Preparation method of high-speed perovskite photodetector and application thereof

Abstract

The application discloses a preparation method of a high-speed perovskite photoelectric detector and application thereof, relates to the technical field of detector devices, and particularly relates to a preparation method of a high-speed perovskite photoelectric detector and application thereof. The method solves the problems of a large dark current, an unmatched energy level, a high series resistance and an unfavorable interface carrier extraction of an existing perovskite-based photoelectric detector. The method comprises the following steps: providing a substrate and pre-treating the substrate to obtain a pre-treated substrate; spin-coating a NiOx solution on the pre-treated substrate and annealing to obtain a pre-treatment film layer; spin-coating a 2Br-POOH solution on the surface of the pre-treatment film layer and annealing to obtain a first treatment piece; dropping a perovskite precursor solution on the first treatment piece and spin-coating and annealing to obtain a perovskite thin film; and evaporating electrodes on the substrate to obtain a photoelectric detector. The method promotes the longitudinal growth of perovskite crystals, is favorable for the collection and transmission of carriers, and is high in device stability and response.

Description

Technical Field

[0001] This invention relates to the field of detector device technology, and in particular to a method for fabricating a high-speed perovskite photodetector and its application. Background Technology

[0002] As is well known, optical communication and imaging are crucial in fields such as positioning and navigation, intelligent interactive systems, and image sensing. Traditional photodetectors typically rely on materials such as silicon (Si) and indium gallium arsenide (InGaAs). While their performance meets requirements, they require expensive and complex manufacturing processes. Therefore, there is an urgent need for more economical and available materials that can also provide similar performance in optical communication and imaging. Metal halide perovskites are promising candidates for next-generation photodetectors due to their excellent photoelectric properties, low-temperature solution processing and fabrication, readily available raw materials, and simple integration with complementary metal-oxide-semiconductor (CMOS) technology.

[0003] However, high-performance optical communication and imaging detectors must possess high responsivity, high detectivity, low noise, and ultrafast response speed. In recent years, researchers have improved the performance of perovskite-based detectors through compositional engineering, defect passivation, interface engineering, and crystallization control.

[0004] However, the key to designing high-performance perovskite photodetectors is the optimization of materials, structure, and other aspects. This is the result of multi-faceted collaboration, not unilateral optimization, and is a complex and time-consuming process.

[0005] Therefore, existing perovskite-based photodetectors generally suffer from defects such as dark current, interface barrier, and high series resistance, which are not conducive to the extraction of interface carriers. Summary of the Invention

[0006] The purpose of this invention is to address the problems of high dark current, interface barrier, and series resistance in existing perovskite-based photodetectors, which hinder interface carrier extraction. This invention provides a low-cost, high-performance perovskite photodetector fabrication method and its application. It employs a perovskite dual-interface passivation strategy assisted by 4-(3,6-dibromo-9-aminocarbazole-9-yl)butylphosphonic acid (2Br-POOH-EHOA) and 2-hydrazino-2-ethyl oxyacetate (EHOA), which synergistically act on the upper and lower surfaces of the perovskite layer. This synergistic optimization of the transport layer and the perovskite layer results in a better energy level match for the entire device, facilitating carrier extraction and collection. The stable and non-destructive passivation of the entire interface leads to excellent photodetector performance, exhibiting high speed and high response, demonstrating significant advantages.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for fabricating a high-speed perovskite photodetector, comprising the following steps: S1, providing a substrate and pretreating it to obtain a pretreated substrate; S2, spin-coating a NiOx solution onto the pretreated substrate and annealing it to obtain a pretreated film layer; S3, spin-coating a 2Br-POOH solution onto the surface of the pretreated film layer and annealing it to obtain a first processed object; S4, dropping a perovskite precursor solution onto the first processed object and spin-coating and annealing it to obtain a perovskite thin film; S5, thermally evaporating an electrode on the substrate to obtain a photodetector.

[0009] Furthermore, in S1, the substrate is a transparent conductive substrate that can withstand high temperatures above 150°C.

