Perovskite infrared detector structure, preparation method thereof and infrared imaging chip

Abstract

The invention provides a perovskite infrared detector structure, a preparation method of the perovskite infrared detector structure and an infrared imaging chip. Comprising a substrate, a P-type semiconductor layer arranged on the substrate, an aluminum oxide layer arranged on the P-type semiconductor layer, a photosensitive perovskite layer arranged on the aluminum oxide layer, an N-type semiconductor layer arranged on the photosensitive perovskite layer, a buffer layer arranged on the N-type semiconductor layer and a back electrode arranged on the buffer layer, the material of the photosensitive perovskite layer is FA < 0.7 > MA < 0.3 > Pb < 0.5 > Sn < 0.5 > I < 3 >, and the optical band gap is lt; 1.26 eV, 1.26 eV; the whole detector structure is carried out by adopting a specific preparation process, and a perovskite thin film with relatively good surface appearance, relatively low defect state density and relatively good quality can be obtained, so that the device has excellent performances of high detection rate, high response speed, wide spectral response range, good process compatibility, good imaging quality and the like; the method is suitable for the technical field of semiconductor photoelectric materials and devices.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor optoelectronic materials and devices, and in particular to a perovskite infrared detector structure, a preparation method thereof, and an infrared imaging chip. Background Art

[0002] Photodetectors can convert optical signals into measurable electrical signals. As a key connection point between different devices, they are the foundation of modern industrial interconnection and artificial intelligence. Infrared radiation has a wide range of applications in life and health, national defense security, autonomous driving, optical imaging, and optical communications. Therefore, infrared photodetectors are of great significance in military and civilian fields.

[0003] Usually, the photosensitive materials used in commercial infrared photodetectors are inorganic non-metallic materials, such as silicon, germanium and indium gallium arsenide. The crystal growth of these materials requires extremely harsh high temperature and high vacuum environments, which leads to high energy consumption and high manufacturing costs. In contrast, metal halide perovskites have excellent photoelectric properties and high light absorption coefficients (≈10 5 cm -1 ), adjustable optical band gap (1.2–3.0 eV), low preparation cost, fast solution processing, extremely high defect tolerance and low defect state density, high carrier mobility, long carrier lifetime and diffusion length, and are widely used in the preparation of infrared photodetectors.

[0004] With the rapid development of perovskite infrared detectors, the demand for infrared detectors in various fields is also growing, including but not limited to high detection sensitivity, fast response speed and broadband detection range. However, existing perovskite infrared detectors still have problems such as low sensitivity to infrared radiation detection, slow response speed, and difficulty in compatibility with heterogeneous readout circuit chips, which makes it difficult to meet market demand. Summary of the invention

[0005] In order to solve one of the above-mentioned technical defects, the present application provides a perovskite infrared detector structure, a preparation method thereof and an infrared imaging chip.

[0006] According to the first aspect of the present application, a perovskite infrared detector structure is provided, including: a substrate; a P-type semiconductor layer: arranged on a substrate; an aluminum oxide layer: arranged on the P-type semiconductor layer; a photosensitive perovskite layer: arranged on the aluminum oxide layer; an N-type semiconductor layer: arranged on the photosensitive perovskite layer; a buffer layer: arranged on the N-type semiconductor layer; and a back electrode: arranged on the buffer layer.

[0007] Preferably, the photosensitive perovskite layer is made of a narrow bandgap metal halide FA 0.7 MA 0.3 Pb 0.5 Sn0.5 I3, whose optical band gap is <1.26 eV.

[0008] Preferably, the substrate is prepared from indium-doped tin oxide; the P-type semiconductor layer is prepared from [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid; the N-type semiconductor layer is prepared from fullerene; the buffer layer is prepared from bathocuproine; and the back electrode is prepared from silver.

[0009] Preferably, the thickness range of the P-type semiconductor layer is 10 to 20 nm; the thickness range of the aluminum oxide layer is 20 to 30 nm; the thickness range of the photosensitive perovskite layer is 400 to 500 nm; the thickness range of the N-type semiconductor layer is 25 to 30 nm; the thickness range of the buffer layer is 5 to 7 nm; and the thickness range of the back electrode is 80 to 120 nm.

[0010] More preferably, the thickness of the P-type semiconductor layer is 15nm; the thickness of the aluminum oxide layer is 30nm; the thickness of the photosensitive perovskite layer is 440nm; the thickness of the N-type semiconductor layer is 28nm; the thickness of the buffer layer is 6nm; and the thickness of the back electrode is 100nm.

[0011] According to the second aspect of the present application, a method for preparing a perovskite infrared detector structure as described above is provided, comprising: S10, providing a substrate; S20, processing a P-type semiconductor material by a spin coating process to form a P-type semiconductor layer on the substrate; S30, processing a nano-aluminum oxide material by a spin coating process to form an aluminum oxide layer on the P-type semiconductor layer; S40, processing a perovskite precursor material by a spin coating process to form a photosensitive perovskite layer on the aluminum oxide layer; S50, processing an N-type semiconductor material by a vacuum evaporation process to form an N-type semiconductor layer on the photosensitive perovskite layer; S60, forming a buffer layer on the N-type semiconductor layer by a vacuum evaporation process; S70, processing a conductive material by a vacuum evaporation process to form a back electrode on the buffer layer.

