A self-powered photoelectric detector based on a Cs2CuBiI6 thin film and a preparation method thereof

Abstract

The application belongs to the technical field of semiconductor photoelectric detection, and particularly relates to a self-powered photoelectric detector based on a Cs2CuBiI6 thin film and a preparation method thereof. 61 The structure is composed of a glass substrate, a PEDOT:PSS conductive polymer layer, a Cs2CuBiI6 thin film layer, a PC The technical scheme disclosed by the application realizes the preparation of a non-lead Cs2CuBiI6 thin film by using a simple preparation method, overcomes the defects of instability and lead toxicity of a traditional perovskite structure, and the prepared photoelectric detector has excellent photoelectric detection performance such as fast response speed, which is of great significance for simplifying the process of a perovskite photoelectric detector, being environment-friendly, and further realizing practical application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor photoelectric detection, and particularly relates to a self-powered photoelectric detector based on a Cs2CuBiI6 film and a preparation method thereof. BACKGROUND

[0002] In recent years, halide lead perovskites are becoming a hot semiconductor in the field of optoelectronics due to their excellent photoelectric properties, i.e. high photoluminescence quantum yield, narrow emission peak, tunable band gap, efficient charge generation and wideband absorption. Although halide lead perovskites are developing rapidly, the presence of toxic lead hinders their further development, prompting researchers to explore lead sequestration technology (to prevent lead leakage) or develop new environmentally friendly lead-free perovskites. Among these lead-free perovskites, bismuth (Bi) -based perovskite materials are a promising candidate to replace toxic Pb-based perovskites due to their excellent environmental stability, high absorption coefficient (~ 105cm -1 ) and similar ionic radius to Pb.

[0003] Cs2ABiX6 is a double perovskite material, which is synthesized by simultaneously replacing Pb metal cations with two different elements, thereby forming a double perovskite material with alternating octahedral structures. Compared with traditional ABX3 perovskite materials, CsABiX6 has higher structural stability and environmental friendliness. In addition, they have a relatively narrow band gap width (about 2.0 electron volts) and good light absorption performance, and have good application prospects in new optical detectors (C.C. Wu, Q.H. Zhang, Y. Liu, W. Luo, X. Guo, Z. Huang, H. Ting, W.H. Sun, X.R. Zhong, S.Y. Wei, S.F. Wang, Z.J. Chen, and L.X. Xiao, Adv. Sci. 1700759 (2017); E.T. McClure, M.R. Ball, W. Windl, and P.M. Woodward, Chem. Mater. 28, 1348 (2016)). Currently, the reported perovskite-based photoelectric detectors are all based on CH3NH3PbX3 and CsPbX3 material systems, and the instability of the materials themselves and the lead toxicity are the main bottlenecks limiting the practical application of this type of device.

[0004] Therefore, it is necessary to conduct in-depth research on perovskite materials, and on the basis of optimizing the preparation process, the material can also achieve high-quality imaging when applied to self-powered photoelectric detectors and reduce harm to the human body. SUMMARY

[0005] In combination with the problems in the prior art, the present application aims at solving the problems of complex process, high cost, high energy consumption and the like in the prior art, and provides a self-powered photoelectric detector based on a Cs2CuBiI6 thin film and a preparation method thereof, which is simple in operation and has excellent photoelectric detection performance.

[0006] To achieve the above-mentioned application purposes, the specific technical solutions of the present application are as follows.

[0007] 1. A self-powered photoelectric detector based on a Cs2CuBiI6 thin film, comprising a substrate, wherein a PEDOT:PSS conductive polymer layer, a Cs2CuBiI6 thin film layer, a PCBM thin film layer, a BCP layer and a silver electrode are sequentially arranged on the substrate. 61 61

[0008] Preferably, the substrate is ITO glass with a thickness of 1.0-1.1 mm.

[0009] Preferably, the PEDOT:PSS conductive polymer layer has a thickness of 160-180 nm, the Cs2CuBiI6 thin film layer has a thickness of 90-110 nm, the PCBM thin film layer has a thickness of 90-110 nm, and the BCP layer has a thickness of 60-80 nm. 61 61

[0010] The above-mentioned self-powered photoelectric detector based on a Cs2CuBiI6 thin film, wherein the preparation method of Cs2CuBiI6 is as follows:

[0011] (1) According to the proportion, CsI, CuI, BiI3, hydroiodic acid and hypophosphorous acid are mixed and heat-treated at 80℃ until completely dissolved;

[0012] (2) The completely dissolved solution is gradually heated to 180-190℃ within 4 hours, and then heat-treated for 2-4 hours, and then the solution is cooled to room temperature within 4 hours, and then the solution is heated to 180-190℃ within 4 hours, and then heat-treated for 2-4 hours, and then the solution is cooled from 180℃ to 100℃ within 72 hours, and then the solution is cooled from 100℃ to 20℃ within 72 hours, and then heat-treated at 20℃ for 4-6 hours, and then the synthesized solid material is filtered out and washed with acetone to obtain Cs2CuBiI6 powder.