[0010] Furthermore, S1 specifically involves providing a substrate and cleaning it with a detergent, deionized water, ultrasonic treatment, and isopropanol solution, respectively. After drying, the substrate is placed in an ultraviolet ozone instrument for 25–35 minutes.

[0011] Furthermore, in S2, the NiOx solution is a NiOx deionized aqueous solution with a concentration of 8-12 mg / ml.

[0012] Further, S2 specifically involves spin-coating the NiOx solution onto the pretreated substrate at a speed of 1800–2100 rpm for 28–32 seconds, then placing it on a hot plate at 115–125°C and annealing it in air for 12–18 minutes to obtain the pretreated film.

[0013] Furthermore, in step S3, the 2Br-POOH solution is a 2Br-POOH ethanol solution with a concentration of 0.3–0.6 mg / ml.

[0014] Further, S3 specifically involves rotating and coating the pretreated film surface with 2Br-POOH solution at a speed of 2800-3200 rpm for 28-32 seconds, followed by annealing at 90-110°C in a nitrogen atmosphere for 8-12 minutes to obtain the first treated part.

[0015] Furthermore, in step S4, the perovskite precursor solution is prepared by dissolving raw materials CsI, FAI, and PbI2 in a DMF / DMSO mixed solvent at a molar stoichiometric ratio of 0.1:0.9:1 to obtain approximately 1 M of Cs0.1FA0.9PbI3 precursor solution.

[0016] Further, S4 specifically involves taking 40-50 μl of perovskite precursor solution and dropping it onto the first treatment element, then rotating and coating it at a speed of 1000-1200 rpm for 10-12 s, followed by rotating and coating it at an acceleration speed of 1000-1200 rpm / s for 5000-5500 rpm for 30 s. During this process, starting from the first 30-32 s, 280-300 μl of chlorobenzene antisolvent is lightly dropped onto the first treatment element. The mixture is then annealed at 145-150 °C for 10-15 min under an atmosphere of 2-hydrazine-2-oxyethyl acetate to obtain a perovskite film.

[0017] In another aspect, the present invention also provides the application of the above-mentioned method for fabricating a high-speed perovskite photodetector in photodetector devices.

[0018] Compared with the prior art, the advantages of the present invention are as follows:

[0019] 1. The method for fabricating a high-speed perovskite photodetector provided by the present invention introduces 2Br-POOH on the nickel oxide interface, which fills the defects in NiOx, adjusts its work function, passivates the uncoordinated Pb2+ at the bottom of the perovskite, and promotes the vertical growth of the perovskite crystal.

[0020] On the other hand, EHOA vapor treatment modifies the work function of the perovskite crystals and surface, reducing the stability of perovskite due to electron accumulation.

[0021] The aforementioned dual-interface passivation effectively promotes carrier transport rate at the interface. At the same time, interface and surface modification promotes charge extraction, suppresses interface recombination, and effectively improves device performance.

[0022] With appropriate device interface design, effective energy level alignment can be established in the perovskite layer and transport layer, resulting in favorable band bending and better carrier generation and transport. Therefore, perovskite devices employing the integrated 2Br-POOH-EHOA synergistic processing method can achieve short response times of less than 30 ns and response times greater than 10 ns. 5 The on / off ratio is less than 6.21 × 10⁻⁶. - 26 A 2 Hz -1 The noise level was also low. Furthermore, optical communication and imaging demonstrations were conducted, further demonstrating that the perovskite photodetector fabricated in this invention is a promising candidate for a low-cost, high-performance photodetector.

[0023] The preparation method of this invention employs a perovskite dual-interface passivation strategy assisted by 4-(3,6-dibromo-9-aminocarbazole-9-yl)butylphosphonic acid (2Br-POOH-EHOA) and ethyl 2-hydrazino-2-oxyethyl acetate (EHOA). These agents synergistically act on the upper and lower surfaces of the perovskite, optimizing the transport layer and the perovskite layer. This results in a better energy level match for the entire device, facilitating carrier extraction and collection, and ensuring stable, non-destructive passivation of the entire interface. Consequently, the prepared photodetector exhibits excellent performance, high speed, and high response, demonstrating significant advantages.

