Preparation method of antimony fluoride doped and passivated lead sulfide quantum dot active layer

Abstract

The invention discloses a preparation method of an antimony fluoride doped and passivated lead sulfide quantum dot active layer. The preparation method of the antimony fluoride doped and passivated lead sulfide quantum dot active layer comprises the following steps: preparing a lead sulfide colloid quantum dot film wrapped by iodine and bromine; dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution; soaking the iodine-bromine-coated lead sulfide colloid quantum dot film in an antimony fluoride acetonitrile solution; and washing the iodine-bromine-coated lead sulfide colloid quantum dot film with acetonitrile for preset times to obtain the antimony fluoride chemical reaction doped and passivated lead sulfide quantum dot active layer. The overall performance of the semiconductor device containing the source layer can be improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing an antimony fluoride-doped passivated lead sulfide quantum dot active layer. Background Art

[0002] Short-wave infrared detectors have high resolution, rich target details, and are not affected by thermal crosstalk; they can also penetrate fog, haze, and smoke, and have a long effective detection distance. Currently, the most mature technology route on the market is the indium gallium arsenide (InGaAs) short-wave infrared detector, but the manufacturing process of the indium gallium arsenide detector is complex, and the InGaAs material cannot be directly epitaxially grown on a silicon substrate, and complex heterojunction bonding technology is required. Lead sulfide colloidal quantum dots have a large Bohr exciton radius, a narrow band gap, and an adjustable band gap; they have a high extinction coefficient and dielectric constant, and the excitons are easy to separate and the charge collection efficiency is high; they have the advantage of being easy to directly integrate with silicon-based readout circuits to achieve array imaging, and have great potential in the field of short-wave infrared detection. However, the absorption cutoff band edge of most current lead sulfide quantum dot infrared detectors is within 1650nm. As the size increases, the surface shape of lead sulfide quantum dots changes from octahedron to truncated octahedron and then to cubic octahedron, and the proportion of non-polar faces increases. It becomes more difficult to connect ligands during ligand exchange, resulting in incomplete ligand passivation in the active layer of PbS CQDs, and more defects are introduced into the active layer. At the same time, wavelength expansion will also cause the P-type doping concentration of the quantum dot active layer in the air to increase. The use of the hole transport layer and electron transport layer energy levels commonly used in small quantum dot devices will lead to energy level mismatch and potential barriers, so that photogenerated carriers cannot be extracted. Therefore, after the wavelength is extended, the overall infrared detector has a large dark current and a small open circuit voltage. The signal cannot be detected in weak light, and charge extraction is difficult in strong light, resulting in poor overall performance of semiconductor devices containing active layers. Summary of the invention

[0003] The present application aims to solve at least one of the above-mentioned technical problems by providing a method for preparing an antimony fluoride-doped passivated lead sulfide quantum dot active layer, thereby improving the overall performance of a semiconductor device containing an active layer.

[0004] On one hand, the present application provides a method for preparing an antimony fluoride-doped and passivated lead sulfide quantum dot active layer, the method for preparing an antimony fluoride-doped and passivated lead sulfide quantum dot active layer comprising:

[0005] Preparation of iodine-bromine-coated lead sulfide colloidal quantum dot films;

[0006] dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution;

[0007] Immersing the lead sulfide colloidal quantum dot film wrapped with iodine and bromine in the antimony fluoride acetonitrile solution;

[0008] The iodine-bromine-wrapped lead sulfide colloidal quantum dot film is washed with acetonitrile for a preset number of times to obtain an antimony fluoride chemically doped and passivated lead sulfide quantum dot active layer.

