A Bi(I 1-x Br x )3 and a preparation method and application thereof

Abstract

The present application relates to a kind of Bi (I 1‑x Br x ) 3 Single Crystal and its preparation method and purposes.The method is with different molar ratio of BiI 3 And BiBr 3 As raw material, mixed in argon environment, in the sealed vacuum quartz tube with single-temperature zone tube furnace heating to make it react, after water cooling, high quality, large size single crystal Bi (I 1‑x Br x ) 3 It can be obtained at the bottom of tube, tube wall and tube plug.The preparation method described in the present application is simple and easy to operate, and the process difficulty is lower, easy to popularize, and high-quality single crystal Bi (I 1‑x Br x ) 3 With different Br doping ratio can be obtained.The single crystal Bi (I 1‑x Br x ) 3 Prepared by this method has less impurity content, high light absorption intensity and stable light response ability, etc. Excellent performance, has great potential application value in the field of photoelectric detector.

Description

TECHNICAL FIELD

[0001] The present application relates to a Bi(I 1-x Br x )3 and a preparation method thereof and application thereof in a photoelectric detector, and belongs to the technical field of photoelectric detection measurement. BACKGROUND

[0002] Semiconductor photoelectric detectors are generally photoelectric detectors with a metal-semiconductor-metal structure formed by plating electrodes on the surface of a semiconductor. Photoelectric detectors can convert optical signals into electrical signals through various sensing effects such as photoconductive effect, photothermal effect, and plasmonic wave auxiliary mechanism. Currently, widely used semiconductor radiation detectors include Ge detectors, Si-based detectors, gallium arsenide detectors, boron nitride, indium antimonide detectors, cadmium telluride detectors, perovskite detectors, thallium bromide, and iodine-containing semiconductor detectors. Among them, heavy metal iodides such as mercury iodide, lead iodide, and bismuth iodide are suitable for use as radiation detectors due to their high density, high atomic number, and large band gap, but they are toxic and have great limitations for practical applications.

[0003] CN114560500A discloses a non-lead perovskite material and a preparation method and application thereof. The structure general formula of the non-lead perovskite material is Cs3Sb 2-x Bi x A 9-y B y , wherein A and B are F, Cl, Br or I; A and B are not the same, 0

[0004] CN110230103A discloses a zero-dimensional bismuth-based iodide R3Bi2I9 perovskite single crystal material. The material (Bi2I9) 3- is surrounded by organic ions R+ to form a three-dimensional spatial point-like discontinuous distribution. The preparation method of the material and the application of such material in an X-ray detector are also disclosed. A new zero-dimensional bismuth-based perovskite single crystal material with high stability and environmental friendliness is provided. Due to the high stability and high attenuation coefficient of the material to X-rays, the prepared detector has good radiation resistance and good signal response to X-rays with a dose rate of only 182nGy air s -1 , which is much lower than the requirement of 5.5μGy air s-1 wherein (Bi2I9) 3- The organic ion R+ around the unit is C n H 2n+1 NH3 + (1≤n≤5), C n H 2n+1 C(=NH)NH2 + (0≤n≤5), C6H5C n H 2n+1 NH3 + (1≤n≤4), C6H5C n H 2n+1 C(=NH)NH2 + (0≤n≤4) or a mixture of one or more thereof. It must employ an organic ion.

[0005] CN111285797A discloses a bismuth-based perovskite material and a preparation method thereof. The material has a chemical formula of (C 12 H 14 N2)BiX5, wherein C 12 H 14 N2 represents a positive divalent methyl viologen cation, and X represents any one or more of Cl, Br and I. The material is prepared by a solvothermal reaction in a methanol solution using a bismuth source, a hydrohalic acid as raw materials, and 4,4'-bipyridine or methyl viologen as a structure directing agent. The preparation method is simple and has good repeatability. The photoelectric properties of the material can be effectively controlled by changing the halogen. Meanwhile, the use of the metal element bismuth instead of the toxic element lead reduces the harm to the human body and the pollution to the environment. The material has good moisture and heat stability, excellent photoelectric properties and good semiconductor performance, and has a wide application prospect in the fields of solar cells, photoelectric materials, photoelectric detection, photo / photoelectric catalysis and the like. It must employ a divalent methyl viologen cation.

