WO2023010746A1

WO2023010746A1 - N-i structured perovskite-based x-ray detector and preparation method therefor

Info

Publication number: WO2023010746A1
Application number: PCT/CN2021/137707
Authority: WO
Inventors: 薛冬峰; 李云龙; 王晓明
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-08-05
Filing date: 2021-12-14
Publication date: 2023-02-09
Also published as: CN113823740A

Abstract

The present application relates to the technical field of photoelectricity, and in particular, to an n-i structured perovskite-based X-ray detector and a preparation method therefor. The n-i structured perovskite-based X-ray detector comprises an n-type perovskite functional layer and an i-type perovskite active layer that are laminated and attached to each other. The n-type perovskite functional layer comprises an APbBr3 perovskite material, and the i-type perovskite active layer comprises A'PbI3 perovskite material, wherein A and A' are each independently selected from alkali metal ions or organic ammonium ions. The n-i structured perovskite-based X-ray detector provided by the present application is simple in device structure, and achieves high sensitivity, low detection limit and low dark current.

Description

N-i structure perovskite-based X-ray detector and preparation method thereof

technical field

The application belongs to the field of optoelectronic technology, and in particular relates to an n-i structure perovskite-based X-ray detector and a preparation method thereof.

Background technique

An X-ray detector is a device that converts X-ray energy into electrical signals that can be recorded. In recent years, with the large-scale promotion and use of X-ray detectors, X-ray detectors have been used more and more in small security inspection equipment, industrial parts inspection, large container inspection, medical treatment and other fields. At present, X-ray detectors are mostly used as indirect conversion X-ray detectors using scintillators, which are usually composed of scintillators, detector chips, and substrates; the working principle is that X photons enter the scintillator and are converted into visible light The output enters the detector chip, and then the photoelectric conversion is performed by the detector chip to form an electrical signal, which is transmitted to the subsequent signal processing chip through the wires on the chip and the substrate to form the final image.

In contrast, direct conversion X-ray detectors can directly convert X-ray absorption into charge carriers, and have the advantages of small radiation dose, high spatial resolution, large contrast range, and simple device structure. There are broader application prospects in terms of application. The core of the direct conversion X-ray flat panel image detector is the X-ray active layer, which is a material that directly converts X-ray absorption into charge carriers. At present, there are few types of direct conversion X-ray active materials with superior performance, and the arsenic-doped amorphous selenium material (a-Se:As) as the X-ray active layer is the mainstream method. However, devices based on this material have harsh fabrication conditions and extremely low detection efficiency for high-energy X-rays. Therefore, finding alternative materials is of great significance for the development of next-generation X-ray image detectors.

Currently, direct conversion X-ray detectors based on amorphous selenium (a-Se) adopt a p-i-n structure, that is, a very thick intrinsic-like a-Se is sandwiched between a p-type and an n-type thin layer a -Se between. Intrinsic a-Se can transfer both electrons and holes, while p-type a-Se can transfer holes well and suppress electron transfer, while n-type a-Se is just the opposite, can transfer electrons well and suppress electron transfer. Inhibit hole transport. However, a-Se-based direct conversion X-ray detectors are expensive and have narrow application fields. Compared with a-Se-based devices, perovskite-based direct conversion X-ray detectors have low cost, easy preparation, and high sensitivity, but the existing perovskite-based direct conversion X-ray detectors have a very large dark current .

Contents of the invention

The purpose of the present application is to provide an n-i structure perovskite-based X-ray detector and its preparation method, aiming to solve the technical problem of high dark current of the perovskite-based X-ray detector to a certain extent.

In order to realize the above-mentioned application purpose, the technical scheme adopted in this application is as follows:

In the first aspect, the present application provides a ni-structure perovskite-based X-ray detector, the ni-structure perovskite-based X-ray detector includes an n-type perovskite functional layer and an i-type calcium Titanium active layer; the n-type perovskite functional layer contains APbBr ₃ perovskite material, and the i-type perovskite active layer contains A'PbI ₃ perovskite material, wherein A and A' are respectively are independently selected from alkali metal ions or organic ammonium ions.

Further, the organic ammonium ion includes: at least one of CH ₃ NH ₃ ⁺ and CH ₂ (NH ₃ ) ₂ ⁺ .

Further, the alkali metal ions include: at least one of Cs ⁺ and Rb ⁺ .

Further, the A and the A' are independently selected from: CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ , Cs ⁺ or Cs ⁺ and Rb ⁺ .

Further, the thickness of the n-type perovskite functional layer is 15-25 μm.

Further, the i-type perovskite active layer has a thickness of 100-1000 μm.

In a second aspect, the present application provides a method for preparing an n-i structure perovskite-based X-ray detector, comprising the following steps:

Obtain a conductive substrate, and prepare a first functional layer on the surface of the conductive substrate;

preparing a second functional layer on the surface of the first functional layer away from the conductive substrate;

preparing a back electrode on the surface of the second functional layer away from the first functional layer to obtain an n-i structure perovskite-based X-ray detector;

Wherein, the first functional layer and the second functional layer are different and are respectively an n-type perovskite functional layer or an i-type perovskite active layer, and the n-type perovskite functional layer includes APbBr ₃ perovskite The ore material, the i-type perovskite active layer contains _A'PbI3 perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions.

Further, the first functional layer is the n-type perovskite functional layer, and the step of preparing the n-type perovskite functional layer includes: mixing ammonium bromide salt or alkali metal bromide salt with lead bromide, The surfactant is mixed with the first organic reagent to obtain the first perovskite solution;

Depositing the first perovskite solution on the surface of the conductive substrate, and performing a first dry annealing to form the n-type perovskite functional layer.

Further, the second functional layer is the i-type perovskite functional layer, and the step of preparing the i-type perovskite functional layer includes: mixing ammonium iodide or alkali metal iodide with lead iodide, Mixing the conductive polymer binder and the second organic reagent to obtain the second perovskite slurry;

Depositing the second perovskite slurry on the surface of the first functional layer, performing a second dry annealing to form the i-type perovskite functional layer.

