Preparation method of trimethylaluminum-doped lead selenide colloidal quantum dot film

Abstract

This application discloses a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film. The method comprises: obtaining a fifth mixed solution; spin-coating the fifth mixed solution onto a target sample and annealing the solution for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film; placing the initial lead selenide colloidal quantum dot film in a chamber, evacuating the chamber until the pressure reaches a preset pressure, heating the initial lead selenide colloidal quantum dot film to a preset temperature; and introducing trimethylaluminum gas into the chamber to obtain the trimethylaluminum-doped lead selenide colloidal quantum dot film. This application can improve the mobility of colloidal quantum dot detectors.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film. Background Art

[0002] Short-wave infrared refers to light with a wavelength ranging from 900nm to 2.5um. Light in this wavelength band has a higher intensity than visible light even in nighttime environments, and has a longer penetration depth in clouds and fog. Therefore, the short-wave infrared band carries more information about the outline, surface texture, size, and other aspects of an object and is therefore widely observed. Colloidal quantum dots are a type of zero-dimensional material synthesized in a liquid phase. By regulating the size, the band gap and wavelength of the material can be controlled. They are studied for their absorption properties in the short-wave infrared band. Currently, the mainstream colloidal quantum dots used for short-wave infrared detection are lead-based colloidal quantum dots. Electrons in the valence band of quantum dots absorb photon energy and transition to the conduction band to form free electrons, increasing the current of the detector, thereby detecting light signals through the detection of the current. The current mainstream lead-based colloidal quantum dot photodetector adopts a PIN-type structure, that is, a lead-based colloidal quantum dot layer (light-absorbing layer) with light-absorbing function is sandwiched between a highly doped functional layer, and a built-in electric field is formed through the high doping concentration of the functional layer to penetrate the light-absorbing layer; under the action of the built-in electric field, the electron-hole pairs generated by light absorption are separated to form efficient carrier extraction. In actual devices, oxide semiconductors such as zinc oxide and tin oxide are mostly used as N-type functional layers, and quantum dot films treated with ethanedithiol are used as P-type functional layers. Lead-based colloidal quantum dot devices based on this structure have the advantages of high responsiveness and high dynamic range and have also been widely reported. However, the shot noise caused by the dark current of colloidal quantum dots is large, which limits the further optimization of the imaging performance of colloidal quantum dot detectors. The high dark current is caused by the reverse saturation current, which is mainly limited by the low mobility. Compared with the mobility of classic semiconductors such as silicon, which is 480cm 2 / V*s, the mobility of lead-based colloidal quantum dot films is only 2*10 -3 -3*10 -3 cm 2 / V*s, 10 lower 5 This determines and limits the ultimate performance of lead-based colloidal quantum dot devices to 2-3 orders of magnitude lower than that of silicon, and is also the main reason for the poor low-light performance of quantum dot detectors. Improving the mobility of colloidal quantum dot detectors is crucial. Summary of the Invention

[0003] The present application aims to solve at least one of the above-mentioned technical problems by providing a preparation method of trimethylaluminum-doped lead selenide colloidal quantum dot film, which can improve the mobility of colloidal quantum dot detectors.

[0004] On one hand, the present application provides a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film, the method comprising:

[0005] Preserving lead selenide colloidal quantum dots in an n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead selenide colloidal quantum dots is oleic acid;

[0006] Dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution;

[0007] filtering the quantum dot n-octane solution and the first mixed solution and then mixing them to obtain a second mixed solution;

[0008] Oscillating the second mixed solution for a first oscillation time and allowing the second mixed solution to stand until the second mixed solution separates into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution;

[0009] Oscillating the third mixed solution for a second oscillation time and allowing the third mixed solution to stand until the third mixed solution is separated into an upper and lower layer of solutions, and removing the upper layer of the third mixed solution to obtain a fourth mixed solution;

[0010] treating the fourth mixed solution to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands;

[0011] The lead selenide quantum dot DMF solution was placed in a centrifuge and the upper yellow liquid was poured out, and vacuum extraction was performed for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots;

[0012] dissolving lead selenide quantum dots in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution;

[0013] Spin-coating the fifth mixed solution on the target sample and annealing the sample for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film;

[0014] placing an initial lead selenide colloidal quantum dot film into a chamber, evacuating the chamber until the air pressure reaches a preset pressure, and heating the initial lead selenide colloidal quantum dot film to a preset temperature;

[0015] Trimethylaluminum gas is introduced into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film.

