A composite active layer for photoelectric detection, a wide-band high-sensitivity photoelectric detector and a preparation method thereof

Abstract

The application discloses a composite active layer for photoelectric detection, a wide-band high-sensitivity photoelectric detector and a preparation method thereof, relates to the technical field of photoelectric detection, and solves the problems that the wide-band response of an existing detector is not comprehensive, the responsivity and sensitivity are limited under low light intensity, and the response speed and stability are difficult to be simultaneously considered. The active layer comprises a perovskite light absorption layer and a BHJ bulk heterojunction layer attached to the surface of the perovskite light absorption layer; wherein the BHJ bulk heterojunction layer is composed of PTB7-Th and SiOTIC-4F. The detector comprises, from bottom to top, an ITO conductive substrate layer, a SnO2 electron transport layer, the composite active layer for photoelectric detection, a PTAA hole transport layer and a silver electrode layer. The detector has the core advantages of wide band, high sensitivity, fast response and high stability, and has good practical application value and broad market prospect in the fields of photoelectric detection such as environmental monitoring, biological imaging, optical communication, security monitoring and industrial detection.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, specifically to a composite active layer for photoelectric detection, a wide-band high-sensitivity photodetector, and its fabrication method. Background Technology

[0002] As a core component for converting optical signals into electrical signals, photodetectors play an irreplaceable role in many fields, including modern information technology, industrial production, and healthcare. With continuous technological advancements, various application scenarios are placing increasingly stringent demands on the performance of photodetectors. These demands not only require broad spectral response capabilities to cover more wavelengths of optical signals, but also high responsivity and sensitivity under low light intensity conditions, while simultaneously ensuring both rapid response speed and long-term stable operation.

[0003] In recent years, perovskite materials have gradually become a research hotspot in the field of photoelectric detection due to their unique optical and electrical properties, such as wide absorption spectral range, high light absorption coefficient, long carrier diffusion length, and excellent solution processability. Photodetectors based on perovskite materials have shown great development potential, and related research has made significant progress. However, existing photodetectors still face many technical bottlenecks, making it difficult to meet the stringent requirements of practical applications: First, they lack wide-band response coverage. Traditional semiconductor-based detectors can usually only achieve effective response within specific narrow bands, while existing perovskite-based detectors, although performing well in the visible band, have weak response capabilities in the ultraviolet or near-infrared bands, making it difficult to achieve efficient detection across the entire spectrum. Second, their response performance under low light intensity is limited. Due to the easy formation of defect states on the surface of perovskite thin films, photogenerated carrier recombination losses are severe, resulting in insufficient responsivity and sensitivity of the detector under weak light signals, making it difficult to break through high-level detection rates. Third, it is difficult to balance response speed and stability. On the one hand, the ion migration characteristics of perovskite materials and the charge transport impedance of heterojunction interfaces lead to long device response times, limiting their application in high-speed optical signal detection scenarios. On the other hand, perovskite materials are sensitive to oxygen and moisture in the environment, and the compatibility of heterojunction interfaces is poor, which can easily lead to rapid degradation of device performance during long-term use, resulting in insufficient environmental stability and operational reliability.

[0004] To address these issues, researchers have attempted improvements through various methods, including compositional manipulation, interface modification, and device structure optimization. For example, they have adjusted the band structure of perovskite materials by doping to broaden the spectral response range; used surface passivators to modify the surface of perovskite films to reduce defect state density; and designed novel device structures to optimize charge separation and transport paths. However, existing improvement schemes often only optimize a single performance indicator, making it difficult to achieve a synergistic improvement in wide-band response, high sensitivity, fast response, and high stability. For instance, some schemes can broaden the spectral response range but sacrifice response speed or stability; while schemes focusing on stability improvement may lead to a decrease in responsivity or detectivity. Furthermore, existing heterojunction interface engineering designs often focus on modifying a single interface, failing to fully consider the band matching and charge transport synergy between the perovskite active layer and the auxiliary transport layer. This results in significant interface charge recombination losses, and the efficiency of carrier separation and transport needs further improvement.