[0006] CN113897681A discloses a preparation method of a non-lead perovskite single crystal with (110) orientation. The method comprises the following steps: step S1: dissolving CH3NH3X, BiX3 and a butylamine cation source in a solvent to prepare a single crystal growth solution; and step S2: evaporating the solvent in the single crystal growth solution to obtain the non-lead perovskite single crystal (CH3NH3)3Bi2X9 at the bottom of the single crystal growth solution, wherein X is one or more of I, Br and Cl. The use of the butylamine cation source as an additive enables the controllable orientation of the (CH3NH3)3Bi2X9 single crystal surface, and the (CH3NH3)3Bi2X9 perovskite single crystal with (110) orientation, regular shape and high quality can be easily obtained. It employs a butylamine cation source.

[0007] The principle of the BiI3 semiconductor photodetector is based on the photoconductive effect, the semiconductor is irradiated with light, the photons with energy greater than the band gap of the semiconductor are absorbed by the semiconductor, the electrons in the valence band are absorbed and transition to the conduction band to generate electron-hole pairs. The electron-hole pairs are separated under the action of bias and move to the two poles, respectively, thereby increasing the current, so that the optical signal is converted into an electrical signal. Since BiI3 has a suitable band gap and a high light absorption coefficient in the visible light spectrum, bismuth iodide can be used for photodetectors and solar cells. Since Bi can replace the toxic element lead, the application of bismuth iodide also solves the problem of containing toxic lead in halide perovskite solar cells. SUMMARY

[0008] In view of the defects in the existing photodetector material technology, the present application can effectively change the band gap of Bi(I 1- x Br x )3 single crystal by Br doping. With the increase of Br content, the band gap of Bi(I 1-x Br x )3 single crystal increases from 1.69eV to 1.93eV, further increasing the light response capability. Experiments show that the light absorption of single crystal with high Br content is significantly higher than that of BiI3, indicating that the doping of Br further improves the light absorption capacity of BiI3 and has high stability. The material has great application prospect in the field of photodetection.

[0009] The present application provides a preparation method of a new photodetector material Bi(I 1-x Br x )3. The low-toxicity and non-volatile BiI3 and BiBr3 are used as raw materials, and through a simple process, high-quality large-size single crystal Bi(I 1-x Br x )3 can be obtained, which has great potential application value in the field of photodetection.

[0010] The purpose of the present application is achieved by the following technical solutions:

[0011] A preparation method of Bi(I 1-x Br x )3 single crystal, characterized in that the method comprises the following steps:

[0012] Step 1. BiI3 and BiBr3 are mixed in a glove box filled with argon according to a molar ratio of BiI3:BiBr3 of 20:1-1:20 to obtain a bismuth salt mixture;

[0013] Step 2. The bismuth salt mixture is transferred to a quartz tube, vacuumized, and sealed with a hydrogen compressor;

[0014] Step 3. The sealed quartz tube is placed in a single-zone tube furnace for heating reaction. Preferably, the temperature is first raised to 460-500°C and maintained for 5-15h, then lowered to 300-350°C at a rate of 10-20h, then lowered to 260-300°C at a rate of 20-40h, and finally cooled naturally to obtain condensed Bi(I 1-x Br x )3 single crystal, and x is 0.05-0.95.

[0015] Preferably, the Bi(I 1-x Br x )3 single crystal obtained in Step 3 is taken out in an environment filled with argon protection gas.

[0016] Preferably, the purity of elemental BiI3 and BiBr3 is not less than 99.5%. Too low purity of starting materials can cause defects in the single crystal, thereby adversely affecting the stability of the performance of the single crystal.

[0017] Preferably, BiI3 and BiBr3 are mixed in Step 1 at different molar ratios, with a molar ratio of 20:1-1:20, preferably 9:1-1:9. If the doping ratio of Br is too low, the expected synergistic effect cannot be achieved, and if the doping ratio of Br is too high, the final photoelectric response is too weak to be detected.

[0018] Preferably, elemental BiI3 and BiBr3 are mixed at different molar ratios, such as a molar ratio of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, or 1:9, to produce single crystals with different doping ratios. If the optimal ratio is further adjusted, the molar ratio can be further optimized, but the preferred molar ratio range should not exceed 9:1-1:9.

[0019] Preferably, elemental BiI3 and BiBr3 are reacted in a closed quartz tube without the presence of oxygen or water. Although there is no exact principle analysis, it is believed that the presence of oxygen or water molecules can affect the quality of the single crystal; a possible explanation is that the defects in the single crystal affect the performance of the final product.