[0012] Preferably, step S40 specifically comprises: weighing appropriate amounts of iodoformamide, iodomethylamine, lead iodide and stannous iodide; then adding a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio range of 3:1 to 5:1, stirring at room temperature until completely dissolved, to obtain FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I perovskite precursor solution; spin-coating the perovskite precursor solution on the aluminum oxide layer, and adding chlorobenzene anti-solvent during the spin-coating process; after the spin-coating is completed, annealing is performed to obtain a perovskite film to form a photosensitive perovskite layer.

[0013] More preferably, in step S40: the molar ratio of iodoformamidine, iodomethylamine, lead iodide and stannous iodide weighed is 7:3:5:5; the volume ratio of the mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide is 4:1; the obtained FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The concentration of I3 perovskite precursor solution is 1.1 mol / L; when spin coating the perovskite precursor solution, the volume of the perovskite precursor solution is 120 μL, the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 60 seconds; at the 45th second of spin coating, 350 μL of chlorobenzene anti-solvent is added; after spin coating, annealing is performed at 100°C for 10 minutes to obtain a perovskite film with a thickness of 440 nm, forming a photosensitive perovskite layer.

[0014] More preferably, step S10 specifically includes: providing a substrate, and performing the following cleaning treatment on the substrate: first, ultrasonically cleaning the substrate with a cleaning agent for 20 minutes, then ultrasonically cleaning the substrate with deionized water, anhydrous ethanol, acetone and isopropanol for 20 minutes respectively, then drying the substrate for 30 minutes, and finally cleaning the surface again with nitrogen, and treating the substrate with ozone for 20 minutes before use;

[0015] Step S20 specifically includes: first dissolving [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid in ethanol to form a solution with a concentration of 2 mg / mL, and then spin coating 120 μL of the solution on the cleaned substrate 10, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing at 100° C. for 10 minutes to obtain a P-type semiconductor layer with a thickness of 15 nm;

[0016] Step S30 specifically includes: first diluting the nano-aluminum oxide solution in isopropanol at a volume ratio of 1:20, and then spin-coating 150 μL of the diluted solution on the P-type semiconductor layer 20, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing at 120° C. for 20 minutes to obtain an aluminum oxide layer with a thickness of 30 nm;

[0017] Step S50 specifically includes: using a vacuum evaporation process to deposit fullerene material on the photosensitive perovskite layer to obtain an N-type semiconductor layer with a thickness of 28 nm, wherein: the evaporation rate is

[0018] Step S60 specifically includes: using a vacuum evaporation process to deposit a bathocuproin material on the N-type semiconductor layer to obtain a buffer layer with a thickness of 6 nm, wherein: the evaporation rate is

[0019] Step S70 specifically includes: after placing the device into the vacuum coating machine, first reduce the air pressure inside the machine to 5×10 - 4 Pa, and then start preparing the metal silver electrode; when the thickness of the silver electrode is between 0 and 5 nm, control the evaporation rate to After that, the evaporation speed increases with each 5nm increase in thickness. Finally, the evaporation rate is maintained at Until the evaporation is completed.

[0020] According to a third aspect of the present application, an infrared imaging chip is provided, comprising:

[0021] Photodetector: an array structure formed by the aforementioned perovskite infrared detector structure, the array structure is prepared by ultrafast laser etching process, and is used to convert the received infrared radiation signal into a readable current signal;

[0022] TFT readout circuit: electrically connected to the photodetector, used to read the current signal output by the photodetector, form a corresponding graph based on the reading result, and perform imaging output.

[0023] The perovskite infrared detector structure provided in this application has the following advantages over the traditional perovskite infrared detector due to its special structure, perovskite photosensitive material with special components and special preparation process:

[0024] 1. The structure of P-type semiconductor layer + aluminum oxide layer + photosensitive perovskite layer + N-type semiconductor layer + buffer layer + back electrode in the present application can allow infrared radiation to be absorbed by the photosensitive perovskite layer, generate electron-hole pairs, and the electrons are excited to the conduction band and leave holes in the valence band. Then the electrons are extracted by the N-type semiconductor layer and transmitted to the back electrode, and the holes are extracted by the P-type semiconductor layer, flow through the substrate to the back electrode and recombine with the electrons. The directional flow of carriers (electrons and holes) forms a current, thereby realizing the conversion of light radiation signals into measurable current signals. In particular, the nano-aluminum oxide layer introduced between the P-type semiconductor layer and the photosensitive perovskite layer improves the wettability and interface contact of the photosensitive perovskite layer, thereby improving the weak light detection capability and response speed of the entire device to a certain extent;