[0005] Therefore, developing a photodetector that can simultaneously address issues such as insufficient wideband response coverage, limited response performance under low light intensity, and difficulty in balancing response speed and stability, and achieving synergistic optimization of multiple performance indicators, is of great significance for promoting the development of photodetector technology and expanding its application scope. Summary of the Invention

[0006] To address the technical challenges of incomplete wideband response coverage, limited responsivity and sensitivity under low light intensity conditions, and difficulty in simultaneously achieving both response speed and stability in existing photodetectors, this invention proposes a composite active layer for photodetection, a wideband high-sensitivity photodetector, and its fabrication method.

[0007] The specific technical solution of the present invention is as follows: A composite active layer for photoelectric detection includes a perovskite light-absorbing layer and a BHJ bulk heterojunction layer attached to the surface of the perovskite light-absorbing layer. The molecular formula of the perovskite light-absorbing layer is Cs. 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb (I 0.83 Br 0.17 )3; The BHJ body heterojunction layer is composed of conjugated polymer donor material PTB7-Th and non-fullerene acceptor material SiOTIC-4F.

[0008] The present invention also provides a method for preparing the above-mentioned composite active layer for photoelectric detection, comprising the following steps: S1. Add PbI2, FAI, PbBr2, and MABr to a mixed solvent of DMF and DMSO to obtain a mixed solution; dissolve CsI in DMSO to obtain a CsI solution; then add the CsI solution to the above mixed solution to obtain a perovskite precursor solution. S2. In a nitrogen glove box, a two-step spin coating process is used to prepare a perovskite thin film. After spin coating, annealing is performed to obtain a perovskite light-absorbing layer. S3. The conjugated polymer donor material PTB7-Th and the non-fullerene acceptor material SiOTIC-4F were mixed and dissolved in chlorobenzene solvent, and stirred at room temperature to obtain BHJ solution. S4. In a nitrogen glove box, spin-coat the BHJ solution onto the surface of the perovskite light absorption layer, and then perform annealing treatment to obtain a composite active layer for photoelectric detection.

[0009] Preferably, the ratio of PbI2, FAI, PbBr2, MABr, DMF, and DMSO is 1.1 mmol: 1 mmol: 0.2 mmol: 0.2 mmol: 800 μL: 200 μL; the ratio of CsI to DMSO is 1.5 mmol: 900 μL; and the volume ratio of the CsI solution to the mixed solution is 5:95.

[0010] Preferably, the two-step spin coating process in step S2 is as follows: spin coating for 6s and 50s respectively under two consecutive spin coating programs of 600rpm and 4000rpm; at the 20th second, 500 μL of anhydrous diethyl ether is added dropwise onto the film at a uniform rate.

[0011] The annealing process was performed at a temperature of 150°C for 30 minutes.

[0012] Preferably, the ratio of the conjugated polymer donor material PTB7-Th, the non-fullerene acceptor material SiOTIC-4F, and the chlorobenzene solvent in step S3 is 8 mg: 12 mg: 1 mL; The stirring time is 6-10 hours.

[0013] Preferably, in step S4, the spin coating speed is 3000 rpm and the spin coating time is 30 s; the annealing temperature is 80℃ and the annealing time is 20 min.

[0014] The present invention also provides a wide-band high-sensitivity photodetector, which comprises, from bottom to top, an ITO conductive substrate layer, a SnO2 electron transport layer, a composite active layer for photodetection, a PTAA hole transport layer, and a silver electrode layer.

