Perovskite photodetector, perovskite photodetector array and preparation method thereof

Abstract

The present invention discloses a perovskite photodetector, a perovskite photodetector array, and a method for preparing the same. The perovskite photodetector comprises a conductive substrate, a perovskite photodiode layer, a blocking diode layer, and a top electrode stacked in sequence. The perovskite photodetector array comprises a conductive substrate, a perovskite photodiode layer, a blocking diode layer, and a top electrode stacked in sequence. The conductive substrate is etched with a plurality of bottom electrodes equidistantly spaced along a first direction, the plurality of bottom electrodes forming a bottom electrode array. The top electrodes are equidistantly spaced along a second direction, the plurality of top electrodes forming a top electrode array, the bottom electrode array and the top electrode array being arranged perpendicularly and intersectingly. The present invention proposes for the first time a novel perovskite photodetector structure in which a blocking diode is integrated with a perovskite photodiode. The present invention achieves array integration of perovskite photodetectors using a simple structure, which can suppress electrical crosstalk.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and in particular to a perovskite photodetector, a perovskite photodetector array and a preparation method thereof. Background Art

[0002] Organic-inorganic hybrid perovskite materials have been a research hotspot in the field of photoelectric conversion in recent years. Due to their exceptional properties, such as large absorption coefficients, long carrier lifetimes, and suitable and tunable band gaps, organic-inorganic hybrid perovskite-based photodetectors have demonstrated outstanding performance in wide-spectrum detection, infrared detection, weak-light detection, X-ray detection, and narrow-band detection. Furthermore, due to the numerous and simple synthesis methods available for perovskites, they can be flexibly used as photoactive layers in photodiodes, photoconductive detectors, and phototransistors.

[0003] Photodiode-based perovskite photodetectors, due to their transport layer-assisted carrier separation, exhibit low dark and noise currents, a wide linear dynamic range, excellent response linearity, and fast response speed. These photodetectors hold great potential for a variety of practical applications, such as light meters, image sensors, and optical communication devices. Practical photodetector applications often require integration into array devices. However, a major obstacle to integrating photodiodes into image sensors is that as light intensity increases, the current generated by the photodiode increases, causing the photodiode to lose its rectification properties and become unable to turn off. Furthermore, due to the built-in electric field at the pixel level, when individual detectors are integrated into an array device, leakage currents within the array and crosstalk currents between pixels become extremely complex under illumination, preventing proper area-array light detection. To address this issue, pixels in an image sensor array must also exhibit rectification properties under illumination, resulting in minimal leakage current when the pixels are off. Existing research has proposed integrating photodiodes into IGZO thin-film transistor circuits and integrating silicon blocking diodes alongside the photodiodes to achieve pixel-level rectification. However, these methods often include processes such as photolithography and laser cutting, which inevitably introduce complex micro-nano processing processes on the one hand, and on the other hand also reduce pixel density, increase the number of leads, and complicate the readout circuit.

[0004] Generally speaking, perovskite photodiodes use a vertical device structure, making them suitable for constructing vertical cross-electrode array image sensors. The n×m array approach, achieved through cross-electrode technology, minimizes wiring, accommodates more pixels within the same area, and is the simplest to manufacture. Therefore, developing a perovskite photodetector structure with self-rectification properties under illumination and compatible with cross-electrode arrays holds great promise. However, no research has yet been conducted on integrating perovskite photodiodes into cross-electrode arrays. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the prior art, the present invention provides a perovskite photodetector, a perovskite photodetector array, and methods for preparing the same. By integrating a perovskite photodiode with a blocking diode, the present invention creates a novel perovskite photodetector. This method, which expands perovskite photodiodes into an array using a cross-electrode structure, mitigates the electrical crosstalk that can occur when perovskite photodiodes are directly integrated into array devices. This method enables array integration of perovskite photodetectors using a simple structure, promoting their practical application.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A perovskite photodetector comprises a conductive substrate, a perovskite photodiode layer, a blocking diode layer and a top electrode stacked in sequence from bottom to top; the blocking diode layer comprises a blocking diode sublayer I and a blocking diode sublayer II stacked in sequence; the blocking diode sublayer I is formed of a material selected from at least one of PbI2, PbCl2, PbBr2 and CsI, and the blocking diode sublayer II is formed of a material selected from at least one of Spiro-TTB, PTAA, MoO3, C8BTBT and Spiro-OMeTAD.

[0008] Preferably, the thickness of the blocking diode sublayer I is 10-150 nm, and the thickness of the blocking diode sublayer II is 10-50 nm.

[0009] Preferably, the perovskite photodiode layer is a PIN-type structure perovskite photodiode layer or a NIP-type structure perovskite photodiode layer; the PIN-type structure perovskite photodiode layer includes a hole transport layer, a perovskite light absorption layer, an electron transport layer and a hole blocking layer stacked in sequence from bottom to top; the NIP-type structure perovskite photodiode layer includes an electron transport layer, a perovskite light absorption layer and a hole transport layer stacked in sequence from bottom to top.

[0010] Preferably, the material of the perovskite light absorbing layer is MAPbI3, CsPbCl3, CsPbBr2Cl, CsPbBr3, CsPbBr 1.5 I 1.5 , at least one of CH3NH3PbBr3, Cs3Sb2Br9, CH(NH2)2PbBr3, (BA)2(MA)Pb2I7 and (BA)2PbI4.

[0011] Preferably, the conductive substrate is made of conductive glass or flexible conductive material; the hole transport layer is made of PEDOT:PSS; the hole blocking layer is made of PCBM; and the top electrode is made of silver.

[0012] A perovskite photodetector array comprises a conductive substrate, a perovskite photodiode layer, a blocking diode layer and a top electrode, which are stacked in sequence from bottom to top; the conductive substrate is etched with multiple bottom electrodes arranged at equal intervals along a first direction, and the multiple bottom electrodes form a bottom electrode array; the top electrodes are arranged at equal intervals along a second direction, and the multiple top electrodes form a top electrode array, and the bottom electrode array and the top electrode array are arranged perpendicularly and crosswise.

