step of preparing the quantum dot dispersant by using 2,6-bis(aminomethyl)pyridine ligand comprises:

[0026] A quaternary dispersion system is prepared, which includes N, N-dimethylformamide, dimethylformamide, n-butylamine, 3-picolylamine;

[0027] A 2,6-bis(aminomethyl)pyridine ligand is dissolved in N, N-dimethylformamide, and a quaternary dispersion system is added to obtain the quantum dot dispersant.

[0028] The step of preparing the photoelectric detector includes:

[0029] A bottom electrode layer is prepared;

[0030] An electron blocking layer is prepared on the bottom electrode layer;

[0031] A P-type layer is prepared on a surface of the electron blocking layer away from the bottom electrode layer;

[0032] The active layer is prepared on a surface of the P-type layer away from the bottom electrode layer by using the active layer precursor;

[0033] A sacrificial layer is prepared on a surface of the active layer away from the bottom electrode layer;

[0034] An electron transport layer is prepared on a surface of the sacrificial layer away from the bottom electrode layer;

[0035] A top electrode layer is prepared on a surface of the electron transport layer away from the bottom electrode layer.

[0036] The top electrode layer and the bottom electrode layer are made of indium tin oxide;

[0037] The material of the electron blocking layer is NiOX;

[0038] The material of the P-type layer is PbS;

[0039] The material of the electron transport layer is C 60 ;

[0040] The material of the electron transport layer is SnO2.

[0041] The step of preparing the bottom electrode layer includes:

[0042] An indium tin oxide film is sputtered by using a magnetron sputtering method, and the indium tin oxide film is patterned by using a laser etching / lithography / nanoimprint process, so as to form the bottom electrode layer;

[0043] The step of preparing the electron blocking layer on the bottom electrode layer includes:

[0044] The electron blocking layer is prepared by vacuum magnetron sputtering on the bottom electrode layer by using a NiO-Li target.

[0045] a step of preparing a sacrificial layer on a surface of the active layer away from the bottom electrode layer, comprising:

[0046] using a thermal evaporation method to deposit a film, heating C 60 a step of preparing a sacrificial layer on a surface of the active layer away from the bottom electrode layer;

[0047] a step of preparing an electron transport layer on a surface of the sacrificial layer away from the bottom electrode layer, comprising:

[0048] using an atomic layer deposition method to deposit a film to prepare an electron transport layer on a surface of the sacrificial layer away from the bottom electrode layer.

[0049] In a second aspect, the application provides a photodetector prepared by the preparation method of the photodetector.

[0050] The technical scheme provided in the embodiments of the application introduces a quantum dot dispersant prepared by a 2,6-bis(aminomethyl)pyridine ligand in an active layer, which can effectively passivate surface defects of quantum dots in a quantum dot solution that are not sufficiently passivated by halogen ligands, so that exposed crystal face defects of PbS CQDs are better passivated, and the photoelectric performance of the photodetector is effectively improved.

[0051] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, the application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0052] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments, and are not meant to limit the application. Moreover, the same reference numerals in the attached drawings indicate the same or similar components. In the drawings:

[0053] Figure 1 is a flowchart of a first embodiment of the preparation method of the photodetector of the application;

[0054] Figure 2 is a flowchart of an embodiment of step S14 in Figure 1

[0055] Figure 3 is a structural schematic diagram of an embodiment of the photodetector of the application. DETAILED DESCRIPTION

[0056] ​Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and so that the scope of the present disclosure can be completely conveyed to those skilled in the art. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0057] Various structural diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These diagrams are not drawn to scale, in which certain details are exaggerated for the purpose of clarity, and certain details can be omitted. The shapes of various regions, layers, and the relative sizes and positional relationships between them shown in the drawings are merely exemplary, and in actuality can be deviated due to manufacturing tolerances or technical limitations, and regions / layers having different shapes, sizes, and relative positions can be additionally designed by those skilled in the art as needed.

