CN110767811A - Photoelectric detector of methylamine lead iodoperovskite single crystal nanowire and preparation method - Google Patents

Abstract

The invention relates to the technical field of design and preparation of micro-nano photodetectors, a methylamine lead iodide perovskite single crystal nanowire photodetector, the methylamine lead iodide perovskite single crystal nanowire photodetector is in glass Evaporated on the substrate are methylamine lead iodide perovskite nanowires with electrodes ranging from 100 to 300 nm in diameter and 100 to 200 μm in length. A one-dimensional lead iodide single crystal nanowire with a length of 100 to 200 microns and a diameter of 100 to 300 nanometers was grown by chemical vapor deposition under the catalysis of metal nano-islands. The single crystal nanowires were converted into methylamine lead iodide perovskite single crystal nanowires, the methylamine lead iodide perovskite nanowires were transferred to a glass substrate, and electrodes were evaporated to obtain methylamine lead iodide perovskite nanowires Photodetector. The invention also relates to a method for preparing a methylamine lead iodide perovskite single crystal nanowire photodetector.

Description

A kind of photodetector of methylamine lead iodide perovskite single crystal nanowire and preparation method

technical field

The invention relates to the technical field of design and preparation of micro-nano photodetectors, in particular to a metal halide perovskite single crystal nanowire and a manufacturing method thereof.

Background technique

A photodetector is an instrument that converts optical signals in a specific band into electrical signals. It has wide application prospects in the fields of optical communication, missile guidance, night vision systems, and biological sensing. Therefore, the research and development of practical micro-detectors have received extensive attention in the world. Organic/inorganic hybrid metal halide perovskite materials have excellent optoelectronic properties: high absorption coefficient, absorption spectrum covering a broad spectral region from ultraviolet to near-infrared, long exciton lifetime, long carrier transport distance, high fluorescence Yield and wavelength tunable, etc. The reported energy conversion efficiency of perovskite solar cells has exceeded 24%. In addition, optoelectronic devices such as LEDs, lasers, photodetectors, and field-effect transistors based on perovskite materials also perform well. In particular, detectors using perovskite materials as light-absorbing layers have the advantages of high intensity, high stability, and easy control.

To date, researchers have used a variety of methods to grow perovskite nanowire structures. These methods are mainly divided into two categories: solution method and chemical vapor deposition method. The chemical vapor deposition method can finely control the length, diameter and crystallinity of nanowires by controlling the substrate position, reaction temperature, reaction time, gas flow rate and gas velocity. Moreover, compared with the solution method, the incorporation of solvent is reduced in the vapor deposition process, which is expected to further improve the crystallization quality of the crystal.

In 2015, Xiong Qihua's group of Nanyang Technological University used chemical vapor deposition to grow methylamine lead iodide perovskite single crystal nanowires on Si/SiO ₂ (285 nm) substrates (Nano letters, 2015, 15(7): 4571 -4577.), according to the data in the paper, methylamine lead iodide perovskite single crystal nanowires are longer than 20 microns and about 200 nanometers in diameter. The preparation method of methylamine lead iodide perovskite single crystal nanowires is as follows: step 1, use acetone, ethanol and deionized water to clean the substrate; step 2, use chemical vapor deposition method to prepare lead iodide nanowires: the deposition temperature is 380 ℃ , the deposition time is 15 minutes; in step 3, chemical vapor deposition method is used to convert the lead iodide nanowires into methylamine lead iodide perovskite single crystal nanowires, but the methylamine lead iodide perovskite single crystal nanowires have a low density and The problem of short length, and the grown nanowires are vertical growth, easy to break during transfer, which is not conducive to the preparation of later optoelectronic devices.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: how to overcome the deficiencies in the background technology, and provide a kind of horizontal growth, high density and long length of methylamine lead iodine perovskite single crystal nanowires to prepare methylamine lead iodide perovskite single crystal Photodetectors of nanowires.

