Preparation method of photoelectric detector based on ultraviolet response of heterojunction material
By fabricating a photodetector made of Cs2NaCeBr6-TiO2 heterojunction material, the problems of signal-to-noise ratio hysteresis and instability in existing photodetectors during solar-blind ultraviolet light monitoring were solved, achieving photoelectric performance with high responsivity, low power consumption and good stability, which is suitable for environmental monitoring and military guidance.
Patent Information
- Application Number
- CN202511128953.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-11-18
AI Technical Summary
Existing photodetector materials suffer from signal-to-noise ratio hysteresis, instability, and high power consumption in solar-blind ultraviolet light monitoring, making it difficult to meet the requirements for high responsivity and low power consumption in extreme environments. Furthermore, the application of traditional perovskite materials is limited by the toxicity and instability of heavy metals.
Cs2NaCeBr6-TiO2 heterojunction material was used to synthesize Cs2NaCeBr6 quantum dots by thermal injection method, and TiO2 core-shell structure was coated on its surface to form Cs2NaCeBr6-TiO2 quantum dots, which were used to prepare photodetectors. They were combined with FTO conductive glass and silver electrodes to form a conductive circuit.
It achieves a milliampere-level photocurrent response at a wavelength of 280 nm, a device photodetectivity ≥10¹² Jones, a response/recovery time in the μs range, good stability at 25% humidity, a photoelectric conversion efficiency of 90%, an external quantum efficiency (EQE) >95%, and low material cost.
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Figure CN120981010A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of photoelectric response materials, and particularly relates to a preparation method of a photoelectric detector based on a heterojunction material ultraviolet response. BACKGROUND
[0002] Solar blind ultraviolet light (200-280nm) has almost no natural background radiation on the ground, and has a very broad application in military guidance, environmental monitoring and other aspects. The monitoring of solar blind ultraviolet mainly relies on wide bandgap semiconductor materials, and the photoelectric detector needs to have higher responsivity, more stable response material and lower power consumption to meet the needs of extreme environment work and weak signal data transmission. However, the existing photoelectric detector material is limited by the physical limit, and the signal-to-noise ratio is lagging behind, which is difficult to further match the growing demand for optical communication.
[0003] Perovskite quantum dot materials have attracted widespread attention due to their high power conversion efficiency and simple solution processing capability. The highest photoelectric conversion efficiency in the full perovskite tandem solar cell has reached 30.1%, showing great potential in future optoelectronic applications. However, traditional perovskite materials have internal lead ion point site occupation, and heavy metal toxicity inhibits the further development of the materials. Rare earth ion replacement can be used for solar blind ultraviolet response band while reducing material toxicity. Perovskite materials are relatively unstable under external environmental stimuli due to their ionic properties. In a humid environment, perovskite can absorb moisture and undergo hydrolysis reaction, leading to material structure damage and performance degradation; exposed to oxygen, perovskite materials are easily oxidized, affecting their photoelectric properties; long-term light exposure can also cause perovskite materials to undergo photodegradation, reducing the detection rate of the detector; this inherent instability brings challenges to the long-term application of perovskite photoelectric detectors and hinders their future commercialization. Therefore, exploring and developing non-toxic and stable perovskite photoelectric response materials has very important scientific significance and social value. SUMMARY
[0004] The purpose of the embodiment of the application is to provide a preparation method of a photoelectric detector based on a heterojunction material ultraviolet response, aiming to solve the problems raised in the above background.
[0005] The embodiment of the application is implemented in the following way: a preparation method of a photoelectric detector based on a heterojunction material ultraviolet response, comprising the following steps:
[0006] Step 1: preparation of Cs2NaCeBr6 quantum dots (PQDs);
[0007] Step 2: synthesis of Cs2NaCeBr6-TiO2 quantum dot material;
[0008] Step 3: Material photodetectors (PDs) synthesis.
[0009] Further technical solutions, the step 1 includes the following specific steps:
[0010] Synthesized by hot injection method, first put 0.65 mmol of Cs(OAC), 0.45 mmol of Na(OAC) and 0.5 mmol of Ce(OAC) 3 into a three-necked flask, add 10 mL of octadecane, 2.5 mL of oleic acid and 0.65 mL of oleylamine as oil ligand, react at 120℃ for 1h until the solute is completely dissolved to clear; then, inject 0.4 mL of trimethylsilyl bromide (TMSBr) as material bromine source at 185℃, and quickly transfer it into an ice water bath to cool to room temperature after 10s reaction; finally, add toluene solution to the solution for centrifugation and cleaning, and Cs2NaCeBr6 PQDs can be obtained.
