A blue light photoelectric detector and blue light hazard index instrument based on perovskite methylamine lead bromine chlorine single crystal

Abstract

The present invention discloses a blue light photoelectric detector based on perovskite methylamine lead bromine chloride single crystal and a blue light hazard index meter, the index meter includes a blue light photoelectric detector based on MAPbBr2Cl single crystal and STO single crystal substrate, a light focusing device, a photoelectric detection back-end circuit and a display module. The blue light hazard index meter of the present invention can accurately and quickly obtain the blue light hazard level of the luminous light source, has a high degree of integration, high cost performance, is convenient to carry, and is simple to operate. The test data conforms to the international blue light hazard standard, and is suitable for detecting blue light hazards of lamps in daily life.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detectors, and in particular relates to a blue light photoelectric detector and a blue light hazard index meter based thereon. Background Art

[0002] Blue light is everywhere in people's daily lives. For example, the light emitted by electronic devices such as mobile phones, tablets, computer screens, and LED lights all contain blue light. The harm of blue light to the human eye is mainly manifested in the eye pathological harm that causes myopia, cataracts, and macular degeneration, as well as the harm to human rhythm. Therefore, it is necessary to detect the blue light hazard and classify its hazard level. The classification of blue light hazard levels is based on the application of IEC 62471 in the assessment of blue light hazards of light sources and lamps and the technical report of IEC / TR62778 on the retinal blue light hazards described in Articles 4.3.3 and 4.3.4 of the IEC 62471:2006 standard.

[0003] Photodetectors are devices that convert light signals into electrical signals. They are widely used in various fields of military and national economy. They are mainly divided into phototubes, photomultiplier tubes, photovoltaic detectors and photoconductive detectors. Among them, photoconductive detectors work by using the photoconductive effect. A whole piece of uniform semiconductor material has a certain resistance when there is no light. When light is irradiated, when the energy absorbed by the semiconductor is greater than the bandgap width of the material, electrons are excited from the valence band to the conduction band, generating free electrons and holes. Electrons and holes flow in a directional manner under the action of an external electric field, thereby generating photocurrent. If you want to detect the hazards of blue light, you need to find a semiconductor material that is very suitable for making blue light photodetectors.

[0004] Perovskite materials are excellent semiconductor materials. They are welcomed by scientific researchers due to their advantages such as long carrier lifetime, large absorption coefficient, long carrier diffusion length, low preparation cost and high carrier mobility. The chemical formula of perovskite materials is ABX3, where A, B and X represent monovalent organic or inorganic cations (cesium, methylamine), divalent metal ions (lead, copper) and halogen atoms (bromine, chlorine and iodine). In recent years, various perovskite materials have been discovered, including one-dimensional perovskite nanowires, two-dimensional perovskite single crystal films and three-dimensional perovskite single crystals, which have made rapid progress. In addition to the application of new high-efficiency solar cells, perovskite materials have also shown great commercial application prospects in new light-emitting diodes, new perovskite nanopiezoelectric materials and new perovskite photodetectors. As a new type of perovskite material, methylamine lead bromine chlorine has an ultra-wide bandgap of ~2.6eV, a strong response to blue light, and is relatively stable in the air with slow performance decay. Therefore, exploring blue light detectors based on methylamine lead bromine chloride has important research value. Summary of the invention

[0005] The present invention provides a blue light photoelectric detector based on perovskite methylamine lead bromine chloride single crystal and a blue light hazard index meter based thereon, aiming to achieve accurate measurement of the blue light hazard level generated by a light source to the retina of a human eye.

[0006] In order to solve the technical problem, the present invention adopts the following technical solution:

[0007] The present invention firstly discloses a blue light photoelectric detector based on perovskite methylamine lead bromine chloride single crystal, which is characterized in that: the blue light photoelectric detector comprises a MAPbBr2Cl single crystal, a pair of gold electrodes are evaporated at intervals on the surface of the MAPbBr2Cl single crystal, and an STO (SrTiO3) single crystal substrate is covered on the MAPbBr2Cl single crystal.