[0020] Preferably, the vacuum in Step 2 is set to a pressure of 10 -3 Pa or less. The vacuum degree is small enough that oxygen is essentially absent, and in general, a vacuum degree of 10 -3 Pa or less is sufficient, and more preferably 10 -5 Pa or less.

[0021] Preferably, in step 3, the temperature is first raised to 465℃ for 10h, then maintained for 10h, then lowered to 315℃ for 15h, and then lowered to 290℃ for 25h. The temperature rising and lowering processes are as gentle as possible to avoid over-activation and cause internal defects of the single crystal. For example, the temperature is raised from room temperature to 465℃ for 10h, and the average temperature rising is 44-48℃ per hour.

[0022] Preferably, in step 4, the Br content can be x=0.088, 0.178, 0.231, 0.276, 0.392, 0.541, 0.673, 0.755, 0.812, for example.

[0023] Preferably, it is characterized in that: x=0.088-0.541. Although experiments show that a higher Br doping ratio can bring the best performance, it is surprisingly found that at this doping ratio, the responsivity and specific detectivity performance can be considered, and the best photodetector performance is achieved. Specifically, as shown in Figure 10 , experiments show that the Bi(I 0.822 Br 0.178 )3 photoelectric response performance is the best. When x=0.178, the photodetector performance of the device is the best, with high responsivity (0.54A / W) and high specific detectivity (1.5×

[0024] 10 13 Jones). Further reasons are under study.

[0025] The application also provides the Bi(I 1-x Br x )3 single crystal prepared by the above preparation method and the application in a photodetector.

[0026] The specific detectivity represents the spectral detectivity per unit surface area (1cm 2 ) and per unit bandwidth (1Hz) of the detector. The unit of specific detectivity is cm·Hz^(1 / 2)·W^(-1) (also known as Jones). BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A photo of the Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 1.

[0028] Figure 2 A photo of the Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 2.

[0029] Figure 3 A photo of the Bi(I0.459 Br 0.541 )3 single crystal.

[0030] Figure 4 Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 1.

[0031] photograph.

[0032] Figure 5 Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 2.

[0033] photograph.

[0034] Figure 6 Bi(I 0.459 Br 0.541 )3 single crystal prepared in Example 3.

[0035] photograph.

[0036] Figure 7 Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 1.

[0037] (c) I-V curves of the photodetector under different incident light power densities; (d) switching cycle of the photodetector

[0038] stability test.

[0039] Figure 8 Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 2.

[0040] (c) I-V curves of the photodetector under different incident light power densities; (d) switching cycle of the photodetector

[0041] stability test.

[0042] Figure 9 Bi(I 0.459 Br 0.541)3 single crystal, (a) I-T curves of the photodetector under different wavelength incident light irradiation; (b) UV-Vis absorption spectrum of the nanosheet; (c) I-V curves of the photodetector under different incident light power density; (d) switch cycle stability test of the photodetector.

[0043] Figure 10 photodetector made of Bi(I 0.822 Br 0.178 )3 prepared in Example 1.

[0044] Figure 11 (a) is the responsivity of Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 1.

[0045] Figure 11 (b) is the specific detectivity of Bi(I 0.822 Br 0.178 )3 single crystal prepared in Example 1.

[0046] Figure 12 (a) is the responsivity of Bi(I 0.459 Br 0.541 )3 single crystal prepared in Example 3.

[0047] Figure 12 (b) is the specific detectivity of Bi(I 0.459 Br 0.541 )3 single crystal prepared in Example 3.

[0048] Figure 13 X-ray diffraction (XRD) spectrum of Bi(I 1-x Br x )3 single crystal prepared in Examples 1, 3-10.

[0049] Figure 14 Photograph of BiI3 single crystal of Comparative Example 1. DETAILED DESCRIPTION

[0050] The present application is further described below in conjunction with the accompanying drawings and specific embodiments, wherein the methods are conventional methods unless otherwise specified, and the raw materials are commercially available unless otherwise specified.

[0051] Example 1

[0052] Step 1. Prepare high-purity BiI3 and BiBr3, respectively, and mix them in a molar ratio of 8:2 in an argon-filled glove box, so that the total mass is 4 g;

[0053] Step 2. Transfer the mixed sample into a quartz tube, vacuumize it to a pressure of about 10 -3 Pa, seal the tube with a hydrogen compressor to ensure that there is no air contact with the sample in the quartz tube.