[0016] Optionally, the concentration of the lead selenide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL.

[0017] Optionally, dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution comprises:

[0018] 0.92 g of lead iodide and 0.58 g of lead bromide were dissolved in 10 ml of DMF solution to obtain a first mixed solution.

[0019] Optionally, the first oscillation duration is 40 seconds, and the second oscillation duration is 40 seconds.

[0020] Optionally, the preset volume is 10 ml.

[0021] Optionally, the preset extraction time is one hour.

[0022] Optionally, the step of placing the lead selenide quantum dot DMF solution in a centrifuge and discarding the upper yellow liquid comprises:

[0023] The lead selenide quantum dot DMF solution was placed in a centrifuge and centrifuged at a speed of 9000 rpm for 4 minutes.

[0024] Optionally, in the mixed solvent of n-butylamine and DMF, the volume ratio of n-butylamine to DMF is 1:1.

[0025] Optionally, the preset annealing time is 10 minutes, and the preset pressure is 10 -6 pa-10 -4 pa, the preset temperature is 20 degrees Celsius to 100 degrees Celsius.

[0026] Optionally, the step of introducing trimethylaluminum gas into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film comprises:

[0027] Trimethylaluminum gas is introduced into the chamber in a pulsed pumping manner to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film, wherein during pulse pumping, a single pumping time is 10 ms, a pumping time interval is 60 s-150 s, the number of pumping times is 10 times-100 times, and the gas pressure of the trimethylaluminum gas is 15 Pa-25 Pa.

[0028] The preparation method of the trimethylaluminum-doped lead selenide colloidal quantum dot film of the present application comprises: preserving the lead selenide colloidal quantum dots in an n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead selenide colloidal quantum dots is oleic acid; dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution; filtering the quantum dot n-octane solution and the first mixed solution and then mixing them to obtain a second mixed solution; oscillating the second mixed solution for a first oscillation time and allowing it to stand until the second mixed solution is separated into two layers of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; oscillating the third mixed solution for a second oscillation time and allowing it to stand until the third mixed solution is separated into two layers of solution, removing the third mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; The upper layer solution is prepared to obtain a fourth mixed solution; the fourth mixed solution is treated to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands; the DMF solution of lead selenide quantum dots is placed in a centrifuge and the upper yellow liquid is poured out, and vacuum extraction is performed for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots; the lead selenide quantum dots are dissolved in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution; the fifth mixed solution is spin-coated on a target sample and annealed for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film; the initial lead selenide colloidal quantum dot film is placed in a chamber, the chamber is vacuumed until the air pressure reaches a preset pressure, and the initial lead selenide colloidal quantum dot film is heated to a preset temperature; trimethylaluminum gas is introduced into the chamber to obtain a lead selenide colloidal quantum dot film based on trimethylaluminum doping. The present application can improve the mobility of colloidal quantum dot detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a flow chart of an embodiment of a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film provided in an embodiment of the present application;

[0030] Figure 2 Schematic diagram of a trimethylaluminum-doped lead selenide colloidal quantum dot film provided in an embodiment of the present application being disposed on a target sample;

[0031] Figure 3 is a graph showing the relationship between the gate voltage and drain current of the target sample before trimethylaluminum doping;

[0032] Figure 4 This is a graph showing the relationship between the gate voltage and drain current of the target sample after trimethylaluminum doping. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0035] In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that one of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, well-known structures and processes are not elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0036] Lead-based colloidal quantum dot films have shown excellent performance in the field of short-wave infrared detection. However, due to the amorphous material structure of colloidal quantum dot films, their film mobility is limited to only 10 -3 cm 2 / (V*s), far lower than similar short-wave infrared detection materials. PN junction infrared detection devices made of low-mobility semiconductor materials suffer from low responsivity and high dark current, which limits their ultimate detection performance. Improving the mobility of lead-based colloidal quantum dots, and thus enhancing the device's ultimate detection performance, is particularly important.

