A (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region and its preparation method

Abstract

The present invention discloses a (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region, comprising a (PEA)2PbI4 single crystal thin film grown by a solution method and gold nanoparticles prepared by an annealing method. Symmetrical metal silver electrodes are provided on the (PEA)2PbI4 single crystal thin film, each having a thickness of 80nm, and the average diameter of the gold nanoparticles is 100nm. The present invention employs a (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region, employing the above-mentioned structure. By adjusting the size of the gold nanoparticles, the detector achieves perfect capture of incident light in the non-absorbent range of the (PEA)2PbI4 single crystal, showing broad application prospects in basic biomedical research and clinical transformation in the second near-infrared region.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing near-infrared responsive photoelectric detectors, and in particular to a (PEA)2PbI4 single crystal thin film photoelectric detector that can respond in the second near-infrared region and can achieve response performance in the wavelength range of 375nm-1310nm. Background Art

[0002] Organic-inorganic hybrid perovskites hold broad application prospects in optoelectronic devices due to their large light absorption coefficients, long carrier diffusion lengths, high carrier mobility, and low-cost solution preparation. However, their stability has been a research challenge. The instability of three-dimensional organic-inorganic hybrid perovskites, represented by MAPbI3, under light, heat, and humidity conditions, has hindered their practical application. Two-dimensional perovskites, due to their unique molecular structure, possess excellent stability. For example, phenylethylammonium lead iodide (PEA)2PbI4 has been extensively studied in optoelectronic devices such as solar cells, photodetectors, and light-emitting diodes. However, due to the inherently wide band gap of two-dimensional perovskite materials, photodetectors based on these materials can only operate in the ultraviolet and visible light ranges, which greatly limits the development of these perovskite-based photodetectors. To extend the response of two-dimensional perovskite photodetectors to the near-infrared, researchers have explored numerous chemical treatments, such as mixing different perovskites or doping with other materials to adjust the band gap of the perovskite material. However, these chemical treatments can cause distortion of the perovskite lattice, resulting in poor device performance. Therefore, it is very important to find a method that is both simple and does not destroy the characteristics of two-dimensional perovskites to realize a two-dimensional perovskite photodetector device with a wide spectrum response. Metallic micro-nano optical antenna structures can perfectly capture incident light in a specific band or a wide spectral range by stimulating the surface plasmon (SPP) effect. This effect can not only enhance the photoelectric conversion performance of the photodetector in the light absorption band of the semiconductor material, but also efficiently generate hot holes in the band where the semiconductor material does not absorb light. At the same time, the field enhancement effect can be used to regulate the carrier energy and momentum distribution, broaden the response bandwidth of the device, and comprehensively improve the overall performance of the device.

[0003] In this study, we fabricated a metallic micro-nanoantenna structure through a simple annealing method and integrated it into a (PEA)2PbI4 single-crystal thin-film photodetector. Under light irradiation, the metallic micro-nanoantenna structure induces the SPP effect, enhancing light scattering and absorption. Near-infrared light excites the metallic nanostructure, generating hot holes that increase the concentration of free carriers within the (PEA)2PbI4 single crystal. This enables the perovskite photodetector to respond in the near-infrared second spectral range (1310 nm), where semiconductors do not absorb light. Compared to three-dimensional polycrystalline thin films, the use of two-dimensional single-crystal thin films not only ensures high crystalline quality and lower dark current in the detector, but also improves device stability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to explore a simple method to make the (PEA)2PbI4 single crystal thin film photodetector respond in the near-infrared region II, so as to promote its application and development in clinical transformation such as basic biomedical research.

[0005] The technical solution adopted by the present invention is: a (PEA)2PbI4 single crystal photodetector that can respond in the near-infrared second region, composed of a substrate, a metal nanostructure layer, a (PEA)2PbI4 single crystal thin film, and a silver electrode, characterized by: substrate (low-cost glass slide), gold nanosphere size (diameter of about 100nm), single crystal thin film (thickness of 5μm), and silver electrode thickness (80nm±0.2nm).

[0006] Preferably, the optical antenna structure surface is a randomly distributed island-shaped metal nanosphere structure formed by depositing a 5nm thick metal film on a glass sheet and annealing it at 500°C in a muffle furnace. The average diameter of the metal nanospheres is 100nm, and the average gap between the spheres is 170nm.

[0007] Preferably, the (PEA)2PbI4 single crystal film is a regular tetragonal single crystal film with a thickness of 5 μm obtained by a solution growth method, and a regular tetragonal single crystal film with a side length of 15 mm×4 mm.

[0008] Preferably, the symmetrical electrode is a silver electrode with a thickness of 80nm±0.2nm deposited by thermal evaporation, the electrode shape is a regular quadrilateral with a side length of 220μm, the electrode spacing is 22μm, and a Schottky contact is formed between the silver electrode and the (PEA)2PbI4 single crystal film.