[0013] Further preferably, the preparation method of Cs2CuBiI6 is as follows:

[0014] (1) 519.62 mg of CsI, 190.45 mg of CuI and 589.69 mg of BiI3 are dissolved in 10 ml of hydroiodic acid (HI) and 2 ml of hypophosphorous acid, and heat-treated at 80℃ until completely dissolved;

[0015] (2) gradually increase the temperature of the completely dissolved solution to 180℃ within 4 hours, keep the temperature for 2 hours, then decrease the temperature of the solution to room temperature within 4 hours, increase the temperature of the solution to 180℃ within 4 hours again, keep the temperature for 2 hours, decrease the temperature of the solution from 180℃ to 100℃ within 72 hours, decrease the temperature of the solution from 100℃ to 20℃ within 72 hours, keep the temperature at 20℃ for 5 hours, filter out the synthesized solid material and wash it with acetone, and obtain a Cs2CuBiI6 powder.

[0016] 2. A preparation method of a self-powered photoelectric detector based on a Cs2CuBiI6 thin film, comprising the following steps:

[0017] (1) dissolving Cs2CuBiI6 powder in dimethyl sulfoxide, heat-treating the solution to form a Cs2CuBiI6 precursor solution for standby;

[0018] (2) dissolving PC 61 BM in chlorobenzene and stirring to dissolve for standby;

[0019] (3) dissolving BCP in isopropanol and heat-treating the solution to dissolve for standby;

[0020] (4) taking ITO glass as a substrate, cleaning and plasma treating to form a hydrophilic surface, coating PEDOT:PSS solution on the surface of the ITO substrate, then annealing at 100℃ for 10 min under nitrogen condition, cooling to form a PEDOT:PSS conductive polymer layer, then coating the Cs2CuBiI6 precursor solution on the surface of the PEDOT:PSS conductive polymer layer, and annealing at 100℃ for 10 min under nitrogen condition, cooling to form a Cs2CuBiI6 thin film layer, and then coating PC 61 BM solution and BCP solution in sequence, and annealing at 100℃ for 10 min under nitrogen condition to form PC 61 BM thin film layer and BCP layer, respectively;

[0021] (5) transferring the obtained device into a vacuum cavity, and plating a silver electrode.

[0022] Further preferably, the preparation method of the self-powered photoelectric detector based on the Cs2CuBiI6 thin film comprises the following steps:

[0023] (1) dissolving 1 mmol of Cs2CuBiI6 powder in 1 mL of dimethyl sulfoxide (DMSO), heating and stirring at 60℃ for 20 min, cooling to room temperature, and filtering with a 0.45 μm filter head for standby;

[0024] (2) dissolving 20 mg of PC 61 BM in 1 mL of chlorobenzene, stirring until the solid is completely dissolved, filtering with a 0.22 μm filter head, and storing in another clean brown bottle for standby;

[0025] (3) 7 mg BCP was dissolved in 10 mL isopropyl alcohol, heated and stirred at 40 DEG C for at least 24 h until the solid was completely dissolved to form a BCP solution for standby;

[0026] (4) ITO glass was used as a substrate, washed with deionized water, then ultrasonically cleaned with anhydrous ethanol and acetone for 20 min, then the surface liquid was blown off with nitrogen and dried in an oven, and finally the substrate was treated with oxygen plasma for 300 s to form a hydrophilic surface, the PEDOT:PSS solution was sucked with a syringe and dropped on the ITO substrate with a 0.22 mu m filter head, and spin-coated at 1000 rpm for 9 s, 3000 rpm for 30 s, and then annealed at 100 DEG C for 10 min under nitrogen, and cooled to room temperature to form a PEDOT:PSS conductive polymer layer, and the Cs2CuBiI6 precursor solution was also spin-coated at 800 rpm for 9 s, 1500 rpm for 30 s, and annealed at 100 DEG C for 10 min under nitrogen, and cooled to form a Cs2CuBiI6 thin film layer, and then PC 61 BM precursor solution and BCP precursor solution were spin-coated at 1000 rpm for 9 s, 3500 rpm for 30 s, and annealed at 100 DEG C for 10 min under nitrogen, respectively, to form PC 61 BM thin film layer and BCP layer;

[0027] (5) The obtained device was transferred into a vacuum chamber, and a silver electrode with a thickness of 150 nm was deposited under the condition of a vacuum degree of 5*10 -4 Pa.