[0024] 2. The method for fabricating a high-speed perovskite photodetector provided by this invention has broad applicability and promising application prospects. Attached Figure Description

[0025] Figure 1 A schematic diagram of the structure and mechanism of the 2Br-POOH modified NiOx substrate of this invention.

[0026] Figure 2 This is a schematic diagram of the molecular structure and mechanism of ethyl 2-hydrazino-2-oxoacetate vapor (EHOA) of the present invention.

[0027] Figure 3 The image shows the IV curves of device 1 prepared in Example 1 of the present invention and device 2 prepared in the comparative example.

[0028] Figure 4 The transient optical response diagrams are of device 1 prepared in Example 1 of the present invention and device 2 prepared in the comparative example.

[0029] Figure 5 The diagram shows the equivalent noise measurement results of device 1 prepared in Embodiment 1 of the present invention and device 2 prepared in the comparative example.

[0030] Figure 6 This is an eye diagram of the on-off keying (OOK) data stream of the photodetector 1 prepared in Embodiment 1 of the present invention.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0032] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Detailed Implementation

[0033] Existing optical fluid control solutions have the drawback of only being able to control the unidirectional transport of liquids and being unable to control the rotational motion of fluids.

[0034] In a first aspect, the present invention provides a method for fabricating a high-speed perovskite photodetector, comprising the following steps: S1, providing a substrate and pretreating it to obtain a pretreated substrate; S2, spin-coating a NiOx solution onto the pretreated substrate and annealing it to obtain a pretreated film layer; S3, spin-coating a 2Br-POOH solution onto the surface of the pretreated film layer and annealing it to obtain a first processed object; S4, dropping a perovskite precursor solution onto the first processed object and spin-coating and annealing it to obtain a perovskite thin film; S5, thermally evaporating an electrode on the substrate to obtain a photodetector.

[0035] Understandably, please refer to Figure 1 and Figure 2 The preparation method provided by this invention introduces 2Br-POOH at the nickel oxide interface, which on the one hand fills the defects in NiOx, adjusts its work function, and passivates the uncoordinated Pb2+ at the bottom of the perovskite, and on the other hand promotes the vertical growth of the perovskite crystal. Furthermore, during the preparation process, this invention adjusts the work function of the perovskite crystal and surface through EHOA vapor treatment, which is beneficial for carrier transport and improves device stability. The preparation method of this invention, through synergistic optimization of the transport layer and the perovskite layer, makes the energy levels of the entire device more matched, which is beneficial for carrier extraction and collection. Therefore, the prepared photodetector has excellent performance, with advantages such as high speed and high response, and possesses significant superiority.

[0036] In some embodiments of the present invention, in step S1, the substrate is a transparent conductive substrate that can withstand temperatures above 150°C.

[0037] In some embodiments, the substrate is preferably an ITO or FTO substrate.

[0038] In some embodiments of the present invention, step S1 specifically involves providing a substrate and cleaning it with a detergent, ultrasonically cleaning it with deionized water, and cleaning it with isopropanol solution, respectively. After drying, the substrate is placed in an ultraviolet ozone instrument for 25-35 minutes. Specifically, after drying, the substrate is placed in an ultraviolet ozone instrument for a preferred time of 30 minutes.

[0039] In some embodiments of the present invention, in step S2, the NiOx solution is a NiOx deionized aqueous solution with a concentration of 8-12 mg / ml. Specifically, the concentration of the NiOx solution is preferably a NiOx deionized aqueous solution with a concentration of 10 mg / ml. The preparation method involves dissolving NiOx powder in deionized water to obtain a NiOx deionized aqueous solution with a concentration of 8-12 mg / ml.

[0040] In some embodiments of the present invention, S2 specifically involves rotating and coating a NiOx solution onto a pretreated substrate at a speed of 1800–2100 rpm for 28–32 seconds, then placing it on a hot plate at 115–125°C and annealing it in air for 12–18 minutes to obtain a pretreated film.

[0041] Specifically, the coating speed is preferably 2000 rpm, the coating time is preferably 30 seconds, the hot plate temperature is preferably 120℃, and the annealing time is preferably 15 minutes.