[0025] 2. The photosensitive perovskite layer in the present application has a specific composition, wherein the synergistic effect of lead (Pb) and tin (Sn) helps to optimize the optical band gap, spectral response characteristics and charge transfer performance of the material. Lead provides good electron transfer capability, while tin helps to reduce the band gap and improve the conductivity of the material, thereby achieving efficient charge separation and transfer in infrared detectors. In addition, tin reduces the band gap of the perovskite material and can enhance the material's absorption capacity for infrared radiation, thereby achieving the purpose of broadening the spectral response range, so that the entire perovskite material can effectively absorb a wide range of spectra, including visible light and infrared light; and the mixed cation structure of FA and MA helps to optimize the structural stability and electronic properties of the perovskite crystal. The combination of the two can improve the crystallization quality of the perovskite film and reduce defects, thereby achieving the purpose of improving the detector response speed and detection sensitivity;

[0026] 3. The preparation process in the present application: the raw materials with the optimal molar ratio are used to prepare the perovskite film, so that the film has a narrow optical band gap and widens the spectral response range of the device; the use ratio of DMF and DMSO in the precursor solution is strictly controlled to form a crystal with a stable lattice; the anti-solvent assisted spin coating method is adopted, which can not only quickly remove the excess polar solvent molecules in the precursor film to form a stable intermediate film, but also has the advantages of simple process and easy adjustment; the evaporation method is used for film preparation in multiple steps, with high controllable repeatability and low large-scale production cost; the array structure is made by a precise laser etching method, which has excellent imaging function, simple process, portable operation, good scalability, and can achieve larger array and higher resolution imaging; all process steps are compatible with the readout circuit process, with low production cost, can be mass-produced, and can be compatible and integrated with CMOS and TFT chips to realize integrated imaging applications with TFT chips;

[0027] By adopting the preparation process in the present application, it is possible to prepare perovskite films with good surface morphology, low defect state density, good quality and other high-quality thin film layers, so that the entire detector finally formed has excellent performance such as high detection rate, fast response speed, wide spectral response range, good process compatibility, and high imaging quality, which is an effect that many perovskite infrared detectors in the prior art cannot achieve.

[0028] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the contents indicated in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0030] Figure 1 It is a schematic structural diagram of a perovskite infrared detector array provided by the present application;

[0031] Figure 2 It is a scanning electron microscope (SEM) image of a perovskite thin film prepared by using the preparation method provided by the present application;

[0032] Figure 3 It is a curve showing the variation of the external quantum efficiency of a perovskite infrared detector prepared by using the preparation method provided by the present application with the irradiation wavelength;

[0033] Figure 4 It is a curve showing the variation of the responsivity of a perovskite infrared detector prepared by using the preparation method provided by the present application with the irradiation wavelength;

[0034] Figure 5 It is the response time of a perovskite infrared detector prepared by using the preparation method provided by the present application;

[0035] Figure 6 It is a curve showing the variation of the specific detectivity of a perovskite infrared detector prepared by using the preparation method provided by the present application with the irradiation wavelength;

[0036] Figure 7 It is an imaging result diagram of the letter "S" by a 5×5 infrared detector array provided by the present application under 980 nm light illumination;

[0037] Figure 8 It is an imaging result diagram of the Chinese characters "Shan Da" by a 64×64 infrared imaging chip based on a TFT readout circuit provided by the present application under 980 nm infrared radiation illumination;

[0038] In the figure: 10 is a substrate, 20 is a P-type semiconductor layer, 30 is an alumina layer, 40 is a photosensitive perovskite layer, 50 is an N-type semiconductor layer, 60 is a buffer layer, and 70 is a back electrode. Detailed implementation manners

[0039] In order to make the technical solutions and advantages in the embodiments of the present application clearer and more understandable, the following further details the exemplary embodiments of the present application with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application and not an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0040] Regarding some problems existing in the prior art:

[0041] In a first aspect, a perovskite infrared detector structure is provided in an embodiment of the present application.

[0042] For example, Figure 1 As shown, the perovskite infrared detector structure includes:

[0043] Substrate 10: used to transfer carriers and pass infrared radiation;

[0044] P-type semiconductor layer 20: disposed on the bottom 10: used for extracting and conducting holes;

[0045] Aluminum oxide layer 30: disposed on the P-type semiconductor layer 20: used to improve the wettability of the perovskite solution on the surface of the P-type semiconductor and suppress the dark current of the device;

[0046] Photosensitive perovskite layer 40: disposed on the aluminum oxide layer 30: used to capture infrared radiation photons;

[0047] N-type semiconductor layer 50: disposed on the photosensitive perovskite layer 40: used for extracting and conducting electrons;

[0048] Buffer layer 60: disposed on the N-type semiconductor layer 50: used for carrier tunneling;

[0049] The back electrode 70 is disposed on the buffer layer 60 and is used for transmitting carriers.