[0013] A method for preparing a perovskite photodetector array comprises the following steps:

[0014] S1. Etching a plurality of equally spaced strip electrodes on a conductive substrate to obtain a bottom electrode;

[0015] S2. forming a perovskite photodiode layer on the surface of the bottom electrode;

[0016] S3. On the side of the perovskite photodiode layer away from the bottom electrode, first forming a blocking diode sublayer I, and then forming a blocking diode sublayer II to obtain a blocking diode layer;

[0017] S4. Deposition is performed on the side of the blocking diode layer away from the perovskite photodiode layer in a direction perpendicular to the bottom electrode to form top electrodes arranged at equal intervals, thereby obtaining a perovskite photodetector array.

[0018] Preferably, the blocking diode sublayer I and the blocking diode sublayer II are prepared by at least one of physical vapor deposition, chemical vapor deposition, solution spin coating, magnetron sputtering and atomic layer deposition.

[0019] Preferably, the method for forming a perovskite photodiode layer comprises the following steps:

[0020] S21. After spin-coating a hole transport layer forming material on one side of the conductive substrate, annealing is performed to form a hole transport layer;

[0021] S22. The perovskite light absorbing layer forming material I is formed into a precursor film on the side of the hole transport layer away from the conductive substrate by evaporation;

[0022] S23. Heating the precursor film and the perovskite light absorbing layer forming raw material II under a vacuum environment to form a perovskite film, and then removing the unreacted perovskite light absorbing layer forming raw material II on the surface of the formed perovskite film, and performing an annealing treatment to obtain a perovskite light absorbing layer;

[0023] S24. Spin-coating an electron transport layer forming material on a side of the perovskite light absorbing layer away from the hole transport layer to form an electron transport layer;

[0024] S25. Spin-coat a hole blocking layer material onto a side of the electron transport layer away from the perovskite light absorbing layer to form a hole blocking layer, thereby obtaining a perovskite photodiode layer.

[0025] Preferably, the method for forming a perovskite photodiode layer comprises the following steps:

[0026] S21. Spin-coating a material for forming an electron transport layer on one side of the conductive substrate to form an electron transport layer;

[0027] S22. The raw material I for forming the perovskite light absorbing layer is evaporated to form a precursor film on the side of the electron transport layer away from the conductive substrate;

[0028] S23. Heating the precursor film and the raw material II for forming the perovskite light absorbing layer under a vacuum environment to form a perovskite film, removing the unreacted raw material II for forming the perovskite light absorbing layer on the surface of the perovskite film, and performing an annealing treatment to obtain a perovskite light absorbing layer;

[0029] S24. Spin-coating a hole transport layer forming material on a side of the perovskite light absorbing layer away from the electron transport layer and annealing to form a hole transport layer;

[0030] S25. Spin-coat a hole blocking layer material onto a side of the electron transport layer away from the perovskite light absorbing layer to form a hole blocking layer, thereby obtaining a perovskite photodiode layer.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. This invention proposes for the first time a new perovskite photodetector structure, which integrates a blocking diode with a perovskite photodiode, and can suppress the current of the perovskite photodetector under 0V and positive bias.

[0033] 2. The present invention expands the perovskite photodiode into a perovskite photodetector array through a cross-electrode structure, which can suppress the electrical crosstalk problem that exists when the perovskite photodiode is directly integrated into a perovskite photodetector array device, and realizes the array integration of perovskite photodetectors with a simple structure, thereby promoting the practical application of perovskite photodetectors.

[0034] 3. The perovskite photodetector array structure of the present invention is universal. It can be used to integrate photodiode-type devices of any composition into an array device with essentially no degradation in performance, such as responsivity and detectivity. This structure can also be extended to arrays of photodiode-type detectors composed of other thin-film materials.

[0035] 4. The blocking diode integration method of the present invention can be directly deposited on the original perovskite photodiode device to form a stacked device to achieve pixel-level rectification. There is no need to use photolithography, laser processing and other processes to separately prepare switching elements next to the photodiode, which is beneficial to improving pixel density in large-scale area array devices and reducing process difficulty.

[0036] 5. The perovskite photodetector array device of the present invention has high responsiveness and detection rate, can realize the detection of the visible light spectrum, and has real-time imaging capability.

[0037] 6. The perovskite layer and the blocking diode layer of the present invention can be prepared by a vapor phase method. Compared with the array device obtained by the spin coating method, the prepared array device has high uniformity and avoids the introduction of toxic solvents, is environmentally friendly, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the overall structure of a perovskite photodetector of the present invention;

[0039] Figure 2 Schematic diagram of the overall structure of a perovskite photodetector array of the present invention;

[0040] Figure 3 Schematic diagram of the arrangement of the bottom electrode and the top electrode in the perovskite photodetector array in an embodiment of the present invention;

[0041] Figure 4 The current-voltage curves of the perovskite photodetectors prepared in Example 4 of the present invention and Comparative Example 1 under different light powers;

[0042] Figure 5 This is a diagram of the external quantum efficiency of the perovskite photodetector array prepared in Example 1 of the present invention at different bias voltages;

[0043] Figure 6 This is a readout circuit diagram of an imaging array consisting of a perovskite photodetector array, a switching circuit, and a readout circuit prepared in Example 1 of the present invention;

[0044] Figure 7 This is a statistical diagram of the photocurrent distribution of 16 pixels in the perovskite photodetector array prepared in Example 1 of the present invention;

[0045] Figure 8 This is a demonstration diagram of the letter “N” being imaged statically by the perovskite photodetector array prepared in Example 1 of the present invention;

[0046] Figure 9 This is a screenshot of the dynamic imaging demonstration of the perovskite photodetector array prepared in Example 1 of the present invention, demonstrating the dynamic imaging process of an obstruction moving from left to right above the perovskite photodetector array;

[0047] In the picture:

[0048] 1. Conductive substrate; 11. Bottom electrode; 2. Perovskite photodiode layer; 21. Hole transport layer; 22. Perovskite light absorption layer; 23. Electron transport layer; 24. Hole blocking layer; 3. Blocking diode layer; 31. Blocking diode sublayer I; 32. Blocking diode sublayer II; 4. Top electrode; 5. Pixel. DETAILED DESCRIPTION

[0049] The following embodiments of the present invention are described in detail. It will be understood by those skilled in the art that the following embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Unless otherwise specified, if specific techniques or conditions are not clearly described in the following embodiments, those skilled in the art can follow commonly used techniques or conditions in the art or according to the product instructions.

