Tin-lead perovskite near-infrared photoelectric detector and preparation method thereof

Abstract

The invention belongs to the technical field of photoelectric detection, and particularly relates to a tin-lead perovskite near-infrared photoelectric detector and a preparation method thereof. Compared with the prior art, the perovskite thin film with better crystallization quality is obtained by regulating the crystallization kinetics of the thin film and passivating various ion defects by doping thiosulfate, so that the light current of a detector is improved, the dark current is inhibited, and the important performances such as the sensitivity and the responsivity of the device are improved; an effective way is provided for preparing a high-performance near-infrared photoelectric detector, the resolution ratio and the signal-to-noise ratio of an imaging chip are improved, meanwhile, the service life of the imaging chip is remarkably prolonged, and huge application potential is shown.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection technology, and particularly relates to a tin-lead perovskite near-infrared photodetector and its preparation method. Background Technology

[0002] Near-infrared (780–1800 nm) light detection, with its advantages of invisibility, good penetration, low energy damage, strong material compatibility, and anti-interference, is showing increasing potential in various application fields such as safety, security, and health, including security monitoring, material identification and detection, machine vision, optical detection and ranging, and biomedical fluorescence imaging. In particular, optical detection at the 850 nm wavelength is highly attractive and crucial because 850 nm light sources are mature commercial light sources with strong penetrating characteristics, making them very suitable for detection scenarios in complex environments. High-efficiency photodetectors capable of responding to 850 nm wavelengths hold promise for integration into various applications, such as short-range lidar ranging, to drive the development of autonomous driving assistance technologies.

[0003] Currently, commercial near-infrared photodetectors primarily use silicon, indium gallium arsenide (IGaAs), and germanium. However, these traditional semiconductor-based technologies require complex and expensive manufacturing processes. They involve high-temperature thin-film deposition and maintaining a high vacuum to prevent impurity interference, while also demanding precise control of each step, significantly increasing production costs and technical difficulty. Therefore, there is an urgent need for a near-infrared responsive semiconductor that can be manufactured using a simple low-temperature solution process for the fabrication of cost-effective near-infrared photodetectors.

[0004] Perovskite materials, with their significant advantages such as tunable bandgap, high light absorption coefficient, low cost and ability to be prepared via low-temperature solution processes, have become a promising alternative to traditional semiconductor optoelectronic materials. Among them, tin-lead binary perovskite, with its narrow bandgap (ranging from 1.5 eV to a minimum of 1.17 eV), extends its detection range into the near-infrared region, exhibiting unique advantages in the field of near-infrared photodetectors: it not only efficiently absorbs near-infrared light signals but also retains the low-cost characteristics of low-temperature solution preparation of perovskite materials. Furthermore, it possesses excellent carrier mobility and photoconductivity, which helps improve the detector's response speed and sensitivity. Combined with its good flexibility, this makes the development of flexible near-infrared optoelectronic devices possible.

[0005] Doping pure lead perovskite with tin can effectively reduce the band gap and extend the detection range of near-infrared light, but divalent tin (Sn)... 2+ It has a strong tendency to oxidize and is easily oxidized to tetravalent tin (Sn) during material preparation and subsequent use. 4+This not only generates a large number of vacancies and defects within the material, but also induces p-type self-doping, severely hindering the effective generation and collection of photogenerated carriers, thus leading to a significant decrease in the optoelectronic performance of the device. Furthermore, the presence of Pb in polycrystalline thin films... 2+ and Sn 2+ Defects should not be ignored. These defects become defect energy levels for charge carriers, increasing the dark current of the detector and causing the device to still have a high noise signal under no-light conditions. At the same time, the presence of defects will also affect the integrity of the material structure, making the device more susceptible to performance fluctuations when the external environment changes, further reducing its stability and adversely affecting the practical application of near-infrared photodetectors. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a tin-lead perovskite near-infrared photodetector with high near-infrared optical responsivity and external quantum efficiency, and a method for its preparation.