The technical scheme adopted in the present invention is: a methylamine lead iodide perovskite single crystal nanowire photodetector, the methylamine lead iodide perovskite single crystal nanowire photodetector is a vapor deposition on a glass substrate There are methylamine lead iodide perovskite nanowires with electrodes between 100 and 300 nm in diameter and 100 to 200 μm in length. A one-dimensional lead iodide single crystal nanowire with a length of 100 to 200 microns and a diameter of 100 to 300 nanometers was grown by chemical vapor deposition under the catalysis of metal nano-islands. The single crystal nanowires are converted into methylamine lead iodide perovskite single crystal nanowires, the methylamine lead iodide perovskite nanowires are transferred to the glass substrate, and the electrodes are evaporated to obtain methylamine lead iodide perovskite nanowires Photodetector.

A method for preparing a methylamine lead iodine perovskite single crystal nanowire photodetector, which is carried out according to the following steps

Step 1. Prepare evenly distributed gold nano-islands on a glass slide by vacuum thermal deposition;

Step 2: Put the powdered lead iodide medicine into the quartz boat, place the quartz boat in the center of the quartz glass tube, place the glass slide with gold nano-islands in the quartz glass tube, and place the glass slide with gold nano-islands in the quartz glass tube. The tablet is 8-10 cm away from the lead iodide drug center. Under the protection of a mixture of Ar and H ₂ volume ratio of 10:1, the pressure is adjusted to 0.02 MPa, heated to 400 °C for 20 min, and then cooled to room temperature naturally. Lead iodide single crystal nanowires were obtained on glass slides;

Step 3. Put the methyl ammonium iodide medicine into the quartz boat, place the quartz boat in the center of the quartz glass tube, place the glass slide with the lead iodide single crystal nanowires in the quartz glass tube, and place the substrate away from the medicine. The center is 6 cm, and the air is excluded. Under the protection of Ar gas, the pressure is adjusted to 0-0.01 MPa, heated to 120 °C for 90 min, and then cooled to room temperature naturally to obtain methylamine lead iodide perovskite single crystal nanowires on a glass slide. ;

Step 4. Move the methylamine lead iodide perovskite single crystal nanowires on the glass slide to the glass substrate; load a mask in the dense area of the methylamine lead iodide perovskite single crystal nanowires, and then use the vacuum thermal deposition method A gold electrode is evaporated, and the mask is removed after the evaporation is completed to obtain a methylamine lead iodide perovskite single crystal nanowire photodetector.

In step 1, a slow deposition of 0.1 Å/s was used, and the deposition thickness was 20 nm. At this time, the morphology of the gold nano-islands is a random distribution of island-like particles, which are not connected to form a thin film. It is thick enough that these isolated islands can connect to form a film.

In the fourth step, the methylamine lead iodide perovskite single crystal nanowires on the glass slide are moved to a clean glass substrate by means of contact pressure.

In step 4, a copper mesh mask is loaded on the dense area of methylamine lead iodide perovskite single crystal nanowires, and then the gold electrode is evaporated by vacuum thermal deposition method, the evaporation rate is controlled to 2 Å/s, the thickness is 50 nm, and the thickness is 50 nm. A 150 nm aluminum film was evaporated to reinforce the gold electrode, and the evaporation rate of the aluminum electrode was a constant rate of 2 Å/s. After the evaporation was completed, the copper mesh mask was removed to obtain a methylamine lead iodide perovskite single crystal nanowire photodetector.