[0050] In one aspect of the present invention, a perovskite photodetector is provided.

[0051] Please refer to Figure 1 The perovskite photodetector includes a conductive substrate 1, a perovskite photodiode layer 2, a hole blocking layer 24, a blocking diode layer 3 and a top electrode 4 stacked in sequence from bottom to top.

[0052] In another aspect of the present invention, the present invention provides a perovskite photodetector array.

[0053] Please refer to Figure 2 and Figure 3 The perovskite photodetector array includes a conductive substrate 1, a perovskite photodiode layer 2, a blocking diode layer 3 and a top electrode 4 stacked in sequence from bottom to top; the conductive substrate 1 is etched with multiple bottom electrodes 11 arranged at equal intervals along a first direction, and the multiple bottom electrodes 11 form a bottom electrode 11 array, and the top electrodes 4 are provided with multiple equal intervals along a second direction, and the multiple top electrodes 4 form a top electrode 4 array, and the bottom electrode 11 array and the top electrode 4 array are arranged perpendicularly and crosswise.

[0054] The perovskite photodetector array of the present invention forms interdigitated electrodes by vertically arranging bottom electrodes 11 and top electrodes 4. The intersection of the electrodes forms an effective pixel 5. When the number of bottom electrodes 11 is n and the number of top electrodes 4 is m, a perovskite photodetector array with n rows and m columns and n×m pixels 5 can be formed. The resulting perovskite photodetector array has only n+m electrode leads. By reducing the electrode spacing and electrode width, a higher pixel density can be achieved.

[0055] Specifically, the blocking diode layer 3 includes a blocking diode sub-layer I 31 and a blocking diode sub-layer II 32 stacked sequentially from bottom to top.

[0056] More specifically, the blocking diode layer 3 is made of a material combination having a rectifying band arrangement.

[0057] Preferably, the material for forming the blocking diode sublayer I31 is selected from one or more of lead iodide (PbI2), lead chloride (PbCl2), lead bromide (PbBr2), and cesium iodide (CsI), and the material for forming the blocking diode sublayer II32 is selected from 2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-difluorene; 2,2',7,7'-tetrakis(N,N-di-p-tolyl)amino-9,9-spirodifluorene; One or more of fluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), molybdenum trioxide (MoO3), 2,7-dioctyl[1]benzothieno[3,2-B]benzothiophene (C8-BTBT) 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD).

[0058] Specifically, the material of the conductive substrate 1 can be a transparent conductive substrate 1 material commonly used in the art, such as conductive glass. The conductive glass can be selected from one of ITO conductive glass and FTO conductive glass. The conductive glass can also be replaced with a flexible material, such as PET material, to obtain a flexible device.

[0059] Specifically, the perovskite photodiode layer 2 is a PIN-type perovskite photodiode layer or a NIP-type perovskite photodiode layer.

[0060] More specifically, the PIN-type perovskite photodiode layer includes a hole transport layer 21, a perovskite light absorption layer 22, and an electron transport layer 23 stacked in sequence from bottom to top; the NIP-type perovskite photodiode layer includes an electron transport layer 23, a perovskite light absorption layer 22, and a hole transport layer 21 stacked in sequence from bottom to top.

[0061] The hole transport layer 21 may be formed of materials commonly used in the art for forming the hole transport layer 21 .

[0062] In some specific examples of the present invention, the hole transport layer 21 is formed of PEDOT:PSS. PEDOT:PSS is a polymer composed of two substances: PEDOT and PSS. PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer) and PSS is polystyrene sulfonate.

[0063] Specifically, the material forming the perovskite light absorbing layer 22 is methylamine lead iodide (MAPbI3), and can also be other materials with narrow-band absorption characteristics, such as cesium lead chloride (CsPbCl3), CsPbBr2Cl, cesium lead bromine (CsPbBr3), CsPbBr 1.5 I 1.5 , CH3NH3PbBr3, Cs3Sb2Br9, CH(NH2)2PbBr3, (BA)2(MA)Pb2I7, (BA)2PbI4. The above materials can be used to construct a color image sensor array without adding filters; if they are replaced with materials with infrared or ultraviolet absorption properties, infrared or ultraviolet image sensors can be constructed, which can be used in a wider range of applications in military, medical, smart cars and other fields.

[0064] Specifically, the electron transport layer 23 may be formed of a material commonly used in the art for forming the electron transport layer 23 .

[0065] In some specific examples of the present invention, the material for forming the electron transport layer 23 is [6,6]-phenyl-C61-butyric acid isomethyl ester (PCMB).

[0066] Specifically, the hole blocking layer 24 may be formed of materials commonly used in the art for forming the hole blocking layer 24 .