[0054] Step 3. The sealed quartz tube was placed in a single-zone tube furnace, first heated to 465°C at 10h, then kept for 10h, then cooled to 315°C at 15h, then cooled to 290°C at 25h, and finally cooled naturally to obtain condensed Bi(I 1-x Br x )3 single crystal;

[0055] Step 4. Under the protection of argon gas, the quartz tube was opened, and the bulk crystal was taken out with tweezers, which was the Bi(I 1-x Br x )3 single crystal with Br content of x = 0.178. The single crystal photograph is shown in Figure 1 , the morphology and element distribution map are shown in Figure 4 , the photoelectric response test diagram is shown in Figure 7 , the photoelectric detector example is shown in Figure 10 , the responsivity of Bi(I 0.822 Br 0.178 )3 single crystal is shown in Fig. 11(a), and the detectivity is shown in Fig. 11(b); the X-ray diffraction (XRD) spectrum is shown in Figure 13 .

[0056] Example 2

[0057] The other conditions are the same as those in Example 1, except that Step 3 is as follows: the sealed quartz tube is placed in a single-zone tube furnace, first heated to 450°C at 10h, then kept for 40h, and finally cooled naturally to obtain condensed Bi(I 1-x Br x )3 single crystal with Br content of x = 0.178. The single crystal photograph is shown in Figure 2 , the morphology and element distribution map are shown in Figure 5 , and the photoelectric response test diagram is shown in Figure 8 .

[0058] Example 3

[0059] The molar ratio of BiI3 to BiBr3 in Step 1 is 4:6, and x in Step 4 is 0.541; the others are the same as those in Example 1. The single crystal photograph is shown in Figure 3 , the morphology and element distribution map are shown in Figure 6 , and the photoelectric response test diagram is shown in Figure 9 ; the responsivity of Bi(I 0.459 Br 0.541 )3 single crystal is shown in Fig. 12(a), and the detectivity is shown in Fig. 12(b); the X-ray diffraction (XRD) spectrum is shown in Figure 13 .

[0060] Examples 4, 5, 6, 7, 8, 9, and 10

[0061] The molar ratio of BiI3 to BiBr3 in step 1 was 9:1, 7:3, 6:4, 5:5, 3:7, 2:8, and 1:9, respectively, and x in step 4 was 0.088, 0.231, 0.276, 0.392, 0.673, 0.755, and 0.812, respectively; the others were the same as in Example 1. The X-ray diffraction (XRD) spectrum is shown in Figure 13

[0062] Comparative Example 1

[0063] In step 1, only BiI3 was used, and BiBr3 was not used; the others were the same as in Example 1.

[0064] Step 1. High-purity elemental BiI3 was prepared in an argon-filled glove box, and the total mass was 4 g;

[0065] Step 2. The sample was transferred to a quartz tube, and vacuum was applied to a pressure of about 10 -3 Pa. The tube was sealed with a hydrogen compressor to ensure that no air contacted the sample in the quartz tube;

[0066] Step 3. The sealed quartz tube was placed in a single-zone tube furnace, and the temperature was raised to 465°C at a rate of 10 h, then maintained for 10 h, then lowered to 315°C at a rate of 15 h, then lowered to 290°C at a rate of 25 h, and finally naturally cooled to obtain condensed BiI3 single crystals;

[0067] Step 4. Under the protection of an argon-filled environment, the quartz tube was opened, and the bulk crystal was removed with tweezers, which was a single-crystal BiI3 single crystal, as shown in Figure 14 ; and the X-ray diffraction (XRD) spectrum is shown in Figure 13 .​

Claims

1. A kind of Bi(I 1-x Br x )3 A method for preparing a single crystal, characterized in that: The method steps are as follows: Step 1. Mix BiI3 and BiBr3 in a molar ratio of BiI3:BiBr3 of 8:2 in an argon-filled glove box to obtain a bismuth salt mixture; Step 2. Transfer the bismuth salt mixture into a quartz tube, evacuate the tube, and seal the tube with a hydrogen compressor; Step 3. The sealed quartz tube was placed in a single temperature zone tube furnace for heating reaction. The heating reaction was first heated to 465 ° C for 10 h, then maintained for 10 h, then cooled to 315 ° C for 15 h, and then cooled to 290 ° C for 25 h, and finally cooled naturally to obtain condensed Bi(I 1-x Br x )3 single crystal, x is 0.

178.

2. Bi(I) prepared by the preparation method according to claim 1 1-x Br x )3 single crystal.

3. Bi(I) according to claim 2 1-x Br x )3Application of single crystals in photodetectors.

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