Liquid phase preparation method of 2,6-diphenylanthracene organic semiconductor single crystal and application thereof in x-ray detection

Abstract

The application discloses a kind of 2,6-diphenylanthracene organic semiconductor single crystal liquid phase preparation method and its application in X-ray detection, and liquid phase preparation method includes the following steps: 2,6-DPA organic semiconductor seed crystal is added in first saturated solution, constant temperature is placed 12-48 hours until first solvent volatilization, and 2,6-DPA organic semiconductor single crystal is obtained, wherein the first saturated solution is the saturated solution of 2,6-DPA powder in first solvent under 80-120 DEG C condition, and the first solvent is naphthalene, 1-chloronaphthalene, 1-bromonaphthalene, 1-methylnaphthalene, 1-ethylnaphthalene or 2-ethylnaphthalene.The solubility of 2,6-DPA is improved by naphthyl solvent, and the liquid phase preparation of centimeter level 2,6-DPA organic semiconductor single crystal is realized for the first time.The X-ray direct detector is characterized by constructing X-ray direct detection performance, and the results show that 2,6-DPA organic semiconductor single crystal has ultra-low dark current, lower detection limit, fast X-ray response, ultra-large radiation dose rate range, excellent irradiation stability and low voltage response.

Description

Technical Field

[0001] This invention belongs to the field of X-ray detector technology, specifically relating to a liquid-phase preparation method of 2,6-diphenylanthracene (2,6-DPA) organic semiconductor single crystal and its application in X-ray detection. Background Technology

[0002] X-rays have wide applications in medical imaging, non-destructive testing, security inspection, and scientific research, making the development of high-performance X-ray detectors of paramount importance. Semiconductor materials can generate charge carriers under X-ray irradiation. These charge carriers move directionally under an applied bias voltage, forming an electrical signal, thus achieving direct X-ray detection. Traditional materials used for direct X-ray detection are inorganic semiconductor single crystals, such as cadmium telluride and cadmium zinc telluride, due to their high X-ray absorption and good X-ray response. However, the preparation of these materials often requires extremely high temperatures (above 1000℃). Although in recent years, inorganic semiconductor single crystals, represented by perovskites, have been prepared at lower temperatures using solution methods and have shown relatively excellent X-ray detection performance, their poor stability and heavy metal toxicity still limit their applications. Due to their low atomic numbers, organic semiconductor single crystals have weak X-ray absorption, but some reports indicate that they exhibit low dark currents and possess direct X-ray detection capabilities (e.g., 4-hydroxybenzonitrile, 4HCB). Furthermore, organic semiconductor single crystals can typically be prepared using solution methods at relatively low temperatures and exhibit good stability. Organic semiconductor single crystals offer significant advantages in areas such as flexible detectors and reducing the detector's influence on the X-ray dose rate. Currently, there are few reports on organic single crystal materials for direct X-ray detection, and there is still considerable room for improvement in their various properties.

[0003] Low mobility is one of the main reasons limiting the performance of direct X-ray detectors based on organic semiconductor single crystals. 2,6-Diphenylanthracene (2,6-DPA) is an organic semiconductor with high mobility and high luminous efficiency. 2,6-DPA single crystals have been shown to have excellent photoresponse performance, indicating potential for direct X-ray detection. However, increased conjugation leads to a decrease in the solubility of 2,6-DPA, meaning that common solvents (such as ethanol, toluene, tetrahydrofuran, dichloromethane, etc.) are difficult to use for the liquid-phase preparation of 2,6-DPA single crystals. Existing reports indicate that the preparation of 2,6-DPA single crystals is mainly carried out through physical vapor deposition, which requires high temperatures and cannot produce crystals of centimeter size. Direct thin-film deposition significantly degrades material performance. Therefore, developing a simple liquid-phase method for the rapid preparation of large-size 2,6-DPA single crystals is of great significance for their potential applications in direct X-ray detection and other applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a liquid-phase preparation method for 2,6-diphenylanthracene (2,6-DPA) organic semiconductor single crystals. This liquid-phase preparation method increases the solubility of 2,6-DPA by selecting a naphthyl solvent with a high degree of conjugation, thereby achieving rapid solution preparation of large-size, high-quality 2,6-DPA organic semiconductor single crystals at lower temperatures.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] A liquid-phase preparation method for 2,6-DPA organic semiconductor single crystals includes the following steps:

[0007] 2,6-DPA organic semiconductor seed crystals are added to a first saturated solution and kept at a constant temperature for 12-48 hours until the first solvent evaporates to obtain 2,6-DPA organic semiconductor single crystals. The first saturated solution is a saturated solution obtained by dissolving 2,6-DPA powder in a first solvent at 80-120°C. The first solvent is naphthalene, 1-chloronaphthalene, 1-bromonaphthalene, 1-methylnaphthalene, 1-ethylnaphthalene, or 2-ethylnaphthalene.