[0067] In some specific examples of the present invention, the hole blocking layer 24 is 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

[0068] The present invention also discloses a method for preparing the above-mentioned perovskite photodetector array, comprising the following steps:

[0069] S1. Etching a plurality of equally spaced strip electrodes on a conductive substrate 1 to obtain a bottom electrode 11;

[0070] S2. A perovskite photodiode layer 2 is formed on the surface of the bottom electrode 11;

[0071] S3. On the side of the perovskite photodiode layer 2 away from the bottom electrode 11, a blocking diode sublayer Ⅰ31 is first formed, and then a blocking diode sublayer Ⅱ32 is formed to obtain a blocking diode layer 3;

[0072] S4. On the side of the blocking diode layer 3 away from the perovskite photodiode layer 2, deposition is performed in a direction perpendicular to the bottom electrode 11 to form top electrodes 4 arranged at equal intervals, thereby obtaining a perovskite photodetector array.

[0073] In some specific examples of the present invention, according to the characteristics of the specific material forming the blocking diode layer 3, physical vapor deposition, chemical vapor deposition, solution spin coating, magnetron sputtering, atomic layer deposition and other methods can be flexibly selected to prepare the blocking diode layer 3.

[0074] In some specific examples of the present invention, the method for forming a perovskite photodiode layer includes the following steps:

[0075] S21. After spin coating the hole transport layer 21 forming material on one side of the conductive substrate 1, annealing is performed to form the hole transport layer 21;

[0076] S22. The raw material I for forming the perovskite light absorbing layer 22 is evaporated to form a thin film of the raw material I for forming the perovskite light absorbing layer 22 on the side of the hole transport layer 21 away from the conductive substrate 1;

[0077] S23. The perovskite light absorbing layer 22 is formed by heating the raw material I film and the raw material II of the perovskite light absorbing layer 22 in a vacuum environment to form a perovskite film, and then removing the unreacted raw material II of the perovskite light absorbing layer 22 on the surface of the formed perovskite film, and then performing an annealing treatment to obtain the perovskite light absorbing layer 22;

[0078] S24. Spin-coating the material for forming the electron transport layer 23 on the side of the perovskite light absorbing layer 22 away from the hole transport layer 21 to form the electron transport layer 23;

[0079] S25. Spin-coat the material for forming the hole blocking layer 24 onto the side of the electron transport layer 23 away from the perovskite light absorbing layer 22 to form the hole blocking layer 24 and obtain the perovskite photodiode layer 2.

[0080] According to the above-described method for forming the perovskite photodiode layer 2 , an NIP-type perovskite photodiode layer can be obtained.

[0081] In some other specific examples of the present invention, the method for forming a perovskite photodiode layer includes the following steps:

[0082] S21. Spin-coating the material for forming the electron transport layer 23 on one side of the conductive substrate 1 to form the electron transport layer 23;

[0083] S22. The raw material Ⅰ of the perovskite light absorbing layer 22 is formed by evaporation to form a precursor film on the side of the electron transport layer 23 away from the conductive substrate 1;

[0084] S23. The precursor film and the raw material II for forming the perovskite light absorbing layer 22 are heated under a vacuum environment to form a perovskite film, and then the unreacted raw material II for forming the perovskite light absorbing layer on the surface of the perovskite film is removed, followed by annealing to obtain the perovskite light absorbing layer 22;

[0085] S24. Spin-coating the hole transport layer 21 forming material on the side of the perovskite light absorbing layer 22 away from the electron transport layer 23 and annealing to form the hole transport layer 21;

[0086] S25. Spin-coat the material for forming the hole blocking layer 24 onto the side of the hole transport layer 21 away from the perovskite light absorbing layer 22 to form the hole blocking layer 24 and obtain the perovskite photodiode layer 2.

[0087] According to the above-mentioned method for forming the perovskite photodiode layer 2 , a PIN-type perovskite photodiode layer can be obtained.

[0088] The thickness of the precursor film is 150-300 nm, and the amount of raw material II added to form the perovskite light absorbing layer 22 is 50-300 mg. Further preferably, the thickness of the precursor film is 180 nm, and the amount of raw material II added to form the perovskite light absorbing layer 22 is 200 mg.

[0089] The heating temperature is set to 150-200° C., and the heating duration is set to 10-30 minutes.

[0090] The preparation method of the perovskite photodetector array of the present invention is further described below with reference to specific embodiments.

[0091] Example 1

[0092] A method for preparing a perovskite photodetector array comprises the following steps:

[0093] 1. Using ITO conductive glass as a conductive substrate 1, selecting ITO conductive glass as a transparent conductive substrate 1, etching n parallel and equally spaced strip electrodes as bottom electrodes 11;

[0094] 2. Ultrasonic cleaning of the ITO conductive glass and the bottom electrode 11 was performed in sequence with detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes; the cleaned ITO conductive glass and the bottom electrode 11 were blown dry with nitrogen, and then placed in an oxygen plasma cleaning machine for 15 minutes, with an air pressure of 70 Pa and a power of 85 W for O2 plasma treatment to obtain a clean bottom electrode 11.

[0095] 3. Spin-coat the resulting PEDOT:PSS (AI 4083) solution on the bottom electrode 11 using a spin coater. Filter the PEDOT:PSS solution with a 0.22 μm filter before spin coating. The spin coating parameters are 4000 rpm for 30 seconds. Then, anneal the solution on a hot plate at 150°C for 10 minutes to form a PEDOT:PSS film as the hole transport layer 21.

[0096] 4. When the annealing temperature drops to about 80℃, transfer it to the evaporation coating machine and wait for the evaporation coating machine to be pumped to a pressure of 5×10 -4 Pa below, the quartz crucible containing PbI2 powder is heated to evaporate PbI2 and deposit to form a PbI2 film. The evaporation rate is The thickness of the PbI2 film is 180 nm, and a yellow lead iodide film is obtained. At this time, the structure is Glass / ITO / PEDOT:PSS / PbI2;

[0097] 5. Place the deposited yellow PbI2 film facing a long crucible containing 200 mg of methylamine iodide (CH3NH3I, MAI) powder in a vacuum oven. After the vacuum oven pressure is evacuated to below 10 kPa, the heating temperature is set to 180°C and the holding time is set to 15 minutes. During the heating process, the film gradually changes from yellow PbI2 to brown-black MAPbI3 perovskite;

[0098] 6. Then, the sample was moved to a glove box. After the sample cooled, an isopropyl alcohol solution was spin-coated on the surface of the MAPbI3 perovskite film at a speed of 4000 rpm for 30 seconds to remove the MAI attached to the film surface. The film was then annealed on a hot plate at 100°C for 10 minutes to complete the preparation of the MAPbI3 perovskite film and obtain the perovskite light absorbing layer 22.