[0015] The present invention also provides a method for fabricating the above-mentioned wideband high-sensitivity photodetector, comprising the following steps: S1. The ITO conductive substrate is sequentially cleaned, dried, and treated with ultraviolet ozone. S2. The SnO2 colloidal dispersion was mixed with deionized water and then ultrasonically treated to obtain a SnO2 precursor solution. The SnO2 precursor solution was spin-coated onto an ITO conductive substrate and then annealed to obtain a SnO2 electron transport layer. S3. Prepare the composite active layer for photoelectric detection above the SnO2 electron transport layer; S4. Dissolve PTAA in toluene to obtain a PTAA solution; in a nitrogen glove box, spin-coat the PTAA solution uniformly onto the surface of the photoelectric detection composite active layer, and then anneal it to obtain a PTAA hole transport layer. S5. A silver electrode is deposited on the hole transport layer of the PTAA using a vacuum evaporation method to obtain a photodetector based on a perovskite heterojunction.

[0016] Preferably, in step S2, the volume ratio of SnO2 colloidal dispersion to deionized water is 1:3; the ultrasonic treatment time is 4-8 hours; the spin coating speed is 5000 rpm and the time is 30 seconds; the return treatment temperature is 150°C and the time is 30 minutes.

[0017] Preferably, in step S4, the ratio of PTAA to toluene is 2.5 mg: 1 mL; the spin coating speed is 4500 rpm and the time is 30 s; the annealing temperature is 105 °C and the time is 12 min.

[0018] Compared with existing technologies, this invention solves the technical problems of incomplete wide-band response coverage, limited responsivity and sensitivity under low light intensity conditions, and difficulty in simultaneously achieving response speed and stability in existing photodetectors. The specific beneficial effects are as follows: 1. This invention utilizes the combined superposition effect of perovskite and organic non-fullerene heterojunction to compensate for the spectral absorption shortcomings of a single perovskite active layer, enabling the detector's spectral response range to fully cover the ultraviolet-visible-near-infrared broadband band, thus meeting the multi-band photoelectric detection needs in different scenarios.

[0019] 2. This invention utilizes the precise control of energy level matching between layers through the alkyl chains, cyano groups, and sulfur atoms of organic material molecules to effectively passivate perovskite surface defects, significantly reduce charge recombination losses at the heterojunction interface, and greatly enhance the separation and transport efficiency of photogenerated carriers, achieving high-sensitivity detection with a detectivity of up to 10. 15 Jones and above.

[0020] 3. While achieving high sensitivity, the structural design of this invention simultaneously reduces the detector response time to the millisecond level and possesses photoelectric response characteristics with a wide dynamic range. This achieves synergistic optimization of high sensitivity, fast response, and wide dynamic range, resulting in comprehensive detection performance far exceeding that of traditional perovskite photodetectors.

[0021] 4. The introduction of BHJ material in this invention not only optimizes photoelectric performance, but also effectively improves the hydrophobicity of the active layer, reduces the erosion of the perovskite layer by water vapor and air, optimizes the perovskite crystal structure, inhibits crystal deterioration and phase separation, significantly improves the environmental adaptability of the device, and enables it to maintain stable photoelectric response characteristics in complex environments, thereby greatly improving long-term operational reliability.

[0022] The perovskite heterojunction photodetector of this invention has a simple and controllable fabrication process with good repeatability. The raw materials are readily available and inexpensive. The fabricated detector has the core advantages of wide band, high sensitivity, fast response, and high stability. It has good practical application value and broad market prospects in photoelectric detection-related fields such as environmental monitoring, biological imaging, optical communication, security monitoring, and industrial detection. Attached Figure Description

[0023] Figure 1 A schematic diagram of the structure of the wideband high-sensitivity photodetector provided by the present invention; Figure 2 The photodetectors of Example 1 and Comparative Example 1 are IV characteristic test curves under dark and light conditions. Figure 3 The IT response curves of the photodetectors of Example 1 and Comparative Example 1 under different wavelength illumination conditions are shown. Figure 4 The detectivity of the photodetectors in Example 1 and Comparative Example 1 at different wavelengths; Figure 5 The responsivity of the photodetectors in Example 1 and Comparative Example 1 at different wavelengths; Figure 6 The external quantum efficiency of the photodetectors of Example 1 and Comparative Example 1 at different wavelengths; Figure 7 The water contact angle test diagrams are shown for the original Perovskite and Perovskite-BHJ in Comparative Example 1 and Example 1. Figure 8 The XRD stability test results are shown for the original Perovskite and Perovskite-BHJ in Comparative Example 1 and Example 1. Figure 9 The stability test curve of the photodetector of Example 1 for 1000s under ambient humidity of approximately 50% and different wavelengths of light is shown. Detailed Implementation

