Array-type ultraviolet detector based on perovskite quantum dots and preparation method thereof

Abstract

The present invention provides an array ultraviolet detector based on perovskite quantum dots and a preparation method thereof, belonging to the technical field of biomedical ultraviolet imaging. It includes: an array scintillator screen having a plurality of sealed holes distributed in an array, and a perovskite quantum dot liquid is filled in each of the sealed holes. The sealed end of the sealed hole is light-transmissive and the side wall of the sealed hole is light-impermeable; an image sensor is arranged at one end of the array scintillator screen for receiving visible light generated by the perovskite quantum dot liquid under ultraviolet irradiation. By pixelating the scintillator layer to form a plurality of independent detection units, visible light interference can be avoided, and the resolution of the detector can be prevented from being reduced. At the same time, the height of the array scintillator screen is adjustable, and more ultraviolet light can be absorbed without increasing the area.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical ultraviolet imaging, and in particular relates to an array-type ultraviolet detector based on perovskite quantum dots and a preparation method thereof. Background Art

[0002] Ultraviolet radiation is a general term for radiation with wavelengths ranging from 10nm to 400nm in the spectrum. Appropriate ultraviolet radiation can induce the skin to produce vitamin D, thereby promoting the body's absorption of calcium. However, according to research, excessive ultraviolet radiation may cause skin cancer and direct damage to DNA. Long-term exposure to ultraviolet radiation may have acute or chronic health effects on the skin, eyes, immune system, etc. On the other hand, artificial ultraviolet radiation also plays an important role in people's lives. For example, ultraviolet radiation can destroy the nucleoprotein and DNA of microorganisms, thereby achieving the function of sterilization; some specific substances will produce fluorescence through ultraviolet radiation, thereby achieving the function of anti-counterfeiting; ultraviolet radiation will harden some materials, thereby achieving the function of light curing, etc.

[0003] As mentioned above, ultraviolet light detection technology has been widely concerned in many fields such as space exploration, bioanalysis, environmental sensors, communications and imaging. However, the narrowband detectors currently prepared based on traditional methods have problems such as high cost, complex structure and difficulty in integration. Metal halide perovskite materials have a large light absorption coefficient and high and balanced carrier transport capacity, which makes them one of the important candidate materials for high-performance photodetectors. How to significantly improve the imaging spatial resolution and sensitivity while ensuring the stability of device performance and service life, while achieving low-dose ultraviolet irradiation, has always been a key issue that has plagued academic research at home and abroad. Summary of the invention

[0004] In view of this, the present invention proposes an array-type ultraviolet detector based on perovskite quantum dots and a preparation method thereof, which can improve the imaging spatial resolution and sensitivity of the ultraviolet detector.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] An array-type ultraviolet detector based on perovskite quantum dots, comprising an array-type scintillator screen and an image sensor;

[0007] The array-type scintillator screen has a plurality of sealing holes distributed in an array, each of the sealing holes is filled with perovskite quantum dot liquid, the sealing ends of the sealing holes are light-transmissive and the side walls of the sealing holes are light-impermeable.

[0008] The image sensor is arranged at one end of the array scintillator screen and is used to receive the visible light generated by the perovskite quantum dot liquid under ultraviolet radiation.

[0009] Preferably, the array scintillator screen includes a plate body, a first encapsulation layer and a second encapsulation layer. A plurality of through holes are arranged in an array on the plate body. The first encapsulation layer and the second encapsulation layer are respectively arranged on opposite sides of the plate body to seal both ends of the through holes, forming sealed holes.

[0010] Preferably, the image sensor is attached to the first encapsulation layer or the second encapsulation layer.

[0011] Preferably, the aperture range of the sealed holes is 10 - 240 μm.

[0012] Preferably, the first encapsulation layer and the second encapsulation layer are optical glue layers.

[0013] Preferably, the image sensor includes a plurality of photosensitive elements and auxiliary circuits arranged in an array. The photosensitive elements correspond to the sealed holes one by one. The photosensitive elements are used to convert the received optical signals into electrical signals, and the auxiliary circuits are used to transmit the electrical signals.