[0007] This invention provides a tin-lead perovskite near-infrared photodetector, comprising a tin-lead perovskite thin film layer; the tin-lead perovskite thin film layer is formed from a precursor solution;

[0008] The precursor solution comprises perovskite precursor material ABX3 and thiosulfate;

[0009] A is selected from one or more of NH2CHNH2, CH3NH3, C8H9NH3 and Cs; B is selected from Pb and Sn; X is selected from one or more of Cl, Br and I;

[0010] The concentration of thiosulfate in the precursor solution is 0.2~0.4 mg / mL.

[0011] Preferably, the concentration of thiosulfate in the precursor solution is 0.3~0.35 mg / mL;

[0012] And / or, the concentration of the perovskite precursor material ABX3 in the precursor solution is 1~2 mol / L.

[0013] Preferably, A is selected from NH2CHNH2, CH3NH3 and Cs; the molar ratio of NH2CHNH2, CH3NH3 and Cs is (4~8):(2~4):1;

[0014] And / or, the molar ratio of Pb to Sn is 1:(0.5~2).

[0015] Preferably, the thiosulfate is selected from ammonium thiosulfate;

[0016] The ratio of the perovskite precursor material ABX3 to thiosulfate is (1~2) mol: (0.2~0.4) g.

[0017] Preferably, the tin-lead perovskite thin film layer has X-ray diffraction peaks with (100) crystal plane orientation and X-ray diffraction peaks with (111) crystal plane orientation;

[0018] The intensity ratio of the X-ray diffraction peak with the (100) crystal plane orientation to the X-ray diffraction peak with the (111) crystal plane orientation is 15~22.

[0019] Preferably, it includes a first electrode, a hole transport layer, a tin-lead perovskite thin film layer, an electron transport layer, and a second electrode layer stacked together.

[0020] Preferably, the thickness of the hole transport layer is 20~40 nm;

[0021] The thickness of the tin-lead perovskite thin film layer is 200~700 nm;

[0022] The thickness of the electron transport layer is 25~30 nm;

[0023] The hole transport layer includes one or more of molybdenum trioxide, PEDOT:PSS, CuI, CuSCN, CuPc, NiO, P3HT, Spiro-OMeTAD, and PTAA;

[0024] The electron transport layer includes one or more of TiO2, ZnO, C60, C60 derivatives, fullerene, fullerene derivatives, PFN, and BCP.

[0025] The present invention also provides a method for preparing the above-mentioned tin-lead perovskite near-infrared photodetector, comprising the following steps:

[0026] S1) Provides a precursor solution;

[0027] S2) The precursor solution is transferred to the surface of the photodetector semi-finished product, and an antisolvent is added during the transfer process. After annealing, a tin-lead perovskite thin film layer is formed.

[0028] Preferably, the precursor solution is prepared according to the following method:

[0029] Mix AX and BX2 in a solvent, then add thiosulfate, and then filter through a membrane to obtain a precursor solution;

[0030] The solvent is selected from N,N-dimethylformamide and dimethyl sulfoxide; the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (2~4):1;

[0031] The antisolvent is selected from one or more of chlorobenzene, diethyl ether, acetone, toluene, ethyl acetate, and chloroform.

[0032] Preferably, in step S2), the precursor solution is transferred to the surface of the photodetector semi-finished product by spin coating; the spin coating includes spin coating at a first rate and then spin coating at a second rate.

[0033] The first speed is 1000~2000 rpm; the spin coating time at the first speed is 5~20 s;

[0034] The second speed is 3000~5000 rpm; the spin coating time at the second speed is 30~80 s; the anti-solvent is added 5~15 s before the end of spin coating at the second speed;

[0035] The annealing temperature is 70℃~100℃; the annealing time is 5~30 min.

[0036] Compared with existing technologies, this invention utilizes thiosulfate doping to regulate the crystallization kinetics of thin films and passivates various ionic defects, thereby obtaining perovskite thin films with better crystal quality. This results in improved photocurrent and suppressed dark current in the detector, enhancing important performance characteristics such as device sensitivity and responsivity. It not only provides an effective way to prepare high-performance near-infrared photodetectors, but also has the potential to significantly extend the working life of imaging chips while improving their resolution and signal-to-noise ratio, demonstrating enormous application potential. Attached Figure Description

[0037] Figure 1 A schematic diagram of the structure of a specific tin-lead perovskite near-infrared photodetector provided by the present invention;

[0038] Figure 2 The image shows a comparison of the photocurrents of the tin-lead perovskite near-infrared photodetectors obtained in Examples 1-3 and Comparative Examples 1-2 of this invention.