[0009] The present invention has the beneficial effect of simplifying the process and preserving the structural characteristics of the semiconductor material compared to methods that achieve near-infrared response by adjusting the band gap of the semiconductor material. The present invention fabricates a metallic micro-nanoantenna structure through a simple thermal annealing method. Using this metallic micro-nanoantenna structure to excite surface plasmon resonance, the (PEA)2PbI4 single-crystal thin-film photodetector capable of responding in the second near-infrared region is fabricated, promoting both basic biomedical research and clinical translation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 : Structural diagram of the present invention;

[0011] Figure 2 : Response diagram of the present invention and (PEA)2PbI4 single crystal thin film device in the intrinsic absorption band;

[0012] Figure 3 : Response diagram of the present invention in the near infrared band. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0014] The method for manufacturing the above-mentioned (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region is carried out in the following steps:

[0015] Step 1: Prepare the single crystal thin film precursor solution. Mix 325.9 mg of lead iodide (PbI2) and 351.9 mg of phenylethylammonium iodide (C6H5C2H4NH3I) in 1 mL of γ-butyrolactone (γ-GBL) solution. This yields a precursor solution with a molar ratio of 1:2 (PbI2:C6H5C2H4NH3I). Stir the solution on an 80°C hotplate for 24 hours before use.

[0016] Step 2: Clean the glass slide on which the single crystal film will be grown; then drip the (PEA)2PbI4 precursor solution into the gap between the glass slides, using the spatially confined growth method. By programming the air drying oven so that the temperature decreases by 1°C per hour starting from 80°C during the growth process, this allows for the crystallization of the single crystal film to proceed at a reduced temperature.

[0017] Step 3: A 5 nm thick gold film was deposited on the prepared clean glass substrate by magnetron sputtering, and small spheres with an average diameter of 100 nm were obtained by thermal annealing.

[0018] Step 4: Transfer the grown (PEA)2PbI4 single crystal film to a substrate with gold particles that has been prepared in advance, and apply a mask to the flat surface of the single crystal film to evaporate an 80nm silver electrode.

[0019] Example 1

[0020] The materials used in this invention include: lead iodide (PbI2), phenylethylammonium iodide (C6H5C2H4NH3I) (PEAI), γ-butyrolactone (GBL), Jie Er Liang cleansing milk (comprised of surfactants, calcium carbonate, organic acids, and fragrance), Liby dishwashing liquid (comprised of softened water, surfactants, vitamin E ester, and lemon essence), deionized water, acetone, isopropyl alcohol, and ethanol. The combined amounts are as follows:

[0021] PbI2: 325.9mg±1mg

[0022] PEAI: 351.9mg±1mg

[0023] GBL: 1mL

[0024] Gold target: 5nm±0.2nm

[0025] Clean and Bright Cleansing Milk: 1±0.5mL

[0026] Detergent: 2 ± 0.5 mL

[0027] Deionized water: H2O 8000mL±50mL

[0028] Acetone: CH3COCH3 250mL±5mL

[0029] Ethanol: C2H5OH 500mL±5mL

[0030] Slide: 25mm×25mm×1mm,

[0031] The surface plasmon-enhanced, full-spectrum-responsive single-crystal perovskite photodetector of the present invention consists of three layers: a gold particle layer, a single-crystal perovskite active layer, and a silver electrode layer. The gold particle layer is fabricated on a transparent glass substrate, with an absorption layer above it and a silver electrode layer on top. The specific preparation method is as follows:

[0032] (1) Selected chemical substances

[0033] The chemical materials required for preparation must be carefully selected and their quality, purity, concentration, fineness and precision must be controlled:

[0034] PbI2: solid powder, purity 98%

[0035] PEAI: solid powder, purity 99.5%

[0036] GBL: Liquid, purity 99%

[0037] Deionized water: liquid, 99.99% pure

[0038] Acetone: Liquid, 99.5% purity

[0039] Ethanol: Liquid, 99.99% pure

[0040] Glass slide, solid, transmittance about 86%.

[0041] Silver: solid particles, 99.99% purity

[0042] (2) Preparation of active layer solution

[0043] 1) Weigh 325.9 mg of PbI2 and 351.9 mg of PEAI into a 5 mL brown reagent bottle.

[0044] 2) Measure 1 mL of GBL and place it in the above brown reagent bottle;

[0045] 3) Place the solution on a magnetic stirrer and stir at 80°C for at least 24 h.