[0058] The present application studies the passivation of the depletion zone CQD surface defects in PbS CQD photodiodes of photodetectors, analyzes the main defect types of large-size PbS CQD, and proposes a new type of three-terminal ligand, 2,6-bis(aminomethyl)pyridine ligand, for auxiliary passivation in view of the problem that the crystal plane is difficult to effectively passivate. By adding 2,6-bis(aminomethyl)pyridine ligand in the dispersant, dissolving an appropriate amount of 2,6-bis(aminomethyl)pyridine ligand in N,N-dimethylformamide (N,N-Dimethylformamide, DMF) dispersant, adding it to the existing four-component dispersion system, and fully oscillating and dispersing before coating, the defect inhibition of the iodine bromine coated PbS CQD layer film is realized. The inhibition effect of 2,6-bis(aminomethyl)pyridine ligand on CQD defects is verified by various means such as material characterization and device characterization, and finally a photodiode with low dark current is realized.

[0059] The preparation method of the photodetector of the present application will be described in detail below with reference to the accompanying drawings.

[0060] First, refer to Figure 1 , Figure 1 The flowchart of the first embodiment of the preparation method of the photodetector of the present application is shown in the figure, which specifically includes:

[0061] Step S11: preparing a quantum dot solution, the quantum dots in the quantum dot solution are wrapped by halogen.

[0062] The process of preparing the quantum dot solution in step S11 specifically includes:

[0063] 1) preparing an initial quantum dot solution, in which the quantum dots are wrapped by oleic acid ligand.

[0064] Specifically, zinc sulfide quantum dots are synthesized by using thioacetamide and zinc stearate; cation exchange is performed by using lead chloride and the zinc sulfide quantum dots, and the reaction time of the lead chloride and the zinc sulfide quantum dots is controlled, and the zinc sulfide quantum dots are added into n-octane, so as to obtain the initial quantum dot solution.

[0065] In a specific embodiment, the PbS CQD used for preparing the light-absorbing layer of the photodetector are synthesized according to a cation exchange method. First, zinc sulfide quantum dots are synthesized by using thioacetamide as a sulfur source and zinc stearate as a zinc source. Then, cation exchange is performed by using lead chloride as a lead source and the zinc sulfide quantum dots. The absorption peak of the PbS CQD is controlled by controlling the reaction time of the lead chloride and the zinc sulfide quantum dots. The PbS CQD synthesized by the cation exchange method is dissolved in n-octane quantum dot solution at a concentration of 10 mg / ml to obtain an initial quantum dot solution. In the initial quantum dot solution synthesized by this method, the quantum dots PbSCQD are wrapped by oleic acid ligands, the spacing between the quantum dots is too large, and there is a problem of low mobility. Therefore, ligand exchange is needed to replace the long-chain oleic acid ligand with a short-chain halogen such as iodine and bromine monatomic ligand to enhance the electrical performance of the PbS CQD.

[0066] 2) Preparation of a ligand solution.

[0067] Specifically, PbI2 and PbBr2 are mixed with a DMF solution to obtain the ligand solution.

[0068] In a specific embodiment, PbI2 and PbBr2 solid drugs are weighed by a balance and mixed with a DMF solution, and dissolved by fully oscillating to prepare a ligand solution with a PbI2 concentration of 0.0267 mmol / ml and a PbBr2 concentration of 0.0115 mmol / ml.

[0069] 3) The initial quantum dot solution is mixed with the ligand solution to perform ligand exchange, and the quantum dots in the quantum dot solution are wrapped by halogen.

[0070] Specifically, the initial quantum dot solution and the ligand solution are filtered and mixed according to a preset ratio, fully oscillated to perform ligand exchange, the upper solution is removed, n-octane is added, mixed and oscillated to remove the upper liquid, and the lower solution is centrifuged to remove the solvent to obtain the quantum dot solution.