[0039] Figure 3 The dark current comparison diagrams are of the tin-lead perovskite near-infrared photodetectors obtained in Examples 1-3 and Comparative Examples 1-2 of this invention.

[0040] Figure 4 The X-ray diffraction patterns of the tin-lead perovskite layers obtained in Example 1 and Comparative Example 1 of this invention are shown below.

[0041] Figure 5 This is a distribution diagram of NSO in the device in Embodiment 1 of the present invention;

[0042] Figure 6 This is a comparison chart of the IV curves of the tin-lead perovskite near-infrared photodetectors obtained in Example 1 and Comparative Example 1 of the present invention.

[0043] Figure 7 This is a comparison chart of the responsivity of the tin-lead perovskite near-infrared photodetectors obtained in Example 1 and Comparative Example 1. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] In near-infrared tin-lead perovskite photodetectors, defects such as divalent tin oxidation and lead / tin vacancies are key bottlenecks restricting their photoelectric performance and stability.

[0046] To address this problem, this invention proposes an innovative strategy that can simultaneously suppress Sn. 2+ Oxidation and effective passivation of Pb 2+ The tin-lead perovskite near-infrared photodetector, which addresses vacancy defects, comprises a tin-lead perovskite thin film layer. This tin-lead perovskite thin film layer is formed from a precursor solution. The precursor solution comprises a perovskite precursor material ABX3 and thiosulfate. A is one or more of NH2CHNH2 (FA), CH3NH3 (MA), C8H9NH3 (PEA), and Cs; B is Pb and Sn; X is one or more of Cl, Br, and I. The concentration of thiosulfate in the precursor solution is 0.2~0.4 mg / mL.

[0047] In one specific embodiment of the present invention, the precursor solution includes perovskite precursor material ABX3; the concentration of perovskite precursor material ABX3 in the precursor solution is preferably 1~2 mol / L; optionally, the concentration of perovskite precursor material ABX3 in the precursor solution is 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, or any two of the above values.

[0048] In a specific embodiment of the present invention, A is preferably NH2CHNH2, CH3NH3 and Cs; the molar ratio of NH2CHNH2, CH3NH3 and Cs is preferably (4~8):(2~4):1, preferably (5~7):(2~4):1, even more preferably (5.5~7.5):(2.5~3.5):1, and even more preferably 6:3:1.

[0049] In a specific embodiment of the present invention, B is Pb and Sn; the molar ratio of Pb to Sn is preferably 1:(0.5~2); optionally, the molar ratio of Pb to Sn is 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2 or any two of the above values.

[0050] In one specific embodiment of the present invention, X is preferably I.

[0051] In one specific embodiment of the present invention, optionally, the concentration of thiosulfate in the precursor solution is 0.2 mg / mL, 0.22 mg / mL, 0.25 mg / mL, 0.28 mg / mL, 0.3 mg / mL, 0.32 mg / mL, 0.35 mg / mL, 0.38 mg / mL, 0.4 mg / mL, or a range between any two of the above values.

[0052] In one specific embodiment of the present invention, the concentration of thiosulfate in the precursor solution is preferably 0.3~0.35 mg / mL.

[0053] In a specific embodiment of the present invention, the ratio of the perovskite precursor material ABX3 to thiosulfate is preferably (1~2) mol:(0.2~0.4) g, more preferably (1.3~2) mol:(0.25~0.4) g, even more preferably (1.5~2) mol:(0.3~0.35) g, and most preferably 1.8 mol:(0.3~0.35) g.

[0054] In this invention, the precursor solution reacts with thiosulfate and Sn in the perovskite film during the film formation process. 2+ Pb 2+ Coordination, passivation of vacancies and dangling bonds, chemical bonds in thiosulfates, sulfur-oxygen double bonds (S=O) and Sn 2+ The formation of coordinate bonds and the coupling effect make Sn 2+Difficult to oxidize, similarly, S=O coordinates with lead vacancies, not only inhibiting lead precipitation but also passivating surface dangling bonds, thereby further improving the crystallinity of the film. In a specific embodiment provided by the present invention, the tin-lead perovskite film layer has X-ray diffraction peaks with (100) crystal plane orientation and X-ray diffraction peaks with (111) crystal plane orientation; the intensity ratio of the X-ray diffraction peaks with (100) crystal plane orientation to those with (111) crystal plane orientation is preferably 15~22; optionally, the intensity ratio of the X-ray diffraction peaks with (100) crystal plane orientation to those with (111) crystal plane orientation is 15, 16, 17, 18, 19, 20, 21, 22 or any two of the above values.