[0009] Optionally, the preparation of the iodine-bromine-wrapped lead sulfide colloidal quantum dot film comprises:

[0010] Dissolving lead sulfide colloidal quantum dots in n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead sulfide colloidal quantum dots is oleic acid;

[0011] Dissolving lead iodide and lead bromide in an N,N-dimethylformamide solution to obtain a first mixed solution, and mixing the quantum dot n-octane solution and the first mixed solution in equal volumes to obtain a second mixed solution;

[0012] The second mixed solution is shaken and allowed to stand until the second mixed solution is separated into an upper and lower solution, the upper solution of the second mixed solution is removed and a preset volume of n-octane solvent is added to obtain a third mixed solution;

[0013] The third mixed solution is shaken and allowed to stand until the third mixed solution is separated into two layers of solution, and the upper layer of the third mixed solution is removed to obtain a lead sulfide quantum dot ligand solution having iodide ions and bromide ions as ligands;

[0014] The lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands is placed in a centrifuge for the first centrifugation and the upper liquid is poured off to remove the residual ligand solution on the surface, and then vacuum dried to obtain iodine-bromine ligand lead sulfide quantum dot powder;

[0015] Dissolving iodine-bromine ligand lead sulfide quantum dot powder in a dispersant mixed solvent to obtain a fifth mixed solution;

[0016] The fifth mixed solution is shaken and dispersed and placed in a centrifuge for a second centrifugation process;

[0017] The solution after the second centrifugation treatment is spin-coated on the substrate and annealed at a preset annealing temperature and for a preset annealing time to obtain an iodine-bromine-encapsulated lead sulfide colloidal quantum dot film.

[0018] Optionally, the concentration of antimony fluoride in the antimony fluoride acetonitrile solution is 1 mmol / L to 10 mmol / L.

[0019] Optionally, the preset number of times is 2 times.

[0020] Optionally, the concentration of the lead sulfide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL.

[0021] Optionally, dissolving lead iodide and lead bromide in a ligand solution to obtain a first mixed solution comprises:

[0022] 1.844 g of lead iodide and 0.32 g of lead bromide were dissolved in 15 mL of DMF solution to obtain a first mixed solution.

[0023] Optionally, placing the lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands in a centrifuge for a first centrifugal treatment and discarding the upper liquid comprises:

[0024] The lead sulfide quantum dot ligand solution with iodide ions and bromide ions as ligands was placed in a centrifuge, the speed of the centrifuge was adjusted to 9000 rpm, the centrifugation time of the centrifuge was adjusted to 5 minutes, the first centrifugation was performed, and the upper liquid was poured off.

[0025] Optionally, the dispersant mixed solvent is a mixture of DMF solvent, DMSO solvent, BTA solvent and pyridine solvent.

[0026] Optionally, the step of vibrating and dispersing the fifth mixed solution and placing the solution in a centrifuge for a second centrifugation comprises:

[0027] The fifth mixed solution was shaken and placed in a centrifuge, and centrifuged at 2000 rpm for 40 seconds.

[0028] Optionally, the preset annealing temperature is 90 degrees Celsius, and the preset annealing time is 10 minutes.

[0029] In the preparation method of the antimony fluoride doped and passivated lead sulfide quantum dot active layer of the present application, the preparation method of the antimony fluoride doped and passivated lead sulfide quantum dot active layer includes: preparing an iodine-bromine-wrapped lead sulfide colloidal quantum dot film; dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution; soaking the iodine-bromine-wrapped lead sulfide colloidal quantum dot film in the antimony fluoride acetonitrile solution; washing the iodine-bromine-wrapped lead sulfide colloidal quantum dot film with acetonitrile for a preset number of times to obtain an antimony fluoride chemical reaction doped and passivated lead sulfide quantum dot active layer. The present application can improve the overall performance of semiconductor devices containing active layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow chart of an embodiment of a method for preparing an antimony fluoride-doped passivated lead sulfide quantum dot active layer provided in an embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of the synthesised oleic acid-coated lead sulfide colloidal quantum dot powder tested by ultraviolet absorption spectroscopy;

[0032] Figure 3This is a schematic diagram of the chemical reaction of antimony fluoride (SbF3) and iodine-bromine-wrapped lead sulfide (PbS) quantum dots;

