Method for preparing mid-infrared focal plane detector on basis of sn-doped pbse quantum dots

Abstract

A method for preparing a mid-infrared focal plane detector on the basis of Sn-doped PbSe quantum dots. The preparation of a mid-infrared focal plane detector involves: on an ROIC substrate, respectively using an ion beam sputtering method, a spin coating method, the spin coating method and the ion beam sputtering method to sequentially construct an Au bottom electrode, a PbS hole transport layer, an Sn-doped PbSe photosensitive layer and a PIN heterojunction of a ZnO electron transport layer; and finally, using the ion beam sputtering method to deposit an ITO top electrode. The method based on Sn-doped PbSe quantum dots has the advantage of high mid-infrared response; and the method can realize the preparation of low-cost, chip-scale and simple-process uncooled PbSe mid-infrared focal plane detectors.

Description

Preparation method of mid-infrared focal plane detector based on Sn-doped PbSe quantum dots TECHNICAL FIELD

[0001] The present application relates to the technical field of mid-infrared focal plane detector thermal imaging, and more particularly to a preparation method of a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots. BACKGROUND

[0002] Up to now, infrared detectors have experienced development from the first generation to the fourth generation, and gradually developed from single-pixel detectors to large-array, miniaturized, low-cost, dual-color and multi-column array focal plane detectors. According to the working infrared wavelength of atmospheric window, infrared detectors can be divided into near-infrared detectors (1-3 μm), mid-infrared detectors (3-5 μm) and far-infrared detectors (8-10 μm). In addition, according to the use temperature of the detector, infrared detectors can also be divided into refrigeration type and non-refrigeration type detectors. Refrigeration type detectors are widely used due to their high detection rate and low signal-to-noise ratio, but their large size (Dewar bottle packaging) and high energy consumption (liquid nitrogen circulation refrigeration) also limit further development. Non-refrigeration type detectors are favored by the civilian market due to their chip-level size and room temperature working temperature, and can be divided into thermal type detectors and photon type detectors according to their working principles. Among them, the response speed of the photon type detector is 1-2 orders of magnitude higher than that of the thermal type detector, so it has a great advantage in thermal imaging of focal plane array.

[0003] At present, non-refrigeration type photon type infrared detectors at home and abroad have realized breakthroughs in near-infrared (1-3 μm) focal plane detector arrays and achieved commercial applications, including InGaAs detectors, GeSi detectors, PbS detectors and the like. In the mid-infrared region (3-5 μm), domestic refrigeration type focal plane detectors are still in the stage (CdHgTe detector, InSb detector, quantum well detector), and chip-level mid-infrared non-refrigeration type focal plane detector arrays are still blank. In recent years, foreign (Spanish company) has developed chip-level non-refrigeration type PbSe thin film mid-infrared focal plane detectors, but the thermal noise of the thin film bulk material will cause high dark current of the mid-infrared focal plane detector, thereby reducing the detection rate of the detector.

[0004] From the preparation process of the infrared focal plane detector, the currently commercialized detector mainly adopts the detector process of flip-chip packaging on the substrate of Si COMS process readout circuit (ROIC) and the direct thin film growth process. The former mainly realizes flip-chip packaging by the detector thin film indium column and the indium column on the ROIC; the latter grows the detector thin film on the ROIC by the thin film growth technology such as MOCVD or MBE. The two processes are complicated and single in function, high in equipment requirement and process cost, poor in controllability, and large in material size.

[0005] SUMMARY

[0006] The present application provides a kind of middle infrared focal plane detector preparation method based on Sn doped PbSe quantum dots to overcome the defects in the prior art, and the preparation process is simple, and the detection efficiency of the detector is effectively improved.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is:

[0008] A kind of middle infrared focal plane detector preparation method based on Sn doped PbSe quantum dots, comprising the following steps:

[0009] S1. Application of photolithography and ion beam sputtering method is deposited on the ROIC substrate Au array bottom electrode as array bottom electrode;

[0010] S2. PbS quantum dot hole transport layer is prepared on the array bottom electrode by spin coating method;

[0011] S3. Sn doped PbSe quantum dot photosensitive layer is prepared on the PbS quantum dot hole transport layer by spin coating method;

[0012] S4. PIN heterojunction of ZnO electron transport layer is prepared on Sn doped PbSe quantum dot photosensitive layer by ion beam sputtering method;

[0013] S5. ITO thin film is deposited on the ZnO electron transport layer as top electrode by ion beam sputtering method, and the middle infrared focal plane detector is obtained.

