A high-performance tin-based perovskite photodetector, a preparation method thereof and application thereof in covert light information transmission

Abstract

This invention discloses a high-performance tin-based perovskite photodetector, its fabrication method, and its application in covert optical information transmission. The photodetector sequentially comprises a conductive substrate, an electron transport layer, a tin-based perovskite layer, a hole transport layer, and a metal electrode layer. The tin-based perovskite layer is FASnI3, and 1,4-butanediamine hydroiodate is introduced as a molecular additive to suppress Sn. 2+ Oxidation and reduction of defect state density optimize film quality. Based on this, FASnI3 perovskite films with an inverse opal structure were successfully prepared. The slow photon effect significantly enhances perovskite light absorption and promotes carrier transport, and the "lotus leaf effect" introduced by the photonic crystal significantly improves the stability of Sn-based perovskites. The photodetector prepared by this invention achieves highly sensitive, self-powered near-infrared detection under zero bias conditions, exhibiting high responsivity, high detectivity, low dark current, and excellent stability. It can be used in optical communication, information transmission, sensing, and security optoelectronic systems.

Description

Technical Field

[0001] This invention belongs to the field of photodetector design and fabrication technology, specifically relating to a high-performance tin-based perovskite photodetector, its fabrication method, and its application in covert optical information transmission. Background Technology

[0002] Organic-inorganic hybrid perovskites have emerged as promising candidates for next-generation optoelectronic devices due to their superior photoelectric properties. Among them, tin-based perovskites have attracted widespread attention due to their narrow bandgap, long carrier diffusion length, and non-toxicity compared to lead-based perovskites. Despite these advantages, the practical application of tin-based perovskite photodetectors is severely hampered by their high defect density and poor environmental stability. These problems primarily stem from the rapid and uncontrolled crystallization of tin-based perovskites during thin film formation, and the influence of Sn... 2+ Ions are easily oxidized. To address these issues, various strategies have been proposed, including ion doping, additive engineering, and interface modification. However, these advances have primarily focused on the manipulation of two-dimensional planar tin-based perovskite films. Three-dimensional photonic crystal (PC) structures can enhance light trapping through the slow photon effect. Simultaneously, their biomimetic "lotus leaf effect" micro / nanostructures can improve surface hydrophobicity, thereby enhancing the environmental stability of the film. However, given the inherent difficulties in preparing high-quality planar tin-based perovskite films, constructing ordered three-dimensional photonic crystal structures is even more challenging.

[0003] Therefore, this work modulates the colloidal chemistry and crystallization kinetics of formamidinium tin iodide (FASnI3) by introducing the bifunctional organic additive 1,4-butanediamine hydroiodide (BDADI). BDADI and Sn 2+ The strong coordination between them can effectively inhibit Sn 2+ Oxidation promotes the formation of uniformly sized precolloid clusters, thereby improving the quality of perovskite films and reducing defect density. Based on this, an ordered inverse opal structure is further constructed to enhance light trapping, carrier transport, and interfacial charge collection capabilities. Ultimately, the fabricated FASnI3-BDADI IO photodetector exhibits extremely low dark current, high responsivity and detectivity, fast response speed, and excellent unpackaged operational stability. Furthermore, this device was successfully integrated into a near-infrared optical communication system, achieving covert and interference-resistant information transmission, demonstrating its potential in covert optoelectronic applications. Summary of the Invention

[0004] To address the limitations of existing tin-based perovskite photodetectors, such as poor material stability and restricted device performance, this invention provides a high-performance tin-based perovskite photodetector, its fabrication method, and its application in covert optical information transmission. This detector utilizes an inverse opal structure to enhance light absorption and incorporates BDADI molecular additives to optimize thin film quality, thereby improving the photodetector's detection performance and enabling optical information transmission.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for fabricating a high-performance tin-based perovskite photodetector, the fabrication process of which is as follows: (1) An electron transport layer is prepared on a cleaned and pretreated ITO or FTO substrate; (2) The PS ball solution is dropped onto the surface of deionized water to form an ordered monolayer PS film. Sodium dodecyl sulfate solution is added to promote the dense arrangement of PS balls. The substrate is tilted, and the PS monolayer film is picked up on the electron transport layer. The film is dried at 55~65 ℃ for 5~30 min to form a PS film. (3) Spin-coating FASnI3-BDADI precursor solution onto PS film, followed by annealing, template removal, and re-annealing to obtain an inverse opal perovskite layer; (4) Spin-coating P3HT solution onto the inverse opal perovskite layer, annealing to obtain the P3HT hole transport layer, evaporating metal electrodes to complete the device fabrication.