[0071] In one embodiment, the ligand exchange is performed in a nitrogen atmosphere glove box. The initial quantum dot solution and the ligand solution are mixed in a volume ratio of 1:1 using a syringe and a 0.22 μιη pore size filter head, shaken thoroughly, and the ligand exchange is performed. After standing for a period of time, the PbS CQDs with iodine, bromine atom ligands are in the lower DMF polar phase, and the upper n-octane solvent becomes transparent, and the upper solution is removed. Further, to reduce the content of residual oleic acid, an equal amount of n-octane is added, mixed and shaken, and after layering, the upper liquid is removed, and the washing process is repeated twice. Finally, the lower DMF solution containing the PbS CQDs is dispensed into centrifuge tubes, centrifuged at 9000 r / min for 5 min, and the solution is removed, and the residual precipitate quantum dot solution is obtained. The quantum dot PbS CQDs in the quantum dot solution are coated with iodine, bromine atom ligands, and are placed in a low-pressure drying box to further remove residual solvents for use.

[0072] Step S12: preparing a quantum dot dispersant using a 2,6-bis(aminomethyl)pyridine ligand.

[0073] Specifically, a four-component dispersion system is prepared, the four-component dispersion system including N,N-dimethylformamide, dimethylformamide, n-butylamine, and 3-picolylmethylamine; a 2,6-bis(aminomethyl)pyridine ligand is dissolved in N,N-dimethylformamide, and the four-component dispersion system is added to obtain the quantum dot dispersant.

[0074] In one embodiment, a four-component dispersion system is prepared in advance, the four-component dispersion system including N,N-dimethylformamide, dimethylformamide, n-butylamine, and 3-picolylmethylamine, and the ratio of N,N-dimethylformamide, dimethylformamide, n-butylamine, and 3-picolylmethylamine in the four-component dispersion system is 350 ul:250 ul:370 ul:30 ul. 0.01 mmol of a 2,6-bis(aminomethyl)pyridine ligand is dissolved in 350 ul of a DMF dispersant, and the existing four-component dispersion system is added to obtain a quantum dot dispersant with a concentration of 400 mg / ml after thorough shaking and dispersion.

[0075] In the above process, the long-chain oleic acid ligand is replaced by a short-chain halogen, such as iodine or bromine, by using liquid ligand exchange. In this process, there are two stages in which the new ligand material can be added, one stage is added in the ligand exchange part of the ligand material, and the other stage is added in the solvent in the thin film spin coating part. Compared with the latter stage, there are two reasons: first, the newly added 2,6-bis(aminomethyl)pyridine ligand itself has coordination with lead ions, while the original ligand material contains PbI2 and PbBr2 materials, and the three will react in advance, which may cause the precursor to denature and lose its function; second, even if the three can coexist, in the process of acting together with PbS CQD in the solution, competition may occur due to different binding forces, which may cause the original passivation design to fail. However, by adding 2,6-bis(aminomethyl)pyridine to the solvent in the thin film spin coating step, it is expected to perform secondary passivation on the halogen-coated PbS CQD, which can play a role in checking and filling the gaps. More importantly, PbS CQD is relatively dispersed in a liquid environment, and due to the presence of environmental dielectric constant, the CQD spacing is large, and the probability of aggregation is small. However, in the process of spin coating into a film, the solvent volatilizes rapidly, and the CQD accumulates on the substrate, the spacing rapidly decreases, and the crystal face fusion is easily caused. Therefore, 2,6-bis(aminomethyl)pyridine is more suitable as a component of the spin coating solvent.

[0076] Step S13: adding the quantum dot solution into the quantum dot dispersant to obtain a active layer precursor.

[0077] The quantum dot solution is added into the quantum dot dispersant to obtain a active layer precursor.

[0078] The method of the present application more effectively passivates the quantum dots, reduces the surface defects of the quantum dots, suppresses the dark current, and thus improves the detection performance of the device.

[0079] Step S14: preparing an active layer based on the active layer precursor, thereby preparing the photodetector.

[0080] Specifically, please refer to Figure 2 , step S14 specifically includes:

[0081] Step S141: preparing a bottom electrode layer.

[0082] In an embodiment, the material of the bottom electrode layer is indium tin oxide. Specifically, an indium tin oxide film is sputtered on a substrate by a magnetron sputtering method, and the indium tin oxide film is patterned by a laser etching / photoetching / nanoimprint process, thereby forming a bottom electrode layer.

[0083] Step S142: preparing an electron blocking layer on the bottom electrode layer.