[0014] In the present application, the preparation of the middle infrared focal plane detector is on the ROIC substrate, and the Au bottom electrode, PbS hole transport layer, Sn doped PbSe photosensitive layer and PIN heterojunction of ZnO electron transport layer are sequentially constructed by ion beam sputtering method, spin coating method, spin coating method and ion beam sputtering method, respectively.

[0015] According to the technical means, the focal plane detector is prepared based on the Sn-doped PbSe quantum dots, the small size of the PbSe quantum dots can effectively prevent the propagation of thermal noise compared with the PbSe film, the band gap of the quantum dots changes with the size, thereby obtaining the photosensitive material with different spectral responses. For the mid-infrared wave band, the band gap of the PbSe quantum dots is 4.7 mu m, so the PbSe quantum dots can realize the detection of the mid-infrared wave band. In summary, the Sn-doped PbSe quantum dots have the advantages of high mid-infrared response, and realize the preparation of the low-cost, chip, and simple non-cooled PbSe mid-infrared focal plane detector.

[0016] In one of the embodiments, the Sn-doped PbSe quantum dots and the PbS quantum dots are synthesized by a thermal injection method, and the Sn-doped PbSe quantum dots are subjected to surface modification treatment by a room temperature oxidation method and a liquid phase iodization method after synthesis.

[0017] In one of the embodiments, the step S2 comprises:

[0018] S21. Preparing a PbS quantum dot spin coating solution;

[0019] S22. Spinning the PbS quantum dot spin coating solution on the array bottom electrode to obtain a PbS quantum dot spin coating layer;

[0020] S23. Treating the PbS quantum dot spin coating layer spun on the array bottom electrode with an EDT methanol solution for ligand exchange and washing with methanol;

[0021] S24. Repeating the step S23 to make the size of the PbS quantum dots reach a set range, thereby completing the preparation of the PbS quantum dot hole transport layer.

[0022] In one of the embodiments, the step S21 comprises:

[0023] S211. Mixing lead oxide, an ODE solution, and an OA solution to obtain a mixture, and heating the mixture to 140-150 DEG C under a vacuum environment;

[0024] S212. Adding a double sulfide solution diluted with an ODE solution to the mixture of the step S211 and reacting for a period of time to obtain a PbS reaction solution;

[0025] S213. Adding ethanol to the PbS reaction solution for centrifugal precipitation to obtain PbS quantum dots, and dispersing the PbS quantum dots in an octane solution to obtain a PbS quantum dot spin coating solution.

[0026] In one of the embodiments, the step S211 specifically comprises: weighing a proper amount of lead oxide in a container A, then adding an ODE and OA solution with a weight of 2-3 times of the lead oxide in the container A, vacuum heating the container A at 100-110°C for a period of time, and waiting for the temperature to rise to 140-150°C.

[0027] In one of the embodiments, the step S3 comprises:

[0028] S31. preparing a Sn-doped PbSe quantum dot dimethylformamide solution;

[0029] S32. after spin coating the Sn-doped PbSe quantum dot dimethylformamide solution on the PbS quantum dot spin coating layer for a period of time, washing with acetonitrile;

[0030] S33. repeating the step S32 at least twice to make the size of the Sn-doped PbSe quantum dots reach a set range, thereby completing the preparation of the Sn-doped PbSe quantum dot photosensitive layer.

[0031] In one of the embodiments, the step S31 specifically comprises:

[0032] S311. adding a lead acetate trihydrate compound, a tin acetate compound, an oleic acid solution, a diphenyl ether solution, and a trioctylphosphine solution into a container B to mix, and vacuum drying the container B at 70-90°C;

[0033] S312. dissolving a selenium powder in a trioctylphosphine solution to form a trioctylselenium solution, and adding the trioctylselenium solution into the container B under a N2 atmosphere to form a precursor solution;

[0034] S313. taking a diphenyl ether solution and adding the diphenyl ether solution into a container C and vacuum drying the container C at 70-90°C for a period of time; then continuously increasing the temperature to 240-250°C under a N2 atmosphere;

