Perovskite single crystal radiation detector capable of working stably under high bias voltage and preparation method of perovskite single crystal radiation detector

Abstract

The invention relates to a perovskite single crystal radiation detector capable of working stably under high bias voltage and a preparation method thereof, the detector comprises a perovskite single crystal material layer, a titanium electrode layer and a grounding electrode layer, and the titanium electrode layer and the grounding electrode layer are respectively arranged on the upper side and the lower side of the perovskite material layer. The perovskite radiation detector disclosed by the invention can stably work under high bias voltage, and compared with a currently reported perovskite radiation detector, the perovskite radiation detector disclosed by the invention can realize long-term working stability without any passivation or polishing post-processing method on the perovskite single crystal. The perovskite radiation detector can work stably under high bias voltage, and is low in dark current, low in detection limit and high in sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation detector devices, and in particular to a perovskite single crystal radiation detector that operates stably under high bias voltage and a preparation method thereof. Background Art

[0002] Radiation detectors are widely used in fields such as medical diagnosis and industrial testing. The fabrication of high-performance radiation detectors with high resolution and fast response times is of great significance. Perovskite single crystals are considered a new generation of high-energy radiation detection materials due to their high carrier mobility and migration lifetime product (μτ) and efficient absorption of high-energy radiation. However, currently reported high-potential electrode materials used in the preparation of perovskite radiation detectors, such as silver, aluminum, and copper, undergo electrochemical reactions with the perovskite under high bias voltages (Adv. Mater. 2022, 34, e2108616), accelerating the perovskite's decomposition. Due to their inability to operate stably under high bias voltages, the device's imaging resolution and response rate are limited.

[0003] To address the above problems, the following two methods are currently used to improve the stability of the device under high bias: (1) avoid direct contact between the electrode and the perovskite material through interface passivation, but the highly stable passivation layer has poor conductivity, which ultimately affects the device response (Nano Lett. 2022, 22, 2490-2496); (2) separate the electrode and the perovskite material by introducing an electron or hole blocking layer, but it is difficult to prepare a large area of ​​uniform blocking layer (Nat. Energy 2022, 7, 520-527).

[0004] In summary, there is an urgent need to develop an electrode material with a simple preparation method and which can effectively improve the stability under high bias voltage, which is of great significance for realizing high-performance radiation detectors. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a perovskite single crystal radiation detector that operates stably under high bias voltage and a method for preparing the same. This method uses a titanium electrode as the high-potential electrode material during operation of the perovskite radiation detector, effectively suppressing the device's electrochemical reaction and significantly increasing the bias voltage at which the device operates stably, increasing the device's sensitivity to 96,379.44 μCGy. air -1 cm -2 This method has the characteristics of strong repeatability, simple operation and low cost.

[0006] The technical solutions provided by the present invention are as follows:

[0007] A perovskite single crystal radiation detector that operates stably under high bias voltage comprises: a perovskite single crystal material layer, a titanium electrode layer, and a ground electrode layer, wherein the titanium electrode layer and the ground electrode layer are respectively arranged on the upper and lower sides of the perovskite material layer; the perovskite single crystal material layer is a three-dimensional perovskite single crystal with the molecular formula CsPbBr3 or MAPbBr3; and the ground electrode layer is one of Au, Pt, and Cr.

[0008] Furthermore, the thickness of the titanium electrode layer is 70 to 200 nm.

[0009] Furthermore, the ground electrode layer is made of Au, Pt, Cr, and has a thickness of 70 to 200 nm.