[0055] In one specific embodiment of the present invention, the thiosulfate is preferably ammonium thiosulfate (NSO); the NH4 in ammonium thiosulfate + It can form hydrogen bonds with X to further enhance the stability of the device.

[0056] In one specific embodiment of the present invention, the tin-lead perovskite near-infrared photodetector includes a stacked first electrode, a hole transport layer, a tin-lead perovskite thin film layer, an electron transport layer, and a second electrode layer. See also... Figure 1 , Figure 1 This is a schematic diagram of the structure of a specific tin-lead perovskite near-infrared photodetector provided by the present invention.

[0057] In one specific embodiment of the present invention, the first electrode can be any conductive anode known to those skilled in the art, and there are no special limitations, including but not limited to one or more of indium tin oxide, fluorine-doped tin oxide, gold, silver, aluminum, silver nanowires and conductive polymer films.

[0058] In one specific embodiment of the present invention, the hole transport layer can be any hole transport layer known to those skilled in the art, and there are no special limitations, including but not limited to one or more of molybdenum trioxide, PEDOT:PSS, CuI, CuSCN, CuPc, NiO, P3HT, Spiro-OMeTAD and PTAA.

[0059] In one specific embodiment of the present invention, the thickness of the hole transport layer is preferably 20-40 nm; optionally, the thickness of the hole transport layer is 20 nm, 25 nm, 30 nm, 35 nm, 40 nm or any two of the above values.

[0060] In one specific embodiment of the present invention, the thickness of the tin-lead perovskite thin film layer is preferably 550~700 nm; optionally, the thickness of the tin-lead perovskite thin film layer is 550 nm, 580 nm, 600 nm, 620 nm, 623 nm, 650 nm, 680 nm, 700 nm or any two of the above values.

[0061] In one specific embodiment of the present invention, the electron transport layer may be any electron transport layer known to those skilled in the art, and there are no special limitations, including but not limited to one or more of TiO2, ZnO, C60, C60 derivatives, fullerenes, fullerene derivatives, PFN and BCP; the C60 derivatives include but are not limited to Bis-C60; the bis-fullerene derivatives include but are not limited to PCBM and / or ICBA.

[0062] In one specific embodiment of the present invention, the thickness of the electron transport layer is preferably 25-30 nm; optionally, the thickness of the electron transport layer is 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm or any two of the above values.

[0063] In one specific embodiment of the present invention, the second electrode layer can be any conductive cathode known to those skilled in the art, and there are no special limitations, including but not limited to one or more of gold, silver, aluminum, silver nanowires and conductive polymer films.

[0064] In one specific embodiment of the present invention, the thickness of the second electrode layer is preferably 50-100 nm; optionally, the thickness of the second electrode layer is 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or any two of the above values.

[0065] This invention utilizes thiosulfate doping to regulate the crystallization kinetics of thin films and passivate various ionic defects, resulting in perovskite thin films with better crystal quality. This leads to an increase in the photocurrent of the detector, suppression of the dark current, and improvement in important performance characteristics such as device sensitivity and responsivity. It not only provides an effective way to prepare high-performance near-infrared photodetectors, but also has the potential to significantly extend the working life of imaging chips while improving their resolution and signal-to-noise ratio, demonstrating great application potential.

[0066] The present invention also provides a method for preparing the above-mentioned tin-lead perovskite near-infrared photodetector, comprising the following steps: S1) providing a precursor solution; S2) transferring the precursor solution to the surface of the photodetector semi-finished product, and adding an antisolvent during the transfer process, annealing, and forming a tin-lead perovskite thin film layer.