[0035] S314. quickly adding the precursor solution in the container B into the container C, and after a certain period of reaction, placing the container C in an ice water bath to quench, and cooling to room temperature to obtain a Pb 1-x Sn x Se quantum dot reaction solution, wherein x=0-0.11;

[0036] S315. centrifuging the Pb 1-x Sn x Se quantum dots in the reaction solution with ethanol to precipitate, and re-dispersing the Pb 1-x Sn x Se quantum dots in a hexane solution; again centrifuging the Pb 1-x Sn x Se quantum dots in the hexane solution with an ethanol solution to obtain a Pb1-x Sn x Se quantum dots, and Pb 1-x Sn x Se quantum dots are placed in a low oxygen concentration atmosphere at room temperature for drying oxidation;

[0037] S316. The Pb 1-x Sn x Se quantum dots are dispersed in an octane solution to obtain a Pb 1-x Sn x Se quantum dot-octane solution; lead iodide and ammonium acetate are dissolved in a dimethylformamide solution and added to the Pb 1-x Sn x Se quantum dot-octane solution in a volume ratio of 1:1; mixed and vibrated for a period of time until the Pb 1-x Sn x Se quantum dots are transferred from the octane solution to the dimethylformamide solution to obtain a Pb 1-x Sn x Se quantum dot dimethylformamide solution;

[0038] S317. The Pb 1-x Sn x Se quantum dot dimethylformamide solution is centrifuged to obtain a Pb 1-x Sn x Se quantum dot dimethylformamide solution is washed with an octane solution to obtain a Pb 1-x Sn x Se quantum dot dimethylformamide solution is washed with an octane solution to obtain a Pb 1-x Sn x Se quantum dots are dispersed in a dimethylformamide solution.

[0039] In one of the embodiments, the step S311 comprises: weighing lead(II) acetate trihydrate and tin(II) acetate in a container B, wherein the ratio of lead(II) acetate trihydrate and tin(II) acetate is 1:0.5-1; then adding oleic acid, diphenyl ether and trioctylphosphine in a volume ratio of 1:1:1 in the container B; and heating and drying the container B at 70-90°C under vacuum environment.

[0040] In one of the embodiments, the step S312 comprises: dissolving an appropriate amount of selenium powder in a trioctylphosphine solution to form a trioctylselenium solution, and adding the trioctylselenium solution to the container B under N2 atmosphere to form a precursor solution.

[0041] In one of the embodiments, the step S316 comprises: dispersing the Pb 1-x Sn x Se quantum dots in an octane solution to obtain a Pb 1-x Snx Se quantum dots-octane solution; lead iodide and ammonium acetate were dissolved in 1 ml of dimethylformamide solution and added to Pb 1-x Sn x Se quantum dots-octane solution; the mixed solution of the two was shaken vigorously for 1-2 minutes until Pb 1-x Sn x Se quantum dots were transferred from octane to dimethylformamide solution, then the supernatant was removed and washed with octane several times to ensure complete transfer.

[0042] The size of the PbS quantum dots, Sn-doped PbSe quantum dots is determined according to the wavelength range to be detected by the detector.

[0043] Compared with the prior art, the beneficial effects are: the preparation method of the mid-infrared focal plane detector based on Sn-doped PbSe quantum dots provided by the application has the advantages of high mid-infrared response of the Sn-doped PbSe quantum dots, and the method can realize the preparation of a low-cost, chip-based, simple-process non-cooled PbSe mid-infrared focal plane detector. BRIEF DESCRIPTION OF DRAWINGS

[0044] Fig. 1 is a flowchart of the method of the application.

[0045] Fig. 2 is a cross-sectional electron scanning microscope image of the mid-infrared focal plane detector of the application.

[0046] Fig. 3 is a practical device (64x 64 pixel array) of the mid-infrared focal plane detector prepared by the method of the application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. The application will be described below in one of the embodiments with reference to the specific implementation manner. The drawings are only used for illustrative description, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the patent; in order to better illustrate the embodiments of the application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some known structures and their descriptions in the drawings may be omitted.

[0048] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only for exemplary illustration, and cannot be understood as a limitation on the present patent, for those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. In addition, if there is a description of "first", "second" and the like in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implying the number of indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the meaning of "and / or" appearing throughout the text is that it includes three parallel schemes, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme.