[0028] The Cs2CuBiI6 synthesized by the technical solution disclosed in the application has a wide absorption spectrum and is inorganic and lead-free, which greatly reduces the toxicity of the device and increases the stability of the device, and the use of BCP as an electron blocking layer reduces the dark current of the device, thereby increasing the on-off ratio and responsivity of the self-powered photoelectric detection device. The method is easy to operate and control, and the prepared product has excellent performance.

[0029] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, and will be learned from the practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred detailed description of the present application will be combined with the drawings as follows, wherein:

[0031] Figure 1a scanning electron microscope (SEM) image of a Cs2CuBiI6 film;

[0032] Figure 2 a UV-Vis absorption spectrum of a Cs2CuBiI6 film;

[0033] Figure 3 a device structure of photodetectors (PDs);

[0034] Figure 4 I-V curves of the PDs under different wavelength illuminations;

[0035] Figure 5 I-T curves of the PDs under different light intensities at 0 V bias;

[0036] Figure 6 rise and fall response times of the PDs at 0 V bias;

[0037] Figure 7 responsivity and specific detectivity plots of the PDs;

[0038] Figure 8 stability of the PDs under cycling tests;

[0039] Figure 9 stability plots of the PDs in air. DETAILED DESCRIPTION

[0040] Other advantages and benefits of the present application will become apparent to those skilled in the art upon consideration of the disclosure, or can be learned by practice of the application. The application can be realized and achieved by means of the structures and combinations described in this specification and claims, or equivalents thereof. Various modifications of the described embodiments and of the specific details of the structures and combinations can be undertaken as well, without departing from the spirit of the application. It is intended that all such modifications and variations be included within the scope of the application. It is also possible to use some of the features of the disclosed embodiments in combinations other than those explicitly described. The examples provided below are intended to be illustrative of the basic principles of the application and should not be construed as limiting the scope of the application.

[0041] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0042] Before preparing the self-powered photodetector, the bismuth-based inorganic metal halide material Cs2CuBiI6 is prepared according to the following method:

[0043] (1) Dissolve 519.62 mg of CsI, 190.45 mg of Cul and 589.69 mg of BiI3 in 10 mL of hydriodic acid mixed with 2 mL of hypophosphorous acid in a beaker, then place the beaker on a heating plate to stir and heat at 80°C until completely dissolved,

[0044] (2) Then transfer the solution to an absolutely clean inner liner, in an oven, gradually heat the completely dissolved solution to 180°C within 4 hours, keep warm for 2 hours, then cool the solution to room temperature within 4 hours, use 4 hours to heat the solution to 180°C, keep warm for 2 hours, within 72 hours, cool the solution from 180°C to 100°C, then use 72 hours to cool the solution from 100°C to 20°C, keep warm at 20°C for 5 hours, filter out the synthesized solid material and wash with acetone to obtain Cs2CuBiI6 powder.

[0045] Example 1

[0046] A self-powered photoelectric detector based on Cs2CuBiI6 is prepared as follows:

[0047] (1) Dissolve 1 mmol of Cs2CuBiI6 powder in 1 mL of dimethyl sulfoxide, heat and stir at 60°C for 20 min, cool to room temperature, and filter with a 0.45 μm filter head for standby use.

[0048] (2) Dissolve 20 mg of PC 61 BM in 1 mL of chlorobenzene, stir until the solid is completely dissolved, filter with a 0.22 μm filter head, and store in another clean brown bottle for standby use.