[0008] The preparation method of the blue light photodetector of the present invention is as follows:

[0009] Step 1, PbCl2, PbBr2 and MABr are dissolved in DMSO and DMF to form a saturated precursor solution, and then MAPbBr2Cl single crystals are directly grown in the solution by anti-solvent saturated evaporation crystallization method, specifically: 2.78g PbCl2, 3.67g PbBr2 and 2.24g MABr are added to a mixture of 0.2mL DMSO and 1.4mL DMF, heated and stirred at 45°C for 20 to 40min, filtered through a 0.22μm organic filter, sealed to prevent solvent volatilization, and kept warm at 40 to 60°C for 30 to 48h to generate MAPbBr2Cl single crystals.

[0010] Step 2: A pair of gold electrodes are deposited on the upper surface of the MAPbBr2Cl single crystal by electron beam evaporation to form a photoconductive structure; the two gold electrodes are spaced apart to form a conductive channel in the middle.

[0011] Step 3: Cover the MAPbBr2Cl single crystal with a layer of STO single crystal substrate to obtain a blue light photodetector.

[0012] The present invention also discloses a blue light hazard index meter for detecting the blue light hazard level of a luminous light source, which comprises:

[0013] A blue light photodetector, which is the above-mentioned blue light photodetector based on perovskite methylamine lead bromine chloride single crystal, is used to test the blue light irradiance of the light source and generate a corresponding photocurrent signal;

[0014] A light focusing device, used to direct the light from the light source to the blue light photodetector;

[0015] A photoelectric detection back-end circuit, used for converting the photocurrent signal generated by the blue light photodetector into a blue light weighted radiance, and obtaining the blue light hazard level of the luminous light source;

[0016] The display module is used to display the blue light hazard level obtained by the photoelectric detection back-end circuit.

[0017] Furthermore, the light focusing device is a black bottomless cylinder with an inner wall coated with black matte paint and a field of view hole on the upper surface; the light focusing device cover is arranged outside the blue light photodetector, and the field of view hole is located directly above the blue light photodetector.

[0018] Furthermore, the photoelectric detection back-end circuit includes:

[0019] An operational amplifier is used to amplify the photocurrent signal generated by the blue light photodetector into an analog voltage signal, and an LMV358D chip may be used;

[0020] Analog-to-digital converter, used to convert the analog voltage signal obtained by the operational amplifier into a digital signal, which may adopt the XPT2046 chip;

[0021] The central processing unit is used to calculate the weighted radiance of blue light through the digital signal obtained by the analog-to-digital converter, so as to classify the blue light hazard level of the luminous light source, and the STC89C52RC chip can be used.

[0022] Furthermore, the method for obtaining the blue light hazard level is:

[0023] The blue light photodetector is illuminated by the light source to be measured, and the irradiance E of the light source to be measured is calibrated using the photocurrent signal I generated by the blue light photodetector;

[0024] Let the diameter of the field hole on the light focusing device be D and the area be A = (D / 2) 2 *π, the distance between the field of view hole and the blue light photodetector directly below it is H;

[0025] Calculate the radiance L of the light source to be measured: L = E*H 2 / A;

[0026] Thus, the blue light weighted radiance L of the light source to be measured is calculated B :L B =∫ λ B(λ)L(λ)dλ, where B(λ) is the blue light hazard weighting function and λ is the wavelength of the blue light range (400-500nm);

[0027] According to the blue light weighted radiance L B , the blue light hazard levels of luminous light sources are divided according to the IEC / TR62778 standard.

[0028] The blue light weighted radiance L B It is the radiance obtained by spectrally weighting the brightness of the initial light source using the blue light spectral weighting function defined in IEC62471.

[0029] IEC / TR 62778 recommends measuring at 200 mm and 0.011 rad to determine the appropriate boundary conditions for RG1 / 2. Therefore, the solid angle Φ formed by the field of view hole and the photodetector is set to 0.011 rad. D is set to 2.2 mm and H is set to 200 mm.

[0030] The blue light hazard classification standard is: blue light weighted radiance L B Value is 0~100W / (m 2 ·sr) is RG0 (exempt level), between 100~10000W / (m 2 ·sr) is RG1 (primary danger level), between 10000~4000000W / (m 2 sr) is RG2 (medium hazard level). In the IEC / TR62778 standard, it is hoped that light sources with blue light hazards greater than RG2 will not be used.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The blue light photodetector of the present invention is based on the photoconductive structure formed by MAPbBr2Cl single crystal and Au electrode. The absorption peak of light is determined by the band gap of MAPbBr2Cl itself, and the wavelength is about 480nm, so that the device has a good absorption capacity for blue light, thereby making the device show the advantage of high sensitivity. The peak wavelength range of the spectral response characteristic curve of MAPbBr2Cl single crystal plus STO single crystal substrate is 380nm-500nm, and the responsivity is a smooth straight line, which has a better response to the detected blue light, and the responsivity can reach 10mA / W.