[0050] The infrared detector in the embodiment of the present application works based on the photovoltaic effect. When working, infrared radiation photons with energy not less than the perovskite bandgap width are captured and absorbed by the photosensitive perovskite layer, generating electron-hole pairs, and the electrons are excited to the bottom of the conduction band, leaving holes in the valence band. Then the electrons are extracted by the N-type semiconductor layer 50 and transmitted to the back electrode 70, and the holes are extracted by the P-type semiconductor layer 20, flowing through the substrate 10 to the back electrode 70 to recombine with the electrons. This directional flow of carriers (electrons, holes) forms a current, thereby realizing the conversion of light radiation signals into measurable current signals, and finally realizing photoelectric conversion. The nano-aluminum oxide layer 30 introduced between the P-type semiconductor layer 20 and the photosensitive perovskite layer 40 improves the wettability and interface contact of the photosensitive perovskite layer 40, thereby improving the weak light detection capability and response speed of the entire device to a certain extent.

[0051] In some possible implementations of the first aspect:

[0052] The substrate 10 is made of a conductive oxide, which may be fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), or indium gallium zinc oxide (IGZO). In the embodiment of the present application, indium-doped tin oxide (ITO) is preferred.

[0053] The preparation material of the P-type semiconductor layer 20 is nickel oxide (NiO x ), polybis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), P-type assembled single molecule [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACZ), P-type assembled single molecule [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACZ), P-type assembled single molecule [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-6PACZ) or more doped semiconductors, and in the embodiment of the present application, preferably [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-6PACZ);

[0054] The photosensitive perovskite layer 40 is made of a narrow bandgap metal halide perovskite, and the bandgap is adjusted by ion doping. The specific material chemical formula is APb 1-x Sn x X3; wherein: 0≤x≤1, A is a +1-valent cation (such as methylamine (MA), formamidine (FA), cesium (Cs), rubidium (Rb) ions and mixed components thereof), and X is a -1-valent halogen ion (such as fluorine (F), chlorine (Cl), bromine (Br), iodine (I) or mixed ions thereof); FA is preferred in the embodiment of the present application 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3, its optical band gap is <1.26eV; generally, the optical band gap characteristic of narrow band gap metal halide is usually less than 1.58eV, and the optical band gap of the photosensitive perovskite layer 40 material in the present application is less than 1.26eV, which can be said to be a major breakthrough;

[0055] The N-type semiconductor layer 50 may be made of fullerene (C 60 ), or [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), or tin dioxide (SnO2), and in the embodiment of the present application, fullerene (C 60 );

[0056] The buffer layer 60 is made of bathocuproin (BCP).

[0057] The material for preparing the back electrode 70 can be gold (Au), silver (Ag), copper (Cu), or indium-doped tin oxide (ITO). Since the silver electrode is a low-cost, easy-to-deposit and excellently conductive electrode, silver (Ag) is preferred in the embodiment of the present application.

[0058] The photosensitive perovskite layer 40 in the embodiment of the present application has a specific composition, wherein the synergistic effect of lead (Pb) and tin (Sn) helps to optimize the optical band gap, spectral response characteristics and charge transfer performance of the material. Lead provides good electron transfer capability, while tin helps to reduce the band gap and improve the electrical conductivity of the material, thereby achieving efficient charge separation and transfer in the infrared detector. In addition, tin reduces the band gap of the perovskite material and can enhance the material's absorption capacity for infrared radiation, thereby achieving the purpose of broadening the spectral response range, so that the entire perovskite material can effectively absorb a wide range of spectra, including visible light and infrared light; and the mixed cation structure of FA and MA helps to optimize the structural stability and electronic properties of the perovskite crystal. The combination of the two can improve the crystallization quality of the perovskite film and reduce defects, thereby achieving the purpose of improving the detector response speed and detection sensitivity.

[0059] In some possible implementations of the first aspect:

[0060] The thickness of the P-type semiconductor layer 20 is in the range of 10 to 20 nm, and is preferably 15 nm in the embodiment of the present application;

[0061] The thickness of the aluminum oxide layer 30 is in the range of 20 to 30 nm, and is preferably 30 nm in the embodiment of the present application;

[0062] The thickness of the photosensitive perovskite layer 40 is in the range of 400-500 nm, and is preferably 440 nm in the embodiment of the present application;

[0063] The thickness of the N-type semiconductor layer 50 is in the range of 25 to 30 nm, and is preferably 28 nm in the embodiment of the present application;

[0064] The thickness of the buffer layer 60 is in the range of 5 to 7 nm, and preferably 6 nm in the embodiment of the present application;

[0065] The thickness of the back electrode 70 is in the range of 80 to 120 nm, and is preferably 100 nm in the embodiment of the present application.

[0066] In a second aspect, an embodiment of the present application provides a method for preparing the above-mentioned perovskite infrared detector structure.