[0006] Further, in step (1), the ITO or FTO substrate is ultrasonically cleaned sequentially with anhydrous ethanol, conductive glass cleaner, and deionized water, dried with nitrogen, and then treated with ultraviolet-ozone for 10 to 20 minutes.

[0007] Further, in step (1), the electron transport layer is TiO2, which is composed of a dense TiO2 layer and a mesoporous TiO2 layer. The preparation process of the dense TiO2 precursor solution is as follows: anhydrous ethanol, tetrabutyl titanate, concentrated nitric acid and ultrapure water are mixed in a volume ratio of (4~6):1:(0.1~0.3):(0.1~0.3). The mesoporous TiO2 precursor solution is obtained by mixing deionized water and TiO2 slurry in a mass ratio of (6~8):1. First, the dense TiO2 precursor solution is spin-coated on the substrate and annealed at 490~510 ℃ for 20~40 minutes. Then, the mesoporous TiO2 precursor solution is spin-coated on the dense TiO2 layer. First, it is annealed at 90~110 ℃ for 5~15 minutes and then annealed at 490~510 ℃ for 20~40 minutes to obtain the TiO2 electron transport layer. The spin-coating amount of the dense TiO2 precursor solution is 0.5~1 mL / cm. 2 The spin-coating amount of the mesoporous TiO2 precursor solution was 0.6~1 mL / cm. 2 .

[0008] Specifically, the preparation process of the dense TiO2 precursor solution in step (1) is as follows: anhydrous ethanol, tetrabutyl titanate, concentrated nitric acid, and ultrapure water are mixed in a ratio of 5:1:0.2:0.1. After spin-coating the dense TiO2 precursor solution, it is annealed at 500 °C for 30 min. The mesoporous TiO2 precursor solution is obtained by mixing anhydrous ethanol and TiO2 slurry in a mass ratio of 7:1. After spin-coating the mesoporous TiO2 precursor solution, it is first annealed at 100 °C for 10 min, and then annealed at 500 °C for 30 min.

[0009] Further, in step (2), the concentration of the PS sphere solution is 1~2 wt%, and the diameter of the PS spheres is 300~1500 nm; the preparation process of the sodium dodecyl sulfate solution is as follows: sodium dodecyl sulfate is dissolved in a solvent of ethanol and deionized water with a volume ratio of (1~2): (1~2), and the concentration of sodium dodecyl sulfate is 1~3 g / L. The volume ratio of the PS sphere solution to the sodium dodecyl sulfate solution is 10:1. The volume of the PS sphere solution in step (2) is not less than the volume of the FASnI3-BDADI precursor solution in step (3).

[0010] Specifically, in step (2), the PS ball precursor solution is prepared by diluting a 5% concentration of original PS ball solution of different diameters to 1.5 wt% using a water / ethanol mixed solvent (volume ratio 1:1). The concentration of sodium dodecyl sulfate (SDS) aqueous solution is 2 g / L.

[0011] Furthermore, in step (3), the concentration of FASnI3 in the FASnI3-BDADI precursor solution is 0.6~1.0 mol / L, and the amount of BDADI added is 1.5~8.5 mg / mL.

[0012] Further, the preparation process of the FASnI3-BDADI precursor solution in step (3) is as follows: FAI, SnI2 and SnF2 are dissolved in a mixed solvent of DMSO and DMF with a volume ratio of 4:1 according to a molar ratio of 1:1:0.1 to obtain a FASnI3 solution. Then, 1~5 mg of BDADI is added to 500~700 μL of FASnI3 solution and stirred at 25~35℃ for 2~4 h to obtain a FASnI3-BDADI precursor solution with a FASnI3 concentration of 0.6~1.0 mol / L.

[0013] Specifically, the preparation process of the FASnI3-BDADI precursor solution in step (3) is as follows: FAI, SnI2, and SnF2 are dissolved in a mixed solvent of DMSO and DMF with a volume ratio of 4:1 at a molar ratio of 1:1:0.1. Then, 3 mg of BDADI is added to 600 μL of the above solution, and the mixture is stirred at 30 °C for 2-4 h to obtain a FASnI3-BDADI precursor solution with a FASnI3 concentration of 0.8 mol / L. The spin-coating amount of the FASnI3-BDADI precursor solution is 1-2 mL / cm. 2 .