[0049] (3) Dissolve 7 mg of BCP in 10 mL of isopropanol, heat and stir at 40°C for at least 24 h until the solid is completely dissolved to form a BCP solution for standby use;

[0050] (4) Use ITO glass with a thickness of 1 mm and an area of 4 cm 2 square as a substrate, wash it with deionized water, then ultrasonically clean it with anhydrous ethanol and acetone for 20 min each, then blow off the surface liquid with nitrogen and dry it in an oven, finally treat the substrate with oxygen plasma for 300 s to form a hydrophilic surface, use a syringe to take the PEDOT:PSS solution, and drop it on the ITO substrate with a 0.22 μm filter head, spin at 1000 rpm for 9 s, spin at 3000 rpm for 30 s, then spin-coat, and then anneal at 100°C for 10 min under nitrogen conditions, cool to room temperature to form a PEDOT:PSS conductive polymer layer, then similarly spin the Cs2CuBiI6 precursor solution at 800 rpm for 9 s and at 1500 rpm for 30 s, and anneal at 100°C for 10 min under nitrogen conditions, then cool to form a Cs2CuBiI6 thin film layer, and then respectively spin the PC 61The BM precursor solution and the BCP precursor solution were rotated at 1000 rpm for 9 s and 3500 rpm for 30 s respectively, and then annealed at 100 °C for 10 min under nitrogen atmosphere to form PC. 61 BM thin film layer, BCP layer;

[0051] (5) Transfer the device obtained in step 5 into a vacuum chamber, and place it in a vacuum chamber with a vacuum level of 5 × 10⁻⁶. -4 A silver (Ag) electrode with a thickness of 150 nm was deposited under Pa conditions. The result was as follows: Figure 3 The diagram shows the device structure of a photodetector (PD).

[0052] Upon testing, the thickness of the PEDOT:PSS conductive polymer layer in this embodiment is 160nm, the thickness of the Cs2CuBiI6 thin film layer is 90nm, the thickness of the PC61BM thin film layer is 91nm, and the thickness of the BCP layer is 65nm.

[0053] In the manufacturing process of this embodiment, the obtained Cs2CuBiI6 thin film layer was tested, and the results were as follows: Figure 1 The scanning electron microscope images shown, and Figure 2 The ultraviolet-visible absorption spectrum. Figure 1 This shows that the film has a dense morphology. Figure 2 This indicates that the thin film has a broad absorption spectrum.

[0054] The prepared photodetectors (PDs) were subjected to performance testing to obtain... Figure 4 The IV curves of PDs under illumination at different wavelengths are shown. Figure 5 The IT curves of PDs under different light intensities with a 0V bias are shown below. Figure 6 The rise and fall response times of PDs are shown below under a 0V bias. Figure 7 The responsivity and specific detectivity of the PDs are shown. Figure 8 The stability test results of the cyclically tested PDs are shown in the figure. Figure 9 Yes, this is a graph showing the stability of PDs in air.

[0055] Depend on Figures 4-9 This demonstrates that the device has a self-powered function by forming a built-in electric field in the space charge region of the internal components. At the same time, the device also exhibits excellent switching ratio, fast response speed and good stability. The above tests reflect that the photodetector device prepared in this embodiment has a fast response speed.

[0056] Finally, it is to be explained that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions, and all should be covered in the scope of the claims of the present application.

Claims

1. A self-powered photodetector based on a Cs₂CuBiI₆ thin film, comprising a substrate, characterized in that, A PEDOT:PSS conductive polymer layer, a Cs2CuBiI6 thin film layer, and a PC layer are sequentially disposed on the substrate. 61 The Cs2CuBiI6 is prepared by the following methods: BM thin film layer, BCP layer, and silver electrode; (1) According to the ratio, CsI, CuI, BiI3, hydroiodic acid and hypophosphoric acid are mixed and heat-treated at 80°C until completely dissolved; (2) Gradually raise the temperature of the completely dissolved solution to 180-190°C over 4 hours and keep it at that temperature for 2-4 hours. Then, cool the solution to room temperature over 4 hours. Raise the temperature of the solution to 180-190°C over 4 hours and keep it at that temperature for 2-4 hours. Cool the solution from 180°C to 100°C over 72 hours. Then, cool the solution from 100°C to 20°C over 72 hours. Keep the solution at 20°C for 4-6 hours. Filter out the synthesized solid material and wash it with acetone to obtain Cs2CuBiI6 powder.

2. The self-powered photodetector based on a Cs₂CuBiI₆ thin film according to claim 1, characterized in that, The substrate is ITO glass with a thickness of 1.0-1.1 mm.

3. The self-powered photodetector based on a Cs₂CuBiI₆ thin film according to claim 1, characterized in that, PEDOT: The PSS conductive polymer layer thickness is 160-180nm, the Cs2CuBiI6 thin film layer thickness is 90-110nm, and PC... 61 The BM thin film layer has a thickness of 90-110 nm, and the BCP layer has a thickness of 60-80 nm.