[0067] Exemplarily, the preparation method comprises:

[0068] S10, providing a substrate 10;

[0069] S20, treating the P-type semiconductor material by a spin coating process to form a P-type semiconductor layer 20 on the substrate 10;

[0070] S30, treating the nano-aluminum oxide material by a spin coating process to form an aluminum oxide layer 30 on the P-type semiconductor layer 20;

[0071] S40, treating the perovskite precursor material by a spin coating process to form a photosensitive perovskite layer 40 on the aluminum oxide layer 30;

[0072] S50, treating the N-type semiconductor material by a vacuum evaporation process to form an N-type semiconductor layer 50 on the photosensitive perovskite layer 40;

[0073] S60, forming a buffer layer 60 on the N-type semiconductor layer 50 by using a vacuum evaporation process;

[0074] S70 , processing the conductive material by a vacuum evaporation process to form a back electrode 70 on the buffer layer 60 .

[0075] In some possible implementations of the second aspect:

[0076] Step S10 specifically includes: providing a substrate 10, and performing the following cleaning treatment on the substrate 10: first, ultrasonically cleaning with a cleaning agent for 20 minutes to remove grease and organic matter on the surface of the substrate 10, wherein: the cleaning agent is mainly composed of tap water and glass water, and the volume ratio of the two is 1:3; then, ultrasonically cleaning with deionized water, anhydrous ethanol, acetone and isopropanol for 20 minutes respectively, and then drying for 30 minutes, and finally cleaning the surface again with nitrogen, and treating with ozone for 20 minutes before use;

[0077] Step S20 specifically includes: first dissolving [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid in ethanol to form a solution with a concentration of 2 mg / mL, and then spin-coating 120 μL of the solution on the cleaned substrate 10, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing at 100° C. for 10 minutes to obtain a P-type semiconductor layer 20 with a thickness of 15 nm;

[0078] Step S30 specifically includes: first diluting the nano-aluminum oxide solution in isopropanol at a volume ratio of 1:20, and then spin-coating 150 μL of the diluted solution on the P-type semiconductor layer 20, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing at 120° C. for 20 minutes to obtain an aluminum oxide layer 30 with a thickness of 30 nm;

[0079] Step S40 specifically includes: weighing iodoformamide (FAI), iodomethylamine (MAI), lead iodide (PbI2) and stannous iodide (SnI2) powder raw materials in a molar ratio of 7:3:5:5; after a large number of experimental verifications, this ratio can achieve a perovskite film with a narrower optical band gap and broaden the spectral response range of the infrared detector; then adding a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio range of 3:1 to 5:1, stirring at room temperature for 2 hours until completely dissolved, to obtain FA with a concentration range of 0.9 to 1.3 mol / L. 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 perovskite precursor solution; in the embodiment of the present application: the volume ratio of DMF and DMSO is preferably 4:1. After a large number of experimental verifications, this volume ratio can promote the formation of lattice-stable crystals and surface-dense perovskite films, so that the detector achieves the lowest dark current; the obtained FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The concentration of the I3 perovskite precursor solution is preferably 1.1 mol / L. After a large number of experimental verifications, the thickness of the perovskite film at this concentration is about 440 nm, which can obtain the optimal carrier transit length and time and achieve the fastest detector response speed; 120 μL of the perovskite precursor solution is spin-coated on the aluminum oxide layer 30, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 60 seconds; when the spin coating is to the 45th second, 350 μL of chlorobenzene anti-solvent is added dropwise; after a large number of experimental verifications, this step process can form a stable intermediate state film, quickly remove excess polar solvent molecules in the precursor film, and obtain a perovskite film with a smooth and flat surface; after the spin coating is completed, annealing is performed at 100°C for 10 minutes to obtain a perovskite film with a thickness of 440 nm, forming a photosensitive perovskite layer 40;

[0080] Step S50 specifically includes: using a vacuum evaporation process to deposit fullerene (C 60 ) material, to obtain an N-type semiconductor layer 50 with a thickness of 28 nm, wherein: the evaporation rate range is In the present application, it is preferred This steam rate can ensure C 60 The material will not explode.

[0081] Step S60 specifically includes: using a vacuum evaporation process to deposit a bath copper (BCP) material on the N-type semiconductor layer 50 to obtain a buffer layer 60 with a thickness of 6 nm, wherein: the evaporation rate range is In the present application, it is preferred This steaming rate can ensure that the BCP material will not explode;

[0082] Step S70 specifically includes: placing the device after the above process steps face down into the vacuum coating machine, first reducing the air pressure inside the machine to 5×10 -4 Pa, and then start preparing the metal silver electrode; when the thickness of the silver electrode is between 0 and 5 nm, control the evaporation rate to After that, the evaporation speed increases with each 5nm increase in thickness. Finally, the evaporation rate is maintained at Until the evaporation is completed; this step process can avoid overheating of the device surface due to too fast evaporation rate, which affects the device performance; it should be noted that after the evaporation is completed, it is necessary to wait for the internal pressure of the machine to return to the standard atmospheric pressure and cool down before taking out the device.