[0033] Figure 4 is a schematic diagram of the process for preparing dry iodine-bromine ligand PbS CQD powder;

[0034] Figure 5 Schematic diagram of the iodine-bromine-wrapped lead sulfide colloidal quantum dot film obtained by spin coating;

[0035] Figure 6 is a schematic diagram of a lead sulfide quantum dot layer obtained by antimony fluoride treatment;

[0036] Figure 7 It is a schematic structural diagram of an active layer quantum dot detector of a reverse device structure provided in an embodiment of the present application;

[0037] Figure 8 It is a comparison chart of JV curves of quantum dot detectors without antimony fluoride doping and with antimony fluoride doped active layers;

[0038] Fig. 9 The J of 30 doped and undoped SbF3 inverse devices dark Comparative graphs for statistical analysis;

[0039] Fig.10 This is a comparison chart of the wide spectrum external quantum efficiency test of the inverse device at 0V;

[0040] Fig.11 Transient photocurrent (TPC) measurements of SbF3-doped trans devices. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0042] 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 positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which 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 a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, 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, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0043] In this application, the word "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described in this application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any technician in the field to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that a person 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 will not be 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 the present application.

[0044] The present application provides a method for preparing an antimony fluoride-doped and passivated lead sulfide quantum dot active layer, and the method comprises: preparing an iodine-bromine-wrapped lead sulfide colloidal quantum dot film; dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution; immersing the iodine-bromine-wrapped lead sulfide colloidal quantum dot film in the antimony fluoride acetonitrile solution; washing the iodine-bromine-wrapped lead sulfide colloidal quantum dot film with acetonitrile for a preset number of times to obtain an antimony fluoride chemical reaction-doped and passivated lead sulfide quantum dot active layer.

[0045] See also Figure 1 In an embodiment of the present application, a method for preparing an antimony fluoride-doped passivated lead sulfide quantum dot active layer comprises:

[0046] 201. Prepare iodine-bromine coated lead sulfide colloidal quantum dot film.

[0047] In the embodiment of the present application, the preparation of iodine-bromine-encapsulated lead sulfide colloidal quantum dot film includes:

[0048] (1) Dissolving lead sulfide colloidal quantum dots in n-octane solvent to obtain a quantum dot n-octane solution.

[0049] The ligand on the surface of the lead sulfide colloidal quantum dots is oleic acid, and the concentration of the lead sulfide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL.

[0050] First, the synthesized oleic acid-coated lead sulfide colloidal quantum dots (PbS CQD) powder was weighed, and a quantum dot n-octane solution (PbS CQD / n-octane solution) with a concentration of 10 mg / mL was prepared. The solution was filtered using a syringe and an organic filter with a pore size of 0.22 μm, and 15 mL was taken into a glass bottle for later use. The synthesized oleic acid-coated lead sulfide colloidal quantum dots (PbSCQD) powder was tested by ultraviolet absorption spectroscopy. Figure 2 shown.

[0051] (2) Dissolving lead iodide and lead bromide in an N,N-dimethylformamide solution to obtain a first mixed solution, and mixing the quantum dot n-octane solution and the first mixed solution in equal volumes to obtain a second mixed solution.

[0052] In the embodiment of the present application, lead iodide and lead bromide are dissolved in a DMF solution to obtain a first mixed solution, including: dissolving 1.844g of lead iodide and 0.32g of lead bromide in a 15ml DMF (N,N-dimethylformamide) solution, filtering the ligand with a syringe, and obtaining a first mixed solution. Then, a 10mg / mL PbS CQD / n-octane solution is filtered by an equal volume of a syringe and slowly injected into a glass bottle containing a ligand solution, so that the short-chain iodine-bromine ligand fully exchanges the oleic acid ligand to obtain a second mixed solution.

[0053] (3) shaking the second mixed solution 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.

[0054] (4) shaking the third mixed solution 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 third mixed solution to obtain a lead sulfide quantum dot ligand solution having iodide ions and bromide ions as ligands.