[0014] In step (3), the method for removing the template is to soak the sample in toluene for 0.5 to 1.5 minutes and repeat 2 to 4 times; annealing means annealing at 35 to 45 °C for 1 to 3 minutes, and then annealing at 85 to 95 °C for 1 to 2 minutes; re-annealing means annealing at 85 to 95 °C for 5 to 15 minutes.

[0015] Further, in step (4), P3HT is dissolved in chlorobenzene and stirred for 2 hours to obtain a P3HT solution with a concentration of 10~15 mg / mL; annealing treatment refers to annealing at 90~100 ℃ for 5~15 min.

[0016] Specifically, in step (4), the concentration of the P3HT solution is 10 mg / mL. The spin-coating volume of the P3HT solution is 1~1.2 mL / cm. 2 The thickness of the metal cathode is 100~200 nm.

[0017] The high-performance tin-based perovskite photodetector obtained by the above preparation method is illustrated in the schematic diagram of its preparation steps. Figure 1 As shown, the detector mainly consists of a conductive substrate, an electron transport layer, an inverse opal perovskite light-absorbing layer, a hole transport layer, and a metal cathode arranged sequentially; the inverse opal perovskite light-absorbing layer is FASnI3-BDADI, the hole transport layer is P3HT, the electron transport layer is TiO2, and the metal cathode is Ag or Au.

[0018] The application of the aforementioned high-performance tin-based perovskite photodetector in covert optical information transmission includes a modulation circuit, a near-infrared light source (near-infrared LED), a photodetector, an LM386 power amplifier circuit board, a speaker, and a smartphone for transmitting and receiving information. The photodetector is integrated as a receiving unit with the near-infrared light source, signal modulation, and decoding circuitry to achieve array-free near-infrared image transmission and coded communication using a single device. The wavelength of the near-infrared light source is 808 nm.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention uses polystyrene spheres as a soft template and BDADI molecules as an additive to synergistically construct an inverse opal structure tin-based perovskite photodetector. BDADI effectively regulates the colloidal chemistry and crystallization kinetics of FASnI3, inhibiting Sn... 2+ Oxidation and reduction of defect density optimize film quality. Based on this, an inverse opal structure photodetector enhances light trapping and facilitates carrier transport through the slow photon effect. This synergistic strategy enables the device to achieve one of the highest responsivity and detectivity among lead-free tin-based perovskite photodetectors at a wavelength of 808 nm.

[0020] 2. The fabricated FASnI3-BDADI IO photodetector exhibits excellent performance under 808 nm illumination: the ratio of photocurrent to dark current (photocurrent-dark current ratio) reaches 1×10⁻⁶. 6 The detection rate reached 1.06×10 14 Jones, with a response time of 5.90 AW. -1 After working continuously for 10,000 seconds in an air environment, its performance still retains 80% of its initial value, demonstrating good operational and long-term stability.

[0021] 3. This device achieves high-performance near-infrared detection while avoiding the use of lead, making it more environmentally friendly. Based on its superior performance, this invention has successfully applied it to optical information transmission systems, realizing concealed, interference-resistant single-device image transmission and signal decoding, simplifying system architecture, reducing application costs, and demonstrating its application potential in advanced optoelectronics and communications. Attached Figure Description

[0022] Figure 1 A schematic diagram of the preparation process of FASnI3-BDADI IO thin film; Figure 2 This is a SEM cross-sectional view of the PS film; Figure 3 The transmission spectrum of the PS thin film; Figure 4 In the middle: a is a scanning electron microscope image of the FASnI3-BDADI IO thin film; b is the absorption spectrum of each material; Figure 5 In the middle: a is a dynamic light scattering image of Comparative Example 1 and Example 2; b is an X-ray diffraction pattern of Comparative Example 1 and Examples 1-3; Figure 6 In the middle: a represents Comparative Example 1 and Examples 1-3 under a light intensity of 10 mW / cm². 2 b is the curve of the photodetector current changing with time under 808 nm laser light; b is the It curve of comparative example 1, example 2 and example 4; Figure 7In the diagrams, a and b represent the response speed and linear dynamic response of the planar structure detector in Example 2 and the inverse opal structure detector in Example 4, respectively. Figure 8 In the middle: a) It curves of the planar structure detector of Example 2 and the inverse opal structure detector of Example 4 in an air environment after continuous operation for 10,000 s; b) Stability results after 70 days of placement in a glove box;