[0033] 2. The preparation method of MAPbBr2Cl single crystal of the present invention increases the light absorption area of ​​the perovskite and greatly increases the absorption capacity of the perovskite to blue light. Compared with other blue light detection materials, the preparation process of MAPbBr2Cl perovskite used in the present invention is simple and low-cost, and is very suitable for large-scale production.

[0034] 3. The detector of the present invention has high commercial value and good stability.

[0035] 4. The blue light hazard classification of the present invention adopts the IEC / TR62778 standard, which is a standard specifically for evaluating the blue light hazard of light sources and lamps and is more accurate.

[0036] 5. The blue light hazard index meter of the present invention can accurately and quickly obtain the blue light hazard level of the luminous light source, has a high degree of integration, high cost performance, is easy to carry, and is simple to operate. The test data complies with the international blue light hazard standards and is suitable for detecting blue light hazards of lamps in daily life.

[0037] 6. In the blue light hazard index meter of the present invention: the central processing unit adopts the STC89C52RC chip as the main control chip, which is widely used. It is a low-power, high-performance CMOS 8-bit microcontroller with 8K in-system programmable Flash memory. The operational amplifier adopts the dual operational amplifier LMV358D chip, which includes two independent, high-gain, internal frequency-compensated operational amplifiers. It is suitable for single power supply with a wide power supply voltage range, and is also suitable for dual power supply working mode. Under the recommended working conditions, the power supply current is independent of the power supply voltage. Its scope of use includes sensor amplifiers, DC gain modules and all other occasions where operational amplifiers can be used with a single power supply. The analog-to-digital converter adopts the XPT2046 chip, which is a successive approximation analog-to-digital converter (SARADC) with a 12-bit resolution and a conversion rate of 125KHz, and includes functions such as sampling / holding, analog-to-digital conversion, and serial port data output. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the blue light photodetector of the present invention.

[0039] Figure 2 It is a schematic diagram of the placement of the blue light photodetector and the light focusing device of the present invention.

[0040] Figure 3 Schematic diagram of the blue light hazard index instrument of the present invention.

[0041] Figure 4 The blue light photodetector prepared in Example 1 of the present invention has a power of 1.3 μW / cm 2 Up to 1.3mW / cm 2 Time response curve under illumination.

[0042] Figure 5 (a) is a comparison of the spectral response curves of the blue light photodetector prepared in Example 1 of the present invention and the MAPbBr2Cl single crystal without the STO single crystal substrate; Figure 5 (b) is a comparison of the spectral response curve of the blue light photodetector prepared in Example 1 of the present invention and the blue light spectrum.

[0043] Figure 6 The photocurrent of the blue light photodetector prepared in Example 1 of the present invention under different irradiances.

[0044] Figure 7This is the blue light hazard weighting function of the blue light photodetector prepared in Example 1 of the present invention.

[0045] Figure 8 This is the absorption curve of the MAPbBr2Cl single crystal of the blue light photodetector prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0047] Example 1

[0048] like Figure 1 As shown, the blue light photodetector based on the perovskite methylamine lead bromine chloride single crystal in this embodiment includes a MAPbBr2Cl single crystal, a pair of gold electrodes are deposited on the surface of the MAPbBr2Cl single crystal, and an STO single crystal substrate is covered on the MAPbBr2Cl single crystal. The preparation method of the blue light photodetector is as follows:

[0049] Step 1. Add 2.78 g PbCl2, 3.67 g PbBr2 and 2.24 g MABr to a mixture of 0.2 mL DMSO and 1.4 mL DMF, heat and stir at 45 ° C for 30 min, filter through a 0.22 μm organic filter, seal, and keep warm at 50 ° C for 40 h to generate a rectangular MAPbBr2Cl single crystal with a length, width and height of 3 mm × 3 mm × 1 mm.

[0050] Step 2: A pair of gold electrodes with a thickness of 50 nm are deposited on the upper surface of the MAPbBr2Cl single crystal by electron beam evaporation to form a photoconductive structure; the two gold electrodes are spaced apart to form a conductive channel with a width of 3 mm in the middle.