[0037] In order to solve the above problems, the present application provides a preparation method of a trimethylaluminum-doped lead selenide colloidal quantum dot film, which comprises: preserving the lead selenide colloidal quantum dots in an n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead selenide colloidal quantum dots is oleic acid; dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution; filtering the quantum dot n-octane solution and the first mixed solution and then mixing them to obtain a second mixed solution; oscillating the second mixed solution for a first oscillation time and allowing it to stand until the second mixed solution is separated into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; oscillating the third mixed solution for a second oscillation time and allowing it to stand until the third mixed solution is separated into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; oscillating the third mixed solution for a second oscillation time and allowing it to stand until the third mixed solution is separated into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution. The upper layer solution of the three mixed solutions is used to obtain a fourth mixed solution; the fourth mixed solution is treated to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands; the DMF solution of lead selenide quantum dots is placed in a centrifuge and the upper yellow liquid is poured out, and vacuum extraction is performed for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots; the lead selenide quantum dots are dissolved in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution; the fifth mixed solution is spin-coated on a target sample and annealed for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film; the initial lead selenide colloidal quantum dot film is placed in a chamber, the chamber is vacuumed until the air pressure reaches a preset pressure, and the initial lead selenide colloidal quantum dot film is heated to a preset temperature; trimethylaluminum gas is introduced into the chamber to obtain a lead selenide colloidal quantum dot film based on trimethylaluminum doping. The present application can improve the mobility of colloidal quantum dot detectors.

[0038] See Figure 1 In an embodiment of the present application, a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film comprises:

[0039] 201. Preserving lead selenide colloidal quantum dots in n-octane solvent to obtain quantum dot n-octane solution.

[0040] Among them, the ligand on the surface of lead selenide colloidal quantum dots is oleic acid.

[0041] In the embodiment of the present application, the concentration of the lead selenide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL. Specifically, the lead selenide (PbSe) colloidal quantum dots are stored in the n-octane solvent at a concentration of 10 mg / mL, and the ligand on the surface of the quantum dots is oleic acid.

[0042] 202. Dissolve lead iodide and lead bromide in DMF solution to obtain a first mixed solution.

[0043] In an embodiment of the present application, lead iodide and lead bromide are dissolved in a DMF solution to obtain a first mixed solution, comprising: dissolving 0.92 g of lead iodide and 0.58 g of lead bromide in 10 ml of a DMF solution to obtain a first mixed solution.

[0044] 203. Filter the quantum dot n-octane solution and the first mixed solution separately and then mix them to obtain a second mixed solution.

[0045] Specifically, ligand exchange is first required, and the entire process is carried out in a nitrogen environment (oxygen <0.01ppm water <0.01ppm) in a glove box. The specific operation is as follows: First, measure 10mL of PbSe quantum dot n-octane solution; then, weigh 0.92g of lead iodide (PbI2) and 0.58g of lead bromide (PbBr2) and fully dissolve them in 10ml of DMF (N,N-dimethylformamide) solution to obtain a first mixed solution. Filter 10mL of PbSe quantum dot n-octane solution and the first mixed solution (PbI2, PbBr-DMF solution) separately, and mix them in a container to obtain a second mixed solution.

[0046] 204. Oscillating the second mixed solution for a first oscillation time and allowing the second mixed solution to stand until the second mixed solution is separated into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution.

[0047] Due to the separation of polar DMF and nonpolar n-octane, the upper layer of the second mixed solution is now a black n-octane solution of quantum dots, and the lower layer is a yellow DMF solution of PbI2 and PbBr2. The second mixed solution is shaken for the first shaking time and allowed to stand until the second mixed solution separates into two layers. The upper layer of the second mixed solution is removed and a predetermined volume of n-octane solvent is added to obtain a third mixed solution.

[0048] Specifically, the first oscillation time is 40 seconds, and the preset volume is 10 ml. The second mixed solution is shaken for 40 seconds and then allowed to stand. After the upper layer becomes transparent and the lower layer becomes black, the upper clear liquid is discarded and 10 mL of n-octane is added to obtain a third mixed solution.

[0049] 205. Oscillating the third mixed solution for the second oscillation time and allowing the third mixed solution to stand until the third mixed solution is separated into an upper and lower layer of solution, removing the upper layer of the third mixed solution to obtain a fourth mixed solution.

[0050] The second oscillation time was 40 seconds. 10 mL of n-octane was added to obtain a third mixed solution, which was further oscillated for 40 seconds. After standing for stratification, the upper layer of the solution was removed to obtain a fourth mixed solution.

[0051] 206. Treat the fourth mixed solution to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands.

[0052] In a specific embodiment, the fourth mixed solution is a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands.

[0053] In another specific embodiment, the fourth mixed solution is shaken for a second shaking time and allowed to stand until the fourth mixed solution separates into upper and lower layers. The upper layer of the fourth mixed solution is removed to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands. Ultimately, the lower layer is a DMF solution of PbSe quantum dots with iodide ions and bromide ions as ligands.