Further, in the first perovskite solution, the ratio of the molar amount of the ammonium bromide salt or the alkali metal bromide salt to the molar amount of the lead bromide is 1: (1˜1.10).

Further, in the first perovskite solution, the total mass of the ammonium bromide salt, the alkali metal bromide salt and the lead bromide and the surfactant and the first organic reagent The mass ratio is 100:(0.5～1.5):(50～75).

Further, the surfactant is selected from quaternary ammonium salt surfactants.

Further, the first organic solvent includes: at least one of N,N-dimethylformamide, N-methylpyrrolidone, and dimethylsulfoxide.

Further, in the second perovskite slurry, the molar ratio of the ammonium iodide salt or the alkali metal iodide salt to the molar amount of the lead iodide is 1: (1-1.2) .

Further, in the second perovskite slurry, the total mass of the ammonium iodide salt, the alkali metal iodide salt and the lead iodide is mixed with the conductive polymer binder and the first The mass ratio of the two organic reagents is 100:(0.5-2.5):(35-50).

Further, the conductive polymer binder is selected from: polythiophene, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly[bis(4-phenyl ) (4-butylphenyl) amine], at least one of poly-p-phenylene vinylene.

Further, the second organic solvent includes: at least one of chlorobenzene, toluene, dimethyl sulfoxide, and ethylene glycol.

Further, the step of depositing the first perovskite solution on the surface of the conductive substrate includes: spin-coating the first perovskite solution on The surface of the conductive substrate.

Further, the first perovskite solution is scraped on the surface of the conductive substrate under the condition that the scraping speed is 10-15 mm/s and the scraper height is 30-50 μm.

Further, the conditions for the first drying and annealing include: after drying at 20-40° C. for 6-8 hours, annealing at 90-100° C. for 25-30 minutes.

Further, the step of depositing the second perovskite slurry on the surface of the first functional layer includes: under the condition that the scraping speed is 10-15 mm/s and the scraper height is 100-1500 μm, the The second perovskite slurry is doctor-coated on the surface of the first functional layer.

Further, the conditions of the second dry annealing include: after drying for 12-14 hours under the condition of 20-40° C., annealing treatment under the condition of 90-100° C. for 45-60 minutes.

Further, the step of preparing the back electrode includes: the vacuum degree is not lower than 10 ^-6 mbar, and the evaporation rate is

Under the condition that the evaporation time is 100-150s, the metal electrode is deposited by evaporation on the surface of the second functional layer away from the first functional layer.

Further, the surfactant includes: at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride and didodecyldimethylammonium bromide.

Further, the first organic solvent is a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone with a volume ratio of (3-5):1.

Further, the second organic solvent is a mixed solvent of ethylene glycol and chlorobenzene with a volume ratio of 1:(0.33-2).

In the functional layer and active layer of the ni-structure perovskite-based X-ray detector provided in the first aspect of the present application, lead bromide-type perovskite and lead iodide-type perovskite have good bonding stability with electrodes, which is beneficial to reduce The interface impedance can improve the efficiency of carrier migration and transmission, thereby improving the detection sensitivity and stability of the device. Moreover, these perovskite materials have high absorption efficiency for X-rays. In addition, the lead bromide-type APbBr ₃ perovskite material is used as the n-type functional layer, and the lead iodide-type A'PbI ₃ perovskite material is used as the i-type X-ray active layer, which can optimize the performance of the perovskite active layer and the electrode. The level matching relationship improves the transfer efficiency of X-ray-excited carriers in the perovskite active layer. At the same time, the n-type functional layer can prevent carriers from injecting into the perovskite active layer from the electrode, thereby inhibiting the X-ray detection device. the dark current. The ni-structure perovskite-based X-ray detector provided by the present application has a simple device structure and simultaneously realizes high sensitivity, low detection limit and low dark current.

The preparation method of the n-i structure perovskite-based X-ray detector provided in the second aspect of the present application has a simple process, is suitable for industrialized large-scale production and application, and directly prepares a functional layer on the surface of the substrate, improving the n-type perovskite functional layer. The combination of the i-type perovskite active layer and the electrode and the substrate is tight, reducing interface defects, reducing interface resistance, and improving carrier transfer efficiency, thereby obtaining high detection sensitivity; in addition, the prepared n-i structure perovskite-based X-ray The detector can not only further improve the detection sensitivity of the device through the energy level matching of the n-type perovskite functional layer and the i-type perovskite active layer, but also the n-type perovskite functional layer can inhibit the electrode carrier injection into the i-type perovskite The mineral active layer reduces the dark current in the X-ray detector and improves the stability and safety of the device.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only for the present application For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic structural view of an n-i structure perovskite-based X-ray detector provided in Example 1 of the present application;

2 is a cross-sectional SEM diagram of the n-type perovskite functional layer in the n-i structure perovskite-based X-ray detector provided in Example 1 of the present application;

3 is a cross-sectional SEM diagram of the i-type perovskite functional layer in the n-i structure perovskite-based X-ray detector provided in Example 1 of the present application;

Fig. 4 is the dark current i-t test figure of the X-ray detector provided by embodiment 1 of the present application and comparative examples 1-2;

Fig. 5 is a sensitivity test chart of the X-ray detectors provided in Example 1 and Comparative Examples 1-2 of the present application.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application clearer, the present application will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In this application, the term "and/or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, A and/or B may mean: A exists alone, A and B exist simultaneously, and B exists alone Condition. Among them, A and B can be singular or plural. The character "/" generally indicates that the contextual objects are an "or" relationship.

In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one (one) of a, b or c", or "at least one (one) of a, b and c" can mean: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

It should be understood that in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the order of execution, and some or all steps may be executed in parallel or sequentially, and the execution order of each process shall be based on its functions and The internal logic is determined and should not constitute any limitation to the implementation process of the embodiment of the present application.

Terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

The weight of the relevant components mentioned in the description of the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the various components. The scaling up or down of the content of the fraction is within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass in the description of the embodiments of the present application may be μg, mg, g, kg and other well-known mass units in the chemical industry.