[0011] Further technical solutions, the step 2 includes the following steps:
[0012] Add different concentrations of tetrabutyl titanate to Cs2NaCeBr6 PQDs, take 5ml PQDs in a glass vial, heat at 40℃, rotate at 500rpm for 20mins, and then stand at room temperature for 2h to complete the introduction of TiO2 core-shell structure, and synthesize Cs2NaCeBr6-TiO2 PQDs.
[0013] Further technical solutions, in the step 2, different molar ratios of tetrabutyl titanate solution are added to the reaction solution in the intrinsic Cs2NaCeBr6 PQDs, and the molar ratio of Cs(OAC) to tetrabutyl titanate is 1:0.02, 1:0.06, 1:0.08 and 1:0.1 respectively.
[0014] Further technical solutions, the step 3 includes the following specific steps:
[0015] First, put the commercial etched FTO conductive glass into a beaker for cleaning, first add detergent + water in the beaker to remove surface dust and sundries, and cover the surface with plastic wrap, then ultrasonic vibration for 30 minutes, then change the cleaning solvent to methanol, and ultrasonic vibration for 30 minutes, then change the methanol to acetone to remove oily stains, and ultrasonic vibration for 30 minutes, then change the acetone to deionized water to remove the remaining cleaning solvent on the surface, and ultrasonic vibration for 30 minutes, then pour out the deionized water, and put the plastic wrap with air holes in a 70℃ oven for 5h, and dry the surface moisture for use;
[0016] The cleaned FTO conductive glass is placed into the instrument for ozone treatment for 30 minutes before spin coating, the surface is provided with hydrophilic groups and the solution adhesion is increased, the treated FTO conductive glass and the synthesized precursor solution are placed into a glove box, and the inert gas environment is ensured during the synthesis process; first, the cleaned FTO is placed on a spin coater, 100 microliters of Cs2NaCeBr6-TiO2 PQDs solution is placed on the FTO conductive glass, and the FTO conductive glass is rotated at a low speed of 600 revolutions for 12 seconds and a high speed of 2500 revolutions for 30 seconds; after five cycles of operation, the Cs2NaCeBr6-TiO2 perovskite film with a thickness of 500 nm is grown on the surface of the FTO conductive glass.
[0017] Further technical solutions, the length and width of the FTO conductive glass is 2cm*2cm, the etching width is 5mm, and the depth is 500nm.
[0018] The preparation method of the photoelectric detector based on the heterojunction material ultraviolet response provided by the embodiment of the application has the following beneficial effects:
[0019] (1) The Cs2NaCeBr6-TiO2 preparation method is simple, has excellent performance, and is low in material cost;
[0020] (2) Under the irradiation of 280nm wavelength light with a power of 91.74 microwatts, the maximum photocurrent reaches the order of milliamperes without external bias, the device light detection rate is greater than or equal to 1012 Jones, and the response / recovery time is in the order of microseconds;
[0021] (3) The Cs2NaCeBr6-TiO2 is placed under the condition of 25% humidity for 180 days, and no decomposition is visible to the naked eye, and the photoelectric conversion efficiency remains 90% of the initial value;
[0022] (4) The external quantum efficiency EQE of the Cs2NaCeBr6-TiO2 is greater than 95% in the range of 300-350nm. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The Cs2NaCeBr6 PQDs crystal structure is shown in Figure 1;
[0024] Figure 2 The emission spectrum of Cs2NaCeBr6-TiO2 PQDs with different concentrations is shown in Figure 2;
[0025] Figure 3 The structure diagram of the prepared PDs is shown in Figure 3;
[0026] Figure 4 The TEM micrograph of Cs2NaCeBr6 (left) and Cs2NaCeBr6-TiO2 (right) is shown in Figure 4;
[0027] Figure 5 EQE comparison of Cs2NaCeBr6 and Cs2NaCeBr6-TiO2;
[0028] Figure 6 Performance of Cs2NaCeBr6-TiO2 PQDs photodetector over time. DETAILED DESCRIPTION
[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.
[0030] The specific implementation of the present application will be described in detail below with reference to specific embodiments.