[0046] (3) Slide cleaning

[0047] 1) Cut the glass slide into small pieces of uniform size and place them in a mixture of clean and bright cleaning milk and dishwashing liquid for 1 hour;

[0048] 2) Wear disposable gloves and repeatedly rub the front and back of the slide until a uniform water film is formed on both sides after rinsing with deionized water;

[0049] 3) Place the slide in an ultrasonic cleaner, add deionized water, and ultrasonically clean for 15 minutes;

[0050] 4) Place the slide in an ultrasonic cleaner, add acetone, and ultrasonically clean for 15 minutes;

[0051] 5) Place the slide in an ultrasonic cleaner, add isopropyl alcohol, and ultrasonically clean for 15 minutes;

[0052] (4) Growth of (PEA)2PbI4 single crystal thin films

[0053] 1) Dry the washed slides and stack two slides in a group in an oven at 80°C for preheating.

[0054] 2) The pre-stirred perovskite precursor solution is added dropwise between the gaps of the two preheated glass slides, and the oven is set to maintain a constant temperature of 80°C for 2 hours, followed by a cooling rate of 1°C / hour until the temperature drops to 30°C; ensuring that the single crystal perovskite growth is in the process of cooling and crystallization.

[0055] (5) Preparation of metal micro-nano antenna structure layer

[0056] 1) The gold absorption structure nanostructure was prepared by magnetron sputtering to deposit a 5 nm thin film.

[0057] 2) annealing the deposited gold film at 500°C to form gold nanospheres;

[0058] (6) Transfer of (PEA)2PbI4 single crystal thin film

[0059] 1) After gently separating a group of glass slides on which (PEA)2PbI4 single crystal thin films were grown, the single crystals were pushed off the growth substrate using tweezers and placed on a substrate with gold particles;

[0060] 2) The residual precursor solution on the surface of the single crystal film is absorbed by capillary force with dust-free paper so that it can be perfectly bonded to the gold particle substrate.

[0061] (7) Vacuum evaporation, morphology conversion, vapor deposition, thin film growth, preparation of silver electrodes

[0062] 1) Use high-temperature adhesive to stick an electrode mask on the single crystal perovskite film as a mask of the electrode shape.

[0063] 2) Evaporated silver electrode

[0064] ① Preparation is carried out in a vacuum evaporation furnace;

[0065] ② Place the substrate with the mask

[0066] Open the vacuum evaporation furnace and fix the substrate with the mask on the turntable at the top of the furnace chamber, with the substrate with the mask facing down;

[0067] ③Place the evaporation material in the evaporation container

[0068] Place the silver block of the evaporation material in the tungsten boat according to the amount;

[0069] ④ Adjust the quartz thickness probe and quartz monitoring probe on the furnace wall so that the quartz thickness probe is aligned with the base on the turntable and the quartz monitoring probe is aligned with the silver;

[0070] ⑤ Close the door of the vacuum evaporation furnace and seal it;

[0071] ⑥ Turn on the mechanical vacuum pump and molecular vacuum pump to extract the air in the furnace chamber so that the vacuum degree in the furnace is ≤ 0.0005Pa and keep it constant;

[0072] ⑦ Turn on the turntable, and the conductive glass will rotate accordingly. The turntable speed is 5r / min;

[0073] ⑧ Turn on the quartz thickness probe;

[0074] ⑨ Evaporated silver electrode:

[0075] Turn on the power supply of the tungsten boat containing silver to sublime the silver from solid to gas. The gaseous molecules are deposited and grown on the active layer to form a planar film. Adjust the tungsten boat power control knob to increase the power to maintain the film growth rate at 0.1nm / s and the film thickness at 80±0.2nm.

[0076] During the preparation process, the quartz thickness probe measures the vapor deposition thickness, and the thickness value is displayed on the display screen;

[0077] During the preparation process, the middle observation window is used to observe the evaporation process and conditions;

[0078] During the preparation process, the evaporation material is heated and sublimated, undergoing morphological transformation, and then vapor-deposited on the substrate surface with a mask attached to form a planar silver electrode;

[0079] ⑩ Cooling in vacuum state

[0080] After the electrode layer is evaporated, the single crystal perovskite photodetector is left to cool in a vacuum furnace for 10 min;

[0081] Collected product: A two-dimensional single-crystal perovskite photodetector that can respond in the near-infrared region II.

[0082] Turn off the molecular vacuum pump and mechanical vacuum pump;

[0083] Open the intake valve;

[0084] Open the door of the vapor deposition chamber;

[0085] A (PEA)2PbI4 single crystal perovskite photodetector is taken out, that is, a (PEA)2PbI4 single crystal photodetector containing a surface plasmon effect of gold nanoparticles that can respond in the near-infrared second region.