[0067] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0068] In a specific embodiment of the present invention, the precursor solution is preferably prepared by the following method: AX and BX2 are mixed in a solvent, then thiosulfate is added, and the mixture is then filtered through a membrane to obtain the precursor solution; the solvent is preferably N,N-dimethylformamide and dimethyl sulfoxide; the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is preferably (2~4):1; optionally, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 2:1, 3:1, 4:1 or any two of the above ratios; the membrane filtration is preferably performed using a 0.22-micron filter membrane, more preferably using a 0.22-micron PTFE filter membrane.

[0069] In a specific embodiment of the present invention, a precursor solution is transferred to the surface of a photodetector semi-finished product; the photodetector semi-finished product preferably includes a stacked first electrode and a hole transport layer; the transfer method can be any method well known to those skilled in the art and is not particularly limited. In the present invention, the precursor solution is preferably transferred to the surface of the photodetector semi-finished product by spin coating; the spin coating includes spin coating at a first rate and then spin coating at a second rate; the first rate is preferably 1000~2000 rpm; the spin coating time at the first rate is preferably 5~20 s; optionally, the spin coating time at the first rate is 5 s, 8 s, 10 s, 15 s, 20 s or any two of the above values; the second rate is preferably 3000~5000 rpm; the spin coating time at the second rate is preferably 30~80 s; optionally, the spin coating time at the second rate is 30 s, 40 s, 50 s, 60 s, 70 s, 80 s or any two of the above values.

[0070] An antisolvent is added during the transfer process; the antisolvent is preferably one or more of chlorobenzene, diethyl ether, acetone, toluene, ethyl acetate, and chloroform; in a specific embodiment provided by the present invention, the antisolvent is preferably added 5 to 15 s before the end of spin coating at the second rate; optionally, the antisolvent is added 5 s, 8 s, 10 s, 12 s, 15 s before the end of spin coating at the second rate, or within any two of the above values.

[0071] After the transfer is completed, annealing is performed to form a tin-lead perovskite thin film layer. The annealing is preferably carried out in a protective atmosphere. The protective atmosphere can be any atmosphere known to those skilled in the art and is not particularly limited; in this invention, nitrogen is preferred. The annealing temperature is preferably 70℃~100℃. Optionally, the annealing temperature is 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, or any range between two of the above values. The annealing time is preferably 5~30 min. Optionally, the annealing time is 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, or any range between two of the above values.

[0072] In one specific embodiment of the present invention, an electron transport layer and a second electrode layer are sequentially formed on a tin-lead perovskite thin film layer to obtain a tin-lead perovskite near-infrared photodetector.

[0073] This invention provides a method for significantly improving the photoresponsivity and external quantum efficiency of a detector in the near-infrared band by doping a precursor solution of a tin-lead perovskite thin film with thiosulfate. Simultaneously, it directly demonstrates effective suppression of the internal defect state density of the device by drastically reducing dark-state noise current. Furthermore, the tin-lead perovskite detector optimized based on this method can be heterogeneously integrated with thin-film transistors or complementary metal-oxide-semiconductor circuits through processes such as spin coating, thermal evaporation, and sputtering. Therefore, this invention not only provides an effective approach for fabricating high-performance near-infrared photodetectors but also holds promise for significantly extending the operating life of imaging chips while improving their resolution and signal-to-noise ratio, demonstrating enormous application potential.

[0074] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a tin-lead perovskite near-infrared photodetector and its preparation method provided by the present invention.

[0075] All reagents used in the following examples are commercially available.

[0076] Example 1

[0077] 1.1 The ITO glass substrate was sequentially cleaned with glass cleaner, deionized water, acetone, isopropanol, and ethanol for 15 minutes each, and then dried with nitrogen. Next, the ITO substrate was placed in a UV-induced ozone environment for approximately 15 minutes. The treated ITO glass substrate was then transferred to a nitrogen-filled glove box, and a CuI (dissolved in DMSO) layer was spin-coated onto the substrate at 3000 rpm for 60 seconds, followed by annealing at 100°C for 10 minutes to obtain a CuI substrate with a CuI layer thickness of 28 nm.