[0054] 207. Place the lead selenide quantum dot DMF solution in a centrifuge and pour out the upper yellow liquid. Vacuum extract the solution for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots.

[0055] In the embodiment of the present application, the extraction time is preset to one hour. The lead selenide quantum dot DMF solution is placed in a centrifuge and the upper yellow liquid is discarded, comprising: placing the lead selenide quantum dot DMF solution in a centrifuge and centrifuging the lead selenide quantum dot DMF solution at a speed of 9000 rpm for 4 minutes.

[0056] Specifically, a DMF solution of lead selenide quantum dots was placed in a centrifuge and centrifuged at 9000 rpm for 4 minutes. The upper yellow liquid was discarded, and vacuum extraction was performed for one hour to remove the residual DMF solution on the surface, resulting in a black powder of lead selenide quantum dots.

[0057] 208. Dissolve the lead selenide quantum dots in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution.

[0058] In this embodiment of the present application, the volume ratio of n-butylamine and DMF in the mixed solvent is 1:1. Lead selenide quantum dots are dissolved in the mixed solvent of n-butylamine and DMF at a volume ratio of 1:1 at a concentration of 50 μg / μL to 600 μg / μL to obtain a fifth mixed solution. The n-butylamine is used to dissolve the quantum dots, and the DMF is used to raise the boiling point of the solvent to prevent volatilization from affecting the concentration.

[0059] 209. Spin-coat the fifth mixed solution on the target sample and anneal for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film.

[0060] In the embodiment of the present application, the preset annealing time is 10 minutes. After the quantum dots are completely dissolved, a certain amount of the fifth mixed solution is taken with a pipette and spin-coated on the surface of the target sample, and finally an annealing treatment is performed for 10 minutes.

[0061] 210. Place the initial lead selenide colloidal quantum dot film into a chamber, evacuate the chamber until the air pressure reaches a preset pressure, and heat the initial lead selenide colloidal quantum dot film to a preset temperature.

[0062] In the embodiment of the present application, the preset annealing time is 10 minutes and the preset pressure is 10 -6 -10 -4 pa, the preset temperature is 20 degrees Celsius to 100 degrees Celsius. The doping of trimethylaluminum is carried out in a vacuum chamber. The initial lead selenide colloidal quantum dot film prepared in the previous step is placed into the chamber and vacuumed to 10 -6 pa-10 -4 The sample substrate is heated to 20-100 degrees Celsius and the temperature is stabilized.

[0063] 211. Trimethylaluminum gas is introduced into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film.

[0064] In an embodiment of the present application, trimethylaluminum gas is introduced into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film, including: introducing trimethylaluminum gas into the chamber in a pulsed pumping manner to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film, wherein, during the pulsed pumping, the single pumping time is 10ms, the pumping time interval is 60s-150s, the number of pumping times is 10 times-100 times, and the gas pressure of the trimethylaluminum gas is 15Pa-25Pa.

[0065] In an embodiment of the present application, a method for preparing a trimethylaluminum-doped lead selenide colloidal quantum dot film comprises:

[0066] Preliminary preparation of colloidal quantum dot films:

[0067] Lead selenide (PbSe) colloidal quantum dots are stored in n-octane solvent at a concentration of 10 mg / mL, and the ligand on the surface of the quantum dots is oleic acid. First, ligand exchange is required, and the entire process is carried out in a nitrogen environment in a glove box (oxygen <0.01 ppm water <0.01 ppm). The specific operation is as follows: First, measure 10 mL of PbSe quantum dot n-octane solution; then, weigh 0.92 g of lead iodide (PbI2) and 0.58 g of lead bromide (PbBr2) and fully dissolve them in 10 ml of DMF (N, N-dimethylformamide) solution to obtain a first mixed solution. Filter 10 mL of PbSe quantum dot n-octane solution and the first mixed solution (PbI2, PbBr-DMF solution) separately, and mix them in a container to obtain a second mixed solution. Due to the separation of polar DMF and non-polar n-octane, the upper layer of the second mixed solution is now a black quantum dot n-octane solution, and the lower layer is a yellow DMF solution of PbI2 and PbBr2. The second mixed solution is shaken for 40 seconds and then allowed to stand. After the upper layer becomes transparent and the lower layer turns black, the supernatant is discarded and 10mL of n-octane is added to obtain a third mixed solution. 10mL of n-octane is added to obtain a third mixed solution, which is then shaken for another 40 seconds. After standing and stratifying, the upper layer is removed, and the fourth mixed solution is repeated twice. Ultimately, the lower layer is a DMF solution of PbSe quantum dots with iodide ions and bromide ions as ligands. The DMF solution of lead selenide quantum dots is placed in a centrifuge and centrifuged at 9000 rpm for 4 minutes. The upper yellow liquid is discarded and vacuum extracted for one hour to remove the residual DMF solution on the surface, obtaining a black powder of lead selenide quantum dots. Dissolve lead selenide quantum dots at a concentration of 50 μg / μL to 600 μg / μL in a 1:1 volume ratio of n-butylamine and DMF to create a fifth mixed solution. The n-butylamine dissolves the quantum dots, while the DMF raises the boiling point of the solvent to prevent evaporation from affecting the concentration. Once the quantum dots are completely dissolved, pipette a desired amount of the fifth mixed solution and spin-coat it on the target sample surface. Finally, anneal for 10 minutes.