[0014] The preparation method of the above-mentioned array ultraviolet detector based on perovskite quantum dots includes:

[0015] Preparing a colloidal perovskite quantum dot liquid;

[0016] Injecting the colloidal perovskite quantum dot liquid into each of the through holes arranged in an array on the plate body, and sealing opposite ends of the through holes to form sealed holes, wherein the sealed ends of the sealed holes are light-transmissive and the side walls of the sealed holes are light-impermeable;

[0017] Taking one side of the plate body as the ultraviolet irradiation side, and arranging an image sensor on the other side to receive the detection light generated by the perovskite quantum dot liquid under ultraviolet irradiation.

[0018] Further, the method for sealing opposite ends of the through holes to form sealed holes includes:

[0019] Coating optical glue on opposite ends of the plate body respectively;

[0020] Performing a curing treatment on the optical glue to respectively form a first encapsulation layer and a second encapsulation layer, and the first encapsulation layer and the second encapsulation layer respectively seal both ends of the through holes.

[0021] The beneficial effects of the present invention are as follows:

[0022] Traditional perovskite quantum dot thin films are easily contacted with water, oxygen, heat, ultraviolet light, etc., resulting in their short lifespan. However, in the present invention, the perovskite quantum dots are in solution and have a longer lifespan.

[0023] In addition, the sensitivity of an ultraviolet detector using a perovskite quantum dot thin film as a scintillator is not high. In contrast, the liquid perovskite quantum dots encapsulated in an optical fiber array can improve the sensitivity by increasing the thickness of the scintillating layer. At the same time, the array-type ultraviolet detector structure of the present invention forms multiple independent detection units by pixelating the scintillator layer, which can avoid visible light interference. Without increasing the overall area of the detector, more ultraviolet beams can be absorbed to improve the spatial resolution and sensitivity of imaging. Description of the Drawings

[0024] Figure 1 is a schematic diagram of an array-type ultraviolet detector based on perovskite quantum dots in an embodiment of the present invention;

[0025] In the figure: 10 - array-type scintillator screen, 11 - plate body, 12 - first encapsulation layer, 13 - second encapsulation layer, 14 - through hole, 20 - image sensor;

[0026] Figure 2 is an image of the array observed under a microscope;

[0027] Figure 3 is an imaging result obtained by the image sensor under the irradiation of an ultraviolet lamp with a wavelength of 405 nm;

[0028] Figure 4 is the shape structure of the optical fiber array. Detailed Embodiments

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the following describes the detailed embodiments of the present invention with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in the drawings and described according to the drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0030] The present invention provides an array-type ultraviolet detector based on perovskite quantum dots, as Figure 1 shown, including an array-type scintillator screen 10 and an image sensor 20. Among them, the array-type scintillator screen 10 has a plurality of sealed holes distributed in an array, and each of the sealed holes is filled with a perovskite quantum dot liquid. The sealed end of the sealed hole is light-transmissive and the side wall of the sealed hole is light-impermeable. The image of the array observed under a microscope is as Figure 2 shown. The image sensor 20 is disposed at one end of the array-type scintillator screen 10, and ultraviolet rays 30 irradiate the other end of the array-type scintillator screen 10, and visible light generated by the perovskite quantum dot liquid under the irradiation of the ultraviolet rays 30 is received by the image sensor 20.

[0031] In a specific implementation of the present invention, the array scintillator screen 10 includes a plate body 11, a first encapsulation layer 12, and a second encapsulation layer 13. A plurality of through holes 14 are arranged in an array on the plate body 11. The first encapsulation layer 12 and the second encapsulation layer 13 are respectively arranged on opposite sides of the plate body 11 to seal both ends of the through holes 14, forming sealed holes. The aperture range of the sealed holes is 10μm - 240μm, and the height range of the sealed holes is adjustable. The first encapsulation layer 12 and the second encapsulation layer 13 are optical adhesive layers, and OCA optical adhesive can be selected, which is colorless and transparent.

[0032] The image sensor 20 is attached to the first encapsulation layer 12 or the second encapsulation layer 13, where Figure 1 the case where the image sensor 20 is attached to the second encapsulation layer 13 is taken as an example for display. The image sensor 20 includes a plurality of photosensitive elements and auxiliary circuits arranged in an array. The plurality of photosensitive elements correspond to the plurality of sealed holes one by one. The photosensitive elements are used to convert optical signals into electrical signals, and the auxiliary circuits are used to transmit electrical signals. Among them, the image sensor 20 can adopt a CMOS image sensor or a silicon-based photodiode.