[0083] The preparation process in the embodiment of the present application uses the raw materials with the optimal molar ratio to prepare the perovskite film, so that the film has a narrow optical band gap and widens the spectral response range of the device; the use ratio of DMF and DMSO in the precursor solution is strictly controlled to form a crystal with stable lattice; the anti-solvent assisted spin coating method is adopted, which can not only quickly remove the excess polar solvent molecules in the precursor film to form a stable intermediate state film, but also has the advantages of simple process and easy adjustment; multiple steps use the evaporation method for film preparation, with high controllable repeatability and low large-scale production cost. Using the preparation process in the embodiment of the present application, it is possible to prepare a perovskite film with good surface morphology, low defect state density, good quality and other high-quality film layers, so that the entire detector finally formed has excellent performances such as high detection rate, fast response speed, wide spectral response range, good process compatibility and high imaging quality, which is an effect that many perovskite infrared detectors in the prior art cannot achieve.

[0084] In a third aspect, an infrared imaging chip is provided in an embodiment of the present application.

[0085] Exemplarily, the infrared imaging chip includes:

[0086] Photodetector: an array structure formed by the above-mentioned perovskite infrared detector structure, the array structure is prepared by ultrafast laser etching process, and is used to convert the received infrared radiation signal into a readable current signal;

[0087] TFT readout circuit: electrically connected to the photodetector, used to read the current signal output by the photodetector, form a corresponding graph based on the reading result, and perform imaging output.

[0088] In some possible implementations of the third aspect:

[0089] When preparing the array structure, the equipment used is a nanosecond pulse laser with a laser wavelength of 355nm and a laser power of 3W.

[0090] The preparation process in the embodiment of the present application adopts a precise laser etching method to produce the array structure, has excellent imaging function, and has a simple process, portable operation, and good scalability, and can achieve larger array and higher resolution imaging; all process steps are compatible with the readout circuit process, with low production cost, capable of large-scale production, and can also be compatible and integrated with CMOS and TFT chips to realize integrated imaging applications with TFT chips.

[0091] In the embodiments of the present application, after repeated exploration and verification, the optimal perovskite infrared detector structure prepared by the preparation method has the following structural parameters and process parameters:

[0092] Substrate 10, made of indium-doped tin oxide (ITO);

[0093] P-type semiconductor layer 20: made of [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-6PACZ), with a thickness of 15 nm;

[0094] Aluminum oxide layer 30: the material is nano aluminum oxide (Al2O3), the thickness is 30nm;

[0095] Photosensitive perovskite layer 40: material is FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3, thickness is 440nm; during preparation: the molar ratio of iodine formamide (FAI), iodine methylamine (MAI), lead iodide (PbI2) and stannous iodide (SnI2) powder raw materials used is 7:3:5:5, the volume ratio of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is 4:1, and the final FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The concentration of the I3 perovskite precursor solution was 1.1 mol / L. During the spin coating of the precursor solution, 350 μL of chlorobenzene antisolvent was added at 45 seconds.

[0096] N-type semiconductor layer 50: made of fullerene (C 60 ), thickness is 28nm; during preparation: evaporation speed is

[0097] Buffer layer 60: The material is bathocuproin (BCP), the thickness is 6nm; during preparation: the evaporation rate is

[0098] Back electrode 70: Made of silver (Ag), with a thickness of 100 nm; during preparation, first reduce the air pressure inside the machine to 5×10 - 4 Pa, and then start preparing the metal silver electrode. When the thickness of the silver electrode is between 0 and 5 nm, the evaporation rate is controlled to After that, the evaporation speed increases with each 5nm increase in thickness. Finally, the evaporation rate is maintained at Until the evaporation is completed.

[0099] Figure 2 This is a scanning electron microscope (SEM) image of a perovskite film prepared by the preparation method provided in the present application. The SEM image shows the microstructure of the surface of the perovskite film. It can be seen from the figure that the prepared perovskite film has uniform and dense grains, a smooth surface, and no obvious holes or cracks, which indicates that the film has formed a uniform grain distribution and a good crystal structure during the deposition process.

[0100] Figure 3 This is a curve of the external quantum efficiency of the perovskite infrared detector prepared by the preparation method provided in the present application as a function of the irradiation wavelength. It can be seen from the figure that the perovskite infrared detector exhibits excellent detection capabilities in the wavelength range of 300nm to 1100nm, and at a wavelength of 540nm, the detector reaches a peak external quantum efficiency of 87.7%; in the near-ultraviolet to visible light range (300nm to 700nm), the external quantum efficiency of the detector still shows a stable and high value, indicating that it has a good response capability to short-wavelength light; at the same time, in the near-infrared range (780nm to 1100nm), although the external quantum efficiency decreases, it still maintains a high detection performance.

[0101] Figure 4 This is a curve showing the change in the responsivity of the perovskite infrared detector prepared by the preparation method provided in the present application as a function of the irradiation wavelength. It can be seen from the figure that at a wavelength of 840nm, the responsivity of the detector array is 0.47A / W, which indicates the excellent photoelectric conversion capability of the prepared perovskite infrared detector array in the near-infrared band.