[0055] After the second mixed solution is shaken, the glass bottle is left to stand, and after the layers are separated, the supernatant is dripped into the waste liquid bottle with a dropper, and an equal amount of n-octane solvent is added to obtain a third mixed solution. After shaking for 20 seconds, the solution is separated again, and the process is repeated twice to remove excess oleic acid molecules. Then the lower black layer of the lead sulfide quantum dot ligand solution with iodide ions and bromide ions as ligands is evenly divided into centrifuge tubes.

[0056] (5) placing a lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands in a centrifuge for the first centrifugal treatment and pouring out the upper liquid to remove the residual ligand solution on the surface, and then vacuum drying to obtain iodine-bromine ligand lead sulfide quantum dot powder.

[0057] In the embodiment of the present application, the lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands is placed in a centrifuge, the speed of the centrifuge is adjusted to 9000rpm, the centrifugal time of the centrifuge is adjusted to 5min, the first centrifugal treatment is performed, the upper liquid is poured off, the residual ligand solution on the surface is removed, and the iodine-bromine ligand lead sulfide quantum dot powder is obtained, and the iodine-bromine ligand lead sulfide quantum dot powder is a Br-, I-ligand passivated PbS CQD with black precipitate at the bottom. Then, the dry iodine-bromine ligand PbS CQD powder is obtained by vacuum drying to remove the residual solvent.

[0058] (6) Dissolving the iodine-bromine ligand lead sulfide quantum dot powder in the dispersant mixed solvent to obtain a fifth mixed solution.

[0059] In the embodiment of the present application, the dispersant mixed solvent is a mixture of DMF solvent, DMSO solvent, BTA solvent and pyridine solvent.

[0060] The dried iodine-bromine ligand lead sulfide quantum dot powder is weighed and dissolved in a dispersant mixed solvent (DMF:DMSO:BTA:pyridine). DMSO and DMF have high boiling points and polarities, which maintain the electrostatic stability of the slurry. BTA is a short-chain ligand that replaces the remaining oleic acid still on the surface of the quantum dots and dissolves the quantum dots. Methylamine pyridine improves the viscosity of the film, and a thicker light-absorbing layer is obtained in turn. The concentration of the PbS CQD slurry is configured to obtain a suitable thickness.

[0061] (7) The fifth mixed solution is shaken and dispersed and placed in a centrifuge for a second centrifugation treatment.

[0062] In the embodiment of the present application, the fifth mixed solution is shaken and dispersed and placed in a centrifuge for a second centrifugation treatment, including: shaking the fifth mixed solution and placing it in a centrifuge, and centrifuging it at a speed of 2000 rpm for 40 seconds.

[0063] The oscillator was used to accelerate the dispersion. In order to reduce the large residues of the solution, the solution was transferred to a 1 mL centrifuge tube using a pipette and centrifuged again at 2000 rpm for 40 s.

[0064] (8) Spin-coating the solution after the second centrifugation treatment on the substrate and annealing the solution at a preset annealing temperature and for a preset annealing time to obtain an iodine-bromine-encapsulated lead sulfide colloidal quantum dot film.

[0065] Among them, the preset annealing temperature is 90 degrees Celsius, and the preset annealing time is 10 minutes.

[0066] The size is 2.5×2.5cm 2 Place the substrate in the center of the suction cup of the spin coater, turn on the vacuum pump to ensure substrate adsorption, and set the spin coating parameters. Use a 100uL pipette to take out 60μL from the solution after the second centrifugation and drop it on the substrate, and click the spin coating button to deposit the CQD film. Then remove it and place it on a 90℃ hot stage for annealing for about 10 minutes to remove the volatile solvent and excess iodine and bromine ligand molecules to obtain an iodine-bromine-wrapped lead sulfide colloidal quantum dot film.

[0067] 202. Dissolve antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution.

[0068] Wherein, the concentration of antimony fluoride (SbF3) in the antimony fluoride acetonitrile solution is 1 mmol / L to 10 mmol / L.