[0033] Exemplarily, the preparation method of the above array ultraviolet detector includes the following steps:

[0034] Step S10: Prepare a colloidal perovskite quantum dot liquid;

[0035] Step S20: Inject the colloidal perovskite quantum dot liquid into each of the through holes arranged in an array on the plate body, and seal the opposite ends of the through holes to form sealed holes, where the sealed ends of the sealed holes are light-transmissive and the side walls of the sealed holes are light-impermeable;

[0036] Step S30: Arrange an image sensor on one side of the plate body to receive the detection light generated by the perovskite quantum dot liquid under ultraviolet irradiation.

[0037] Specifically, step S10 includes the following steps:

[0038] Step S11: Load a certain proportion of cesium carbonate (Cs 2 CO 3 ), octadecene (ODE), and oleic acid (2.5 mL, OA) into a 100 mL three-necked flask, dry at 120 °C for 30 min to remove water vapor, and then heat to 150 °C under the atmosphere of a protective inert gas until all cesium carbonate reacts with oleic acid to prepare a cesium oleate solution. Since cesium oleate precipitates from octadecene at room temperature, it must be preheated to 120 - 150 °C before injection.

[0039] Step S12: Mix a certain proportion of octadecene (ODE) and lead halide (PbX 2), oleylamine (OLA) and oleic acid (OA) were loaded into a 25 mL three-necked flask and vacuum dried at 120 °C for 30 min. After completely dissolving the PbX 2 salt, the temperature was raised to 140 - 200 °C (for adjusting the size of the nanocrystals), and a certain amount of cesium oleate solution prepared in step S11 was quickly injected. After reacting for 5 s, the reaction mixture was cooled by an ice-water bath.

[0040] Step S13: The solution prepared in step S12 was cooled by a water bath. For the first time, the supernatant was directly centrifuged and poured off. For the second time, it was centrifuged and washed with a mixed solvent of n-octane and methyl acetate. After centrifugation, the supernatant was discarded, and the particles were redispersed in n-octane to form a long-term stable colloidal perovskite quantum dot solution.

[0041] In this example, in the mixed reaction solution of step S11, the mass of cesium carbonate was 0.814 g, the volume of octadecene was 40 mL, and the volume of oleic acid was 2.5 mL. The protective inert gas in step S11 was one of helium, nitrogen, and argon.

[0042] In step S12, the lead halide in the preparation process of the perovskite quantum dot scintillator can be lead iodide (PbI 2 ), lead bromide (PbBr 2 ), lead chloride (PbCl 2 ), or a mixture thereof. In step S12, the volume of octadecene was 5 mL, the lead halide was 0.188 mmol, the volume of oleylamine was 0.6 mL, the volume of oleic acid was 0.6 mL, and the injected cesium oleate solution was 0.125 mol, i.e., 0.4 mL. When preparing CsPbCl 3 The high temperature required for dissolving PbCl 2 was 150 °C, and the required solvent was 1 mL of trioctylphosphine (TOP, 97%).

[0043] In step S13, the volume ratio of the mixed solvent for the second centrifugal cleaning was n-octane: methyl acetate = 1:2.

[0044] In this example, in the above step S20, the prepared perovskite quantum dot liquid was sucked into each through hole 14 by capillary action. The pore diameter and height range of the through hole 14 could be adjusted to maximize the imaging sensitivity. By pixelating the scintillator layer, the present invention can avoid the interference of visible light with each other and improve the imaging resolution.

[0045] Among them, the method for sealing the opposite ends of the sealing holes includes:

[0046] Optical glue was respectively coated on the opposite ends of the plate body;

[0047] The optical adhesive is cured to form a first encapsulation layer 12 and a second encapsulation layer 13 respectively, and the two ends of the through hole 14 are sealed by the first encapsulation layer 12 and the second encapsulation layer 13 respectively.

[0048] Exemplarily, after the liquid optical adhesive is evenly coated on the PET film, the PET film coated with the adhesive is attached to the upper and lower surfaces of the plate body. After the optical adhesive is cured, the PET film is torn off to obtain the encapsulated array scintillator screen 10. The optical adhesive layer (OCA) is colorless and transparent, with a light transmittance of more than 98%, good bonding strength, small curing shrinkage rate, and resistance to yellowing, etc. Therefore, the optical adhesive layer can effectively transmit visible light to the image sensor 20.