[0024] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0025] The conjugated polymer donor material PTB7-Th and the non-fullerene acceptor material SiOTIC-4F used in the following examples were purchased from Beijing Aogtech Technology Co., Ltd. Their structural formulas are as follows: , .

[0026] Example 1. The ITO conductive substrate was ultrasonically cleaned for 20 minutes each with dish soap, deionized water, ethanol and acetone, and then dried in an oven. The cleaned and dried ITO conductive substrate was subjected to 30 minutes of ultraviolet ozone treatment. Preparation of SnO2 precursor solution: SnO2 colloidal dispersion was mixed with deionized water at a volume ratio of 1:3 and ultrasonicated in an ultrasonic machine for 4-8 hours to finally obtain SnO2 precursor solution. On the treated ITO conductive substrate, 80~150μL of SnO2 precursor solution was spin-coated. After spin-coating at 5000rpm for 30s, the substrate was annealed at 150℃ for 30min to obtain the SnO2 electron transport layer. Preparation of CsFAMA perovskite precursor solution: 1.1 mmol PbI2, 1 mmol FAI, 0.2 mmol PbBr2, and 0.2 mmol MABr were added to a mixed solvent of 800 μL DMF and 200 μL DMSO; simultaneously, 1.5 mmol CsI was dissolved in 900 μL DMSO; then, the CsI solution was added to the above solution at a volume ratio of 5:95 (CsI: the above mixed solution) to obtain the CsFAMA perovskite precursor solution. The SnO2 electron transport layer was transferred to a nitrogen glove box, and a perovskite thin film was prepared by a two-step spin coating process: spin coating was performed for 6s and 50s at two consecutive spin coating programs of 600rpm and 4000rpm, respectively. At the 20th second, 500 μL of anhydrous diethyl ether was added dropwise onto the film at a uniform rate. After spin coating, the film was annealed at 150℃ for 30min to obtain the Perovskite light-absorbing layer. Preparation of BHJ solution: 8 mg of conjugated polymer donor material PTB7-Th and 12 mg of non-fullerene acceptor material SiOTIC-4F were mixed and dissolved in 1 mL of chlorobenzene solvent. The mixture was stirred at room temperature for 6-10 h to finally obtain BHJ solution. In a nitrogen glove box, BHJ solution was uniformly spin-coated onto the surface of the Perovskite light-absorbing layer cooled to room temperature at a speed of 3000 rpm for 30 s. Then, it was annealed at 80 °C for 20 min to obtain the CsFAMA perovskite / BHJ composite active layer. Preparation of PTAA hole transport layer solution: 2.5 mg PTAA was dissolved in 1 mL toluene to obtain PTAA hole transport layer solution; In a nitrogen glove box, the PTAA hole transport layer solution was uniformly spin-coated onto the surface of the composite active layer at room temperature at a speed of 4500 rpm for 30 s, and then annealed at 105 °C for 12 min to obtain the hole transport layer. A 100 nm thick silver electrode was deposited on the hole transport layer using vacuum evaporation to obtain a photodetector.

[0027] like Figure 1 As shown, the structure of the broadband high-sensitivity photodetector based on perovskite heterojunction in Embodiment 1 of the present invention is ITO / SnO2 / Perovskite-BHJ / PTAA / Ag.