[0069] 203. Soak the iodine-bromine-wrapped lead sulfide colloidal quantum dot film in antimony fluoride acetonitrile solution.

[0070] Antimony (Sb) is a Group 15 element and is expected to act as an electron donor in the position of Group 14 element lead (Pb). Antimony fluoride can replace the lead position in the perovskite system. First, we evaluated the theoretical feasibility of introducing antimony fluoride to replace lead in the doping chemical reaction. We found through table lookup that since the solid phase material before and after the reaction, the entropy change is relatively small. The Gibbs free energy of the reaction calculated by bond energy is less than 0, and the reaction can proceed in the forward direction. Moreover, due to the surface activity of semiconductor nanocrystals, doping can be carried out without heating or activation, which provides a chemical theoretical basis for the introduction of antimony fluoride into the lead sulfide quantum dot system to achieve n-type doping.

[0071] like Figure 3 As shown, Figure 3 The chemical reaction of antimony fluoride (SbF3) and lead sulfide (PbS) quantum dots coated with iodine and bromine was demonstrated. Figure 3 In the figure on the left, the larger circle inside the octagon is sulfur S, the smaller circle inside the octagon is lead Pb, the two circles at the vertices outside the octagon are iodine I, and the circle at the midpoint of the outer side of the octagon is bromine Br. Figure 2In the figure on the right, the interior of the octagon includes three elliptical areas. The larger circle in the elliptical area is antimony (Sb), and the two smaller circles in the elliptical area are fluorine (F); the larger gray circle in the area outside the elliptical area inside the octagon is sulfur S, and the smaller gray circle is lead Pb; the two circles at the outer vertices of the octagon are iodine I, and the two circles at the midpoints of the outer edges of the octagon are fluorine (F) and bromine Br. As the size of the quantum dots increases, the crystal plane is not completely covered by the ligand, making it easier for Pb on the crystal surface of PbS CQDs to be replaced by Sb, and F is easier to replace S on the surface of lead sulfide, thereby achieving n-doping.

[0072] 204. Wash the iodine-bromine-wrapped lead sulfide colloidal quantum dot film with acetonitrile for a preset number of times to obtain an antimony fluoride chemically doped and passivated lead sulfide quantum dot active layer.

[0073] Among them, the preset number of times is 2 times.

[0074] In an embodiment of the present application, a method for preparing an antimony fluoride-doped passivated lead sulfide quantum dot active layer comprises:

[0075] Prepare the chemicals needed for the experiment: lead iodide (PbI2, 99%, preferred), lead bromide (PbBr2, >98%, preferred), N,N-dimethylformamide (DMF, ultra dry 99.9%, Aladin), n-octane (95%), and the required equipment include nitrogen glove box, electronic balance, high-speed centrifuge, hair dryer, etc.

[0076] like Figure 4As shown, it is necessary to obtain dry iodine-bromine ligand PbS CQD powder by weighing liquid, phase transfer, cleaning, centrifugation and drying. First, the synthesized oleic acid-coated lead sulfide colloidal quantum dot (PbS CQD) powder is weighed, and a quantum dot n-octane solution (PbS CQD / n-octane solution) with a concentration of 10 mg / mL is prepared. The solution is filtered using a syringe and an organic filter head with an aperture of 0.22 μm, and 15 mL is taken in a glass bottle for standby use. Short-chain lead iodide and lead bromide ligand solutions are prepared, 1.844 g of lead iodide and 0.32 g of lead bromide are weighed, and then the ligands are filtered with a syringe to obtain a first mixed solution. The PbSCQD / n-octane solution is then slowly injected into a glass bottle containing a ligand solution so that the short-chain iodine-bromine ligands fully exchange the oleic acid molecules to obtain a second mixed solution. After the second mixed solution is vibrated, the glass bottle is left to stand, and after the supernatant is dripped into the waste liquid bottle with a dropper after stratification, an equal amount of n-octane solvent is added to the bottle to obtain a third mixed solution. After 20 seconds of oscillation, the solution is layered again, and the process is repeated twice to remove excess oleic acid molecules. Then the lower black lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands is divided into centrifuge tubes. The lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands is placed in a centrifuge, the speed of the centrifuge is adjusted to 9000rpm, the centrifugation time of the centrifuge is adjusted to 5min, the first centrifugation is performed, the upper liquid is poured out, the residual ligand solution on the surface is removed, and the iodine-bromine ligand lead sulfide quantum dot powder is obtained, and the iodine-bromine ligand lead sulfide quantum dot powder is a Br-, I-ligand passivated PbS CQD with black precipitation at the bottom. Then by vacuum drying, dry iodine-bromine ligand PbS CQD powder is obtained after removing the residual solvent. All the above processes are completed in a glove box.