[0031] An embodiment of the present application provides a preparation method of a photodetector based on a heterojunction material ultraviolet response, comprising the following steps:
[0032] Step 1: preparation of Cs2NaCeBr6 quantum dots (PQDs);
[0033] The hot injection method is adopted for synthesis. First, 0.65 mmol of Cs(OAC) (cesium acetate), 0.45 mmol of Na(OAC) (sodium acetate) and 0.5 mmol of Ce(OAC)3 (cerium acetate) are placed in a three-necked flask, 10 mL of octadecane, 2.5 mL of oleic acid and 0.65 mL of oleylamine are added as oil ligands, and the solution is reacted at 120°C for 1 h until the solute is completely dissolved to be clear. Subsequently, the temperature is raised to 185°C, 0.4 mL of trimethylsilyl bromide (TMSBr) is injected as a material bromine source, and after 10 s of reaction, the solution is quickly transferred into an ice water bath to cool to room temperature. Finally, toluene solution is added to the solution for centrifugation and cleaning, and Cs2NaCeBr6 PQDs can be obtained. The crystal structure of the prepared Cs2NaCeBr6 PQDs is as shown in FIG. 1. Figure 1
[0034] Step 2: synthesis of Cs2NaCeBr6-TiO2 quantum dot material;
[0035] To the Cs2NaCeBr6 PQDs, different concentrations of tetrabutyl titanate were added dropwise. 5 ml of PQDs were taken in a glass vial, heated at 40°C with 500 rpm rotation for 20 mins, and then left to stand at room temperature for 2 h to complete the introduction of TiO2 core-shell structure to Cs2NaCeBr6-TiO2 PQDs. In the intrinsic Cs2NaCeBr6 PQDs, different molar ratios of tetrabutyl titanate solution were added to the reaction solution, and the molar ratio of Cs(OAC) to tetrabutyl titanate was 1:0.02, 1:0.06, 1:0.08, and 1:0.1, respectively. It was found that due to the introduction of the electron transport layer, the probability of electron-hole radiative recombination of the material was reduced, the carrier lifetime was increased, and the electrical performance was improved, and the best doping concentration was 10%. The emission spectra of Cs2NaCeBr6-TiO2 PQDs with different concentrations are shown in Figure 2 .
[0036] Step 3: Synthesis of material photodetectors (PDs);
[0037] First, the commercial etched FTO conductive glass (length and width 2 cm*2 cm, etched width 5 mm, depth 500 nm) was placed in a beaker for cleaning. First, add detergent + water to the beaker to remove surface dust and debris, and cover the surface with plastic wrap to prevent dust from falling into the beaker again. After ultrasonic vibration for 30 minutes, change the cleaning solvent to methanol, which is used to remove water-based solvents and residues on the surface of the FTO. After 30 minutes of vibration, change the methanol to acetone to remove oil stains. After 30 minutes of vibration, recover the acetone, then add deionized water to cover the top of the FTO to remove the remaining methanol, acetone, and other cleaning solvents on the surface. After 30 minutes of vibration, pour out the deionized water, and place the plastic wrap with air holes in a 70°C oven for 5 h to dry the surface moisture for use.
[0038] Before spin coating, the cleaned FTO conductive glass was placed in the instrument for ozone treatment for 30 mins to add hydrophilic groups to the surface and increase the adhesion of the solution. The treated FTO and the synthesized precursor solution were placed in the glove box to ensure that they were always in an inert gas environment during the synthesis process. First, place the cleaned FTO on the spin coater, and then place 100 μL of Cs2NaCeBr6-TiO2 PQDs solution on the FTO at a low speed of 600 rpm for 12 s and a high speed of 2500 rpm for 30 s. After five cycles of operation, a Cs2NaCeBr6-TiO2 perovskite film with a thickness of 500 nm will grow on the surface of the FTO. The stable transmission perovskite quantum dot PD device structure is shown in Figure 3 .
[0039] As a preferred embodiment of the present application, a Cs2NaCeBr6-TiO2 perovskite film is spin-coated on the FTO upper layer, a 100nm-thick silver electrode is plated on the surface to form a conductive loop, and various characterizations are performed to explore the successful synthesis of the Cs2NaCeBr6-TiO2 perovskite photodetector. Figure 4 On the basis of steps 1-3, the intrinsic Cs2NaCeBr6 and Cs2NaCeBr6-TiO2 are respectively tested by transmission electron microscopy (TEM), and the quantum dot film micrograph is as shown in Figure 5 As shown in the figure, with the successful coating of the shell, the quantum dot size changes significantly, and in the case of the same 20nm scale, the average particle size diameter before coating is 17nm, and the average particle size after coating reaches 33nm, and it can be seen from the overall particle that there are different core-shell structure components. EQE external quantum efficiency test is performed on Cs2NaCeBr6-TiO2 and intrinsic Cs2NaCeBr6, as shown in Figure 5 At the same time of improving stability, TiO2 inhibits carrier recombination through electron transport capture and improves photocurrent response, greatly improving the electrical performance.