[0028] Comparative Example 1. The ITO conductive substrate was ultrasonically cleaned for 20 minutes each with dish soap, deionized water, ethanol and acetone, and then dried in an oven. The cleaned and dried ITO conductive substrate was subjected to 30 minutes of ultraviolet ozone treatment. Preparation of SnO2 precursor solution: SnO2 colloidal dispersion and deionized water were mixed at a volume ratio of 1:3 and ultrasonicated in an ultrasonic machine for 4-8 hours to finally obtain SnO2 precursor solution; On the treated ITO conductive substrate, 80~150μL of SnO2 precursor solution was spin-coated. After spin-coating at 5000rpm for 30s, the substrate was annealed at 150℃ for 30min to obtain the SnO2 electron transport layer. Preparation of CsFAMA perovskite precursor solution: 1.1 mmol PbI2, 1 mmol FAI, 0.2 mmol PbBr2, and 0.2 mmol MABr were added to a mixed solvent of 800 μL DMF and 200 μL DMSO; simultaneously, 1.5 mmol CsI was dissolved in 900 μL DMSO; then, the CsI solution was added to the above solution at a volume ratio of 5:95 (CsI: the above mixed solution) to obtain the CsFAMA perovskite precursor solution. The SnO2 electron transport layer was transferred to a nitrogen glove box, and a perovskite thin film was prepared by a two-step spin coating process: spin coating was performed for 6s and 50s at two consecutive spin coating programs of 600rpm and 4000rpm, respectively. At the 20th second, 500 μL of anhydrous diethyl ether was added dropwise onto the film at a uniform rate. After spin coating, the film was annealed at 150℃ for 30min to obtain the Perovskite light-absorbing layer. Preparation of PTAA hole transport layer solution: 2.5 mg PTAA was dissolved in 1 mL toluene to obtain PTAA hole transport layer solution; In a nitrogen glove box, the PTAA hole transport layer solution was uniformly spin-coated onto the surface of the Perovskite perovskite light absorption layer cooled to room temperature at a speed of 4500 rpm for 30 s. Then, it was annealed at 105 °C for 12 min to obtain the hole transport layer. A 100 nm thick silver electrode was deposited on the hole transport layer using vacuum evaporation to obtain a photodetector.

[0029] Example of results. The IV characteristic test curves of the photodetectors of Example 1 and Comparative Example 1 under dark and light conditions are shown in the figure. Figure 2 Figure (a) shows the curve corresponding to Comparative Example 1, and (b) shows the curve corresponding to Example 1. It can be seen that under different wavelengths of light and in dark environments, the photocurrent-to-dark current ratio of the detector of this invention is as high as 10. 3 The magnitude indicates that the introduction of BHJ effectively passivates perovskite defects, suppresses carrier recombination, and broadens the spectral response range, significantly improving the detector's signal-to-noise ratio and detection sensitivity.

[0030] The IT response curves of the photodetectors of Example 1 and Comparative Example 1 under different wavelength illumination conditions are shown in the figure. Figure 3The left side (a) shows the curve corresponding to Comparative Example 1, and the right side (b) shows the curve corresponding to Example 1. It can be seen that after introducing BHJ, the curve exhibits a clear and significant step change in photocurrent, and the photocurrent signal intensity in the infrared band is identifiable and shows no significant attenuation. This proves that the introduction of BHJ enables the detector to achieve effective photoelectric response in the infrared region, directly broadening the detection band. Furthermore, it effectively passivates defects in the perovskite thin film, suppresses nonradiative recombination, and reduces defect density, significantly optimizing the response performance.

[0031] based on Figure 3 IT curve and formula (D*=R) The detectivity of the photodetectors of Example 1 and Comparative Example 1 at different wavelengths was calculated, and the results are shown in the figure. Figure 4 The left side shows the curve corresponding to Comparative Example 1, and the right side shows the curve corresponding to Example 1. The results show that the material used in this invention effectively achieves spectral broadening and defect passivation, and one of the core performance indicators of the detector, the detectivity, increases from 10 in Comparative Example 1. 12 Jones was upgraded to 10 in Example 1. 15 Jones.