The beneficial effects of the invention are as follows: the length of the lead iodide nanowires deposited by chemical vapor deposition under the catalysis of the metal nano-island is greatly improved, and the length of the methylamine lead iodide perovskite nanowires converted by chemical vapor deposition is also corresponding longer. The synthesis process of the invention has the advantages of simple operation, high success rate, easy control and low cost. Metal nano-islands are prepared by vacuum thermal deposition, and a large number of substrates can be prepared at one time. Slides are easy to cut and clean and are an economical substrate material. The nanowires grown in combination with chemical vapor deposition and gold nano-islands are 100 to 200 microns in length and 100 to 300 nanometers in diameter. Step 3 of the present invention converts lead iodide single crystal nanowires into methylamine lead iodide perovskite single crystal nanowires Wires, and obtained methylamine lead iodide perovskite single crystal nanowires synthesized by chemical vapor deposition much longer than reported in the literature. At present, thermal evaporation combined with patterned masks to prepare electrodes is widely used in optoelectronic devices. For coplanar photodetectors, the nanowire length is too short, which is not conducive to the electrode preparation of the device, and requires a finer mask. The relatively long nanowires provide great convenience in this respect, which is beneficial to the preparation of photodetectors and is more beneficial to the practical application of materials. Moreover, long nanowires are easier to realize the integration of devices on a single nanowire, which provides greater possibilities for device regulation.

Description of drawings

Figure 1: Optical micrographs and SEM images of methylamine lead iodide perovskite nanowire crystals;

Figure 2: Absorption and fluorescence spectra of lead iodide and methylamine lead iodide perovskite nanowire crystals;

Figure 3: XRD diffraction pattern of methylamine lead iodide perovskite nanowire crystals;

Figure 4: Dark and bright state current-voltage (I-V) curves of methylamine lead iodide perovskite nanowire photodetectors.

Detailed ways

The materials used in the present invention are: lead iodide (lead iodide), methylammonium iodide (CH ₃ NH ₃ I), glass slides, ethanol, isopropanol, deionized water, argon, hydrogen, washing detergent. The dosage is as follows:

Lead iodide: 0.15 g ± 0.001 g

CH ₃ NH ₃ I: 0.15 g ± 0.001 g

Ethanol: 50 mL ± 5 mL

Isopropyl alcohol: 50 mL±5 mL

Deionized water: 100 mL±5 mL

Dishwashing liquid: 2 mL±0.1 mL

Slide: 10 mm × 7 mm

The invention relates to a preparation method of one-dimensional methylamine lead iodide perovskite nanowires. Gold nano-islands are thermally evaporated on a glass slide cleaned with deionized water, ethanol and isopropanol, and chemical vapor deposition One-dimensional lead iodide nanowires were grown on glass slides, and the lead iodide nanowires were transformed into methylamine lead iodide perovskite single crystal nanowires by chemical vapor deposition.

The specific preparation method is as follows:

1. Selected chemicals

The chemical materials required for the preparation should be selected, and the quality, purity, concentration, fineness and precision should be controlled:

Lead iodide: solid particles, purity 99.999%

CH ₃ NH ₃ I: solid powder, purity 99.5 %

Acetone: liquid liquid, purity 99.8 %

Ethanol: liquid liquid, analytically pure

Isopropyl alcohol: liquid liquid, purity 99.8 %

Deionized water: 18.2 MΩ*cm

Glass slides: Sailing glass slides

Argon: 99.9%

Hydrogen: 99.9%

2. Cutting and cleaning of slides

The slides were cut into 10 mm × 7 mm size, ultrasonically cleaned with detergent and decontamination powder for 30 minutes, scrubbed front and back for 1 minute, ultrasonically cleaned with deionized water, ethanol, and isopropanol for 15 minutes, respectively, and stored in Isopropanol solution for use.

3. Preparation of metal seed islands

1) Check whether the vacuum thermal deposition equipment is running normally, and whether the tungsten boat is in good contact with the power supply;

2) Take a clean dried glass slide and stick it under the evaporation mask with high temperature tape;

3) Turn on the vacuum thermal deposition equipment, fix the mask on the top turntable in the chamber, pay attention to the placement process, and be careful to contaminate the substrate;

4) Put the metal on the ready-to-use tungsten boat at the bottom of the cavity;

5) Check whether the quartz crystal probe to be used in the cavity is in normal use, and adjust its position to align with the substrate to be deposited;