The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features.

The term "n-type" is an abbreviation for n-type semiconductor, which means a semiconductor that is mainly electronically conductive; the term "i-type" is an abbreviation for intrinsic semiconductor, intrinsic semiconductor.

The first aspect of the embodiment of the present application provides a ni-structure perovskite-based X-ray detector, including an n-type perovskite functional layer and an i-type perovskite active layer that are stacked and laminated; the n-type perovskite function The layer contains APbBr ₃ perovskite material, and the i-type perovskite active layer contains A'PbI ₃ perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions.

The ni-structure perovskite-based X-ray detector provided in the first aspect of the embodiment of the present application includes an n-type perovskite functional layer comprising APbBr ₃ perovskite material and an n-type perovskite functional layer comprising A'PbI ₃ perovskite The i-type perovskite active layer of the ore material constitutes an all-perovskite direct conversion X-ray detector with a ni structure. In the functional layer and active layer of the ni-structure perovskite-based X-ray detector in the embodiment of the present application, lead bromide-type perovskite and lead iodide-type perovskite have good bonding stability with electrodes, which is beneficial to reduce interface impedance. Improve the carrier transfer efficiency, thereby improving the detection sensitivity and stability of the device. Moreover, these perovskite materials have high X-ray absorption efficiency, high charge carrier mobility, long charge carrier diffusion length, and very good bulk defect tolerance, which can directly absorb photons to generate electrons. And hole pairs, and then these electrons and hole pairs are converted into free carriers and migrate to the electrodes under the action of an external electric field, and are finally collected by their respective electrodes, with high detection sensitivity and low detection limit. In addition, the lead bromide-type APbBr ₃ perovskite material is used as the n-type functional layer, and the lead iodide-type A'PbI ₃ perovskite material is used as the i-type X-ray active layer. Compared with the A'PbI ₃ perovskite material, The APbBr ₃ perovskite material has a deeper valence band energy level and a shallower conduction band energy level, which can optimize the energy level matching relationship between the titanium active layer and the electrode, and improve the X-ray excited carriers in the titanium active layer. At the same time, it can prevent the injection of carriers from the electrode into the perovskite active layer, thereby suppressing the dark current in the X-ray detection device. The ni-structure perovskite-based X-ray detector provided in the embodiment of the present application has a simple device structure, and the perovskite materials in the n-type and i-type functional layers in the detector have high X-ray absorption efficiency and excellent carrier Characteristics such as mobility and lifetime, through the interaction of n-type and i-type functional layers, not only makes the detector have high sensitivity, but also reduces interface defects and dark current. A better low detection limit.

In some embodiments, the organic ammonium ion includes: at least one of CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ . In the perovskite-based X-ray detector with ni structure in the embodiment of the present application, in the A'PbI ₃ perovskite material and the APbBr ₃ perovskite material, these organic ammonium ions preferred at the A and A' positions can effectively improve the perovskite The film-forming properties of the material.

In some embodiments, the alkali metal ions include: at least one of Cs ⁺ and Rb ⁺ . In the perovskite-based X-ray detector with ni structure in the embodiment of the present application, in the A'PbI ₃ perovskite material and the APbBr ₃ perovskite material, these alkali metal ions preferred at the A and A' positions can effectively improve the perovskite The thermal stability of the material.

In some specific embodiments, A and A' are independently selected from: CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ , Cs ⁺ or Cs ⁺ and Rb ⁺ . That is, in the A'PbI ₃ perovskite material, A' is CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ , Cs ⁺ or Cs ⁺ and Rb ⁺ ; in the APbBr ₃ perovskite material, A is CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ , Cs ⁺ or Cs ⁺ and Rb ⁺ .

In some embodiments, the thickness of the n-type perovskite functional layer is 15 to 25 μm; this thickness not only ensures the uniformity, smoothness, and compactness of the n-type perovskite functional layer, but also ensures that the n-type perovskite The inhibitory effect of the mineral functional layer on the dark current. If the thickness of the n-type perovskite functional layer is too high, the uniformity and density of the film layer will be poor, which will affect the carrier transport; if the thickness of the n-type perovskite functional layer is too low, it will not be conducive to the adjustment of the i-type perovskite active layer and The energy level of the electrode is not effective in suppressing the dark current of the device. In some specific embodiments, the thickness of the n-type perovskite functional layer may be 15-20 μm, 20-23 μm, 23-25 μm, etc.

In some embodiments, the i-type perovskite active layer has a thickness of 100-1000 μm, which ensures the absorption and conversion efficiency of the i-type perovskite active layer for X-rays, thereby ensuring the detection sensitivity of the X-ray detector. If the i-type perovskite active layer is too thin, the X-ray absorption will be weak; if the i-type perovskite active layer is too thick, it will cause serious carrier recombination in the perovskite active layer. In some specific embodiments, the thickness of the i-type perovskite active layer may be 100-200 μm, 200-300 μm, 300-500 μm, 500-800 μm, 800-1000 μm, etc.

In some specific embodiments, the thickness of the n-type perovskite functional layer is 15-25 μm; the thickness of the i-type perovskite active layer is 100-1000 μm, so that the n-type perovskite functional layer and the i-type perovskite are active The layer has a better energy level matching effect, which is conducive to improving the detection sensitivity of the n-i structure perovskite-based X-ray detector and reducing the dark current.

The perovskite-based X-ray detector with n-i structure in the embodiment of the present application can be prepared by the method in the following embodiment.

The second aspect of the embodiment of the present application provides a method for preparing an n-i structure perovskite-based X-ray detector, comprising the following steps:

S10. Obtain a conductive substrate, and prepare a first functional layer on the surface of the conductive substrate;

S20. preparing a second functional layer on the surface of the first functional layer away from the conductive substrate;

S30. Prepare a back electrode on the surface of the second functional layer away from the first functional layer to obtain an n-i structure perovskite-based X-ray detector;

Among them, the first functional layer and the second functional layer are different, they are n-type perovskite functional layer or i-type perovskite active layer respectively, the n-type perovskite functional layer contains APbBr ₃ perovskite material, i-type perovskite functional layer The titanium ore active layer contains A'PbI ₃ perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions.