[0032] based on Figure 3 IT curve and formula (R= The responsivity of the photodetectors of Example 1 and Comparative Example 1 at different wavelengths was calculated, and the results are shown in the figure. Figure 5 The left side shows the curve corresponding to Comparative Example 1, and the right side shows the curve corresponding to Example 1. The results show that the material used in this invention achieves spectral broadening and defect passivation, and one of the core performance indicators of the detector, the responsivity, is improved from 20 mA / W in Comparative Example 1 to 400 mA / W in Example 1.

[0033] based on Figure 3 IT curve and formula (EQE= The external quantum efficiency of the photodetectors of Example 1 and Comparative Example 1 at different wavelengths was calculated, and the results are shown in [the table below]. Figure 6 The left side shows the curve corresponding to Comparative Example 1, and the right side shows the curve corresponding to Example 1. The results show that the material used in this invention achieves spectral broadening and defect passivation, and the external quantum efficiency, one of the core performance indicators of the detector, is increased from 50% in Comparative Example 1 to 800% in Example 1.

[0034] Figure 7 The figures show the water contact angle test results of PDs prepared in Comparative Example 1 and Example 1 of this invention, using the original Perovskite as the active layer and the modified PDs using Perovskite-BHJ as the active layer. As can be seen from the figures, the introduction of BHJ increases the water contact angle of the active layer, enhances hydrophobicity, and is beneficial for improving the humidity stability of the perovskite film.

[0035] Figure 8 The XRD patterns of the active layers of Comparative Example 1 and Example 1 after 0 days and 30 days were used to observe the changes in diffraction peaks of the perovskite characteristic crystal planes (110, 220, 310). This figure provides a supplementary characterization of humidity stability / structural stability. It can be seen that in the Comparative Example, after 30 days of room temperature storage, the intensity of the main characteristic peak at 110 decreased, and the peak shape became broadened and blurred. However, in Example 1, after 30 days of room temperature storage, the positions of the characteristic peaks at 110, 220, and 310 remained unchanged, and the peak shapes remained sharp and symmetrical, with the crystal plane characteristics almost identical to the fresh pattern from day 0. This demonstrates that the active layer of this invention can ensure the long-term stability of the perovskite crystal structure, ultimately achieving stable operation of the device under actual illumination.

[0036] Figure 9 The figures show the stability test curves of the photodetectors of Example 1 and Comparative Example 1 under different wavelengths of light at an ambient humidity of approximately 50% for 1000 seconds. As can be seen from the figures, the PDs of Example 1 exhibit good stability under specific power illuminations of 300nm, 500nm, 700nm, and 1300nm.

[0037] In summary, the improvement in detector detectivity, responsivity, and external quantum efficiency, as well as the broadening of the response range, are mainly due to the introduction of BHJ. Its functions include improving the quality of the absorber layer film, reducing nonradiative recombination and defect density, and optimizing the separation and extraction efficiency of charge carriers.

[0038] The above description is merely a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made under the principles and spirit of the present invention should be included within the scope of protection of the present invention. The scope of protection of this patent shall be determined by the appended claims.

Claims

1. A composite active layer for photoelectric detection, characterized in that, It includes a perovskite light-absorbing layer and a BHJ bulk heterojunction layer attached to the surface of the perovskite light-absorbing layer; The molecular formula of the perovskite light-absorbing layer is Cs. 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb (I 0.83 Br 0.17 )3; The BHJ body heterojunction layer is composed of conjugated polymer donor material PTB7-Th and non-fullerene acceptor material SiOTIC-4F.