6) Close the chamber door, operate the vacuum thermal deposition equipment to automatically evacuate, and wait until the vacuum degree in the chamber reaches 6 ´ 10 ^-4 Pa;

7) Turn on the turntable to rotate the substrate along with it to ensure that the film layer is uniform;

8) Start heating the tungsten boat, turn on the quartz crystal probe to monitor the deposition rate, and when the rate is stable, open the large baffle and start evaporation;

9) When the film thickness monitoring reaches the required thickness, the evaporation is completed;

10) Take the sample, carefully remove the high temperature tape with tweezers, be careful not to scratch the film layer, which will affect the subsequent experiments;

11) The prepared substrate plated with the metal seed layer is stored in a glove box for later use, in order to isolate water and oxygen in the air and prevent the oxidation of the metal seed layer.

4. Preparation of one-dimensional lead iodide nanowires

1) Take a quartz glass tube with a length of 50 cm and an inner diameter of 2.54 cm for cleaning, and then put it into a drying box to dry (10min).

2) Blow the dried quartz glass tube with nitrogen for 1 min, and mark the front and end of the quartz glass tube.

3) Fix the glass slide with gold nano-islands on the top of the downstream position of the quartz glass tube (8cm from the end of the tube) with high-temperature tape, with the surface of the gold nano-islands facing down.

4) Weigh 0.15 g lead iodide medicine with a purity of 99.999%, grind it into powder, place the lead iodide medicine in a quartz boat, and push the quartz boat into the center of the quartz glass tube.

5) Put the quartz glass tube containing medicines and glass slides into the tube furnace. The front end and end of the quartz glass tube are connected to the inlet valve and the gas outlet valve respectively, and the quartz glass tube is evacuated through the gas outlet (2 min) and closed. Air outlet valve, Ar+H ₂ mixed gas (Ar 95%, H ₂ 5%) is introduced into the tube. When the pressure in the tube reaches 0.03MPa, the air outlet valve is opened to discharge the residual trace air in the tube.

6) Heat the quartz glass tube to 400 °C, keep the constant temperature at 400 °C for 20 min, set the airflow rate Ar: 30 sscm, H ₂ : 3 sccm, and adjust the pressure in the tube to 0.02 MPa by adjusting the air outlet valve.

7) After the constant temperature stage, close the inlet valve. When the pressure in the tube drops to 0 MPa, close the outlet valve and let the quartz glass tube cool to room temperature naturally, and the deposited one-dimensional lead iodide nanoparticles are obtained on the slide. Line crystals.

5. Conversion of lead iodide nanowires to methylamine lead iodide perovskite nanowires

1) Use a ruler and a marker to mark the center position of the quartz tube (marked as the drug position) and the position 6 cm away from the center (marked as the sample position);

2) Paste the lead iodide nanowire sample on the corresponding position inside the quartz tube with high temperature tape;

3) Weigh 0.15 g of MAI medicine, put it into the quartz boat, and push the quartz boat into the center of the quartz tube;

4) Put the quartz tube with the lead iodide nanowire sample and the medicine into the tube furnace, so that the medicine is facing the center of the heating zone;

5) Fix and seal the quartz tube with a flange;

6) Before heating the medicine, it needs to be vacuumed for 2 minutes, and then the inert gas Ar gas is introduced, the flow rate is 30 sccm, and the pressure in the tube is controlled between 0 Mpa and 0.01 Mpa;

7) Heat the quartz tube to 120 °C, after 90 min of reaction, stop the gas flow and seal the quartz tube.

8) After the quartz tube has cooled to room temperature, take out the sample.