[0042] In some embodiments of the present invention, in step S3, the 2Br-POOH solution is a 2Br-POOH ethanol solution with a concentration of 0.3 to 0.6 mg / ml.

[0043] Specifically, the concentration of the 2Br-POOH solution is preferably 0.5 mg / ml.

[0044] In some embodiments of the present invention, S3 specifically involves rotating and coating a 2Br-POOH solution onto the surface of the pretreated film at a speed of 2800-3200 rpm for 28-32 seconds, followed by annealing at 90-110°C for 8-12 minutes in a nitrogen atmosphere to obtain the first treated part.

[0045] Specifically, step S3 is preferably performed by rotating and coating the pretreated film surface with 2Br-POOH solution at 3000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes in a nitrogen-filled glove box to obtain the first treated part.

[0046] In some embodiments of the present invention, in step S4, the perovskite precursor solution is prepared by dissolving raw materials CsI, FAI and PbI2 in a DMF / DMSO mixed solvent at a molar stoichiometric ratio of 0.1:0.9:1 to obtain approximately 1 M of Cs0.1FA0.9PbI3 precursor solution.

[0047] In some embodiments, the perovskite precursor solution is used after being filtered with a 0.22 μm filter.

[0048] In some embodiments of the present invention, step S4 specifically involves taking 40-50 μl of perovskite precursor solution and dropping it onto the first processing element, then rotating and coating it at a speed of 1000-1200 rpm for 10-12 s, followed by rotating and coating it at an acceleration speed of 1000-1200 rpm / s for 5000-5500 rpm for 30 s. During this process, starting from the first 30-32 s, 280-300 μl of chlorobenzene antisolvent is lightly dropped onto the first processing element, and the mixture is annealed at 145-150 °C for 10-15 min under an atmosphere of ethyl 2-hydrazine-2-oxyethyl acetate to obtain a perovskite film.

[0049] Please refer to the following: Figure 2 In the fabrication process, this invention adjusts the work function of the perovskite crystal and surface through EHOA (ethyl 2-hydrazine-2-oxyethyl acetate) vapor treatment, which is beneficial for carrier transport and improves device stability. The fabrication method of this invention, through synergistic optimization of the transport layer and the perovskite layer, makes the energy levels of the entire device more matched, which is beneficial for carrier extraction and collection. This results in a photodetector with excellent performance, exhibiting high speed and high response, demonstrating significant advantages.

[0050] In another aspect, the present invention also provides the application of the above-mentioned method for fabricating a high-speed perovskite photodetector in photodetector devices.

[0051] Example 1

[0052] 1.1 Device fabrication process

[0053] In this embodiment, an ITO glass substrate was selected as the substrate. The ITO glass substrate was cleaned with a detergent, deionized water (DI) ultrasonically, and isopropanol solution, respectively. Then, the dried glass substrate was placed in an ultraviolet-ozone instrument for 30 minutes. After applying NiOx solution to the ITO substrate by spin coating at 2000 rpm for 30 seconds, it was annealed on a hot plate at 120°C in air for 15 minutes.

[0054] The NiOx precursor solution is prepared by dissolving NiOx powder in deionized water to obtain a NiOx solution with a concentration of 10 mg / ml.

[0055] Subsequently, the 2Br-POOH buffer layer was spin-coated on a NiOx / ITO substrate at 3000 rpm for 30 s and then annealed at 100 °C for 10 min in a nitrogen-filled glove box (2Br-POOH molecules were dissolved in ethanol, with an optimal concentration of 0.5 mg ml-1).

[0056] Then, 50 μl of the perovskite precursor solution was dropped onto the prepared NiOx substrate, and spin-coated at 1000 rpm for 10 s, followed by spin-coating at 1000 rpm / s for 5000 rpm for 30 s. During this process, starting from the 32nd s, 280 μl of CB antisolvent was lightly dropped onto the wet perovskite substrate (CsI, FAI, and PbI2 were dissolved in a DMF / DMSO mixed solvent at a molar ratio of 0.1:0.9:1 to prepare a 1 M Cs0.1FA0.9PbI3 precursor solution. The perovskite precursor solution was filtered through a 0.22 μm filter before use). The film was then annealed at 150 °C for 10 min under an ethyl 2-hydrazine-2-oxyethyl acetate (EHOA) atmosphere to obtain the perovskite film. After cooling to room temperature, C60 (25nm), BCP (7nm), and silver (100nm) were sequentially thermally evaporated onto the substrate to complete the fabrication of photodetector 1.