[0102] Figure 5 The response time of the perovskite infrared detector prepared by the preparation method provided in the present application can be seen from the figure that the rise time of the detector array is 377.3ns and the fall time is 860.1ns. The detector array prepared in the example of the present application significantly exceeds the current cutting-edge level of perovskite infrared detector arrays in response speed, achieving an ultra-fast response speed of hundreds of nanoseconds.

[0103] Figure 6 The variation curve of the specific detectivity of the perovskite infrared detector prepared by using the preparation method provided in this application with the irradiation wavelength. It can be seen from the figure that at a wavelength of 840 nm, the specific detectivity of the detector array is 8.3×10 13 Jones, which indicates that the detector has extremely high response ability to the infrared band.

[0104] Figure 7 This is the imaging result diagram of the 5×5 infrared detector array provided in this application for the letter "S" under 980 nm light illumination. It can be seen from the figure that under the irradiation of 980 nm infrared radiation, the pixels show an observable photocurrent of approximately 0.985 μA, while other areas show very weak dark currents, and the shape contour of the letter "S" can be clearly observed in the current contrast mapping, with good resolution.

[0105] Figure 8 This is the imaging result diagram of the 64×64 imaging chip based on the TFT readout circuit provided in this application for the Chinese character "Shan Da" under 980 nm infrared radiation illumination. Under the irradiation of 980 nm infrared radiation, the Chinese character "Shan Da" can be clearly observed, with good resolution.

[0106] In this application, under the combined action of the most optimized means such as specific detector structure, the optimal thickness and material composition of each layer of thin film in the structure, the optimization means adopted in the preparation process, the optimal control ratio of each component, and the optimal parameters of each process step, a perovskite infrared detector with the optimal performance is finally obtained. This detector can achieve efficient detection in the wide spectral range of 300 nm to 1100 nm, with a peak external quantum efficiency of up to 87.7%, a responsivity of 0.47 A / W, and a specific detectivity as high as 8.3×10 13 Jones, a response time as short as 377.3 ns / 860.1 ns, can be compatible and integrated with CMOS or TFT chips, and realizes the integrated imaging application with a 64×64 TFT chip, solving the technical problems that have always existed in the existing infrared detector manufacturing technology, such as high production cost of high-vacuum and high-temperature processes, low detection sensitivity of devices, slow response speed, and inability to be compatible and integrated with heterogeneous chips.

[0107] In summary, this application realizes a high-performance, wide-spectrum infrared detector array and an infrared imaging chip compatible with complementary metal oxide semiconductor (CMOS) or thin film transistor (TFT) readout circuits through scalable solution processing technology, ultrafast laser processing technology, and vertical heterostack device preparation methods, significantly reducing the manufacturing cost of the infrared imaging chip, improving the response speed of the infrared detector and the imaging quality of the chip, and having outstanding substantive features and remarkable technical progress.

[0108] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the term "on" or the like is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0109] In addition, in this application, unless otherwise clearly specified and limited, the term "disposed" and other terms should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected, electrically connected, or able to communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0110] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0111] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A perovskite infrared detector structure, characterized in that: include: A substrate (10); A P-type semiconductor layer (20) is disposed on the substrate (10); Aluminum oxide layer (30): disposed on the P-type semiconductor layer (20); A photosensitive perovskite layer (40) is disposed on the aluminum oxide layer (30); N-type semiconductor layer (50): disposed on the photosensitive perovskite layer (40); Buffer layer (60): disposed on the N-type semiconductor layer (50); Back electrode (70): arranged on the buffer layer (60).

2. The perovskite infrared detector structure according to claim 1, characterized in that: The photosensitive perovskite layer (40) is made of a narrow bandgap metal halide FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3, whose optical band gap is <1.26 eV.

3. The perovskite infrared detector structure according to claim 1, characterized in that: The substrate (10) is made of indium-doped tin oxide; The preparation material of the P-type semiconductor layer (20) is [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid; The preparation material of the N-type semiconductor layer (50) is fullerene; The buffer layer (60) is made of bathocuproin; The back electrode (70) is made of silver.

4. The perovskite infrared detector structure according to any one of claims 1 to 3, characterized in that: The thickness of the P-type semiconductor layer (20) is in the range of 10 to 20 nm; The thickness of the aluminum oxide layer (30) is in the range of 20 to 30 nm; The thickness of the photosensitive perovskite layer (40) is in the range of 400 to 500 nm; The thickness of the N-type semiconductor layer (50) is in the range of 25 to 30 nm; The thickness of the buffer layer (60) is in the range of 5 to 7 nm; The thickness of the back electrode (70) is in the range of 80 to 120 nm.

5. The perovskite infrared detector structure according to any one of claims 1 to 3, characterized in that: The thickness of the P-type semiconductor layer (20) is 15 nm; The thickness of the aluminum oxide layer (30) is 30 nm; The thickness of the photosensitive perovskite layer (40) is 440 nm; The thickness of the N-type semiconductor layer (50) is 28 nm; The thickness of the buffer layer (60) is 6 nm; The thickness of the back electrode (70) is 100 nm.