[0099] 7. After the annealed MAPbI3 perovskite film cools, a layer of PCBM film is spin-coated in a glove box as the electron transport layer 23. The solution concentration is 20 mg / mL and the spin-coating parameters are 1500 rpm for 30 seconds. After completion, a layer of BCP film is spin-coated as the hole blocking layer 24. The solution concentration is 1 mg / mL and the spin-coating parameters are 4000 rpm for 30 seconds. The perovskite photodiode is now fabricated. The device structure is Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP.

[0100] 8. Transfer the device obtained in step 7 to a thermal evaporation coating machine, first evaporate a 20nm layer of PbI2 on the BCP film, and then evaporate a 15nm layer of Spiro-TTB to complete the preparation of the blocking diode film;

[0101] 9. Finally, a 60 nm thick Ag electrode is thermally evaporated as the top electrode 4. The Ag electrode pattern is m parallel and equally spaced strip electrodes. The strip Ag electrodes are deposited in a direction perpendicular to the bottom electrode 11 to form a complete device with a structure of Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP / PbI2 / Spiro-TTB / Ag.

[0102] The perovskite photodetector array in this embodiment forms a cross electrode by vertically arranging the bottom electrode 11 and the top electrode 4 , and an effective pixel 5 is formed at the intersection of the electrodes.

[0103] like Figure 2 As shown, in this embodiment, the number n of bottom electrodes 11 is 4, and the number m of top metal electrodes is 4, forming a perovskite photodetector array with 4 rows and 4 columns and 16 pixels 5, and the number of electrode leads is only 4+4.

[0104] The selected ITO conductive glass has a square resistance of 7Ω / □ and an area of 15mm×15mm. The width of the four bottom electrodes 11 is 2mm, and the electrode spacing is 0.5mm.

[0105] Example 2

[0106] A method for preparing a perovskite photodetector array comprises the following steps:

[0107] 1. Using ITO conductive glass as a conductive substrate 1, selecting ITO conductive glass as a transparent conductive substrate 1, etching n parallel and equally spaced strip electrodes as bottom electrodes 11;

[0108] 2. Ultrasonic cleaning of the ITO conductive glass and the bottom electrode 11 was performed in sequence with detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes; the cleaned ITO conductive glass and the bottom electrode 11 were blown dry with nitrogen, and then placed in an oxygen plasma cleaning machine for 15 minutes, with an air pressure of 70 Pa and a power of 85 W for O2 plasma treatment to obtain a clean bottom electrode 11.

[0109] 3. Spin-coat the resulting PEDOT:PSS (AI 4083) solution on the bottom electrode 11 using a spin coater. Filter the PEDOT:PSS solution with a 0.22 μm filter before spin coating. The spin coating parameters are 4000 rpm for 30 seconds. Then, anneal the solution on a hot plate at 150°C for 10 minutes to form a PEDOT:PSS film as the hole transport layer 21.

[0110] 4. When the annealing temperature drops to about 80℃, transfer it to the evaporation coating machine and wait for the evaporation coating machine to be pumped to a pressure of 5×10 -4 Pa below, the quartz crucible containing PbI2 powder is heated to evaporate PbI2 and deposit to form a PbI2 film. The evaporation rate is The thickness of the PbI2 film is 150 nm, and a yellow lead iodide film is obtained. At this time, the structure is Glass / ITO / PEDOT:PSS / PbI2;

[0111] 5. Place the deposited yellow PbI2 film facing a long crucible containing 50 mg of methylamine iodide (CH3NH3I, MAI) powder in a vacuum oven. After the vacuum oven pressure is evacuated to below 10 kPa, the heating temperature is set to 150°C and the holding time is set to 30 minutes. During the heating process, the film gradually changes from yellow PbI2 to brown-black MAPbI3 perovskite;

[0112] 6. Then, the sample was moved to a glove box. After the sample cooled, an isopropyl alcohol solution was spin-coated on the surface of the MAPbI3 perovskite film at a speed of 4000 rpm for 30 seconds to remove the MAI attached to the film surface. The film was then annealed on a hot plate at 100°C for 10 minutes to complete the preparation of the MAPbI3 perovskite film and obtain the perovskite light absorbing layer 22.

[0113] 7. After the annealed MAPbI3 perovskite film cools, a layer of PCBM film is spin-coated in a glove box as the electron transport layer 23. The solution concentration is 20 mg / mL and the spin-coating parameters are 1500 rpm for 30 seconds. After completion, a layer of BCP film is spin-coated as the hole blocking layer 24. The solution concentration is 1 mg / mL and the spin-coating parameters are 4000 rpm for 30 seconds. The perovskite photodiode is now fabricated. The device structure is Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP.

[0114] 8. Transfer the device obtained in step 7 to a thermal evaporation coating machine, first evaporate a 10nm layer of PbI2 on the BCP film, and then evaporate a 10nm layer of Spiro-TTB to complete the preparation of the blocking diode film;

[0115] 9. Finally, a 200 nm thick Ag electrode is thermally evaporated as the top electrode 4. The Ag electrode pattern is m parallel and equally spaced strip electrodes. The strip Ag electrodes are deposited in a direction perpendicular to the bottom electrode 11 to form a complete device with a structure of Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP / PbI2 / Spiro-TTB / Ag.

[0116] The perovskite photodetector array in this embodiment forms a cross electrode by vertically arranging the bottom electrode 11 and the top electrode 4 , and an effective pixel 5 is formed at the intersection of the electrodes.