6. Preparation of methylamine lead iodide perovskite nanowire photodetectors—electrode preparation

1) Attach the substrate of the grown nanowires to the clean glass substrate, apply a certain pressure, and then separate the two substrates, so that part of the nanowires are transferred to the insulating glass substrate;

2) Observe the optical micrograph of the nanowires on the transferred glass substrate, find the position where the nanowires are denser, and mark the reverse side of the substrate;

3) Take the copper mesh mask and place it in a place where the nanowires are dense. Use high temperature tape to fix the copper mesh mask. Be careful not to cover the electrode area with the tape, and paste it carefully to prevent damage to the single crystal nanowires. Paste a few more copper meshes. , as a backup;

4) Use vacuum thermal deposition equipment to evaporate gold electrodes for the samples, the evaporation rate is controlled to 2 Å/s, the thickness is 50 nm, and the electrodes are reinforced with an aluminum film with a thickness of 150 nm, and the evaporation rate of the aluminum electrodes is also a uniform rate of 2 Å /s, pay attention to closing the small baffle of another metal source before evaporating one metal to prevent contamination of the metal source;

5) After the evaporation is completed, take out the sample and carefully remove the copper mesh mask with tweezers, taking care not to scratch the sample during the process.

7. Detection, Analysis, Characterization

The prepared one-dimensional methylamine lead iodide perovskite nanowire crystals were detected, analyzed and characterized. The appearance of lead iodide nanowires was characterized by Hitachi SEM scanning electron microscope and Nikon LV-150 optical microscope. The macroscopic absorption spectra of the prepared lead iodide nanowires and methylamine lead iodide perovskite nanowires were measured by Shimadzu UV-2600 ultraviolet-visible absorption spectrometer. The XRD patterns of lead iodide nanowires and methylamine lead iodide perovskite nanowires were qualitatively analyzed by X-ray diffraction spectrometer. The methylamine lead iodide perovskite nanowire photodetectors were characterized by semiconductor analyzer Agilent B1500A and THORLAB M375L4.

Conclusion: Figure 1(a) characterizes the microscopic crystal morphology of the prepared methylamine lead iodide perovskite nanowires, using a 20 nm thick gold seed island substrate, and the obtained methylamine lead iodide calcium The length of the titanite nanowires is greater than 100 μm . Figure 1(b) is the SEM image of the single methylamine lead iodide perovskite nanowires obtained by transferring the methylamine lead iodide perovskite nanowires from the gold seed island substrate to the glass substrate. The appearance is uniform, the line width is about 300 nm, and the crystal quality is good. Figure 2 characterizes the UV-Vis absorption spectra of methylamine lead iodide perovskite nanowires. Figure 2 compares the absorption spectra of lead iodide nanowires and methylamine lead iodide perovskite nanowires, and gives the steady-state fluorescence spectrum of methylamine lead iodide perovskite nanowires. Compared with lead iodide nanowires that only absorb in the ultraviolet to about 540 nm, the absorption spectrum of methylamine lead iodide perovskite nanowires covers the wavelength range from ultraviolet to near-infrared, and the cut-off wavelength is 800 nm. The fluorescence spectrum full width at half maximum (FWHM) of methylamine lead iodide perovskite nanowires under 325 nm laser irradiation is 44 nm, and the peak position is 767 nm. Figure 3 characterizes the XRD spectrum of the methylamine lead iodide perovskite nanowires. It can be seen that the crystal diffraction peaks are at 14.06°, 20.08°, 28.59°, 31.92°, 40.56° and 43.21°, and the corresponding crystal plane indices are (110) , (112), (220), (310), (224) and (314), corresponding to the square-structured perovskite materials. We tested the performance of methylamine lead iodide perovskite nanowire photodetectors using a semiconductor analyzer Agilent B1500A and a red LED (wavelength 660 nm) as the light source. As shown in Figure 4, it is the dark state IV curve of the methylamine lead iodide perovskite nanowire photodetector and the bright state IV curve under the incident optical density of 127.3 mW/cm ^2. It can be concluded that the device is under 1V bias. The bright-dark current ratio is 56.