6. A method for preparing a perovskite infrared detector structure as claimed in any one of claims 1 to 3, characterized in that: include: S10, providing a substrate (10); S20, processing the P-type semiconductor material by a spin coating process to form a P-type semiconductor layer (20) on the substrate (10); S30, treating the nano-aluminum oxide material by a spin coating process to form an aluminum oxide layer (30) on the P-type semiconductor layer (20); S40, treating the perovskite precursor material by a spin coating process to form a photosensitive perovskite layer (40) on the aluminum oxide layer (30); S50, treating the N-type semiconductor material by a vacuum evaporation process to form an N-type semiconductor layer (50) on the photosensitive perovskite layer (40); S60, forming a buffer layer (60) on the N-type semiconductor layer (50) by using a vacuum evaporation process; S70, using a vacuum evaporation process to process the conductive material to form a back electrode (70) on the buffer layer (60).

7. The method for preparing a perovskite infrared detector structure according to claim 6, characterized in that: Step S40 specifically includes: Weigh appropriate amounts of iodoformamidine, iodomethylamine, lead iodide and stannous iodide; Then, a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio range of 3:1 to 5:1 was added and stirred at room temperature until completely dissolved to obtain FA. 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 perovskite precursor solution; Spin coating the perovskite precursor solution on the aluminum oxide layer (30), and dropwise adding chlorobenzene anti-solvent during the spin coating process; After the spin coating is completed, an annealing treatment is performed to obtain a perovskite film, thereby forming a photosensitive perovskite layer (40).

8. The method for preparing a perovskite infrared detector structure according to claim 7, characterized in that: In step S40: The molar ratio of iodoformamidine, iodomethylamine, lead iodide and stannous iodide weighed is 7:3:5:5; The volume ratio of the mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide is 4:1; Obtained FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The concentration of the I3 perovskite precursor solution was 1.1 mol / L; When the perovskite precursor solution is spin-coated, the volume of the perovskite precursor solution is 120 μL, the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 60 seconds; at the 45th second of the spin coating, 350 μL of chlorobenzene antisolvent is added dropwise; After the spin coating is completed, annealing is performed at 100° C. for 10 minutes to obtain a perovskite film with a thickness of 440 nm, thereby forming a photosensitive perovskite layer (40).

9. The method for preparing a perovskite infrared detector structure according to claim 8, characterized in that: Step S10 specifically includes: Providing a substrate (10), and performing the following cleaning treatment on the substrate (10): first, ultrasonically cleaning the substrate with a cleaning agent for 20 minutes, then ultrasonically cleaning the substrate with deionized water, anhydrous ethanol, acetone and isopropanol for 20 minutes respectively, then drying the substrate for 30 minutes, and finally, cleaning the surface again with nitrogen, and performing ozone treatment for 20 minutes before use; Step S20 specifically includes: First, [6-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid is dissolved in ethanol to form a solution with a concentration of 2 mg / mL, and then 120 μL of the solution is spin-coated on the substrate (10) after the cleaning process, wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing is performed at 100° C. for 10 minutes to obtain a P-type semiconductor layer (20) with a thickness of 15 nm; Step S30 specifically includes: First, the nano-aluminum oxide solution is diluted in isopropanol at a volume ratio of 1:20, and then 150 μL of the diluted solution is spin-coated on the P-type semiconductor layer (20), wherein: the rotation speed of the spin coater is 6000 rpm, the acceleration is 3000 rpm, and the time is 30 seconds; after the spin coating is completed, annealing is performed at 120° C. for 20 minutes to obtain an aluminum oxide layer (30) with a thickness of 30 nm; Step S50 specifically includes: A fullerene material is deposited on the photosensitive perovskite layer (40) by a vacuum evaporation process to obtain an N-type semiconductor layer (50) with a thickness of 28 nm, wherein: the evaporation rate is Step S60 specifically includes: A bath copper material is deposited on the N-type semiconductor layer (50) by a vacuum evaporation process to obtain a buffer layer (60) with a thickness of 6 nm, wherein: the evaporation rate is Step S70 specifically includes: After placing the device in the vacuum coating machine, first reduce the air pressure inside the machine to 5×10 -4 Pa, and then start preparing the metal silver electrode; when the thickness of the silver electrode is between 0 and 5 nm, control the evaporation rate to After that, the evaporation speed increases with each 5nm increase in thickness. Finally, the evaporation rate is maintained at Until the evaporation is completed.

10. An infrared imaging chip, characterized in that: include: Photodetector: an array structure formed by the perovskite infrared detector structure as described in any one of claims 1 to 3, wherein the array structure is prepared by ultrafast laser etching process and is used to convert the received infrared radiation signal into a readable current signal; TFT readout circuit: electrically connected to the photodetector, used to read the current signal output by the photodetector, form a corresponding graph based on the reading result, and perform imaging output.

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