[0049] The array ultraviolet detector is irradiated with a UV lamp with a wavelength of 405 nm. The shape of the ultraviolet detector is as Figure 4 shown, and the imaging result obtained by the image sensor is as Figure 3 shown.

[0050] The array ultraviolet detector based on perovskite quantum dots and its preparation method disclosed in this embodiment form a plurality of independent detection units by pixelating the scintillator layer. The porous structure of the array can avoid the reduction of the resolution of the detector caused by optical crosstalk, and improve the spatial resolution and sensitivity of imaging.

[0051] The above are only specific embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. An array ultraviolet detector based on perovskite quantum dots, characterized in that, it includes an array scintillator screen and an image sensor; The array scintillator screen has a number of sealed holes distributed in an array, and each of the sealed holes is filled with a perovskite quantum dot liquid. The sealed end of the sealed hole is light-transmissive and the side wall of the sealed hole is light-impermeable; the array scintillator screen includes a plate body, a first encapsulation layer and a second encapsulation layer. A number of through holes are arranged in an array on the plate body. The first encapsulation layer and the second encapsulation layer are respectively arranged on opposite sides of the plate body to seal both ends of the through holes to form sealed holes, and the aperture range of the sealed holes is 10-240 μm; The preparation process of the perovskite quantum dot liquid is as follows: Put cesium carbonate, octadecene and oleic acid into a three-necked flask, dry at 120 °C for 30 min to remove water vapor, and heat to 150 °C under the atmosphere of a protective inert gas until all cesium carbonate reacts with oleic acid to prepare a cesium oleate solution; Put octadecene, lead halide, oleylamine and oleic acid into a three-necked flask together, vacuum dry at 120 °C for 30 min. After completely dissolving the lead halide, raise the temperature to 140-200 °C, and quickly inject the prepared cesium oleate solution. After reacting for 5 s, cool the reaction mixture by an ice-water bath; Cool the prepared solution by water bath. For the first time, directly centrifuge and pour off the supernatant. For the second time, centrifuge and wash with a mixed solvent of n-octane and methyl acetate; after centrifugation, the supernatant is discarded, and the particles are redispersed in n-octane to form a long-term stable colloidal perovskite quantum dot solution; The image sensor is arranged at one end of the array scintillator screen and is used to receive the visible light generated by the perovskite quantum dot liquid under ultraviolet irradiation.

2. The array ultraviolet detector based on perovskite quantum dots according to claim 1, characterized in that, the image sensor is attached to the first encapsulation layer or the second encapsulation layer.

3. The array ultraviolet detector based on perovskite quantum dots according to claim 1, characterized in that, the first encapsulation layer and the second encapsulation layer are optical adhesive layers.

4. The array ultraviolet detector based on perovskite quantum dots according to claim 1, characterized in that, the image sensor includes a number of photosensitive elements and auxiliary circuits distributed in an array. The photosensitive elements correspond to the sealed holes one by one. The photosensitive elements are used to convert the received optical signal into an electrical signal, and the auxiliary circuit is used to transmit the electrical signal.

5. A preparation method for the array ultraviolet detector based on perovskite quantum dots according to any one of claims 1 to 4, characterized in that, it includes: Preparing a colloidal perovskite quantum dot liquid; Injecting the colloidal perovskite quantum dot liquid into each of the through holes distributed in an array on the plate body, and sealing the opposite ends of the through holes to form sealed holes, wherein the sealed end of the sealed hole is light-transmissive and the side wall of the sealed hole is light-impermeable; Taking one side of the plate body as the ultraviolet irradiation side, and arranging an image sensor on the other side to receive the detection light generated by the perovskite quantum dot liquid under ultraviolet irradiation.

6. The preparation method of the array-type ultraviolet detector based on perovskite quantum dots according to claim 5, characterized in that, the method for sealing the opposite ends of the through hole to form a sealed hole includes: coating optical glue on the opposite ends of the plate body respectively; performing a curing treatment on the optical glue to respectively form a first encapsulation layer and a second encapsulation layer, and the first encapsulation layer and the second encapsulation layer respectively seal the two ends of the through hole.

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