Compared with the background art, the present invention has obvious advantages. We use metal nano-islands to induce chemical vapor deposition of lead iodide nanowires. The metal nano-islands catalyze the directional growth of the nanowires into 100-200 μm long, 100-300 nanometer diameter and longitudinally uniform wires. Lead nanowires are transformed into methylamine lead iodide perovskite nanowires. Compared with the preparation process in the literature, this scheme adds the first step. In the reaction process of the second step, the metal nano-islands catalyze the growth of lead iodide nanowires, which greatly improves the growth of nanowires simply without metal catalysis. length and density, and the third-step chemical vapor deposition effectively converts lead iodide nanowires into methylamine lead iodide perovskite nanowires. The preparation process adds a step of vacuum thermal evaporation to prepare metal nano-islands, but this metal nano-island substrate can be prepared in large quantities at one time, and the overall process is simple. Ammonium lead iodine single crystal nanowires. The invention contributes to the practical development of the methylamine lead iodine miniature photodetector.

Claims (5)

1. The methylamine lead iodoperovskite single crystal nanowire photoelectric detector is characterized in that: the methylamine lead perovskite single crystal nanowire photoelectric detector is a methylamine lead perovskite nanowire which is positioned on a glass substrate, is plated with an electrode, has the diameter of 100-300 nm and the length of 100-200 mu m.

2. A preparation method of a methylamine lead iodoperovskite single crystal nanowire photoelectric detector is characterized by comprising the following steps: the method comprises the following steps

Step one, preparing gold nanometer isolated islands which are uniformly distributed on a glass slide by a vacuum thermal deposition method;

putting the powdered lead iodide drug into a quartz boat, putting the quartz boat into the central position in a quartz glass tube, putting a glass slide with a gold nano island into the quartz glass tube, wherein the distance between the glass slide with the gold nano island and the center of the lead iodide drug is 8-10 cm between Ar and H₂Under the protection of mixed gas with the volume ratio of 10:1, adjusting the pressure to be 0.02 MPa, heating to 400 ℃, preserving the temperature for 20 min, naturally cooling to room temperature, and obtaining lead iodide single crystal nanowires on a glass slide;

putting a methyl ammonium iodide drug into a quartz boat, putting the quartz boat into the central position in a quartz glass tube, putting a glass slide with lead iodide single crystal nanowires into the quartz glass tube, keeping the substrate position 6 cm away from the center of the drug, exhausting air, adjusting the pressure to 0-0.01 MPa under the protection of Ar gas, heating to 120 ℃, preserving the temperature for 90 min, naturally cooling to room temperature, and obtaining methylamine lead perovskite single crystal nanowires on the glass slide;

moving the methylamine lead perovskite monocrystal nanowire on the glass slide to a glass substrate; loading a mask plate in a dense region of the methylamine lead perovskite single crystal nanowire, then evaporating a gold electrode by using a vacuum thermal deposition method, and removing the mask plate after evaporation is finished to obtain the methylamine lead perovskite single crystal nanowire photoelectric detector.

3. The method for preparing the methylamine lead perovskite single crystal nanowire photoelectric detector as claimed in claim 2, wherein in the step one, the slow deposition of 0.1 Å/s is selected, and the deposition thickness is 20 nm.

4. The method for preparing the methylamine lead perovskite single crystal nanowire photoelectric detector as claimed in claim 2, wherein the method comprises the following steps: and in the fourth step, the methylamine lead perovskite monocrystal nanowire on the glass slide is moved to a clean glass substrate by a contact pressurization method.

5. The method for preparing the methylamine lead perovskite single crystal nanowire photoelectric detector as claimed in claim 2, wherein a copper mesh mask plate is loaded in a region where methylamine lead perovskite single crystal nanowires are dense, then a gold electrode is evaporated by a vacuum thermal deposition method, the evaporation rate is controlled to be 2 Å/s, the thickness is 50 nm, a 150 nm aluminum film reinforced gold electrode is evaporated, the evaporation rate of the aluminum electrode is 2 Å/s at a constant speed, and the copper mesh mask plate is removed after evaporation is completed, so that the methylamine lead perovskite single crystal nanowire photoelectric detector is obtained.

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