[0068] Doping with trimethylaluminum:

[0069] The doping of trimethylaluminum is carried out in a vacuum chamber. The initial lead selenide colloidal quantum dot film prepared in the previous step is placed into the chamber and vacuumed to 10 -6 pa-10 -4The sample substrate was heated to 20-100 degrees Celsius and allowed to stabilize. Trimethylaluminum gas was introduced into the chamber using pulsed pumping to produce a trimethylaluminum-doped lead selenide colloidal quantum dot film. The pulsed pumping had a single pumping time of 10 ms, a pumping interval of 60s-150s, and a pumping frequency of 10-100 cycles. The trimethylaluminum gas pressure was 15 Pa-25 Pa.

[0070] Mobility test:

[0071] The mobility of trimethylaluminum-doped lead selenide colloidal quantum dot film was characterized by field effect transistor (FET) method. The structure of the entire target sample is as follows Figure 2 As shown, the field-effect transistor includes an n-heavily doped Si layer, a SiO2 layer, a source electrode, a drain electrode, and a gate electrode. A colloidal quantum dot film based on trimethylaluminum doping is placed at the source and drain electrodes. A three-probe test platform is used to probe the source, drain, and gate electrodes for testing. The test is conducted in a nitrogen environment (oxygen <0.01ppm and water <0.01ppm) in the absence of light (illuminance <30nW / cm2, 400nm-1700nm). The gate voltage is fixed at 0V, the source voltage is swept from 0V to 1V, and the drain current is measured to verify whether the electrode is in ohmic contact with the quantum dot film. Based on the ohmic contact, the source voltage is fixed at 0.5V, the gate voltage is swept from -40V to 40V, and the drain current is measured to obtain the transfer characteristic curve of the quantum dot film. The linear region near 0V is selected for fitting of the test results to obtain the mobility of the film.

[0072] Experimental results: Figure 3 and Figure 4 As shown, Figure 3 This is the relationship curve between gate voltage and drain current before trimethylaluminum doping. Figure 4 This is the relationship curve between gate voltage and drain current after trimethylaluminum doping. Figure 3 and Figure 4 In the figure, the horizontal axis is the gate voltage in V, and the vertical axis is the drain current in A. After trimethylaluminum doping, the slope of the test curve of the trimethylaluminum-doped lead selenide colloidal quantum dot film increased by 5 times, proving that trimethylaluminum doping can bring a 5-fold increase in mobility.

[0073] The strategy of this application is to achieve a certain degree of trimethylaluminum doping by post-treating the prepared colloidal quantum dot film with trimethylaluminum gas in a vacuum environment. By controlling the purge time and reaction temperature of trimethylaluminum, the doping effect in the quantum dot film can be more precisely controlled, and the mobility of the film after doping can be improved by 1-2 orders of magnitude. The technical solution of trimethylaluminum gas doping can increase the mobility of colloidal quantum dots by 1-2 orders of magnitude, thereby improving the ultimate performance of the detector prepared therefrom.