In the method for preparing the Ni structure perovskite-based X-ray detector provided in the second aspect of the embodiment of the present application, the first functional layer of the perovskite material comprising _APbBr3 or _A'PbI3 is directly prepared on the surface of the conductive substrate, and then On the surface of the first functional layer, a second functional layer different from the first functional layer is prepared on the surface of the perovskite material containing _A'PbI3 or _APbBr3 , and then the back electrode layer is prepared to obtain a ni-structured perovskite base X-ray detector. The preparation method of the ni-structure perovskite-based X-ray detector provided in the embodiment of the present application has a simple process, is suitable for industrialized large-scale production and application, and directly prepares a functional layer on the surface of the substrate, which improves the performance of the n-type perovskite functional layer and The combination of the i-type perovskite active layer with the electrode and the substrate is tight, reducing interface defects, reducing interface resistance, and improving carrier transfer efficiency, thereby obtaining high detection sensitivity; in addition, the prepared ni-structure perovskite-based X-ray detection The energy level matching of the n-type perovskite functional layer and the i-type perovskite active layer can not only further improve the detection sensitivity of the device, but also the n-type perovskite functional layer can inhibit the electrode carrier injection into the i-type perovskite The active layer reduces the dark current in the X-ray detector and improves the stability and safety of the device.

In some embodiments, in the above step S10, the conductive substrate is selected from transparent glass with indium tin oxide. In some embodiments, the size of the conductive base is (1-3 inches) x (1-3 inches).

In some embodiments, a method for preparing an n-i structure perovskite-based X-ray detector includes the steps of:

S11. Obtain a conductive substrate, and prepare an n-type perovskite functional layer on the surface of the conductive substrate as the first functional layer;

S21. Prepare an i-type perovskite active layer on the surface of the first functional layer away from the conductive substrate as the second functional layer;

S31. Prepare a back electrode on the surface of the second functional layer away from the first functional layer to obtain a ni-structure perovskite-based X-ray detector; wherein, the n-type perovskite functional layer contains APbBr ₃ perovskite materials, i-type The perovskite active layer contains A'PbI ₃ perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions. The embodiment of this application considers the dissolution characteristics of A'PbI ₃ or APbBr ₃ perovskite materials, in order to avoid the preparation of the functional layer of APbBr ₃ perovskite materials, the solvent dissolution destroys the deposited A'PbI ₃ perovskite materials , the n-type perovskite functional layer containing APbBr ₃ perovskite material is preferentially prepared on the surface of the conductive substrate, and then the i-type perovskite active layer and back electrode containing A'PbI ₃ perovskite material are prepared, which is conducive to improving ni Stability of structural perovskite-based X-ray detectors.

In some embodiments, in the above step S11, the first functional layer is an n-type perovskite functional layer, and the step of preparing the n-type perovskite functional layer includes:

S111. Mix ammonium bromide salt or alkali metal bromide salt with lead bromide, a surfactant and a first organic reagent to obtain a first perovskite solution;

S112. Deposit the first perovskite solution on the surface of the conductive substrate, and perform the first dry annealing to form an n-type perovskite functional layer.

In the preparation of the n-type perovskite functional layer in the embodiment of the present application, ammonium bromide salt or alkali metal bromide salt and lead bromide are used as raw material components, and perovskite is prepared by mixing with a surfactant and a first organic reagent ore solution; then the first perovskite solution is deposited on the surface of the conductive substrate, and the self-assembly of the perovskite material is performed while the solution is drying to form a film, thereby generating APbBr ₃ perovskite crystal material in situ on the surface of the conductive substrate. The n-type perovskite functional layer prepared by the solution method in the embodiment of the present application, on the one hand, improves the film-forming performance of the n-type perovskite functional layer, makes the film layer denser, has uniform thickness, smooth surface, and reduces film defects. , so that the life of the film layer is longer, and the carrier diffusion length is increased, thereby improving the mobility of the perovskite functional layer; The perovskite crystals in the titanium ore functional layer can induce crystal growth in the i-type perovskite functional layer, reduce interface defects, reduce interface resistance, and further improve the migration and transmission efficiency of carriers, thereby improving the detection sensitivity of the detector.

In some embodiments, in the above step S111, in the first perovskite solution, the ratio of the molar amount of ammonium bromide salt or alkali metal bromide salt to the molar amount of lead bromide is 1: (1-1.2); The molar ratio fully ensures the contact reaction between the raw material components. Preferably, a slightly excessive amount of lead bromide is used, which is beneficial to make ammonium bromide salt or alkali metal bromide and lead bromide fully contact and react in the process of slurry and drying film formation, and generate _APbBr3 perovskite crystal material , to improve the stability of perovskite crystals. In some specific embodiments, the ratio of the molar amount of ammonium bromide salt or alkali metal bromide salt to the molar amount of lead bromide may be 1:1, 1:1.1, 1:1.2, etc.

In some embodiments, in the first perovskite solution, the mass ratio of the total mass of ammonium bromide salt, alkali metal bromide salt and lead bromide to the surfactant and the first organic reagent is 100:(0.5～1.5 ): (50-75), the mass ratio of the raw material components not only makes the first perovskite solution have a suitable viscosity, but also has good dispersion stability of each component in the solution, which is conducive to subsequent spin coating, scraping It is suitable for large-area preparation of n-type perovskite functional layers. In addition, this mass ratio ensures the content of the APbBr ₃ perovskite material in the functional layer, thereby ensuring the detection sensitivity of the n-type perovskite functional layer to the X-ray detector, the improvement of the absorption and conversion efficiency of X-rays, and Inhibition of dark current, and the n-type perovskite functional layer obtained by this ratio has a smooth surface morphology, and a high-crystallinity perovskite crystalline film can be obtained. If the solvent content is too low, the solubility of the solvent to the raw materials will be poor, and at the same time, the viscosity of the first perovskite solution will be too large, which is not conducive to slurry coating deposition; if the solvent content is too high, the first perovskite The viscosity of the ore solution is too low, the solution is difficult to deposit and form, and it is also not conducive to the preparation of the film layer. If the content of the surfactant is too high or too low, the film-forming performance of the first perovskite solution will be reduced.