[0051] Step 3: Cover the MAPbBr2Cl single crystal with a layer of STO single crystal substrate to obtain a blue light photodetector.

[0052] like Figure 2 As shown, this embodiment also constructs a blue light hazard index meter based on the above-mentioned blue light photoelectric detector, which includes:

[0053] A blue light photodetector is used to test the blue light irradiance of the light source and generate a corresponding photocurrent signal;

[0054] A light focusing device, used to direct the light from the luminous light source to the blue light photodetector;

[0055] A photoelectric detection back-end circuit is used to convert the photocurrent signal generated by the blue light photodetector into a blue light weighted radiance and obtain the blue light hazard level of the luminous light source;

[0056] The display module is used to display the blue light hazard level obtained by the photoelectric detection back-end circuit.

[0057] Specifically, Figure 3 As shown, the light focusing device is a black bottomless cylinder, the inner wall of which is coated with black matte paint and the upper surface is provided with a viewing hole; the light focusing device cover is arranged outside the blue light photodetector, and the viewing hole is located directly above the blue light photodetector. Let the diameter of the viewing hole on the light focusing device be D and the area be A = (D / 2) 2 *π, the distance between the field of view hole and the blue light photodetector directly below it is H; IEC / TR 62778 recommends measuring at 200mm and 0.011rad to determine the appropriate boundary conditions of RG1 / 2. Therefore, the solid angle Φ formed by the field of view hole and the photodetector is set to 0.011rad. D is set to 2.2mm and H is set to 200mm.

[0058] Specifically, the photoelectric detection back-end circuit includes: an operational amplifier, which is used to amplify the photocurrent signal generated by the blue light photodetector into an analog voltage signal. This embodiment uses the LMV358D chip; an analog-to-digital converter, which is used to convert the analog voltage signal obtained by the operational amplifier into a digital signal. This embodiment uses the XPT2046 chip; a central processing unit, which is used to calculate the weighted radiance of blue light through the digital signal obtained by the analog-to-digital converter, thereby dividing the blue light hazard level of the luminous light source. This embodiment uses the STC89C52RC chip. The two gold electrodes of the blue light photodetector are led out with silver wire as electrode leads. One end of the electrode is connected to the operational amplifier, and the other end is connected to the 5V voltage. The connection method of each component in the back-end circuit adopts a standard method to meet the detection needs of the present invention.

[0059] In this embodiment, the method for obtaining the blue light hazard level is:

[0060] The blue light photodetector is illuminated by the light source to be measured, and the photocurrent signal I generated by the blue light photodetector is used to calibrate the irradiance E of the light source to be measured; a standard relationship curve between I and E can be established.

[0061] Calculate the radiance L of the light source to be measured: L = E*H 2 / A;

[0062] Thus, the blue light weighted radiance L of the light source to be measured is calculated B :L B =∫ λ B(λ)L(λ)dλ, where B(λ) is the blue light hazard weighting function and λ is the wavelength of the blue light range.

[0063] According to the blue light weighted radiance L B According to the IEC / TR62778 standard, the blue light hazard level of the luminous source is divided into: blue light weighted radiance L B Value is 0~100W / (m 2 ·sr) is RG0 (exempt level), between 100~10000W / (m 2 ·sr) is RG1 (primary danger level), between 10000~4000000W / (m 2 sr) is RG2 (medium hazard level). In the IEC / TR62778 standard, it is hoped that light sources with blue light hazards greater than RG2 will not be used.

[0064] Figure 4 The blue light photodetector prepared in this embodiment has a wavelength of 430nm and a power of 1.3μW / cm 2 Up to 1.3mW / cm 2 From the time response curve under illumination, it can be seen that the photocurrent of the device increases with the increase of incident light intensity.

[0065] Figure 5 (a) is a comparison of the spectral response curves of the blue light photodetector prepared in this embodiment and the MAPbBr2Cl single crystal without the STO single crystal substrate. It can be seen that the detector has a high responsivity and a horizontal response curve. Figure 5 (b) is a comparison between the spectral response curve of the blue light photodetector prepared in this embodiment and the blue light spectrum. It can be seen that the detection range of the detector obtained in this embodiment is the blue light band.

[0066] Figure 6 The photocurrent of the blue light photodetector prepared in this embodiment under different irradiances is used to calibrate the irradiance of the light source to be measured.