[0074] The preparation method of the trimethylaluminum-doped lead selenide colloidal quantum dot film of the present application comprises: preserving the lead selenide colloidal quantum dots in an n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead selenide colloidal quantum dots is oleic acid; dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution; filtering the quantum dot n-octane solution and the first mixed solution and then mixing them to obtain a second mixed solution; oscillating the second mixed solution for a first oscillation time and allowing it to stand until the second mixed solution is separated into two layers of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; oscillating the third mixed solution for a second oscillation time and allowing it to stand until the third mixed solution is separated into two layers of solution, removing the third mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; The upper layer solution is prepared to obtain a fourth mixed solution; the fourth mixed solution is treated to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands; the DMF solution of lead selenide quantum dots is placed in a centrifuge and the upper yellow liquid is poured out, and vacuum extraction is performed for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots; the lead selenide quantum dots are dissolved in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution; the fifth mixed solution is spin-coated on a target sample and annealed for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film; the initial lead selenide colloidal quantum dot film is placed in a chamber, the chamber is vacuumed until the air pressure reaches a preset pressure, and the initial lead selenide colloidal quantum dot film is heated to a preset temperature; trimethylaluminum gas is introduced into the chamber to obtain a lead selenide colloidal quantum dot film based on trimethylaluminum doping. The present application can improve the mobility of colloidal quantum dot detectors.

[0075] The above is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot film, characterized in that: The preparation method of the trimethylaluminum-doped lead selenide colloidal quantum dot film comprises: Preserving lead selenide colloidal quantum dots in an n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead selenide colloidal quantum dots is oleic acid; Dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution; filtering the quantum dot n-octane solution and the first mixed solution and then mixing them to obtain a second mixed solution; Oscillating the second mixed solution for a first oscillation time and allowing the second mixed solution to stand until the second mixed solution separates into an upper and lower layer of solution, removing the upper layer of the second mixed solution and adding a preset volume of n-octane solvent to obtain a third mixed solution; Oscillating the third mixed solution for a second oscillation time and allowing the third mixed solution to stand until the third mixed solution is separated into an upper and lower layer of solutions, and removing the upper layer of the third mixed solution to obtain a fourth mixed solution; treating the fourth mixed solution to obtain a DMF solution of lead selenide quantum dots with iodide ions and bromide ions as ligands; The lead selenide quantum dot DMF solution was placed in a centrifuge and the upper yellow liquid was poured out, and vacuum extraction was performed for a preset extraction time to remove the residual DMF solution on the surface to obtain lead selenide quantum dots; dissolving lead selenide quantum dots in a mixed solvent of n-butylamine and DMF to obtain a fifth mixed solution; Spin-coating the fifth mixed solution on the target sample and annealing the sample for a preset annealing time to obtain an initial lead selenide colloidal quantum dot film; placing an initial lead selenide colloidal quantum dot film into a chamber, evacuating the chamber until the air pressure reaches a preset pressure, and heating the initial lead selenide colloidal quantum dot film to a preset temperature; Trimethylaluminum gas is introduced into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film.

2. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 1, characterized in that: The concentration of the lead selenide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL.

3. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 2, characterized in that: The step of dissolving lead iodide and lead bromide in a DMF solution to obtain a first mixed solution comprises: 0.92 g of lead iodide and 0.58 g of lead bromide were dissolved in 10 ml of DMF solution to obtain a first mixed solution.

4. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 3, characterized in that: The first oscillation duration is 40 seconds, and the second oscillation duration is 40 seconds.

5. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 4, characterized in that: The preset volume is 10 ml.

6. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 5, characterized in that: The preset extraction time is one hour.

7. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 6, characterized in that: The step of placing the lead selenide quantum dot DMF solution in a centrifuge and discarding the upper yellow liquid comprises: The lead selenide quantum dot DMF solution was placed in a centrifuge and centrifuged at a speed of 9000 rpm for 4 minutes.

8. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 7, characterized in that: In the mixed solvent of n-butylamine and DMF, the volume ratio of n-butylamine to DMF is 1:

1.

9. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 8, characterized in that: The preset annealing time is 10 minutes, and the preset pressure is 10 -6 pa-10 -4 pa, the preset temperature is 20 degrees Celsius to 100 degrees Celsius.

10. The method for preparing trimethylaluminum-doped lead selenide colloidal quantum dot thin film according to claim 9, characterized in that: The method of introducing trimethylaluminum gas into the chamber to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film comprises: Trimethylaluminum gas is introduced into the chamber in a pulsed pumping manner to obtain a trimethylaluminum-doped lead selenide colloidal quantum dot film, wherein during pulse pumping, a single pumping time is 10 ms, a pumping time interval is 60 s-150 s, the number of pumping times is 10 times-100 times, and the gas pressure of the trimethylaluminum gas is 15 Pa-25 Pa.

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