[0010] The present invention also provides a method for preparing a perovskite single crystal radiation detector that works stably under high bias voltage, which is characterized by comprising the following steps: step 1, covering a mask plate on one side of the perovskite single crystal surface; step 2, utilizing a DC magnetron sputtering coating process, using a Ti target with a purity of 99.99% as the material, and evacuating the vacuum to a degree higher than 4×10 -4 Pa, argon gas is passed to adjust the gas pressure to 0.9 Pa, the coating rate is 0.8 to 1 angstrom / second, and 70nm to 200nm of Ti is plated on the part of the perovskite single crystal material layer not covered by the mask as a side electrode.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1. The present invention utilizes the strong corrosion resistance and low diffusion properties of metallic titanium. It does not react with halogens at room temperature and does not react with the perovskite material layer under high voltage. The stable working bias of the device is greatly improved, and the performance of the device is also better, with better repeatability, higher device response, and a simpler process flow.

[0013] 2. Titanium metal is inexpensive and, when combined with perovskite single crystal surface defect passivation technology, effectively controls the manufacturing cost of perovskite radiation detectors while achieving higher stability and lower dark current.

[0014] 3. Although the present invention is based on organic-inorganic hybrid perovskite materials, it can be easily extended to a wider range of perovskite single crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of Example 1 of a perovskite single crystal radiation detector that operates stably under high bias voltage according to the present invention;

[0016] Figure 2 The relationship between the response current and time of the perovskite single crystal radiation detector under a bias voltage of 10 V and different X-ray dose rates according to Example 1 of the present invention is shown;

[0017] Figure 3 The relationship between the response current and time of the perovskite single crystal radiation detector under a bias voltage of 50V and different X-ray dose rates according to Example 1 of the present invention;

[0018] Figure 4 The relationship between the response current and time of the perovskite single crystal radiation detector under a bias voltage of 100 V and different X-ray dose rates according to Example 1 of the present invention;

[0019] Figure 5 These are the dose rate and sensitivity results under different bias voltages of Example 1 of the present invention.

[0020] Figure 6 This is the relationship between dark current and time of Example 1 of the present invention when it continuously works for 10 hours at a bias voltage of 2.5 V / mm.

[0021] Figure 7 This is the relationship between current and time at a bias voltage of 2.5 V / mm within one week in Example 1 of the present invention.

[0022] Figure 8 This is the relationship between the sensitivity and time of Example 1 of the present invention within one week under a bias voltage of 50 V / mm. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this should not limit the scope of protection of the present invention.

[0024] Example 1

[0025] like Figure 1 As shown, a perovskite single crystal radiation detector that works stably under high bias voltage includes a perovskite single crystal material layer 1, the perovskite single crystal material layer uses MAPbBr3 single crystal, and a titanium electrode layer 2 and a gold electrode layer 3 are respectively provided at the upper and lower ends of the perovskite single crystal material layer 1.

[0026] A method for preparing a perovskite single crystal radiation detector that operates stably under high bias voltage comprises the following steps:

[0027] 1. Cover the mask on one side of the MAPbBr3 single crystal;

[0028] 2. Using DC magnetron sputtering coating process, with 99.99% purity Ti target as material, the vacuum degree is higher than 4×10 -4 Under the condition of 1.5 Pa, argon gas was passed to adjust the pressure to 0.9 Pa, the deposition rate was 0.8 angstroms / second, and 70 nm of Ti was deposited on the portion of the perovskite single crystal material layer not covered by the mask as a side electrode;

[0029] 3. Cover the mask on the other side of the MAPbBr3 single crystal;

[0030] 4. Using vacuum evaporation coating process, with 99.99% purity Au particles as material, the vacuum degree is higher than 4×10 -4 Under the conditions of Pa, the coating rate is 0.8 angstroms / second, and 70nm of Au is plated on the part of the perovskite single crystal material layer not covered by the mask as a side electrode;

[0031] 5. Prepare conductive leads on the gold and titanium electrodes respectively, and cover and protect the titanium electrodes, gold electrodes and conductive leads with high-temperature insulating tape;

[0032] Under 10V bias and X-ray irradiation (silver target, Amptek Mini-X2), the radiation response was measured using a Keithley 2634B source meter. The test results are as follows: Figure 2 As shown. Figure 2 It can be seen from the figure that under the bias voltage of 10V, the device works stably. Under different X-ray dose conditions, the response current of the device increases with the increase of the incident dose.