In some embodiments, the surfactant is selected from quaternary ammonium salt surfactants, which can more effectively adjust the surface tension of the solution and improve the film-forming properties of the perovskite slurry. In some specific embodiments, the surfactant includes: cetyltrimethylammonium bromide CTAB, cetyltrimethylammonium chloride CTAC, didodecyldimethylammonium bromide DDAB at least one.

In some embodiments, the first organic solvent includes: at least one of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide, and these organic solvents are sensitive to ammonium bromide or bromide Alkali metal salts, lead bromide, surfactants and other raw material components all have good solubility, which is conducive to the full contact reaction of each raw material component. In some specific embodiments, the first organic solvent is a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone with a volume ratio of (3-5):1; The combined effect of two solvents, formamide and N-methylpyrrolidone, can better improve the dispersion stability of each raw material component in the solution.

In some embodiments, in the above step S112, the step of depositing the first perovskite solution on the surface of the conductive substrate includes: spinning the first perovskite solution under the condition that the rotation speed of the spin coating is 5000-7000rmp/s Apply to conductive substrate surfaces. The deposition of the first perovskite solution in the embodiment of the present application under this condition can improve the uniformity and stability of the film layer, and make the film layer flat and dense.

In some other embodiments, the first perovskite solution is deposited on the surface of the conductive substrate by scraping, specifically, under the condition that the scraping speed is 10-15 mm/s and the scraper height is 30-50 μm, the second A perovskite solution is scraped and coated on the surface of the conductive substrate to make the formed film layer uniform, compact and smooth.

In some embodiments, the conditions for the first dry annealing include: after drying at 20-40°C for 6-8 hours to remove excess solvent in the perovskite solution, annealing at 90-100°C for 25- 30 minutes; while the perovskite slurry is solidified and formed, the APbBr ₃ perovskite is self-assembled to improve the order, structural integrity and purity of the APbBr ₃ perovskite material crystal form in the n-type perovskite functional layer , performance stability and other characteristics. If the annealing temperature is too low, then the perovskite active layer in the perovskite crystal form, the optimization effect of purity, etc. is not good, which is not conducive to improving the photoelectricity and stability of the perovskite active layer; if the annealing temperature is too high, then It is easy to cause the decomposition of the perovskite material itself, which destroys the stability of the perovskite active layer.

In some embodiments, in the above step S21, the second functional layer is an i-type perovskite functional layer, and the step of preparing the i-type perovskite functional layer includes:

S211. Mix ammonium iodide salt or alkali metal iodide salt with lead iodide, a conductive polymer binder and a second organic reagent to obtain a second perovskite slurry;

S212. Deposit the second perovskite slurry on the surface of the first functional layer, and perform a second dry annealing to form an i-type perovskite functional layer.

The preparation of the i-type perovskite functional layer in the embodiment of the present application uses ammonium iodide salt or alkali metal iodide salt and lead iodide as raw material components, and is prepared by mixing with a conductive polymer binder and a second organic reagent Perovskite slurry; then the second perovskite slurry is deposited on the surface of the first functional layer, and during the drying process of the slurry, the ordered self-assembly of the perovskite material is induced by the first functional layer, so that in the In-situ generation of A'PbI ₃ perovskite crystal material with matching crystal form on the surface of a functional layer. The i-type perovskite functional layer prepared by the slurry method in the embodiment of the present application, on the one hand, is conducive to the preparation of a thicker i-type functional layer, thereby ensuring the absorption and conversion efficiency of the detector for full-band X-rays, and on the other hand , through the induction of the first functional layer, not only the self-assembly effect of the perovskite material is improved, the film-forming performance of the i-type perovskite functional layer is improved, the film layer is denser, the thickness is uniform, the surface is smooth, and the The tightness of the combination of the i-type perovskite functional layer and the surface of the n-type first functional layer reduces interface defects, reduces interface resistance, and improves carrier migration and transmission efficiency, thereby improving the detection sensitivity of the detector.

In some embodiments, in the above step S211, in the second perovskite slurry, the ratio of the molar amount of ammonium iodide salt or alkali metal iodide to the molar amount of lead iodide is 1: (1-1.1) ; This ratio is conducive to the full contact reaction of ammonium iodide and or alkali metal iodide and lead iodide in the process of slurry and dry film formation, to generate APbI ₃ perovskite crystal materials, and improve the stability of perovskite crystals sex. In some preferred embodiments, the ratio of the molar weight of ammonium iodide or alkali metal iodide to the molar weight of lead iodide is 1: (1.05～1.1), and slightly excessive lead iodide is more conducive to improving the Crystallization and film-forming properties of diperovskite slurries. In some specific embodiments, in the second perovskite slurry, the ratio of the molar weight of ammonium iodide salt or alkali metal iodide to the molar weight of lead iodide can be 1:1.05, 1:1.08, 1:1: 1.10 etc.

In some embodiments, in the second perovskite slurry, the mass ratio of the total mass of ammonium iodide salt, alkali metal iodide salt and lead iodide to the conductive polymer binder and the second organic reagent is 100: (0.5～2.5): (35～50); the mass ratio of the raw material components makes the second perovskite slurry have a suitable viscosity, and the dispersion stability of each component in the slurry is good, which is beneficial to Subsequent film deposition by scraping and other methods is suitable for large-area preparation of i-type perovskite functional layers. At the same time, the mass ratio ensures the content of the APbI ₃ perovskite material in the functional layer, thereby ensuring the detection sensitivity of the i-type perovskite functional layer to the X-ray detector and the improvement of the absorption and conversion efficiency of X-rays. If the solvent content is too low, the viscosity of the second perovskite slurry is too high, which is not conducive to slurry coating deposition; if the solvent content is too high, the viscosity of the second perovskite slurry is too low, and the slurry is difficult to deposit Forming is also unfavorable for film layer preparation. The conductive polymer binder can not only increase the viscosity of the second perovskite slurry, improve the conductivity of the functional layer, but also make the perovskite crystals formed by self-assembly in the functional layer tightly bonded, and the It plays the role of fixing the perovskite crystallites. If the content of the conductive polymer binder is too high or too low, the film-forming performance of the second perovskite slurry will be reduced.