2. A method for preparing a composite active layer for photoelectric detection as described in claim 1, characterized in that, Includes the following steps: S1. Add PbI2, FAI, PbBr2, and MABr to a mixed solvent of DMF and DMSO to obtain a mixed solution; dissolve CsI in DMSO to obtain a CsI solution; CsI ​​solution was then added to the above mixed solution to obtain a perovskite precursor solution; S2. In a nitrogen glove box, a two-step spin coating process is used to prepare a perovskite thin film. After spin coating, annealing is performed to obtain a perovskite light-absorbing layer. S3. The conjugated polymer donor material PTB7-Th and the non-fullerene acceptor material SiOTIC-4F were mixed and dissolved in chlorobenzene solvent, and stirred at room temperature to obtain BHJ solution. S4. In a nitrogen glove box, spin-coat the BHJ solution onto the surface of the perovskite light absorption layer, and then perform annealing treatment to obtain a composite active layer for photoelectric detection.

3. The method for preparing the composite active layer for photoelectric detection according to claim 2, characterized in that, The ratio of PbI2, FAI, PbBr2, MABr, DMF, and DMSO is 1.1 mmol: 1 mmol: 0.2 mmol: 0.2 mmol: 800 μL: 200 μL; the ratio of CsI to DMSO is 1.5 mmol: 900 μL; and the volume ratio of the CsI solution to the mixed solution is 5:

95.

4. The method for preparing the composite active layer for photoelectric detection according to claim 2, characterized in that, The two-step spin coating process in step S2 is as follows: spin coating for 6s and 50s respectively under two consecutive spin coating programs of 600rpm and 4000rpm; at the 20th second, 500 μL of anhydrous diethyl ether is added dropwise onto the film at a uniform rate. The annealing process was performed at a temperature of 150°C for 30 minutes.

5. The method for preparing a composite active layer for photoelectric detection according to claim 2, characterized in that, In step S3, the ratio of the conjugated polymer donor material PTB7-Th, the non-fullerene acceptor material SiOTIC-4F, and the chlorobenzene solvent is 8 mg: 12 mg: 1 mL. The stirring time is 6-10 hours.

6. The method for preparing a composite active layer for photoelectric detection according to claim 2, characterized in that, In step S4, the spin coating speed is 3000 rpm and the spin coating time is 30 s; the annealing temperature is 80℃ and the annealing time is 20 min.

7. A wide-band high-sensitivity photodetector, characterized in that, From bottom to top, it includes an ITO conductive substrate layer, a SnO2 electron transport layer, a composite active layer for photoelectric detection as described in claim 1, a PTAA hole transport layer, and a silver electrode layer.

8. A method for fabricating a wide-band high-sensitivity photodetector as described in claim 7, characterized in that, Includes the following steps: S1. The ITO conductive substrate is sequentially cleaned, dried, and treated with ultraviolet ozone. S2. The SnO2 colloidal dispersion was mixed with deionized water and then ultrasonically treated to obtain a SnO2 precursor solution. The SnO2 precursor solution was spin-coated onto an ITO conductive substrate and then annealed to obtain a SnO2 electron transport layer. S3. Prepare the composite active layer for photoelectric detection above the SnO2 electron transport layer; S4. Dissolve PTAA in toluene to obtain a PTAA solution; in a nitrogen glove box, spin-coat the PTAA solution uniformly onto the surface of the photoelectric detection composite active layer, and then anneal it to obtain a PTAA hole transport layer. S5. A silver electrode is deposited on the hole transport layer of the PTAA using a vacuum evaporation method to obtain a photodetector based on a perovskite heterojunction.

9. The method for fabricating a wide-band high-sensitivity photodetector according to claim 8, characterized in that, In step S2, the volume ratio of SnO2 colloidal dispersion to deionized water is 1:3; the ultrasonic treatment time is 4-8 hours; the spin coating speed is 5000 rpm and the time is 30 seconds; the return treatment temperature is 150°C and the time is 30 minutes.

10. The method for fabricating a wideband high-sensitivity photodetector according to claim 8, characterized in that, In step S4, the ratio of PTAA to toluene is 2.5 mg: 1 mL; the spin coating speed is 4500 rpm and the time is 30 s; the annealing temperature is 105 °C and the time is 12 min.

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