[0057] Comparative Example

[0058] The preparation method is the same as in Example 1, except that: the 2Br-POOH solution is not coated and the annealing is not performed under an ethyl 2-hydrazine-2-oxyethyl (EHOA) atmosphere.

[0059] The specific method is as follows: An ITO glass substrate is selected as the substrate, and it is cleaned with a detergent, deionized water (DI) ultrasonically, and isopropanol solution, respectively. Then, the dried glass substrate is placed in an ultraviolet-ozone instrument for 30 minutes. A NiOx solution is then spin-coated onto the ITO substrate at 2000 rpm for 30 seconds, followed by annealing on a hot plate at 120°C in air for 15 minutes.

[0060] The NiOx precursor solution is prepared by dissolving NiOx powder in deionized water to obtain a NiOx solution with a concentration of 10 mg / ml.

[0061] Subsequently, it was annealed at 100°C for 10 min in a nitrogen-filled glove box (2Br-POOH molecules were dissolved in ethanol, with an optimal concentration of 0.5 mg / ml).

[0062] Then, 50 μl of perovskite precursor solution was dropped onto the prepared NiOx substrate, and spin-coated at 1000 rpm for 10 s, followed by spin-coating at 1000 rpm / s for 5000 rpm for 30 s. During this process, starting from the 32nd s, 280 μl of CB antisolvent was gently dropped onto the wet perovskite substrate (CsI, FAI, and PbI2 were dissolved in a DMF / DMSO mixed solvent at a molar ratio of 0.1:0.9:1 to prepare a 1 M Cs0.1FA0.9PbI3 precursor solution. The perovskite precursor solution was filtered through a 0.22 μm filter before use). Annealing was performed at 150 °C for 10 min to obtain a perovskite film. After cooling to room temperature, C60 (25 nm), BCP (7 nm), and silver (100 nm) were sequentially thermally evaporated onto the substrate, completing the fabrication of device 2. Example 1 tested the performance of device 1 prepared in Example 1.

[0063] 1.1 Test Operation

[0064] The IV curves, transient optical response, and noise level of the devices prepared in Example 1 and the comparative example 2 were measured. The eye diagram of the on-off keying (OOK) data stream of device 1 prepared in Example 1 was also tested. The results are shown in [Figure 1]. Figure 3 , Figure 4 , Figure 5 and Figure 6 . ( Figure 3-5 In this context, the target group is the experimental group (device 1), and the control group is the control group (device 2).

[0065] 1.2 Results Analysis

[0066] See Figure 3 As shown in the measurement results (Voltage represents voltage, Current represents current, Control-Dark represents the dark state of the control group, Control represents the control group, Target-Dark represents the dark state of the experimental group, Target represents the experimental group), the photodetector device 1 after 2Br-POOH-EHOA co-modification in Example 1 exhibits a smaller dark current (1.30 nA) at -0.2V, which is lower than the dark current of device 2 (3.29 nA). Simultaneously, the photocurrent of device 1 (107 μA) is larger than that of device 2 (54.5 μA), mainly due to the better surface morphology and energy level arrangement of the device.

[0067] Response speed is another important indicator of optical communication. See also Figure 4The measurement results (Time represents time, Normalized response represents normalized response, Target is the experimental group, and Control is the control group) show that the response speed of device 1 prepared in Example 1 was measured using an oscilloscope under nanosecond pulsed laser irradiation (wavelength 517nm, pulse width 18ns, laser linewidth 4nm). Figure 4 As can be seen, the photoresponse speed of the dual-interface passivated photodetector is 28.3 ns, significantly faster than that of device 2. If the active region area is further reduced, the response speed could be even faster. This faster speed is likely attributed to the excellent crystallinity and energy level alignment of the fabricated perovskite detector.