[0084] The electron blocking layer is made of NiOX. The electron blocking layer is fabricated on the bottom electrode layer by vacuum magnetron sputtering of a NiO-Li target. The target material is a Li-doped NiOx target. Specifically, the target-substrate distance is set to 80 cm, radio frequency sputtering is used, argon gas is introduced to maintain a chamber pressure of approximately 2.0 Pa, the sputtering power is 200 W, and the sputtering time is 5 min, resulting in a NiOx film approximately 20 nm thick, thus forming the electron blocking layer.

[0085] Step S143: Prepare a P-type layer on the surface of the electron blocking layer away from the bottom electrode layer.

[0086] The p-type layer material is PbS. Specifically, the p-type layer 113 is a PbS quantum dot material with EDT as the ligand and an absorption wavelength of 880 nm. In one embodiment, the operation is carried out in a fume hood. PbS CQD with an absorption peak of 880 nm is dissolved in n-octane to prepare a quantum dot solution of 40 mg / ml. The EDT solution (ethylene glycol diaminetetraacetic acid) is dispersed in acetonitrile to prepare a ligand solution with an EDT mass fraction of 0.01%. Using solid-phase exchange, the spin-coating parameters are set to 4000 r / min for 20 s. First, a layer of quantum dot solution is spin-coated, and then the ligand solution is dropped onto the film. After standing for 30 s to allow the ligand exchange to complete, the surface is washed twice with acetonitrile to obtain a PbS-EDT film with a thickness of about 20 nm, thereby preparing the p-type layer.

[0087] Step S144: The active layer is prepared on a surface of the P-type layer away from the bottom electrode layer using the active layer precursor.

[0088] In one embodiment, an active layer precursor can be spin-coated onto a surface of the P-type layer away from the bottom electrode layer to form an active layer.

[0089] Step S145: Prepare a sacrificial layer on a surface of the active layer away from the bottom electrode layer.

[0090] The material of the electron transport layer is C. 60 The device with the active layer fabricated was placed on a thermal evaporation apparatus, and a film was deposited using thermal evaporation, with C heated via a tungsten boat. 60 By maintaining an evaporation rate of 0.005–0.015 nm / s, a C layer approximately 15 nm thick was prepared. 60 The sacrificial layer was prepared.

[0091] Step S146: Prepare an electron transport layer on a surface of the sacrificial layer away from the bottom electrode layer.

[0092] The material of the electron transport layer is SnO2, and the electron transport layer is prepared by atomic layer deposition on a surface of the sacrificial layer away from the bottom electrode layer. Specifically, atomic layer deposition is used for film plating, tetrakis(dimethylamino)tin (TDMASn) is used as a tin source, water is used as an oxygen source, the tin source temperature is set to 60 DEG C, the substrate temperature is set to 90 DEG C, and the reaction is allowed to proceed as much as possible. After 250 cycles, a SnO2 film with a thickness of about 40 nm is obtained, and the electron transport layer is prepared.

[0093] Step S147: preparing a top electrode layer on a surface of the electron transport layer away from the bottom electrode layer.

[0094] The material of the top electrode layer is indium tin oxide. The top electrode is plated by using a magnetron sputtering JCP500, the target material is indium-doped tin oxide, the distance between the target and the substrate is set to 80 cm, direct current mode sputtering is used, argon and oxygen are introduced to make the cabin pressure about 0.5 Pa, the ratio of the gas flow rates of argon and oxygen is 99:1, the sputtering power is set to 100 W, the sputtering time is 15 min, an ITO film with a thickness of about 200 nm is obtained, the top electrode layer is prepared, and finally the photodetector is prepared.

[0095] In the photodetector prepared by the method of the present application, the exposed crystal face defects of the PbSCQDs are better passivated by the ligand supplementing and passivation method, and the photoelectric performance of the photodetector is effectively improved, which is specifically manifested as follows: the dark current of the device with a detection wavelength of 1550 nm is lower than 40 nA / cm2 at -0.01 V and lower than 300 nA / cm2 at -0.5 V, the external quantum efficiency (EQE) can be more than 70% while maintaining a low dark current.