[0023] Figure 9 A schematic diagram and photograph of a secure optical information transmission system; Figure 10 These are the original image and the image after transmission of optical information. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0025] A method for fabricating a high-performance FASnI3-BDADI perovskite photodetector involves the following raw materials: Solution A (dense TiO2 precursor solution): 2.5 mL anhydrous ethanol, 0.5 mL tetrabutyl titanate, 0.1 mL nitric acid (commercially available concentrated nitric acid) and 50 μL ultrapure water were stirred at room temperature for 6 hours to obtain the solution.

[0026] Solution B (mesoporous TiO2 precursor solution): TiO2 slurry (model 30NR-D, purchased from Xi'an Baolai Optoelectronic Technology Co., Ltd.) and anhydrous ethanol were mixed at a weight ratio of 1:7 and stirred at room temperature for 6 hours.

[0027] Solution C (polystyrene sphere aqueous solution): The PS sphere precursor solution was diluted to 1.5 wt% with a 5 wt% PS stock solution (purchased from Shanghai Huizhi Biotechnology Co., Ltd.) by a water / ethanol mixture (volume ratio 1:1). The PS spheres had a diameter of 1000 nm.

[0028] Solution D (sodium dodecyl sulfate (SDS) aqueous solution): 0.02 g SDS dissolved in 10 mL of anhydrous ethanol and deionized water in a 1:1 volume ratio.

[0029] Solution E (perovskite precursor solution): FASnI3-BDADI solutions with different amounts of 1,4-butanediamine hydroiodide (BDADI) were mainly composed of FAI (0.0825 g, 0.48 mmol), SnI2 (0.1788 g, 0.48 mmol), and SnF2 (0.0075 g, 0.048 mmol), dissolved in a mixed solvent of 480 μL dimethyl sulfoxide (DMSO) and 120 μL N,N-dimethylformamide (DMF), with BDADI added at amounts of 0 mg (E0), 1 mg (E1), 3 mg (E2), and 5 mg (E3), respectively. The mixture was stirred at 30 °C for 4 h in a glove box to obtain a 0.8 mol / L FASnI3-BDADI precursor solution.

[0030] Solution F (P3HT solution): 10 mg of poly-3-hexylthiophene (P3HT) (purchased from Xi'an Riyu Solar Energy Technology Co., Ltd.) was dissolved in 1 mL of chlorobenzene solvent and stirred at 60 °C in the dark for 4 hours.

[0031] Examples 1, 2, and 3 are based on FASnI3-BDADI precursor solutions with different BDADI doping amounts.

[0032] Example 1: Planar detector with 1 mg of BDADI (1) Cleaning of FTO substrate: ultrasonically cleaned with anhydrous ethanol, conductive glass cleaner and deionized water for 20 minutes in sequence, dried with nitrogen and treated with ultraviolet-ozone for 15 minutes.

[0033] (2) Preparation of TiO2 electron transport layer: 30 μL of solution A was spin-coated at 4000 rpm for 30 seconds and annealed at 500 ℃ for 30 minutes to obtain a dense layer. Then, 35 μL of solution B was spin-coated at 3000 rpm for 30 seconds, annealed at 100 ℃ for 10 minutes, and then annealed at 500 ℃ for 30 minutes to obtain a TiO2 layer (FTO / TiO2) with a thickness of about 100 nm.

[0034] (3) Preparation of perovskite light-absorbing layer: In a glove box, 60 μL of solution E1 was spin-coated onto FTO / TiO2 at 5000 rpm for 60 seconds. The film was first annealed on a hot plate at 40 °C for 2 minutes, and then annealed at 90 °C for 1 minute. A planar FASnI3-1mg BDADI film was obtained.

[0035] (4) Preparation of hole transport layer and electrode: 45 μL of solution F was spin-coated onto the perovskite layer at 3000 rpm for 30 seconds, and annealed at 100 °C for 10 minutes to obtain the P3HT layer. An Ag electrode with a thickness of approximately 150 nm was deposited by vacuum thermal evaporation. The substrate area was 0.04 cm².2 .

[0036] Example 2: Planar detector with 3 mg BDADI addition The steps are the same as in Example 1, but the perovskite precursor solution uses solution E2 to prepare a planar FASnI3-3mg BDADI detector.