[0078] 1.2 Dissolve 185.7 mg formamidinium iodide (FAI), 85.8 mg methylamine iodide (MAI), 46.8 mg cesium iodide (CsI), 335.3 mg stannous iodide (SnI2), 414.9 mg lead iodide (PbI2), and 14.1 mg stannous fluoride (SnF2) in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (3:1) to prepare 1.8 MFA. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 solution. Add 0.35 mg of ammonium thiosulfate (NSO) additive to the above solution. After complete dissolution and filtration through a 0.22 μm PTFE membrane, a precursor solution is obtained. The precursor solution is spin-coated onto a CuI substrate at 1000 rpm for 10 seconds, then at 5000 rpm for 50 seconds, with 120 μL of toluene added dropwise at the 40th second. Subsequently, annealing is performed at 80°C for 15 minutes under a nitrogen atmosphere to obtain a substrate with a deposited tin-lead perovskite layer, wherein the thickness of the tin-lead perovskite layer is 623 nm.

[0079] 1.3 The substrate on which the tin-lead perovskite layer is deposited is placed at 2×10 -4 In a vacuum of Pa, a 20 nm thick C60 layer, a 7 nm thick BCP layer, and a 65 nm thick silver electrode are sequentially formed by thermal deposition to obtain a tin-lead perovskite near-infrared photodetector.

[0080] Example 2

[0081] The preparation method is the same as in Example 1, except that 0.3 mg of ammonium thiosulfate (NSO) additive is added.

[0082] Example 3

[0083] The preparation method is the same as in Example 1, except that 0.4 mg of ammonium thiosulfate (NSO) additive is added.

[0084] Comparative Example 1

[0085] The preparation method is the same as in Example 1, except that ammonium thiosulfate (NSO) additive is not added.

[0086] Comparative Example 2

[0087] The preparation method is the same as in Example 1, except that 0.5 mg of ammonium thiosulfate (NSO) additive is added.

[0088] The photocurrents of the tin-lead perovskite near-infrared photodetectors obtained in Examples 1-3 and Comparative Examples 1-2 were detected, and the photocurrent comparison diagrams are shown below. Figure 2 As shown; the dark current comparison diagram is as follows. Figure 3 As shown. By Figure 2 and Figure 3 It can be seen that the detector's photocurrent reaches its highest point and its dark current reaches its lowest point when the concentration is 0.35 mg / mL.

[0089] The deposited tin-lead perovskite layers in the substrates of Example 1 and Comparative Example 1 were examined using X-ray diffraction, and their XRD comparison images are shown below. Figure 4 As shown, the experimental group is Example 1, and the control group is Comparative Example 1. Figure 4 It can be seen that the experimental group (NSO-doped film) showed a significant improvement in (100) orientation compared to the control group, while the (111) orientation was suppressed, with the (100) / (111) ratio increasing from 13.5 to 19. This is because a denser film with a higher (100) orientation maximizes carrier transport efficiency, improves responsivity and external quantum efficiency, and, due to surface stability, helps reduce dark current and improve overall device stability. A higher (111) orientation, on the other hand, implies more film defects, poor stability, and increased ion migration. Therefore, the results demonstrate that the experimental group film exhibited significantly improved crystal quality and other aspects.

[0090] The elemental distribution of the tin-lead perovskite near-infrared photodetector in Example 1 was analyzed layer by layer using sputtering etching-depth profiling technology, and the distribution of NSO in the device was obtained as follows: Figure 5 As shown. By Figure 5 It can be seen that after the device is doped, NSO is mainly distributed on the upper and lower surfaces of the active thin film, which indirectly confirms that NSO mainly passivates defects such as dangling bonds on the device surface.

[0091] Figure 6 This is a comparison chart of the IV curves of the tin-lead perovskite near-infrared photodetectors obtained in Example 1 and Comparative Example 1. Figure 6 It can be seen that by comparing the detector IV curves of the experimental group and the control group (Comparative Example 1) under the same test conditions, the photocurrent of the experimental group (Example 1) was improved, indicating that the quality of the active layer thin film was improved, which is beneficial to the extraction of photogenerated carriers. At the same time, the dark current of the experimental group was suppressed, which proves on the one hand that the material quality was improved and the internal defects were effectively suppressed, and on the other hand that the signal-to-noise ratio and detection limit of the detector were fundamentally improved.