[0117] In this embodiment, the number n of bottom electrodes 11 is 64, and the number m of top metal electrodes is 64, forming a perovskite photodetector array with 64 rows and 64 columns and 64×64 pixels 5, and the number of electrode leads is 64+64.

[0118] Example 3

[0119] A method for preparing a perovskite photodetector array comprises the following steps:

[0120] 1. Using ITO conductive glass as a conductive substrate 1, selecting ITO conductive glass as a transparent conductive substrate 1, etching n parallel and equally spaced strip electrodes as bottom electrodes 11;

[0121] 2. Ultrasonic cleaning of the ITO conductive glass and the bottom electrode 11 was performed in sequence with detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes; the cleaned ITO conductive glass and the bottom electrode 11 were blown dry with nitrogen, and then placed in an oxygen plasma cleaning machine for 15 minutes, with an air pressure of 70 Pa and a power of 85 W for O2 plasma treatment to obtain a clean bottom electrode 11.

[0122] 3. Spin-coat the resulting PEDOT:PSS (AI 4083) solution on the bottom electrode 11 using a spin coater. Filter the PEDOT:PSS solution with a 0.22 μm filter before spin coating. The spin coating parameters are 4000 rpm for 30 seconds. Then, anneal the solution on a hot plate at 150°C for 10 minutes to form a PEDOT:PSS film as the hole transport layer 21.

[0123] 4. When the annealing temperature drops to about 80℃, transfer it to the evaporation coating machine and wait for the evaporation coating machine to be pumped to a pressure of 5×10 -4 Pa below, the quartz crucible containing PbI2 powder is heated to evaporate PbI2 and deposit to form a PbI2 film. The evaporation rate is The thickness of the PbI2 film is 300 nm, and a yellow lead iodide film is obtained. At this time, the structure is Glass / ITO / PEDOT:PSS / PbI2;

[0124] 5. Place the deposited yellow PbI2 film facing a long crucible containing 300 mg of methylamine iodide (CH3NH3I, MAI) powder in a vacuum oven. After the vacuum oven pressure is evacuated to below 10 kPa, the heating temperature is set to 200°C and the holding time is set to 10 minutes. During the heating process, the film gradually changes from yellow PbI2 to brown-black MAPbI3 perovskite;

[0125] 6. Then, the sample was moved to a glove box. After the sample cooled, an isopropyl alcohol solution was spin-coated on the surface of the MAPbI3 perovskite film at a speed of 4000 rpm for 30 seconds to remove the MAI attached to the film surface. The film was then annealed on a hot plate at 100°C for 10 minutes to complete the preparation of the MAPbI3 perovskite film and obtain the perovskite light absorbing layer 22.

[0126] 7. After the annealed MAPbI3 perovskite film cools, a layer of PCBM film is spin-coated in a glove box as the electron transport layer 23. The solution concentration is 20 mg / mL and the spin-coating parameters are 1500 rpm for 30 seconds. After completion, a layer of BCP film is spin-coated as the hole blocking layer 24. The solution concentration is 1 mg / mL and the spin-coating parameters are 4000 rpm for 30 seconds. The perovskite photodiode is now fabricated. The device structure is Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP.

[0127] 8. Transfer the device obtained in step 7 to a thermal evaporation coating machine, first evaporate a 150nm layer of PbI2 on the BCP film, and then evaporate a 50nm layer of Spiro-TTB to complete the preparation of the blocking diode film;

[0128] 9. Finally, a 100 nm thick Ag electrode is thermally evaporated as the top electrode 4. The Ag electrode pattern is m parallel and equally spaced strip electrodes. The strip Ag electrodes are deposited in a direction perpendicular to the bottom electrode 11 to form a complete device with a structure of Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP / PbI2 / Spiro-TTB / Ag.

[0129] 10. The perovskite photodetector array in this embodiment forms a cross electrode by vertically arranging the bottom electrode 11 and the top electrode 4, and an effective pixel 5 is formed at the intersection of the electrodes.

[0130] 11. In this embodiment, the number n of bottom electrodes 11 is 1920, and the number m of top metal electrodes is 1080, forming a perovskite photodetector array with 1920 rows and 1080 columns and a number of pixels 5 of 1920×1080, and the number of electrode leads is 1920+1080.

[0131] The preparation method of the perovskite photodetector of the present invention is further described below with reference to specific embodiments.

[0132] Example 4

[0133] A method for preparing a perovskite photodetector array comprises the following steps:

[0134] 1. Select ITO conductive glass as the transparent conductive substrate 1, and clean and treat the ITO conductive glass according to the method of step 2 in Example 1 to obtain a clean conductive substrate 1;

[0135] 2. According to the method of step 3 in Example 1, a PEDOT:PSS thin film is formed on the surface of the conductive substrate 1 as a hole transport layer 21;

[0136] 3. According to the method of step 4 in Example 1, a yellow lead iodide film is obtained;

[0137] 4. Following the method of step 5 in Example 1, a brown-black MAPbI3 perovskite was obtained;

[0138] 5. According to the method of step 6 in Example 1, the MAPbI3 perovskite film is prepared to obtain the perovskite light absorbing layer 22;

[0139] 6. According to the method of step 7 in Example 1, a PCBM film is sequentially prepared as the electron transport layer 23 and a BCP film is prepared as the hole blocking layer 24 to obtain a perovskite photodiode layer 2;

[0140] 7. Prepare a blocking diode thin film according to the method of step 8 in Example 1 to obtain a blocking diode layer 3;

[0141] 8. Finally, a 100 nm thick Ag electrode was thermally evaporated as the top electrode 4 to form a complete perovskite photodetector with a structure of Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP / PbI2 / Spiro-TTB / Ag;

[0142] Example 5

[0143] A method for preparing a perovskite photodetector array comprises the following steps:

[0144] 1. Select ITO conductive glass as the transparent conductive substrate 1, and clean and treat the ITO conductive glass according to the method of step 2 in Example 3 to obtain a clean conductive substrate 1;

[0145] 2. According to the method of step 3 in Example 2, a PEDOT:PSS thin film is formed on the surface of the conductive substrate 1 as a hole transport layer 21;

[0146] 3. According to the method of step 4 in Example 2, a yellow lead iodide film is obtained;

[0147] 4. Following the method of step 5 in Example 2, a brown-black MAPbI3 perovskite was obtained;

[0148] 5. According to the method of step 6 in Example 2, the MAPbI3 perovskite film is prepared to obtain the perovskite light absorbing layer 22;

[0149] 6. According to the method of step 7 in Example 2, a PCBM film is prepared as the electron transport layer 23, and a BCP film is prepared as the hole blocking layer 24, to obtain a perovskite photodiode layer 2;

[0150] 7. Prepare a blocking diode thin film according to the method of step 8 in Example 2 to obtain a blocking diode layer 3;

[0151] 8. Finally, a 100 nm thick Ag electrode was thermally evaporated as the top electrode 4 to form a complete perovskite photodetector with a structure of Glass / ITO / PEDOT:PSS / MAPbI3 / PCBM / BCP / PbI2 / Spiro-TTB / Ag;

[0152] Comparative Example 1

[0153] The difference between this comparative example and Example 4 is:

[0154] The preparation method of the perovskite photodetector in this comparative example does not include the step of preparing the blocking diode layer 3 , and the structure of the finally formed perovskite photodetector does not include the blocking diode layer 3 .

[0155] Product performance testing

[0156] The performance of the perovskite photodetector array prepared in Example 1, as well as the perovskite photodetectors prepared in Examples 4 and 5 and Comparative Example 1, was tested. The test results of the perovskite photodetectors prepared in Examples 1 and 5 were similar. The test results of Examples 1 and 4 are used as examples for illustration, as follows:

[0157] (1) The perovskite photodetectors prepared in Example 4 and Comparative Example 1 were tested for current-voltage curves under different power illumination. The light source used was a 532 nm laser with an illumination power of 70 μW. The measured results are as follows: Figure 4 The external quantum efficiency test of the perovskite photodetector array prepared in Example 1 was performed, and the test results are shown as follows: Figure 5 shown.

[0158] Depend on Figure 4 It can be found that the current of the perovskite photodetector obtained in Example 4 under forward bias is significantly lower than that of the ordinary photodetector without blocking diode layer 3 obtained in Comparative Example 1. The advantage of this is that when applied to a perovskite photodetector array device, when the perovskite photodetector is at 0V or under forward bias, the leakage current of the perovskite photodetector array device will be significantly suppressed. In addition, because the perovskite photodetector obtained in Example 1 has a blocking diode added, while the perovskite photodetector obtained in Comparative Example 1 does not have a blocking diode, the on-off ratio of the perovskite photodetector obtained in Example 1 when operating at -1.0V is not attenuated compared to the on-off ratio of the perovskite photodetector obtained in Comparative Example 1 when operating at 0V.

[0159] from Figure 5 It can be seen that the external quantum efficiency test results also confirm that the response capability of the perovskite photodetector array can be adjusted by applying different bias voltages. However, if the blocking diode layer 3 is not added to the perovskite photodetector array device, and the device is directly made into a perovskite photodetector array with cross-electrodes, the photocurrent will pass through the electrodes through potential paths, resulting in significant electrical crosstalk.

[0160] (2) The perovskite photodetector array obtained in Example 1 of the present invention is connected to a switching circuit and a readout circuit to obtain the following Figure 6 The simplified imaging array readout circuit shown applies a negative bias to each row of pixels through a switching circuit, turning on the entire row. This allows the pixels 5 in that row to respond effectively to light signals. The readout circuit then samples the current generated by the pixels 5 in that row, column by column. Once all pixels 5 in that row have been sampled, the switching circuit turns on the next row and begins sampling the signals from the next row, thus completing the acquisition of signals from the entire image sensor. Because each pixel incorporates a blocking diode layer 3, even if pixels in the same row are simultaneously turned on and generate photocurrent, the current is blocked by the blocking diode layer 3 within the same row, preventing it from flowing through adjacent pixels 5 and suppressing electrical crosstalk. For additional requirements on the readout signal, the readout circuit can connect the devices to a signal amplifier for sampling. For higher readout speed requirements, a parallel sampling signal readout method can also be used to achieve high-speed imaging. To further suppress crosstalk between rows, a suitable positive bias can be applied to the remaining rows that are not selected for activation, further reducing leakage current.

[0161] (3) Figure 7 This is a statistical diagram of the photocurrent distribution of 16 pixels 5 in the perovskite photodetector array prepared in Example 1. Figure 7 It can be seen that the perovskite photodetector array prepared in Example 1 has good uniformity and has great potential in realizing large-format image sensors with high density and consistent pixel 5 performance. This is because the perovskite photodiode layer 2 and the blocking diode layer 3 in Example 1 are both prepared by the vapor phase method, and the perovskite photodetector array prepared by the vapor phase method has higher uniformity than that prepared by the spin coating method.

[0162] Figure 8 This is a demonstration diagram of the static imaging of the letter "N" by the perovskite photodetector array prepared in Example 1. Figure 8 It can be seen that the letter "N" is demonstrated by performing static imaging of the perovskite photodetector array prepared in Example 1. The obtained image has obvious contrast and the shape of "N" can be clearly identified.

[0163] Figure 9This is a screenshot of the dynamic imaging demonstration of the perovskite photodetector array prepared in Example 1, specifically demonstrating the dynamic imaging process of an obstruction moving from left to right above the perovskite photodetector array. Figure 9 It can be seen that since the perovskite photodetector array prepared in Example 1 has a light response speed of <50 μs, the current of 16 pixels 5 is collected sequentially using an amplification circuit, which can achieve a frame rate of >25 fps, realizing smooth real-time dynamic imaging.