[0037] Example 3: Planar detector with 5 mg BDADI addition The steps are the same as in Example 1, but the perovskite precursor solution uses solution E3 to prepare a planar FASnI3-5mg BDADI detector.

[0038] Comparative Example 1: Planar structure detector without BDADI addition The steps are the same as in Example 1, but the perovskite precursor solution uses solution E0 (without adding BDADI) to prepare a planar FASnI3 detector.

[0039] Example 4: FASnI3-3mg BDADI detector with inverse opal structure (optimal example) (1) Cleaning of FTO substrate and preparation of TiO2 electron transport layer: Same as steps (1) and (2) in Example 1.

[0040] (2) Preparation of polystyrene spherical soft template: 60 μL of solution C (containing 1000 nm diameter PS spheres) was slowly dropped onto the surface of deionized water to form a monolayer film. 6 μL of solution D was added to promote alignment. The monolayer film was slowly picked up by tilting the FTO / TiO2 substrate and dried on a 60 ℃ heating plate for 10 minutes to obtain FTO / TiO2 / PS.

[0041] (3) Preparation of the inverse opal perovskite layer: In a glove box, 60 μL of solution E2 was spin-coated onto FTO / TiO2 / PS at 5000 rpm for 60 seconds. The sample was then annealed at 40 °C for 2 minutes, followed by annealing at 90 °C for 1 minute. The sample was then immersed in toluene for 1 minute, repeated three times to remove the PS template. Finally, the sample was annealed at 90 °C for 10 minutes to obtain the inverse opal structure FASnI3-BDADI light-absorbing layer (FASnI3-BDADI IO).

[0042] (4) Preparation of hole transport layer and electrode: Same as step (4) in Example 1, to obtain inverse opal structure detector.

[0043] Performance Testing and Result Analysis At 10 mW / cm 2 The device performance was tested under 808 nm laser irradiation, and key parameters were as follows: Figure 6 And as shown in Table 1 like Figure 6Ultimately, the FASnI3-BDADI IO photodetector was observed to have the highest photoelectric performance compared to Comparative Example 1 and Example 2. The FASnI3-BDADI IO photodetector exhibited good photoelectric performance under 808 nm laser light, with a photocurrent-to-dark-current ratio of 10. 6 The detection rate reached 1.06×10 14 Jones's detector rate is nearly an order of magnitude higher than that of planar FASnI3-BDADI. This is mainly due to the larger pore size of the inverse opal, which allows P3HT to penetrate into the perovskite pores, increasing the contact area between P3HT and FASnI3 and facilitating carrier transport. Furthermore, the 1000 nm aperture photonic crystal's optical field enhancement range overlaps with the optical absorption range of FASnI3-BDADI, further enhancing the device's photoelectric performance under 808 nm laser light.

[0044] Table 1. Performance parameters of Comparative Example 1 and Examples 1-4

[0045] Figure 2 This is a SEM cross-sectional view of a PS soft template. Figure 3 The image shows the transmission spectrum of the PS soft template. The periodic arrangement of the closely packed PS spheres results in a spatial periodicity of the refractive index, forming a photonic bandgap (PBG). The PBG can reduce the group velocity of photons at wavelengths near it, thus the absorption of light in a specific wavelength band can be improved by adjusting the diameter of the PS spheres. A PS sphere film with a diameter of 1000 nm corresponds to an increase in light absorption of about 861 nm, proving the successful fabrication of a photonic crystal soft template.

[0046] Figure 4 Image a shows the SEM image of the inverse opal FASnI3-BDADI perovskite film after the PS soft template has been removed. It can be seen that a periodically arranged inverse opal structure with a diameter of 1000 nm has been formed. Figure 4 Figure b shows the absorption spectra of each material. The presence of the soft template enhances the absorption of the perovskite, with an additional absorption peak near 861 nm, indicating the successful preparation of the anti-protein perovskite. Furthermore, its enhanced light absorption range coincides with that of FASnI3-BDADI, which is beneficial for enhancing its near-infrared light absorption, thereby improving the photoelectric performance of the photodetector.