[0092] Figure 7 This is a comparison of the responsivity of the tin-lead perovskite near-infrared photodetectors obtained in Example 1 and Comparative Example 1. Figure 7 It can be seen that the responsivity of the optimized detector has been greatly improved, reaching a maximum of 0.52 AW in the visible-near infrared band. -1.

[0093] The above results demonstrate that this method has great application potential in realizing high-performance tin-lead perovskite near-infrared detectors.

[0094] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A tin-lead perovskite near-infrared photodetector, characterized in that, Includes a tin-lead perovskite thin film layer; the tin-lead perovskite thin film layer is formed from a precursor solution; The precursor solution comprises perovskite precursor material ABX3 and thiosulfate; A is selected from one or more of NH2CHNH2, CH3NH3, C8H9NH3 and Cs; B is selected from Pb and Sn; X is selected from one or more of Cl, Br and I; The concentration of thiosulfate in the precursor solution is 0.2~0.4 mg / mL.

2. The tin-lead perovskite near-infrared photodetector according to claim 1, characterized in that, The concentration of thiosulfate in the precursor solution is 0.3~0.35 mg / mL; And / or, the concentration of the perovskite precursor material ABX3 in the precursor solution is 1~2 mol / L.

3. The tin-lead perovskite near-infrared photodetector according to claim 1, characterized in that, The A is selected from NH2CHNH2, CH3NH3 and Cs; the molar ratio of NH2CHNH2, CH3NH3 and Cs is (4~8):(2~4):1; And / or, the molar ratio of Pb to Sn is 1:(0.5~2).

4. The tin-lead perovskite near-infrared photodetector according to claim 3, characterized in that, The thiosulfate is selected from ammonium thiosulfate; The ratio of the perovskite precursor material ABX3 to thiosulfate is (1~2) mol: (0.2~0.4) g.

5. The tin-lead perovskite near-infrared photodetector according to claim 1, characterized in that, The tin-lead perovskite thin film layer has X-ray diffraction peaks with (100) crystal plane orientation and X-ray diffraction peaks with (111) crystal plane orientation. The intensity ratio of the X-ray diffraction peak with the (100) crystal plane orientation to the X-ray diffraction peak with the (111) crystal plane orientation is 15~22.

6. The tin-lead perovskite near-infrared photodetector according to claim 1, characterized in that, It includes a stacked first electrode, a hole transport layer, a tin-lead perovskite thin film layer, an electron transport layer, and a second electrode layer.

7. The tin-lead perovskite near-infrared photodetector according to claim 6, characterized in that, The thickness of the hole transport layer is 20~40 nm; The thickness of the tin-lead perovskite thin film layer is 550~700 nm; The thickness of the electron transport layer is 25~30 nm; The hole transport layer includes one or more of molybdenum trioxide, PEDOT:PSS, CuI, CuSCN, CuPc, NiO, P3HT, Spiro-OMeTAD, and PTAA; The electron transport layer includes one or more of TiO2, ZnO, C60, C60 derivatives, fullerene, fullerene derivatives, PFN, and BCP.

8. A method for preparing the tin-lead perovskite near-infrared photodetector according to claim 1, characterized in that, Includes the following steps: S1) Provides a precursor solution; S2) The precursor solution is transferred to the surface of the photodetector semi-finished product, and an antisolvent is added during the transfer process. After annealing, a tin-lead perovskite thin film layer is formed.

9. The preparation method according to claim 8, characterized in that, The precursor solution is prepared according to the following method: Mix AX and BX2 in a solvent, then add thiosulfate, and then filter through a membrane to obtain a precursor solution; The solvent is selected from N,N-dimethylformamide and dimethyl sulfoxide; the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (2~4):1; The antisolvent is selected from one or more of chlorobenzene, diethyl ether, acetone, toluene, ethyl acetate, and chloroform.

10. The preparation method according to claim 8, characterized in that, In step S2), the precursor solution is transferred to the surface of the photodetector semi-finished product by spin coating; the spin coating includes spin coating at a first rate and then spin coating at a second rate. The first speed is 1000~2000 rpm; the spin coating time at the first speed is 5~20 s; The second speed is 3000~5000 rpm; the spin coating time at the second speed is 30~80 s; the anti-solvent is added 5~15 s before the end of spin coating at the second speed; The annealing temperature is 70℃~100℃; the annealing time is 5~30 min.

Images