[0096] Please refer to Figure 3 , Figure 3 is a structural schematic diagram of an embodiment of the photodetector of the present application, and the photodetector of the present application is prepared by the method described above. The photodetector specifically 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 electron transport layer 116, and a top electrode layer 117.

[0097] The active layer 114 is a PbS CQD layer, which can absorb the energy of photons under the irradiation of 1550 nm light to generate an optical signal. The electron blocking layer 112, the p-type layer 113, the active layer 114, the electron transport layer 115 and the electron transport layer 116 form an ohmic contact between the bottom electrode layer 111 and the top electrode layer 117. The electron blocking layer 112, the p-type layer 113, the active layer 114, the electron transport layer 115 and the electron transport layer 116 form a p-i-n structure as a whole. Under the irradiation of 1550 nm light, the active layer 114 generates electrons and vacancies, the electrons move along the electron transport layer 115 to the electron transport layer 116, and the vacancies reach the p-type layer 113. The electron blocking layer 112 prevents the electrons from moving from the active layer 114 to the p-type layer 113. The p-type layer 113 and the electron transport layer 116 form a p-n junction (light-emitting diode structure), and 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, and the unit area optical signal is the responsivity of 1550 nm light.

[0098] The material of the bottom electrode layer 111 is the same as that of the top electrode layer 117, and both are indium tin oxide films.

[0099] The material of the electron transport layer 116 is SnO2.

[0100] The material of the electron transport layer 115 is C 60 .

[0101] The material of the p-type layer 113 is PbS. Specifically, the p-type layer 113 is a PbS quantum dot material with EDT as a ligand and an absorption wavelength of 880 nm.

[0102] The material of the electron blocking layer 112 is NiOX.

[0103] The electron blocking layer 112 is p-type, the active layer 114 is i-type, and the electron transport layer 115 is n-type.

[0104] The method of introducing ligands to supplement passivation in the active layer 114 can better passivate the exposed crystal defects of PbS QDs, effectively improving the photoelectric performance of the photodetector. Specifically, the dark current of the device at a detection wavelength of 1550 nm is less than 40 nA / cm2 at -0.01 V and less than 300 nA / cm2 at -0.5 V, and the external quantum efficiency (EQE) can exceed 70% while maintaining a low dark current.

[0105] The algorithms and displays presented herein are not inherently related to any particular computer, virtual system, or other apparatus. Various general purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent from the description above. In addition, the present application is not intended to be limited to a particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the application as described herein, and any references below to specific languages are provided for disclosure of enablement only.

[0106] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application can be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been described in detail in order to not obscure the understanding of this description.

[0107] Similarly, it is to be understood that the mechanical details of the application that have been set forth above in the context of a few illustrative embodiments are presented by way of example and should not be construed as limiting the scope of the application unless otherwise indicated.

[0108] Those skilled in the art will appreciate that the modules in the apparatuses in the embodiments can be adapted and placed in one or more apparatuses other than the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and further can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of the features and / or processes or units are mutually exclusive, all combinations of all features disclosed in the specification (including the accompanying abstract and drawings) and all processes or units of any methods or apparatuses disclosed so far can be adopted. Unless explicitly stated otherwise, each feature disclosed in the specification (including the accompanying abstract and drawings) can be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0109] Further, those skilled in the art will appreciate that a combination of features of different embodiments means within the scope of the application and forms a different embodiment.

[0110] It should be noted that the above-mentioned embodiments illustrate rather than limit the application. Any reference signs in the claims should not be construed as limiting the scope of the application. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application can be implemented by means of both hardware and software, and any combination thereof. In the embodiments using a plurality of devices, these devices can be implemented by one and the same item of hardware. The use of the words first, second and third, etc. do not imply any ordering. These words are to be interpreted as names.

Claims

1. A method for fabricating a photodetector, characterized in that, include: A quantum dot solution is prepared, wherein the quantum dots in the quantum dot solution are encapsulated by halogens; Quantum dot dispersants were prepared using 2,6-bis(aminomethyl)pyridine ligands; The quantum dot solution is added to the quantum dot dispersant to obtain an active layer precursor; The active layer is prepared based on the active layer precursor, thereby fabricating the photodetector.