[0047] Figure 5In Figure 'a', the nucleus size in the perovskite precursor solution state of Comparative Example 1 and Example 2 is characterized by dynamic light scattering. After the addition of BDADI, the original FASnI3 precursor solution exhibits a bimodal size distribution, with peaks located at approximately 25 nm and 147 nm, indicating the simultaneous presence of pre-nucleated clusters with significant size differences in the solution. During film formation, such size differences may lead to inhomogeneous nucleation and growth kinetics, which is detrimental to the formation of high-quality perovskite films. In contrast, the FASnI3-BDADI precursor solution exhibits a single and narrow size distribution, with peaks concentrated at approximately 124 nm, indicating that its colloidal system is more stable and homogeneous. Figure 5 As shown in Figure b, after the addition of 3 mg BDADI, the diffraction intensity of the (100) and (200) crystal planes was significantly enhanced, and the half-width at half maximum (WHM) was significantly reduced relative to the original FASnI3 film. This indicates that BDADI affects the crystallization of FASnI3 by influencing the size of the pre-nucleated clusters in the FASnI3 precursor solution.

[0048] Figure 6 In Figure a, the It curves of Comparative Example 1 and Examples 1-3 under 808 nm laser light are shown. Example 2 has the highest photocurrent and the lowest dark current, which reflects that BDADI effectively optimizes FASnI3 crystallization to improve film quality and suppress defect generation. Therefore, Example 2 has the best photoelectric performance. Figure 6 In Example 4, b is a photodetector prepared using the inverse opal structure. The slow photon effect of the inverse opal structure significantly improves the photoelectric performance of FASnI3-BDADI.

[0049] Figure 7 The photoresponse speeds of the inverse opal structure detector in Example 4 and the planar detector in Example 2 are compared. The rise and fall times of the FASnI3-BDADI planar detector in Example 2 are 68.1 / 82.2 μs, while the rise and fall times of the FASnI3-BDADI IO detector in Example 4 are only 14.1 / 25.3 μs. This demonstrates that the inverse opal structure provides a faster transport channel for charge carriers, thereby improving the response speed of the photodetector.

[0050] Figure 8 The operational stability of the unencapsulated inverse opal structure detector of Example 4 and the planar detector of Example 2 in an air environment and their long-term stability in a glove box were assessed. Under a 10-second on / off cycle, the photocurrent decreased by only 20% after 10,000 seconds of continuous operation. After 50 days of storage in a nitrogen environment in a glove box, the detector still maintained 80% of its initial responsivity, demonstrating significant environmental stability. This performance is not only due to BDADI's suppression of Sn... 2+The effect is also attributed to the "lotus effect" brought about by the photonic crystal structure, which improves the hydrophobicity of the material.

[0051] Application demonstration: Based on the superior photoelectric performance of the inverse opal structure FASnI3-BDADI IO under 808 nm laser light in Example 4, this invention designs a near-infrared optical communication system in which a photodetector acts as an optical signal receiver, aiming to achieve encrypted information transmission. Figure 9 Figure a shows a schematic diagram of a covert, interference-resistant optical information transmission system. It includes a modulation circuit, a near-infrared light source (near-infrared LED), a photodetector, an LM386 power amplifier circuit board, a speaker, and a smartphone. The smartphone transmits a signal, and the modulation circuit connects to the near-infrared light source (near-infrared LED), thus projecting the modulated near-infrared light carrying information onto the photodetector. The photodetector is connected to the LM386 power amplifier circuit board via an external circuit, which is then connected to a speaker to generate a sound signal. Another smartphone receives the sound signal.

[0052] like Figure 9 In the near-infrared acoustic-optical communication system shown in Figure b, image information from a mobile phone is encrypted via the SSTV EncoderAPP and transmitted as light emitted by a near-infrared LED modulated by a modulation circuit. A perovskite photodetector receives the near-infrared light signal and converts it into an electrical signal, which is then emitted as sound by a speaker. The receiving mobile phone decodes and reconstructs the transmitted image information via the Robot36 App. Figure 10 As shown, even with a sheet of paper in between, image information can be transmitted with almost no noticeable distortion, demonstrating the application potential of the FASnI3-BDADI IO perovskite photodetector in optical communication.