[0077] The dried iodine-bromine ligand lead sulfide quantum dot powder is weighed and dissolved in a dispersant mixed solvent (DMF:DMSO:BTA:pyridine). DMSO and DMF have high boiling points and polarity, which maintain the electrostatic stability of the slurry. BTA is a short-chain ligand that replaces the remaining oleic acid still on the surface of the quantum dots and dissolves the quantum dots. Methylamine pyridine improves the viscosity of the film, and a thicker light-absorbing layer is obtained in turn. The concentration of the PbS CQD slurry is configured to obtain a suitable thickness. The oscillator oscillates to accelerate the dispersion. In order to reduce the large pieces of dissolved residue, the solution is transferred to a 1 mL centrifuge tube using a pipette and centrifuged again at 2000 rpm for 40 seconds. Figure 5 As shown, the size is 2.5×2.5cm 2Place the substrate in the center of the suction cup of the spin coater, turn on the vacuum pump to ensure substrate adsorption, and set the spin coating parameters. Use a 100uL pipette to take out 60μL from the solution after the second centrifugation and drop it on the substrate, and click the spin coating button to deposit the CQD film. Then remove it and place it on a 90℃ hot stage for annealing for about 10 minutes to remove the volatile solvent and excess iodine and bromine ligand molecules to obtain an iodine-bromine-wrapped lead sulfide colloidal quantum dot film.

[0078] like Figure 6 As shown, a certain amount of antimony fluoride is taken and then dissolved in acetonitrile. The PbS CQDs film layer that has been wrapped by iodine and bromine after ligand exchange is briefly immersed in an antimony fluoride and acetonitrile (ACN) solution, and then washed twice with acetonitrile to remove excess reactants and avoid the enrichment of reactants on the surface of lead sulfide quantum dots, thereby obtaining a lead sulfide quantum dot layer treated with antimony fluoride. In order to avoid damage to the surface of the lead sulfide film by post-treatment chemical doping, we chose antimony fluoride, which has the mildest reaction in theory, to conduct the experiment. At the same time, in order to avoid damage to the film caused by excessive concentration, the concentration of antimony fluoride acetonitrile solution was selected to be 1mmol / L to 10mmol / L.

[0079] In order to characterize the advantages of the active layer after chemical doping, we designed an active layer quantum dot detector with a reverse device structure. The reverse device structure of quantum dots from top to bottom is electrode ITO, hole transport layer NiOx, hole transition layer PbS-EDT, lead sulfide quantum dot layer PbS-PbI2-SbF3 treated with antimony fluoride, transition layer C 60 , electron transport layer SnO, top electrode ITO. The active layer quantum dot detector of the inverted device structure is as follows Figure 7 shown.

[0080] Figure 8 This is a comparison chart of the JV curves of the active layer quantum dot detector prepared without antimony fluoride doping and with antimony fluoride doping. The horizontal axis is voltage, the vertical axis is current density, control dark represents the dark current density of the active layer without antimony fluoride doping, control light represents the photocurrent density of the active layer without antimony fluoride doping, With SbF3dark represents the dark current density of the active layer doped with antimony fluoride, and With SbF3 light represents the photocurrent density of the active layer doped with antimony fluoride.