[0049] Embodiment 1:

[0050] The present embodiment provides a method for synthesizing Sn-doped PbSe quantum dots (Pb 1-x Sn x The present embodiment provides a method for synthesizing Sn-doped PbSe quantum dots (Pb

[0051] Step 1: weigh 1.5-3 mmol of lead (II) acetate trihydrate and 0.75-3 mmol of tin (II) acetate in an A flask, then add oleic acid, diphenyl ether and triphenylphosphine to the A flask in a volume ratio of 1:1:1. The A flask is heated and dried under vacuum at 70-90°C for 1 hour.

[0052] Step 2: dissolve 1.5-3 mmol of selenium powder in 1-2 mL of triphenylphosphine to form a triphenylphosphine selenium solution, and add it to the A flask under N2 atmosphere to form a precursor solution;

[0053] Step 3: take 1 mL of diphenyl ether in a B flask and dry it under vacuum at 70-90°C for 1 hour, and continue to raise the temperature to 240-250°C under N2 atmosphere.

[0054] Step 4: quickly inject all the A flask precursor solution into the B flask, and after 1 min of reaction, place the B flask in an ice water bath for quenching, and cool to room temperature.

[0055] Step 5: use ethanol (volume ratio 2:1) to precipitate the Pb 1-x Sn xSe (x = 0-0.11) quantum dots were centrifuged and precipitated, and then re-dispersed in hexane. The re-precipitation was performed again by the same method. Finally, Pb 1-x Sn x Se quantum dots were placed in a low oxygen concentration (10 ppm) atmosphere at room temperature and dried for two days.

[0056] Step 6: Pb 1-x Sn x Se quantum dots were dispersed in a 15-25 mg / mL octane solution for liquid phase iodization; 0.10-0.2 mol of lead iodide and 0.04-0.1 mol of ammonium acetate were dissolved in 1-2 mL of dimethylformamide solution (DMF), and added to the above Pb 1-x Sn x Se quantum dot-octane solution at a volume ratio of 1:1; the mixed solution was shaken vigorously for 1-2 minutes until the Pb 1-x Sn x Se quantum dots were transferred from octane to DMF solution, and then the supernatant was removed and washed with octane several times (3-4 times) to ensure complete transfer.

[0057] Step 7: Pb 1-x Sn x Se quantum dots were precipitated by centrifugation, washed with octane (3-4 times) to remove residual impurity ions, and re-dispersed in a DMF solution (1-2 mL).

[0058] Example 2

[0059] The present embodiment provides a method for synthesizing PbS quantum dots, comprising the following steps:

[0060] Step 1: 0.3-1 g of lead oxide was weighed into container C, and 0.6-2 mL of ODE and 0.6-2 mL of OA were added to container C. Container C was heated under vacuum at 100-110°C until the temperature reached 140-150°C.

[0061] Step 2: Bis(trimethylsilyl) sulfide (1 mL) diluted with 10 mL of ODE solution was injected and reacted for 4 minutes to obtain a PbS reaction solution.

[0062] Step 3: PbS quantum dots were obtained by centrifugation after adding ethanol (volume ratio 1:3) to the PbS reaction solution.

[0063] Example 3

[0064] As shown in FIGS. 1 and 2, the present embodiment provides a method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots, comprising the following steps:

[0065] Step 1: Au array bottom electrode (100 nm) was deposited on ROIC substrate (64*64 pixel array) as array bottom electrode by photolithography and ion beam sputtering method.

[0066] Step 2: PbS quantum dot hole transport layer was prepared on array bottom electrode by spin-coating method.

[0067] S21. PbS quantum dot spin-coating solution was prepared by using PbS quantum dots prepared in Example 2: PbS quantum dots were dispersed into octane solution at 25-35 mg / mL to obtain PbS spin-coating solution.

[0068] S22. PbS quantum dot spin-coating was performed on array bottom electrode at 2000-3000 r / min to obtain PbS quantum dot spin-coating layer.

[0069] S23. The PbS quantum dot spin-coating layer spin-coated on array bottom electrode was treated with 0.1 mol EDT in methanol solution (1 ml) for at least 40 seconds for ligand exchange, and washed with methanol for at least 40 seconds.