[0053] Conclusion: A high-performance lead-free tin-based perovskite photodetector was successfully fabricated by synergistically integrating molecular additive engineering with an inverse opal photonic structure. The BDADI additive effectively modulates the crystallization process of FASnI3 and inhibits Sn... 2+ Oxidation was used to reduce defect density and optimize film quality. Based on this, an inverse opal structure was successfully fabricated, and its slow photon effect was utilized to further enhance light absorption and carrier transport. The final FASnI3-BDADI inverse opal photodetector exhibited 5.90 AW light absorption. -1 High responsiveness and 1.06 × 10 14 Jones's specific detectivity demonstrates excellent operational and long-term stability even in unpackaged conditions. This device also enables near-infrared covert optical communication with anti-interference capabilities, achieving high-fidelity image reconstruction and reliable time-domain encoded signal decoding, highlighting the enormous potential of lead-free tin-based perovskite photodetectors in secure near-infrared optoelectronics and communication applications.

[0054] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 method for preparing high-performance tin-based perovskite photodetectors, characterized in that, Includes the following steps: (1) An electron transport layer is prepared on a cleaned and pretreated ITO or FTO substrate; (2) The PS ball solution is dropped onto the surface of deionized water to form an ordered monolayer PS film. Sodium dodecyl sulfate solution is added to promote the dense arrangement of PS balls. The substrate is tilted and the PS monolayer film is picked up on the electron transport layer. The film is dried at 55~65 ℃ for 5~30 min to form a PS film. (3) Spin-coating FASnI3-BDADI precursor solution onto PS film, followed by annealing, template removal, and re-annealing to obtain an inverse opal perovskite layer; (4) Spin-coating P3HT solution onto the inverse opal perovskite layer, annealing to obtain the P3HT hole transport layer, evaporating metal electrodes to complete the device fabrication.

2. The production method according to claim 1, characterized by, In step (2), the concentration of the PS ball solution is 1~2wt%, and the diameter of the PS ball is 300~1500 nm.

3. The production method according to claim 1, characterized by, In step (2), the sodium dodecyl sulfate solution is prepared by dissolving sodium dodecyl sulfate in a mixed solvent of ethanol and deionized water in a volume ratio of (1~2):(1~2), and the concentration is 1~3 g / L.

4. The production method according to claim 1, characterized by, In step (3), the concentration of FASnI3 in the FASnI3-BDADI precursor solution is 0.6~1.0 mol / L, and the amount of BDADI added is 1.5~8.5 mg / mL.

5. The production method according to claim 1, characterized by, In step (3), the method for removing the template is to soak the sample in toluene for 0.5 to 1.5 minutes and repeat 2 to 4 times; annealing means annealing at 35 to 45 °C for 1 to 3 minutes, and then annealing at 85 to 95 °C for 1 to 2 minutes; re-annealing means annealing at 85 to 95 °C for 5 to 15 minutes.

6. The production method according to claim 1, characterized by, In step (4), P3HT is dissolved in chlorobenzene to obtain a P3HT solution with a concentration of 10~15 mg / mL; annealing treatment refers to annealing at 90~100 ℃ for 5~15 min.

7. The production method according to claim 1, characterized by, In step (1), the electron transport layer is TiO2, which consists of a dense TiO2 layer and a mesoporous TiO2 layer. The preparation process of the dense TiO2 precursor solution is as follows: anhydrous ethanol, tetrabutyl titanate, nitric acid and ultrapure water are mixed in a volume ratio of (4~6):1:(0.1~0.3):(0.1~0.3). The mesoporous TiO2 precursor solution is obtained by mixing anhydrous ethanol and TiO2 slurry in a mass ratio of (6~8):

1. First, the dense TiO2 precursor solution is spin-coated on the substrate and annealed at 490~510 ℃ for 20~40 minutes. Then, the mesoporous TiO2 precursor solution is spin-coated on the dense TiO2 layer and annealed at 90~110 ℃ for 5~15 minutes and then annealed at 490~510 ℃ for 20~40 minutes to obtain the TiO2 electron transport layer.

8. The production method according to claim 4, characterized by, The preparation process of the FASnI3-BDADI precursor solution in step (3) is as follows: FAI, SnI2, and SnF2 are respectively dissolved in a mixed solvent of DMSO and DMF in a volume ratio of 4:1 to obtain a FASnI3 solution according to a molar ratio of 1:1:0.1, 1-5 mg of BDADI is added to 500-700 μL of the FASnI3 solution, and stirring is performed at 25-35 °C for 2-4 h to obtain a FASnI3-BDADI precursor solution with a FASnI3 concentration of 0.6-1.0 mol / L.

9. The high-performance tin-based perovskite photodetector prepared by the preparation method of any one of claims 1 to 8.

10. The application of the high-performance tin-based perovskite photodetector of claim 9 in covert optical information transmission.

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