In some embodiments, the conductive polymer binder is selected from the group consisting of: polythiophene, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly[bis(4-phenyl) Base) (4-butylphenyl) amine], at least one of poly-p-phenylene vinylene; these conductive polymer adhesives have good electrical conductivity, not only make the perovskite crystals in the functional layer tightly combined , and through the combination of perovskite crystals and conductive polymers to form a conductive network, it is beneficial to improve the mobility and transport performance of carriers in the i-type perovskite functional layer; in addition, these conductive polymer binders can improve the performance of perovskite The viscosity of the slurry improves the bonding stability between the perovskite slurry and the first functional layer.

In some embodiments, the second organic solvent includes: at least one of chlorobenzene, toluene, dimethyl sulfoxide, and ethylene glycol, which not only has a good solubility for conductive polymer materials, but also has a good solubility for ammonium iodide. Salt, alkali metal iodide, lead iodide and other perovskite raw materials and self-assembled perovskite have good uniform dispersion performance, so that the components in the perovskite slurry can be uniformly and stably dispersed in the solvent, A perovskite slurry with a suitable viscosity is formed, which is conducive to subsequent deposition and film formation. In some specific embodiments, the second organic solvent is a mixed solvent of ethylene glycol and chlorobenzene with a volume ratio of 1: (0.33～2), and the compound use of the two solvents of ethylene glycol and chlorobenzene can better Improve the dispersion stability of each raw material component in the slurry.

In some embodiments, in the above step S212, the step of depositing the second perovskite slurry on the surface of the first functional layer includes: under the condition that the scraping speed is 10-15 mm/s and the scraper height is 100-1500 μm and scrape coating the second perovskite slurry on the surface of the first functional layer. The deposition of the second perovskite slurry in the embodiment of the present application under this condition can improve the uniformity and stability of the film layer, and make the film layer flat and dense.

In some embodiments, the conditions for the second dry annealing include: after drying at 20-40°C for 12-14 hours to remove excess solvent in the perovskite slurry, annealing at 90-100°C for 45 ~60 minutes, while the perovskite slurry is solidified and formed, the A'PbI ₃ perovskite is self-assembled to improve the order of the crystal form of the A'PbI ₃ perovskite material in the i-type perovskite functional layer, Structural integrity, purity, performance stability and other characteristics. If the annealing temperature is too low, then the perovskite active layer in the perovskite crystal form, the optimization effect of purity, etc. is not good, which is not conducive to improving the photoelectricity and stability of the perovskite active layer; if the annealing temperature is too high, then It is easy to cause cracks in the perovskite active layer, and it will also cause the material to decompose, destroying the stability of the perovskite active layer.

In some embodiments, in the above step S30, the step of preparing the back electrode includes: the vacuum degree is not lower than 10 ^-6 mbar, and the evaporation rate is

Under the condition that the evaporation time is 100-150s, the metal electrode is deposited by evaporation on the surface of the second functional layer away from the first functional layer. If the vacuum is too low, the electrode material is easily contaminated, and at the same time, the evaporation temperature will increase to decompose the perovskite material in the first functional layer and the second functional layer, destroying the stability of the material and the functional layer. If the evaporation rate is too fast, the surface of the perovskite active layer will be damaged; if the evaporation rate is too low, the deposition efficiency will be low. In addition, on the one hand, the length of the evaporation time will affect the stability of the deposited film, and on the other hand, the length of the deposition time can be determined according to the thickness of the deposited film. The evaporation time of the embodiment of this application is 100-1500s. The stability of the film layer makes the thickness of the deposited electrode meet the application requirements of X-ray detection devices. In some specific embodiments, the material of the back electrode includes Al, Ag, Au, Cu and other metal materials. In some other embodiments, the back electrode may also be a carbon electrode prepared by a deposition method.

In order to make the above-mentioned implementation details and operations of the present application clearly understood by those skilled in the art, as well as the remarkable performance of the n-i structure perovskite-based X-ray detector and its preparation method in the embodiment of the present application, the following is implemented through multiple An example is used to illustrate the above-mentioned technical solution.

Example 1

An n-i structure perovskite-based X-ray detector, the preparation of which comprises the steps of:

1. Mix CH ₃ NH ₃ Br, lead bromide, CTAB with a mixed solvent of DMF and NMP to make the first perovskite solution, wherein the volume ratio of DMF and NMP is 4:1, CH ₃ NH ₃ Br and The mass ratio of the total mass of lead bromide to CTAB and solvent is 100:0.75:70; the first perovskite solution is spin-coated on indium oxide under the condition that the spin-coating rotation speed is 6000rmp/s and the spin time is 60s. The conductive substrate of tin ITO transparent glass is dried at room temperature for 6 hours, and then annealed at 100°C for 30 minutes to form an n-type perovskite functional layer of CH ₃ NH ₃ PbBr ₃ with a thickness of 7 μm;

2. Mix CH ₃ NH ₃ I, lead iodide, polythiophene with a mixed solvent of ethylene glycol and chlorobenzene to make the second perovskite slurry, wherein the volume ratio of ethylene glycol and chlorobenzene is 1:2, The mass ratio of the total mass of CH ₃ NH ₃ I and lead iodide to polythiophene and solvent is 100:0.5:50; under the condition that the scraping speed is 10mm/s and the scraper height is 1200μm, the second perovskite The slurry is spin-coated on the surface of the n-type perovskite functional layer, dried at room temperature for 6 hours, and then annealed at 100°C for 60 minutes to form an i-type perovskite functional layer of CH ₃ NH ₃ PbI ₃ with a thickness of 500μm;

3. At a vacuum of 10 ^-6 mbar, the evaporation rate is

Under the condition that the evaporation time is 100s, Au is vacuum-deposited on the surface of the i-type perovskite functional layer to form an Au metal back electrode, and a ni-structured perovskite-based X-ray detector with a structure of ITO/CH ₃ is obtained. NH ₃ PbBr ₃ /CH ₃ NH ₃ PbI ₃ /Au, the structure is shown in Figure 1.