2. The preparation method according to claim 1, characterized in that, The steps for preparing quantum dot solutions include: An initial quantum dot solution is prepared, wherein the quantum dots are encapsulated by oleic acid ligands in the initial quantum dot solution; Preparation of ligand solutions; The initial quantum dot solution is mixed with the ligand solution to perform ligand exchange, thereby obtaining the quantum dot solution in which the quantum dots are encapsulated by halogens.

3. The preparation method according to claim 2, characterized in that, The steps for preparing the initial quantum dot solution include: Zinc sulfide quantum dots were synthesized using thioacetamide and zinc stearate. The initial quantum dot solution is obtained by cation exchange using lead chloride and zinc sulfide quantum dots, controlling the reaction time of the lead chloride and zinc sulfide quantum dots, and then adding the zinc sulfide quantum dots to n-octane.

4. The preparation method according to claim 2, characterized in that, The steps for preparing the ligand solution include: The ligand solution was obtained by mixing PbI2 and PbBr2 with N,N-dimethylformamide solution.

5. The preparation method according to claim 2, characterized in that, The step of mixing the initial quantum dot solution with the ligand solution to perform ligand exchange and obtain the quantum dot solution includes: The initial quantum dot solution and the ligand solution are filtered and mixed according to a preset ratio, and then shaken thoroughly to perform ligand exchange. Remove the supernatant solution, add n-octane, mix and shake, then remove the supernatant liquid. The lower layer solution was centrifuged to remove the solvent, yielding the quantum dot solution.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The steps for preparing quantum dot dispersants using 2,6-bis(aminomethyl)pyridine ligands include: A quaternary dispersion system was prepared, wherein the quaternary dispersion system comprises N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine, and 3-pyridinemethylamine; The 2,6-bis(aminomethyl)pyridine ligand was dissolved in N,N-dimethylformamide and added to a quaternary dispersion system to obtain the quantum dot dispersant.

7. The preparation method according to claim 6, characterized in that, The steps for fabricating the photodetector based on the active layer precursor include: Fabrication of the bottom electrode layer; An electron blocking layer is prepared on the bottom electrode layer; A P-type layer is prepared on a surface of the electron blocking layer that is away from the bottom electrode layer; The active layer is prepared using the active layer precursor on a surface of the P-type layer away from the bottom electrode layer; A sacrificial layer is prepared on a surface of the active layer that is away from the bottom electrode layer; An electron transport layer is prepared on a surface of the sacrificial layer away from the bottom electrode layer; A top electrode layer is prepared on a surface of the electron transport layer away from the bottom electrode layer.

8. The preparation method according to claim 7, characterized in that, The top electrode layer and the bottom electrode layer are made of indium tin oxide; The electron blocking layer is made of NiOX; The material of the P-type layer is PbS; The material of the sacrificial layer is C. 60 ; The electron transport layer is made of SnO2.

9. The preparation method according to claim 7, characterized in that, The steps for fabricating the bottom electrode layer include: Indium tin oxide (ITO) thin films are sputtered using magnetron sputtering and then patterned using laser etching / photolithography / nanoimprinting processes to form a bottom electrode layer. The step of fabricating an electron blocking layer on the bottom electrode layer includes: The electron blocking layer is prepared by vacuum magnetron sputtering of a NiO-Li target on the bottom electrode layer. The step of preparing a sacrificial layer on a surface of the active layer away from the bottom electrode layer includes: The coating is deposited using thermal evaporation, with C heated in a tungsten boat. 60 A sacrificial layer is prepared on a surface of the active layer that is away from the bottom electrode layer; The step of fabricating an electron transport layer on a surface of the sacrificial layer away from the bottom electrode layer includes: An electron transport layer is prepared by atomic layer deposition on the surface of the sacrificial layer away from the bottom electrode layer.

10. A photodetector, characterized in that, The photodetector is prepared by the photodetector preparation method according to any one of claims 1 to 9.

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