[0086] (8) Detection, analysis, and characterization

[0087] Detect, analyze and characterize the performance of the prepared surface plasmon single crystal perovskite photodetector;

[0088] The device's current-time curve was measured using a Keisight B1500 digital source meter. A Zolix Omni-λ300 Monochromator / Spectrography and a darkroom were used to measure the photocurrent curves of the surface plasmon-enhanced full-spectrum-response single-crystal perovskite photodetector and a standard device at different wavelengths, comparing the performance of devices with and without the gold nanoparticle layer. A RIGOL DG1022U function signal generator was used to modulate light sources of varying wavelengths, emitting light at a specific frequency. The semiconductor device analyzer B1500A was used to measure the device's full-spectrum response in the UV-Vis-NIR region.

[0089] Conclusion: The single crystal perovskite photodetector without gold particles is called a standard device. Figure 1 ) analysis, first, the gold nanostructures were directly prepared on low-cost glass slides through thermal annealing, avoiding the use of expensive electron beam exposure equipment and reducing the cost of preparing metal nanostructures. Second, by transferring (PEA)2PbI4 single crystal films into contact with gold nanoparticles, a surface plasmon-perovskite system was directly formed, avoiding the impact of the nanostructure on the crystalline quality of the (PEA)2PbI4 single crystal film. Finally, through surface illumination, the metal nanostructures stimulated the SPP effect to generate hot holes, enhancing the photoelectric properties of the perovskite.

[0090] Figure 2The device's response performance was tested under UV and visible light at different wavelengths. When a -1V bias voltage was applied, the gold-incorporated device exhibited a significant improvement in photocurrent compared to the standard device across the 375nm-565nm intrinsic absorption spectrum.

[0091] Figure 3 The response diagram shows that the device has a significant response in the near-infrared range outside the intrinsic absorption band of the (PEA)2PbI4 single crystal. This is attributed to the efficient generation of hot holes by the gold nanoparticles through the SPP effect, while the field enhancement effect can simultaneously regulate the carrier energy and momentum distribution. This can achieve perfect capture of incident light in the semiconductor's non-absorption band, broaden the device's response bandwidth, and comprehensively improve the device's optoelectronic performance.

[0092] Compared with the background technology, the present invention has obvious advantages. We introduce the metal micro-nano antenna structure after low-cost thermal annealing treatment into the (PEA)2PbI4 single crystal thin film photodetector as an optical structure layer to stimulate the SPP effect to generate hot holes. While ensuring the low dark current of the (PEA)2PbI4 single crystal thin film photodetector, the (PEA)2PbI4 single crystal thin film photodetector has improved response performance in the intrinsic absorption band. At the same time, it also has response performance to near-infrared light, realizing full spectrum detection of the device from 375nm-1310nm, and broadening the perovskite photoelectric detection range to the second near-infrared region. The present invention uses the metal micro-nano antenna structure to stimulate the SPP effect, adjusts the (PEA)2PbI4 single crystal response spectrum, avoids the use of chemical methods to change the band gap, causes the perovskite to lattice distortion, and thus leads to problems such as poor device performance. At the same time, it also avoids the use of expensive equipment such as electron beam lithography to prepare the metal nanoantenna structure, greatly reducing the preparation cost of the device. Therefore, using the SPP effect to broaden the response spectrum of perovskite to the second near-infrared region is a simple and low-cost method with potential application value in basic biomedical research and clinical transformation.

Claims

1. A (PEA)2PbI4 single crystal thin film photodetector capable of responding in the near-infrared region II, comprising an optical antenna structure, a (PEA)2PbI4 single crystal thin film, and a symmetrical silver electrode layer, characterized in that: The optical antenna structure is composed of gold nanospheres with an average particle size of 100 nm, a (PEA)2PbI4 single crystal thin film with a light absorption layer thickness of 5 μm, and a symmetrical silver electrode with a thickness of 80 nm ± 0.2 nm. The optical antenna structure is a randomly distributed island-shaped metal nanosphere structure formed by a 5nm thick metal film deposited on a glass sheet and annealed at 500°C in a muffle furnace. The average diameter of the metal nanospheres is 100nm, and the average gap between the spheres is 170nm.

2. The (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region according to claim 1, characterized in that: The (PEA)2PbI4 single crystal film is a regular tetragonal single crystal film with a thickness of 5 μm and a side length of 15 mm × 4 mm obtained by a solution growth method.

3. The (PEA)2PbI4 single crystal thin film photodetector capable of responding in the second near-infrared region according to claim 1, characterized in that: The symmetrical electrode is a silver electrode with a thickness of 80nm±0.2nm deposited by thermal evaporation. The electrode shape is a regular quadrilateral with a side length of 220μm and an electrode spacing of 22μm. Schottky contact is formed between the silver electrode and the (PEA)2PbI4 single crystal film.

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