[0067] Figure 7 The blue light hazard weighting function of the blue light photodetector prepared in this embodiment is obtained by integrating the blue light weighted radiance with the radiance.

[0068] Figure 8 This is the absorption curve of the MAPbBr2Cl single crystal of the blue light photodetector prepared in this embodiment. The absorption peak around 480nm is the absorption peak of the MAPbBr2Cl single crystal.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A blue light hazard index meter, characterized in that: include: A blue light photodetector is used to test the blue light irradiance of the light source and generate a corresponding photocurrent signal; The blue light photodetector comprises a MAPbBr2Cl single crystal, a pair of gold electrodes are evaporated at intervals on the surface of the MAPbBr2Cl single crystal, and an STO single crystal substrate is covered on the outside of the MAPbBr2Cl single crystal; A light focusing device, used for directing the light of the luminous light source to the blue light photodetector; the light focusing device is a black bottomless cylinder, the inner cylinder wall is coated with black matte paint, and a field of view hole is opened on the upper surface; the light focusing device is covered outside the blue light photodetector, and the field of view hole is located directly above the blue light photodetector; A photoelectric detection back-end circuit, used for converting the photocurrent signal generated by the blue light photodetector into a blue light weighted radiance, and obtaining the blue light hazard level of the luminous light source; The display module is used to display the blue light hazard level obtained by the photoelectric detection back-end circuit.

2. The blue light hazard index meter according to claim 1, characterized in that: The peak wavelength range of the blue light photodetector is 380nm-500nm.

3. The blue light hazard index meter according to claim 1 or 2, characterized in that: The method for preparing the blue light photodetector comprises the following steps: Step 1, PbCl2, PbBr2 and MABr are dissolved in DMSO and DMF to form a saturated precursor solution, and then MAPbBr2Cl single crystals are directly grown in the solution by anti-solvent saturated evaporation crystallization method; Step 2: a pair of gold electrodes are deposited on the upper surface of the MAPbBr2Cl single crystal by electron beam evaporation to form a photoconductive structure; the two gold electrodes are spaced apart to form a conductive channel in between; Step 3: Cover the MAPbBr2Cl single crystal with a layer of STO single crystal substrate to obtain a blue light photodetector.

4. The blue light hazard index meter according to claim 3, characterized in that: The specific method of step 1 is: add 2.78g PbCl2, 3.67g PbBr2 and 2.24g MABr to a mixture of 0.2mL DMSO and 1.4mL DMF, heat and stir at 45°C for 20-40min, filter through a 0.22μm organic filter, seal, and keep warm at 40-60°C for 30-48h to generate MAPbBr2Cl single crystal.

5. The blue light hazard index meter according to claim 1, characterized in that: The photoelectric detection back-end circuit comprises: An operational amplifier, used for amplifying a photocurrent signal generated by a blue light photodetector into an analog voltage signal; An analog-to-digital converter, used to convert the analog voltage signal obtained by the operational amplifier into a digital signal; The central processing unit is used to calculate the weighted radiance of blue light through the digital signal obtained by the analog-to-digital converter, so as to classify the blue light hazard level of the luminous light source.

6. The blue light hazard index meter according to claim 5, characterized in that: The operational amplifier adopts LMV358D chip, the analog-to-digital converter adopts XPT2046 chip, and the central processing unit adopts STC89C52RC chip.

7. The blue light hazard index meter according to claim 1, characterized in that: The method for obtaining the blue light hazard level is: The blue light photodetector is illuminated by the light source to be measured, and the irradiance E of the light source to be measured is calibrated using the photocurrent signal I generated by the blue light photodetector; Let the diameter of the field hole on the light focusing device be D and the area be A = (D / 2) 2 *π, the distance between the field of view hole and the blue light photodetector directly below it is H; Calculate the radiance L of the light source to be measured: L = E * H 2 / A; Thus, the blue light weighted radiance L of the light source to be measured is calculated B :L B =∫ λ B(λ)L(λ)dλ, where B(λ) is the blue light hazard weighting function and λ is the wavelength of the blue light range; According to the blue light weighted radiance L B , the blue light hazard levels of luminous light sources are divided according to the IEC / TR 62778 standard.

8. The blue light hazard index meter according to claim 7, characterized in that: The solid angle Φ formed by the field of view hole and the photodetector is set to 0.011 rad.

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