Example 2

A ni structure perovskite-based X-ray detector, the difference between it and Example 1 is that in step 1, CH ₂ (NH ₃ ) ₂ Br is used to obtain n-type calcium of CH ₂ (NH ₃ ) ₂ PbBr ₃ Titanium functional layer, Ni structure Perovskite-based X-ray detector has a structure of ITO/CH ₂ (NH ₃ ) ₂ Br/CH ₃ NH ₃ PbI ₃ /Au.

Example 3

A ni-structure perovskite-based X-ray detector, the difference from Example 1 is that in step 2, CH ₂ (NH ₃ ) ₂ I is used to obtain CH ₂ (NH ₃ ) ₂ PbI ₃ i-type calcium Titanium functional layer, Ni structure Perovskite-based X-ray detector has a structure of ITO/CH ₃ NH ₃ PbBr ₃ /CH ₂ (NH ₃ ) ₂ I/Au.

Example 4

A ni structure perovskite-based X-ray detector, the difference between it and embodiment 1 is: adopt CsBr in step 1, make the n-type perovskite functional layer of _CsPbBr3 , ni structure perovskite-based X-ray detection The structure of the device is ITO/CsPbBr ₃ /CH ₃ NH ₃ PbI ₃ /Au.

Example 5

A kind of Ni structure perovskite-based X-ray detector, its difference with embodiment 1 is: adopt CsI in step 2, make the i-type perovskite functional layer of CsPbI ₃ , Ni structure perovskite-based X-ray detection The structure of the device is ITO/CH ₃ NH ₃ PbBr ₃ /CsPbI ₃ /Au.

Example 6

A kind of Ni structure perovskite base X-ray detector, its difference with embodiment 1 is: adopt CsBr in step 1, make the n-type perovskite functional layer of CsPbBr ₃ ; Adopt CsI in step 2, make CsPbI The i-type perovskite functional layer of ₃ , the structure of the ni structure perovskite-based X-ray detector is ITO/CsPbBr ₃ /CsPbI ₃ /Au.

Comparative example 1

1. Mix CH ₃ NH ₃ I, lead iodide, polythiophene with a mixed solvent of ethylene glycol and chlorobenzene to make the second perovskite slurry, wherein the volume ratio of ethylene glycol and chlorobenzene is 1:2, The mass ratio of the total mass of CH ₃ NH ₃ I and lead iodide to polythiophene and solvent is 100:0.5:50; under the condition that the scraping speed is 10mm/s and the scraper height is 1200μm, the second perovskite The slurry is spin-coated on the conductive substrate surface of indium tin oxide ITO transparent glass, dried at room temperature for 6 hours, and then annealed at 100°C for 60 minutes to form the i-type perovskite function of CH ₃ NH ₃ PbI ₃ layer with a thickness of 500 μm;

2. At a vacuum of 10 ^-6 mbar, the evaporation rate is

Under the condition that the evaporation time is 100s, Au is vacuum-deposited on the surface of the i-type perovskite functional layer to form Au metal back dot gold, and a perovskite-based X-ray detector is obtained, and its structure is ITO/CH ₃ NH ₃ PbI ₃ /Au.

Comparative example 2

An amorphous selenium-based X-ray detector from Canada Analogic was used as Comparative Example 2.

Further, in order to verify the progress of the embodiment of the present application, the following performance tests were carried out:

1. Observation of the cross-sectional morphology of the n-type perovskite functional layer and the i-type perovskite functional layer in the n-i structure perovskite-based X-ray detector prepared in Example 1 by scanning electron microscopy, the test diagram is as follows As shown in accompanying drawings 2 to 3, wherein, Fig. 2 is a cross-sectional SEM image of an n-type perovskite functional layer prepared by a solution method, and the film layer has good compactness; Fig. 3 is an i-type perovskite prepared by a slurry method The cross-sectional SEM image of the functional layer shows that the crystal size is relatively uniform and the crystals are tightly combined.

2. The X-ray detectors prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were subjected to a photocurrent test, i.e., an I-t test, to obtain the X-ray response electricity of the detectors at different doses, thereby obtaining the detector detectors respectively X-ray sensitivity (S, Sensitivity); And by I-t test, obtain the dark current density (Dark Current) under detector dark field respectively, wherein, the dark current i-t test figure of embodiment 1 and comparative example 1-2 is as attached As shown in Fig. 4, the abscissa is time, and the ordinate is current density; the sensitivity test chart of embodiment 1 and comparative example 1-2 is shown in accompanying drawing 5, and abscissa is dose, and ordinate is electric charge. The test results are shown in Table 1 below:

Table 1

From the above test results, it can be known that the ni-structure perovskite-based X-ray detectors prepared in Examples 1-4 of the present application exhibit higher detection sensitivity and lower dark current density. The ni-structure perovskite-based X-ray detectors prepared in Examples 5-6 also have lower dark current. In addition, since the i-type perovskite functional layer adopts the _CsPbI3 perovskite material, the phase state of the material is stable The performance is relatively poor, and the transition from α phase to δ phase is prone to occur, resulting in a decrease in the detection sensitivity of the device. It shows that the ni-structure perovskite-based X-ray detector in the embodiment of the present application can effectively suppress the dark current of the device while improving the detection sensitivity of the device through the synergistic effect of the i-perovskite active layer and the n-type perovskite functional layer . The X-ray detector of Comparative Example 1 is a device formed by directly setting electrodes on both sides of the perovskite active layer, and the dark current is as high as 463nA/cm ² . In comparison example 2, the amorphous selenium-based X-ray detector of Canada Analogic has a low detection sensitivity of only 20 μC Gy _air ^-1 cm ^-2 .