[0033] Under 50V bias and X-ray irradiation (silver target, Amptek Mini-X2), the radiation response was measured using a Keithley 2634B source meter. The test results are as follows: Figure 3 As shown. Figure 3 It can be seen from the figure that the device still works stably when the voltage increases to 50V. Under different X-ray dose conditions, the response current of the device increases with the increase of incident dose.

[0034] Under 100V bias and X-ray irradiation (silver target, Amptek Mini-X2), the radiation response was measured using a Keithley 2634B source meter. The test results are as follows: Figure 4 As shown. Figure 4 It can be seen from the figure that when the voltage increases to 100V, the device still works stably. Under different X-ray dose conditions, the response current of the device increases with the increase of incident dose.

[0035] like Figure 5 As shown, as the bias voltage increases to 100 V, the sensitivity of the device increases to 96,379.44 μC Gy air -1 cm -2 , and the detection limit of the device remains at 5nGy s -1 the following

[0036] like Figure 6As shown in the figure, the device worked continuously for 10 hours under a bias of 5V, and the dark current drift was only 1.4nA, indicating that the titanium electrode effectively suppressed the electrochemical reaction at the perovskite interface and greatly improved the stability of the device.

[0037] like Figure 7 As shown, the dark current level of the device did not show significant changes within a week, and the current drift was within 1nA.

[0038] like Figure 8 As shown in the figure, the sensitivity of the device did not change significantly within one week, and the sensitivity remained at (9.6±0.05)×10 4 μC Gy air -1 cm -2 .

[0039] The difference between Example 2 and Example 1 is that the perovskite single crystal material layer uses CsPbBr3 single crystal.

[0040] The difference between Example 3 and Example 1 is that the thickness of the titanium electrode is 100 nm.

[0041] The difference between Example 4 and Example 1 is that the titanium electrode coating rate is 1 angstrom / second

[0042] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A perovskite single crystal radiation detector that operates stably under high bias voltage, characterized in that: It includes a perovskite single crystal material layer, and a titanium electrode layer and a ground electrode layer respectively arranged on the upper and lower surfaces of the perovskite single crystal material layer; The perovskite single crystal material layer is a three-dimensional perovskite single crystal with a molecular formula of CsPbBr3 or MAPbBr3; The ground electrode layer is made of one of Au, Pt and Cr.

2. The perovskite single crystal radiation detector that operates stably under high bias voltage according to claim 1, characterized in that: The thickness of the titanium electrode layer is 70 to 200 nm, and the thickness of the ground electrode layer is 70 to 200 nm.

3. The perovskite single crystal radiation detector that operates stably under high bias voltage according to claim 1, characterized in that The bias voltage for stable operation of CsPbBr3 or MAPbBr3 single crystal radiation detectors is increased by more than 50V / mm, the current drift for long-term (≥10h) stable operation is less than 1.5nA, and the time for maintaining initial performance is extended to 7 days.

4. A method for preparing a perovskite single crystal radiation detector under high bias voltage, characterized in that: The steps include: Step 1: Using DC magnetron sputtering coating process, with 99.99% purity Ti target as material, the vacuum degree is higher than 4×10 -4 Under the condition of 1.5-2.5 Pa, argon gas is passed to adjust the gas pressure to 0.9-1 Pa, the coating rate is 0.8-1 angstrom / second, and 70-200 nm of Ti is plated on one surface of the perovskite single crystal material layer as a titanium electrode layer; Step 2: Using vacuum evaporation coating process, Au, Pt or Cr particles with a purity of 99.99% are used as materials, and the vacuum degree is higher than 4×10 -4 Under the condition of Pa, the coating rate is 0.8 angstroms / second, and 70 to 200 nm of metal is plated on the surface of the other side of the perovskite single crystal material layer as a ground electrode layer; Step 3. Prepare conductive leads on the titanium electrode layer and the ground electrode layer respectively.

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