4. The self-powered photodetector based on a Cs₂CuBiI₆ thin film according to claim 1, characterized in that, The preparation method of Cs2CuBiI6 is as follows: (1) Dissolve 519.62 mg CsI, 190.45 mg CuI and 589.69 mg BiI3 in 10 ml hydroiodic acid and 2 ml hypophosphoric acid, and heat treat at 80 °C until completely dissolved; (2) The solution after complete dissolution is gradually heated to 180°C over 4 hours and kept at that temperature for 2 hours. Then the solution is cooled to room temperature over 4 hours. The solution is then heated to 180°C over 4 hours and kept at that temperature for 2 hours. The solution is then cooled from 180°C to 100°C over 72 hours. The solution is then cooled from 100°C to 20°C over 72 hours. The solution is kept at 20°C for 5 hours. The synthesized solid material is filtered out and washed with acetone to obtain Cs2CuBiI6 powder.

5. A method for fabricating a self-powered photodetector based on a Cs₂CuBiI₆ thin film, characterized in that, Includes the following steps: (1) Dissolve Cs2CuBiI6 powder in dimethyl sulfoxide and heat-treat to form a Cs2CuBiI6 precursor solution for later use; (2) PC 61 BM is dissolved in chlorobenzene and stirred until dissolved for later use; (3) Dissolve BCP in isopropanol and heat-treat to dissolve for later use; (4) Using ITO glass as a substrate, a hydrophilic surface is formed by cleaning and plasma treatment. A PEDOT:PSS solution is coated onto the upper surface of the ITO substrate, and then annealed at 100°C for 10 min under nitrogen atmosphere. After cooling, a PEDOT:PSS conductive polymer layer is formed. A Cs2CuBiI6 precursor solution is then coated onto the surface of the PEDOT:PSS conductive polymer layer, and annealed at 100°C for 10 min under nitrogen atmosphere. After cooling, a Cs2CuBiI6 thin film layer is formed. Then, PC is sequentially coated onto the substrate. 61 The coating was performed using BM solution and BCP solution, followed by annealing at 100°C for 10 min under nitrogen atmosphere to form PC. 61 BM thin film layer, BCP layer; (5) Transfer the obtained device into a vacuum chamber and plate it with silver electrodes.

6. The method for fabricating a self-powered photodetector based on a Cs₂CuBiI₆ thin film according to claim 5, characterized in that, Includes the following steps: (1) Dissolve 1 mmol of Cs2CuBiI6 powder in 1 mL of dimethyl sulfoxide (DMSO), heat and stir at 60 °C for 20 min, cool to room temperature and filter with a 0.45 μm filter for later use; (2) Take 20mg PC 61 Dissolve BM in 1 mL of chlorobenzene, stir until the solid is completely dissolved, filter through a 0.22 μm filter and store in another clean small brown bottle for later use; (3) Dissolve 7 mg BCP in 10 mL of isopropanol, heat and stir at 40 °C for at least 24 h until the solid is completely dissolved to form a BCP solution for later use; (4) Using ITO glass as a substrate, clean it with deionized water, then sonicate it with anhydrous ethanol and acetone for 20 min each, then blow off the surface liquid with nitrogen and dry it in an oven. Finally, treat the substrate with oxygen plasma for 300 s to form a hydrophilic surface. Use a syringe to draw up PEDOT:PSS solution and drop it onto the ITO substrate through a 0.22 μm filter. Spin coat it at 1000 rpm for 9 s and 3000 rpm for 30 s. Then anneal it at 100 °C for 10 min under nitrogen and cool it to room temperature to form a PEDOT:PSS conductive polymer layer. Then, similarly, spin coat the Cs2CuBiI6 precursor solution at 800 rpm for 9 s and 1500 rpm for 30 s and anneal it at 100 °C for 10 min under nitrogen. After cooling, form a Cs2CuBiI6 thin film layer. Then, apply PC... 61 The BM precursor solution and the BCP precursor solution were rotated at 1000 rpm for 9 s and 3500 rpm for 30 s respectively, and then annealed at 100 °C for 10 min under nitrogen atmosphere to form PC. 61 BM thin film layer, BCP layer; (5) Transfer the obtained device into a vacuum chamber, and place it in a vacuum chamber with a vacuum level of 5×10⁻⁶. -4 A silver electrode with a thickness of 150 nm was deposited under Pa conditions.

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