The above descriptions are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application should be included in the protection of the application. within range.

Claims

A ni structure perovskite-based X-ray detector, characterized in that the ni structure perovskite-based X-ray detector includes an n-type perovskite functional layer and an i-type perovskite active layer that are stacked and bonded. layer; the n-type perovskite functional layer contains APbBr 3 perovskite material, and the i-type perovskite active layer contains A'PbI 3 perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions.
The ni-structure perovskite-based X-ray detector according to claim 1, wherein the organic ammonium ions include: at least one of CH 3 NH 3 + and CH 2 (NH 3 ) 2 + ;

And/or, the alkali metal ions include: at least one of Cs + and Rb + .
The ni-structure perovskite-based X-ray detector according to claim 2, wherein said A and said A' are independently selected from: CH 3 NH 3 + , CH 2 (NH 3 ) 2 + , Cs + or Cs + and Rb + .
The n-i structure perovskite-based X-ray detector according to any one of claims 1 to 3, wherein the n-type perovskite functional layer has a thickness of 15 to 25 μm;

And/or, the i-type perovskite active layer has a thickness of 100-1000 μm.
A method for preparing an n-i structure perovskite-based X-ray detector, characterized in that it comprises the following steps:

Obtain a conductive substrate, and prepare a first functional layer on the surface of the conductive substrate;

preparing a second functional layer on the surface of the first functional layer away from the conductive substrate;

preparing a back electrode on the surface of the second functional layer away from the first functional layer to obtain an n-i structure perovskite-based X-ray detector;

Wherein, the first functional layer and the second functional layer are different and are respectively an n-type perovskite functional layer or an i-type perovskite active layer, and the n-type perovskite functional layer includes APbBr 3 perovskite The ore material, the i-type perovskite active layer contains A'PbI3 perovskite material, wherein A and A' are independently selected from alkali metal ions or organic ammonium ions.
The preparation method of the n-i structure perovskite-based X-ray detector according to claim 5, wherein the first functional layer is the n-type perovskite functional layer, and the n-type perovskite is prepared The step of the functional layer includes: mixing ammonium bromide salt or alkali metal bromide salt with lead bromide, a surfactant and a first organic reagent to obtain a first perovskite solution;

Depositing the first perovskite solution on the surface of the conductive substrate, and performing a first dry annealing to form the n-type perovskite functional layer.
The preparation method of the n-i structure perovskite-based X-ray detector according to claim 6, wherein the second functional layer is the i-type perovskite functional layer, and the i-type perovskite is prepared The step of the functional layer includes: mixing ammonium iodide or alkali metal iodide with lead iodide, a conductive polymer binder and a second organic reagent to obtain a second perovskite slurry;

Depositing the second perovskite slurry on the surface of the first functional layer, performing a second dry annealing to form the i-type perovskite functional layer.
The preparation method of the n-i structure perovskite-based X-ray detector according to claim 7, characterized in that, in the first perovskite solution, the ammonium bromide salt or the alkali metal bromide salt The ratio of the molar weight to the molar weight of the lead bromide is 1: (1-1.2);

And/or, in the first perovskite solution, the total mass of the ammonium bromide salt, the alkali metal bromide salt and the lead bromide and the surfactant and the first organic reagent The mass ratio is 100:(0.5～1.5):(50～75);

And/or, the surfactant is selected from quaternary ammonium salt surfactants;

And/or, the first organic solvent includes: at least one of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide;

And/or, in the second perovskite slurry, the ratio of the molar weight of the ammonium iodide salt or the alkali metal iodide salt to the molar weight of the lead iodide is 1:(1-1.10 );

And/or, in the second perovskite slurry, the total mass of the ammonium iodide salt, the alkali metal iodide salt and the lead iodide is mixed with the conductive polymer binder and the The mass ratio of the second organic reagent is 100:(0.5～2.5):(35～50);

And/or, the conductive polymer binder is selected from: polythiophene, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly[bis(4-phenyl At least one of (4-butylphenyl)amine], poly(p-phenylene vinylene);

And/or, the second organic solvent includes: at least one of chlorobenzene, toluene, dimethyl sulfoxide, and ethylene glycol.
The preparation method of the n-i structure perovskite-based X-ray detector according to claim 8, wherein the step of depositing the first perovskite solution on the surface of the conductive substrate comprises: Spin-coating the first perovskite solution on the surface of the conductive substrate under the condition of 5000-7000rmp/s;

Alternatively, under the condition that the scraping speed is 10-15 mm/s and the scraper height is 30-50 μm, scrape-coat the first perovskite solution on the surface of the conductive substrate;

And/or, the conditions for the first dry annealing include: after drying at 20-40°C for 6-8 hours, annealing at 90-100°C for 25-30 minutes;

And/or, the step of depositing the second perovskite slurry on the surface of the first functional layer comprises: under the condition that the scraping speed is 10-15 mm/s and the scraper height is 100-1500 μm, depositing the The second perovskite slurry is scraped on the surface of the first functional layer;

And/or, the conditions of the second dry annealing include: after drying for 12-14 hours under the condition of 20-40° C., annealing treatment under the condition of 90-100° C. for 45-60 minutes.
The method for preparing the Ni-structure perovskite-based X-ray detector according to claim 9, wherein the step of preparing the back electrode comprises: the vacuum degree is not lower than 10 -6 mbar, and the evaporation rate is
Under the condition that the evaporation time is 100-150s, the metal electrode is deposited by evaporation on the surface of the second functional layer away from the first functional layer;

And/or, the surfactant includes: at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, didodecyldimethylammonium bromide;

And/or, the first organic solvent is a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone with a volume ratio of (3-5):1;

And/or, the second organic solvent is a mixed solvent of ethylene glycol and chlorobenzene with a volume ratio of 1:(0.33-2).