[0081] In the dark and under 1650 nm LED illumination (270 μW cm -2 ) conditions, we recorded the current density-voltage (JV) curve of the photodiode. Figure 8 We found that the dark current density (J dark) is significantly lower than that of the undoped inverse device. Under -10mV bias, the J dark Up to 31nA cm -2 , compared with the J of the trans-type device dark Reaching 218nA cm -2 As the reverse bias increases, the dark current density J dark Under -0.5V bias, the J of SbF3-doped inverse device dark Maintained at 750nA cm -2 Below. We carefully observe the photocurrent density-voltage (Jphoto-V) curve under 1650nm illumination and 270uW cm -2 At a power density of 1.5 volts, the open circuit voltage of the SbF3-doped trans device was 0.22 V, while the open circuit voltage of the control trans group was 0.18 V, indicating that the built-in electric field of the SbF3-doped trans device was stronger and could effectively collect photogenerated carriers. This also shows that the chemical doping of SbF3 reduces the barrier between the lead sulfide quantum dot film and the tin oxide, allowing photogenerated carriers to be collected more efficiently. This enhancement is mainly attributed to the improvement of carrier transport and the reduction of carrier recombination losses.

[0082] At the same time, in order to avoid the possibility of accidental occurrence, we conducted a J test on 30 doped or undoped SbF3 trans devices. dark Statistical analysis shows that the SbF3-doped inverse device significantly suppresses dark current under reverse bias of 0.1V. The results are as follows Fig. 9 As shown in the figure, this post-treatment method of chemical doping with antimony fluoride can effectively reduce the dark current of the device and improve the overall performance of the device. The results are generally universal.

[0083] Since the photoresponse of our detector reaches saturation at zero bias. Fig.10 As shown, we performed a wide spectrum external quantum efficiency test at 0V. It is worth noting that the external quantum efficiency (EQE) of the SbF3 doped trans device at the peak reaches 56.5%, which is a significant improvement over the 28% external quantum efficiency of the standard trans device. We also calculated the corresponding responsivity (R) of the SbF3 chemically doped trans device at 1.65μm under 0V bias to be 0.738AW -1 , compared with 0.36AW of the control trans device at 0V bias -1 There is a significant improvement compared to the previous study.

[0084] To analyze the dynamics of photogenerated carrier transport and recombination in the detector, we performed transient photocurrent (TPC) measurements, such as Fig.11As shown. A 532nm ultrafast pulsed laser was used to illuminate the detector, and the oscilloscope displayed the signal changes at both ends of the sample under test. During the TPC measurement, only a 50Ω series resistor was connected, requiring the photogenerated carriers to be transferred to an external circuit for collection. In general, the lifetime obtained from the TPC measurement reflects the carrier transport lifetime in the quantum dot detector, and a shorter lifetime indicates a faster charge transfer and a more efficient charge extraction process. The results show that the charge transfer lifetime of the antimony fluoride doped trans device is 6μs (eg Fig.11 As shown), it is higher than the general standard trans-type device.

[0085] In the preparation method of the antimony fluoride doped and passivated lead sulfide quantum dot active layer of the present application, the preparation method of the antimony fluoride doped and passivated lead sulfide quantum dot active layer includes: preparing an iodine-bromine-wrapped lead sulfide colloidal quantum dot film; dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution; soaking the iodine-bromine-wrapped lead sulfide colloidal quantum dot film in the antimony fluoride acetonitrile solution; washing the iodine-bromine-wrapped lead sulfide colloidal quantum dot film with acetonitrile for a preset number of times to obtain an antimony fluoride chemical reaction doped and passivated lead sulfide quantum dot active layer. The present application can improve the overall performance of semiconductor devices containing active layers.