[0164] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the scope of protection of the present invention.

Claims

1. A perovskite photodetector, characterized in that: The invention comprises a conductive substrate (1), a perovskite photodiode layer (2), a blocking diode layer (3) and a top electrode (4) stacked in sequence from bottom to top; the blocking diode layer comprises a blocking diode sublayer I (31) and a blocking diode sublayer II (32) stacked in sequence; the blocking diode sublayer I is formed of PbI2, and the blocking diode sublayer II is formed of Spiro-TTB.

2. The perovskite photodetector according to claim 1, wherein The thickness of the blocking diode sublayer I (31) is 10-150 nm, and the thickness of the blocking diode sublayer II (32) is 10-50 nm.

3. The perovskite photodetector according to claim 1, wherein The perovskite photodiode layer (2) is a PIN-type structure perovskite photodiode layer or a NIP-type structure perovskite photodiode layer; the PIN-type structure perovskite photodiode layer comprises a hole transport layer (21), a perovskite light absorption layer (22), an electron transport layer (23), and a hole blocking layer (24) stacked in sequence from bottom to top; the NIP-type structure perovskite photodiode layer comprises an electron transport layer (23), a perovskite light absorption layer (22), a hole transport layer (21), and a hole blocking layer (24) stacked in sequence from bottom to top.

4. The perovskite photodetector according to claim 3, wherein The perovskite light absorbing layer (22) is formed of materials such as MAPbI3, CsPbCl3, CsPbBr2Cl, CsPbBr3, CsPbBr 1.5 I 1.

5. At least one of CH3NH3PbBr3, Cs3Sb2Br9, CH(NH2)2PbBr3, (BA)2(MA)Pb2I7 and (BA)2PbI4.

5. The perovskite photodetector according to claim 3, wherein The conductive substrate (1) is made of conductive glass or flexible conductive material; the hole transport layer (21) is made of PEDOT:PSS; the hole blocking layer (24) is made of PCBM; and the top electrode (4) is made of silver.

6. A perovskite photodetector array, comprising the perovskite photodetector according to claim 1, characterized in that: The invention comprises a conductive substrate (1), a perovskite photodiode layer (2), a blocking diode layer (3) and a top electrode (4) which are sequentially stacked from bottom to top; the conductive substrate (1) is etched with a plurality of bottom electrodes (11) arranged at equal intervals along a first direction, the plurality of bottom electrodes (11) forming a bottom electrode array, the top electrodes (4) are arranged at equal intervals along a second direction, the plurality of top electrodes (4) forming a top electrode array, and the bottom electrode array and the top electrode array are arranged perpendicularly and crosswise.

7. A method for preparing a perovskite photodetector array, for preparing the perovskite photodetector array according to claim 6, characterized in that: The steps include: S1. Etching a plurality of strip electrodes arranged at equal intervals on a conductive substrate (1) to obtain a bottom electrode; S2. forming a perovskite photodiode layer (2) on the surface of the bottom electrode; S3. On the side of the perovskite photodiode layer (2) away from the bottom electrode, first forming a blocking diode sublayer I (31), and then forming a blocking diode sublayer II (32), to obtain a blocking diode layer (3); S4. Depositing the blocking diode layer (3) on a side away from the perovskite photodiode layer (2) in a direction perpendicular to the bottom electrode to form top electrodes arranged at equal intervals, thereby obtaining a perovskite photodetector array.

8. The preparation method according to claim 7, characterized in that The blocking diode sublayer I (31) and the blocking diode sublayer II (32) are prepared by at least one of physical vapor deposition, chemical vapor deposition, solution spin coating, magnetron sputtering and atomic layer deposition.

9. The preparation method according to claim 7, characterized in that The method for forming a perovskite photodiode layer comprises the following steps: S21. Spin-coating the hole transport layer forming material on one side of the conductive substrate (1) and then annealing to form a hole transport layer (21); S22. The raw material I for forming the perovskite light absorbing layer is evaporated to form a precursor film for forming the perovskite light absorbing layer on the side of the hole transport layer (21) away from the conductive substrate (1); S23. Heating the precursor film and the perovskite light absorbing layer forming raw material II under a vacuum environment to form a perovskite film, removing the unreacted perovskite light absorbing layer forming raw material II on the surface of the formed perovskite film, and performing annealing to obtain a perovskite light absorbing layer (22); S24. Spin-coating an electron transport layer forming material on a side of the perovskite light absorbing layer (22) away from the hole transport layer (21) to form an electron transport layer (23); S25. Spin-coating a hole blocking layer material onto the side of the electron transport layer (23) away from the perovskite light absorbing layer (22) to form a hole blocking layer (24) and obtain a perovskite photodiode layer (2).

10. The preparation method according to claim 7, characterized in that The method for forming a perovskite photodiode layer comprises the following steps: S21. Spin-coating a material for forming an electron transport layer onto one side of the conductive substrate (1) to form an electron transport layer (23); S22. The raw material I for forming the perovskite light absorbing layer is evaporated to form a precursor film on the side of the electron transport layer (23) away from the conductive substrate (1); S23. Heating the precursor film and the raw material II for forming the perovskite light absorbing layer under a vacuum environment to form a perovskite film, removing the unreacted raw material II for forming the perovskite light absorbing layer on the surface of the perovskite film, and performing an annealing treatment to obtain a perovskite light absorbing layer (22); S24. Spin-coating a hole transport layer forming material on a side of the perovskite light absorbing layer (22) away from the electron transport layer (23), and annealing to form a hole transport layer (21); S25. Spin-coating a hole blocking layer material onto a side of the electron transport layer away from the perovskite light absorbing layer to form a hole blocking layer (24) and obtain a perovskite photodiode layer (2).

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