[0068] See Figure 5 As shown in the measurement results (Frequency represents frequency, Noise current density represents noise current density, Target is the experimental group, and Control is the control group), the noise current of the improved device 1 prepared in Example 1 is only 6.21 × 10⁻²⁶ A. 2 Hz -1 This is much smaller than the noise current of device 2, which is 2.21 × 10⁻²⁵ A. 2 Hz -1 Notably, all noise currents decrease linearly, indicating that 1 / f noise dominates up to 10 kHz. This low noise current level stems from enhanced thin film quality and energy level alignment.

[0069] See Figure 6 As shown in the measurement results (Time represents time, Amplitude represents amplitude), the eye diagram collected by the dual-interface passivated photodetector prepared in Example 1 has a clear outline and a speed of 1 Mbit / s, indicating the accuracy of high-speed data transmission.

[0070] In summary, the device 1 prepared in Example 1 has superior performance compared to the device 2 prepared using conventional methods, with advantages such as high speed and high response, and has strong superiority.

[0071] The above embodiments are merely one implementation of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for fabricating a high-speed perovskite photodetector, characterized in that, Includes the following steps: S1. Provide a substrate and pretreat it to obtain a pretreated substrate; S2. Spin-coat a NiOx solution onto the pretreated substrate and anneal it to obtain a pretreated film layer; S3. Spin-coat a 2Br-POOH solution onto the surface of the pretreated film layer and anneal it to obtain a first treated piece, wherein the 2Br-POOH solution is a 2Br-POOH ethanol solution with a concentration of 0.3~0.6 mg / ml; S4. Drop a perovskite precursor solution onto the first treated piece and spin-coat and anneal it to obtain a perovskite thin film, wherein the perovskite precursor solution is prepared by dissolving raw materials CsI, FAI and PbI2 in a DMF / DMSO mixed solvent at a molar stoichiometric ratio of 0.1:0.9:1 to obtain a 1 M Cs0.1FA0.9PbI3 precursor solution; S4 specifically involves dropping 40~50µl of the perovskite precursor solution onto the first treated piece and spin-coating 10~12 μl of the solution at a speed of 1000~1200 rpm. S5, then spin-coating at 1000~1200 rpm / s for 5000~5500 rpm for 30 s, during which 280~300 µl of chlorobenzene antisolvent is lightly dropped onto the first treatment material starting from the first 30~32 s. Annealing is carried out at 145~150℃ for 10~15 min under the atmosphere of ethyl 2-hydrazine-2-oxyethyl to obtain a perovskite film; S6, the electrode is thermally evaporated on the substrate to obtain a photodetector.

2. The method for fabricating a high-speed perovskite photodetector according to claim 1, characterized in that, In step S1, the substrate is a transparent conductive substrate that can withstand temperatures above 150°C.

3. The method for fabricating a high-speed perovskite photodetector according to claim 1, characterized in that, Specifically, S1 involves providing a substrate and cleaning it with a detergent, deionized water, ultrasonication, and isopropanol solution, respectively. After drying, the substrate is placed in an ultraviolet ozone instrument for 25-35 minutes.

4. The method for fabricating a high-speed perovskite photodetector according to claim 1, characterized in that, In step S2, the NiOx solution is a NiOx deionized aqueous solution with a concentration of 8-12 mg / ml.

5. The method for fabricating a high-speed perovskite photodetector according to claim 1, characterized in that, Specifically, S2 involves rotating and coating the NiOx solution onto the pretreated substrate at a speed of 1800-2100 rpm for 28-32 seconds, then placing it on a hot plate at 115-125°C and annealing it in air for 12-18 minutes to obtain the pretreated film.

6. The method for fabricating a high-speed perovskite photodetector according to claim 1, characterized in that, Specifically, S3 involves rotating and coating the pretreated film surface with 2Br-POOH solution at a speed of 2800~3200 rpm for 28~32s, followed by annealing at 90~110℃ for 8~12min in a nitrogen atmosphere to obtain the first treated part.

7. The application of a method for fabricating a high-speed perovskite photodetector according to any one of claims 1 to 6 in photodetector devices.

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