[0086] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, 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 an antimony fluoride doped passivated lead sulfide quantum dot active layer, characterized in that: The method for preparing the antimony fluoride doped passivated lead sulfide quantum dot active layer comprises: Preparation of iodine-bromine-coated lead sulfide colloidal quantum dot films; dissolving antimony fluoride in acetonitrile to obtain an antimony fluoride acetonitrile solution; Immersing the lead sulfide colloidal quantum dot film wrapped with iodine and bromine in the antimony fluoride acetonitrile solution; The iodine-bromine-wrapped lead sulfide colloidal quantum dot film is washed with acetonitrile for a preset number of times to obtain an antimony fluoride chemically doped and passivated lead sulfide quantum dot active layer.

2. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 1, characterized in that: The method for preparing the iodine-bromine-wrapped lead sulfide colloidal quantum dot film comprises: Dissolving lead sulfide colloidal quantum dots in n-octane solvent to obtain a quantum dot n-octane solution, wherein the ligand on the surface of the lead sulfide colloidal quantum dots is oleic acid; Dissolving lead iodide and lead bromide in an N,N-dimethylformamide solution to obtain a first mixed solution, and mixing the quantum dot n-octane solution and the first mixed solution in equal volumes to obtain a second mixed solution; The second mixed solution is shaken and allowed to stand until the second mixed solution is separated into an upper and lower solution, the upper solution of the second mixed solution is removed and a preset volume of n-octane solvent is added to obtain a third mixed solution; The third mixed solution is shaken and allowed to stand until the third mixed solution is separated into two layers of solution, and the upper layer of the third mixed solution is removed to obtain a lead sulfide quantum dot ligand solution with iodine and bromine as ligands; The lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands is placed in a centrifuge for the first centrifugation and the upper liquid is poured off to remove the residual ligand solution on the surface, and then vacuum dried to obtain iodine-bromine ligand lead sulfide quantum dot powder; Dissolving iodine-bromine ligand lead sulfide quantum dot powder in a dispersant mixed solvent to obtain a fifth mixed solution; The fifth mixed solution is shaken and dispersed and placed in a centrifuge for a second centrifugation process; The solution after the second centrifugation treatment is spin-coated on the substrate and annealed at a preset annealing temperature and for a preset annealing time to obtain an iodine-bromine-encapsulated lead sulfide colloidal quantum dot film.

3. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 2, characterized in that: The concentration of the antimony fluoride in the antimony fluoride acetonitrile solution is 1 mmol / L to 10 mmol / L.

4. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 3, characterized in that: The preset number of times is 2 times.

5. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 4, characterized in that: The concentration of the lead sulfide colloidal quantum dots in the quantum dot n-octane solution is 10 mg / mL.

6. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 5, characterized in that: The step of dissolving lead iodide and lead bromide in a ligand solution to obtain a first mixed solution comprises: 1.844 g of lead iodide and 0.32 g of lead bromide were dissolved in 15 mL of DMF solution to obtain a first mixed solution.

7. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 6, characterized in that: The method of placing the lead sulfide quantum dot ligand solution with iodine ions and bromide ions as ligands in a centrifuge for a first centrifugal treatment and discarding the upper liquid comprises: The lead sulfide quantum dot ligand solution with iodide ions and bromide ions as ligands was placed in a centrifuge, the speed of the centrifuge was adjusted to 9000 rpm, the centrifugation time of the centrifuge was adjusted to 5 minutes, the first centrifugation was performed, and the upper liquid was poured off.

8. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 7, characterized in that: The dispersant mixed solvent is formed by mixing DMF solvent, DMSO solvent, BTA solvent and pyridine solvent.

9. The method for preparing an antimony fluoride doped passivated lead sulfide quantum dot active layer according to claim 8, characterized in that: The step of vibrating and dispersing the fifth mixed solution and placing the mixed solution in a centrifuge for a second centrifugation comprises: The fifth mixed solution was shaken and placed in a centrifuge, and centrifuged at 2000 rpm for 40 seconds.

10. The method for preparing an antimony fluoride doped and passivated lead sulfide quantum dot active layer according to claim 9, characterized in that: The preset annealing temperature is 90 degrees Celsius, and the preset annealing time is 10 minutes.

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