[0040] As a preferred embodiment of the present application, in order to further verify the application stability of PDs, as shown in Figure 6 At an environmental humidity of 25%, the intrinsic Cs2NaCeBr6 and Cs2NaCeBr6-TiO2 are respectively stored, the external quantum efficiency of the intrinsic Cs2NaCeBr6 quenches after 120 days and completely disappears, in contrast, the Cs2NaCeBr6-TiO2 still maintains more than 90% of the initial external quantum efficiency after 180 days of storage, fully proving that the introduction of the core-shell structure greatly improves the working stability of the material.
[0041] The above only describes the preferred embodiments of the present application and does not limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for fabricating a photodetector based on the ultraviolet response of a heterojunction material, characterized in that, Includes the following steps: Step 1: Preparation of Cs2NaCeBr6 PQDs; Step 2: Synthesis of Cs2NaCeBr6-TiO2 PQDs material; Step 3: PDs synthesis.
2. The method for fabricating a photodetector based on the ultraviolet response of a heterojunction material according to claim 1, characterized in that, Step 1 includes the following specific steps: The synthesis was performed using a hot-injection method. First, 0.65 mmol of Cs(OAC), 0.45 mmol of Na(OAC), and 0.5 mmol of Ce(OAC)3 were placed in a three-necked flask. 10 mL of octadecene, 2.5 mL of oleic acid, and 0.65 mL of oleylamine were added as oily ligands. The mixture was reacted at 120 °C for 1 h until the solutes were completely dissolved and the solution was clear. Then, the temperature was raised to 185 °C and 0.4 mL of trimethylbromosilane was injected as the bromine source. After reacting for 10 s, the mixture was quickly transferred to an ice-water bath to cool to room temperature. Finally, toluene solution was added to the solution, followed by centrifugation and washing to obtain Cs2NaCeBr6 PQDs.
3. The method for fabricating a photodetector based on the ultraviolet response of a heterojunction material according to claim 1, characterized in that, Step 2 includes the following steps: Different concentrations of tetrabutyl titanate were added dropwise to Cs2NaCeBr6 PQDs. 5 ml of PQDs was placed in a glass vial and rotated at 500 rpm for 20 mins under heating conditions at 40℃. The vial was then allowed to stand at room temperature for 2 h to complete the introduction of the TiO2 core-shell structure and synthesize Cs2NaCeBr6-TiO2 PQDs.
4. The method for fabricating a photodetector based on the ultraviolet response of a heterojunction material according to claim 3, characterized in that, In step 2, the molar ratios of Cs(OAC) to tetrabutyl titanate are 1:0.02, 1:0.06, 1:0.08, and 1:0.1, respectively.
5. The method for fabricating a photodetector based on the ultraviolet response of a heterojunction material according to claim 1, characterized in that, Step 3 includes the following specific steps: First, place the commercially etched FTO conductive glass into a beaker for cleaning. Add dish soap and water to the beaker to remove surface dust and debris, and cover the surface with plastic wrap. After ultrasonically vibrating the beaker for 30 minutes, replace the cleaning solvent with methanol and vibrate for 30 minutes. Then replace the methanol with acetone to remove oily stains. After vibrating for 30 minutes, recover the acetone. Next, add deionized water to cover the top of the FTO to remove the residual cleaning solvent on the surface. After vibrating for 30 minutes, pour out the deionized water. Poke holes in the plastic wrap and place it in a 70°C oven for 5 hours to dry the surface moisture for use. Before spin coating, the cleaned FTO conductive glass was placed in the instrument for ozone treatment for 30 minutes to add hydrophilic groups to the surface and increase solution adhesion. The treated FTO conductive glass and the synthesis precursor solution were placed in a glove box to ensure that they were in an inert gas environment throughout the synthesis process. First, the cleaned FTO was placed on a spin coater, and 100 μL Cs2NaCeBr6-TiO2 PQDs solution was placed on the FTO conductive glass and rotated at a low speed of 600 rpm for 12 seconds, followed by a high speed of 2500 rpm for 30 seconds. After five cycles, a Cs2NaCeBr6-TiO2 perovskite film with a thickness of 500 nm, which is the PDs, was grown on the surface of the FTO conductive glass.
6. The method for fabricating a photodetector based on the ultraviolet response of a heterojunction material according to claim 5, characterized in that, The FTO conductive glass has a length and width of 2cm*2cm, an etching width of 5mm, and a depth of 500nm.