[0070] S24. Step S23 was repeated to make the size of PbS quantum dots reach 100-300 nm, and thus the preparation of PbS quantum dot hole transport layer was completed.

[0071] Step 3: Sn-doped PbSe quantum dot photosensitive layer was prepared on PbS quantum dot hole transport layer by spin-coating method.

[0072] S31. Sn-doped PbSe quantum dot dimethylformamide solution was prepared by using Sn-doped PbSe quantum dots prepared in Example 1.

[0073] S32. Sn-doped PbSe quantum dot dimethylformamide solution was spin-coated on PbS quantum dot spin-coating layer at 2000-3000 r.p.m. for 40 seconds, and then washed with acetonitrile.

[0074] S33. Step S32 was repeated at least twice to make the size of Sn-doped PbSe quantum dots reach 500-2000 nm, and thus the preparation of Sn-doped PbSe quantum dot photosensitive layer was completed.

[0075] Step 4: 200-300 nm ZnO electron transport layer was prepared on Sn-doped PbSe quantum dot photosensitive layer by ion beam sputtering method.

[0076] Step 5: 200-800 nm ITO film was deposited on ZnO electron transport layer as top electrode by ion beam sputtering method to obtain mid-infrared focal plane detector, as shown in FIG. 2 and FIG. 3.

[0077] In the application, the preparation of the mid-infrared focal plane detector is on the ROIC substrate, and the Au bottom electrode, the PbS hole transport layer, the Sn-doped PbSe photosensitive layer, the ZnO electron transport layer PIN heterojunction are sequentially constructed by ion beam sputtering method, spin coating method, spin coating method, ion beam sputtering method respectively, and finally the ITO top electrode is evaporated by ion beam sputtering method to form.

[0078] According to the above technical means, the focal plane detector is prepared based on the Sn-doped PbSe quantum dots, the smaller size of the PbSe quantum dots can effectively prevent the propagation of thermal noise compared with the PbSe film, and the band gap of the quantum dots changes with the size, so that the photosensitive material with different spectral responses is obtained. For the mid-infrared waveband, the band gap of the PbSe quantum dots is 4.7 mu m, so the PbSe quantum dots can realize the detection of the mid-infrared waveband; in summary, the Sn-doped PbSe quantum dots have the advantages of high mid-infrared response, and realize the preparation of the low-cost, chip, simple and non-cooled PbSe mid-infrared focal plane detector.

[0079] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0080] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the implementation manner of the application. Based on the above description, those skilled in the art can make other different forms of changes or modifications. Here, all the implementation manners do not need to be exhausted. Any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the claims of the application.

Claims

1. A method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots, characterized in that: The following steps are involved: S1. Depositing an Au array bottom electrode on the ROIC substrate using photolithography and ion beam sputtering as the array bottom electrode; S2. Prepare a PbS quantum dot hole transport layer on the bottom electrode array by spin coating; S3. Prepare a Sn-doped PbSe quantum dot photosensitive layer on the PbS quantum dot hole transport layer by spin coating; S4. Fabricate a PIN heterojunction of a ZnO electron transport layer on a Sn-doped PbSe quantum dot photosensitive layer by ion beam sputtering; S5. An ITO thin film was deposited on the ZnO electron transport layer by ion beam sputtering as the top electrode to obtain a mid-infrared focal plane detector.

2. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 1, characterized in that: Sn-doped PbSe quantum dots and PbS quantum dots were synthesized by hot injection method, wherein Sn-doped PbSe quantum dots were surface modified by room temperature oxidation method and liquid phase iodination method after synthesis.

3. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 2, characterized in that: The step S2 comprises: S21. Preparation of PbS quantum dot spin coating solution; S22. The PbS quantum dot spin coating solution is spin-coated on the bottom electrode array to obtain a PbS quantum dot spin coating; S23. The PbS quantum dot coating layer spin-coated on the bottom electrode of the array was treated with a methanol solution of EDT for ligand exchange and rinsed with methanol; S24. Repeat step S23 to make the size of the PbS quantum dots reach the set range, thus completing the preparation of the PbS quantum dot hole transport layer.

4. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 3, characterized in that: The step S21 includes: S211. The lead oxide, the ODE solution, the OA solution is mixed to obtain a mixture, and the mixture is heated to 140 ℃ ~ 150 ℃ under vacuum; S212. Add the disulfide solution diluted with the ODE solution to the mixture of step S211 and react for a period of time to obtain a PbS reaction solution; S213. Add ethanol to the PbS reaction solution for centrifugal precipitation to obtain PbS quantum dots, and redisperse the PbS quantum dots in an octane solution to obtain a PbS quantum dot spin coating solution.

5. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 4, characterized in that: The step S211 specifically includes: weighing an appropriate amount of lead oxide into container A, then adding ODE and OA solutions in an amount 2 to 3 times the weight of the lead oxide into container A, and heating container A in a vacuum at 100° C. to 110° C. for a period of time until the temperature rises to 140° C. to 150° C.

6. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 2, characterized in that: The step S3 comprises: S31. Preparation of Sn-doped PbSe quantum dots in dimethylformamide solution; S32. After the Sn-doped PbSe quantum dot dimethylformamide solution was spin-coated on the PbS quantum dot coating layer for a period of time, it was washed with acetonitrile; S33. Repeat step S32 at least twice to make the size of the Sn-doped PbSe quantum dots reach the set range, thereby completing the preparation of the Sn-doped PbSe quantum dot photosensitive layer.

7. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 6, characterized in that: The step S31 specifically includes: S311. Lead acetate trihydrate, tin acetate, oleic acid solution, diphenyl ether solution and trioctylphosphine solution are added to container B and mixed, and the container B is heated and dried at 70 ℃ to 90 ℃ under vacuum; S312. The selenium powder is dissolved in a trioctylphosphine solution to form a trioctylselenium solution, and is added to the container B under a N2 atmosphere to form a precursor solution; S313. Take the diphenyl ether solution into container C and vacuum dry at 70 ℃ ~ 90 ℃ for a period of time; then continue to raise the temperature to 240 ℃ ~ 250 ℃ under N2 atmosphere; S314. The precursor solution in container B is quickly added to container C. After a certain reaction time, container C is placed in an ice water bath to quench and cool to room temperature to obtain Pb 1-x Sn x Se quantum dot reaction solution, wherein x = 0 to 0.11; S315. Use ethanol to remove Pb 1-x Sn x Pb in Se quantum dot reaction solution 1-x Sn x Se quantum dots were centrifuged and precipitated, and redispersed in hexane solution; Pb in hexane solution was dispersed again with ethanol solution. 1-x Sn x Se quantum dots were centrifuged and precipitated to obtain Pb 1-x Sn x Se quantum dots and Pb 1-x Sn x Se quantum dots were placed at room temperature and dried and oxidized in a low oxygen concentration atmosphere; S316. Pb obtained in step S315 1-x Sn x Se quantum dots were dispersed in octane solution to obtain Pb 1-x Sn x Se quantum dots-octane solution; lead iodide and ammonium acetate were dissolved in dimethylformamide solution and added to Pb 1-x Sn x Se quantum dots-octane solution; mix and vibrate for a while until Pb 1-x Sn x Se quantum dots were transferred from octane solution to dimethylformamide solution to obtain Pb 1-x Sn x Se quantum dots dimethylformamide solution; S317.Pb 1-x Sn x Se quantum dots in dimethylformamide solution were centrifuged to obtain Pb 1-x Sn x Se quantum dots, Pb washed with octane solution 1-x Sn x After Se quantum dots remove the residual impurity ions, Pb 1-x Sn x Se quantum dots were rinsed and dispersed in dimethylformamide solution.

8. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 7, characterized in that: The step S311 includes: weighing lead (II) acetate trihydrate and tin (II) acetate into a container B, wherein the molar ratio of lead (II) acetate trihydrate to tin (II) acetate is 1:0.5-1; then adding oleic acid, diphenyl ether, and trioctylphosphine into the container B in a volume ratio of 1:1:1; and heating and drying the container B at 70°C-90°C under a vacuum environment.

9. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 8, characterized in that: The step S312 includes: dissolving an appropriate amount of selenium powder in a trioctylphosphine solution to form a trioctylselenium solution, and adding the solution into the container B under a N2 atmosphere to form a precursor solution.

10. The method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots according to claim 9, characterized in that: The sizes of the PbS quantum dots and Sn-doped PbSe quantum dots are determined according to the wavelength range that the detector needs to detect.

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