[0008] In the above technical solution, the temperature of the constant temperature static setting is 80-120℃.

[0009] In the above technical solution, the preparation method of the 2,6-DPA organic semiconductor seed crystal is as follows: 2,6-DPA powder is dissolved in a second solvent to obtain a saturated solution at 80-120°C, and the solution is kept at a constant temperature of 80-120°C for 24-48 hours to allow the second solvent to evaporate, thereby obtaining the 2,6-DPA organic semiconductor seed crystal, wherein the second solvent is 1-chloronaphthalene or 1-bromonaphthalene.

[0010] The 2,6-DPA organic semiconductor single crystal obtained by the above liquid-phase preparation method.

[0011] The above-mentioned application of 2,6-DPA organic semiconductor single crystals in X-ray direct detector structures.

[0012] In the above technical solution, the X-ray direct detector structure is a vertical photoconductive structure or a horizontal photoconductive structure, wherein...

[0013] The vertical photoconductive structure is formed by fabricating an electrode on the upper and lower surfaces of a 2,6-DPA organic semiconductor single crystal.

[0014] The horizontal photoconductive structure consists of two electrodes fabricated on one surface of a 2,6-DPA organic semiconductor single crystal.

[0015] The electrode is a gold electrode.

[0016] In the above technical solution, the electrode is prepared on the 2,6-DPA organic semiconductor single crystal by vapor deposition.

[0017] This invention improves the solubility of 2,6-DPA using a naphthyl solvent, achieving for the first time the liquid-phase preparation of centimeter-scale 2,6-DPA organic semiconductor single crystals. The X-ray direct detection performance was characterized by constructing an X-ray direct detector, and the results show that the 2,6-DPA organic semiconductor single crystal possesses an ultra-low dark current (Ig). dark The X-ray direct detector with a horizontal photoconductor structure exhibits superior performance compared to the control group (4HCB organic semiconductor single crystal), including a lower detection limit (LoD), fast X-ray response, ultra-wide radiation dose rate range, excellent irradiation stability, and low voltage response. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the liquid phase preparation method of the present invention;

[0019] Figure 2 A photograph of the 2,6-DPA organic semiconductor single crystal prepared in Example 1;

[0020] Figure 3 A photograph of the 2,6-DPA organic semiconductor single crystal prepared in Example 2;

[0021] Figure 4 The X-ray diffraction pattern of the 2,6-DPA organic semiconductor single crystal prepared in Example 1;

[0022] Figure 5 The X-ray diffraction pattern of the 2,6-DPA organic semiconductor single crystal prepared in Example 2;

[0023] Figure 6 A schematic diagram of the (0 0 1) crystal plane structure of a 2,6-DPA organic semiconductor single crystal.

[0024] Figure 7 This is a schematic diagram of the structure of an X-ray direct detector (vertical photoconductive structure);

[0025] Figure 8 This is a schematic diagram of the structure of an X-ray direct detector (horizontal photoconductive structure);

[0026] Figure 9 The figure shows the IV curves for a 2,6-DPA organic semiconductor single-crystal X-ray direct detector, where I(vertical) is the irradiation current of the vertical photoconductor structure, I(horizontal) is the irradiation current of the horizontal photoconductor structure, and I... dark (Vertical) represents the dark current of the vertical photoconductive structure, I. dark (Horizontal) represents the dark current of the horizontal photoconductive structure;

[0027] Figure 10 The current-dose rate curve is shown for a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure).

[0028] Figure 11 The square-dose rate curve of the current and its fitting results are shown for a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure).

[0029] Figure 12 The sensitivity and fitting results of a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure) are presented.

[0030] Figure 13 The results show the response time of a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure).

[0031] Figure 14 The results show the stability test results of a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure).

[0032] Figure 15The figures show the IV curves for X-ray direct detectors (horizontal photoconductive structures) based on 2,6-DPA and 4HCB organic semiconductor single crystals, where I(2,6-DPA) is the irradiation current based on the 2,6-DPA organic semiconductor single crystal horizontal photoconductive structure, and I(4HCB) is the irradiation current based on the 4HCB organic semiconductor single crystal horizontal photoconductive structure. dark (2,6-DPA) represents the dark current I based on the 2,6-DPA organic semiconductor single-crystal horizontal photoconductive structure. dark (4HCB) represents the dark current based on the 4HCB organic semiconductor single-crystal horizontal photoconductive structure.

[0033] Figure 16 The detection limit of X-ray direct detectors (horizontal photoconductive structure) based on 2,6-DPA organic semiconductor single crystal and 4HCB organic semiconductor single crystal under a 5V bias voltage;

[0034] Figure 17 The detection limit of a 2,6-DPA organic semiconductor single-crystal X-ray direct detector (horizontal photoconductive structure) under a 1V bias voltage. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0036] The room temperature is 20-25℃.

[0037] The 2,6-DPA (CAS: 95950-70-2) powder used in this embodiment was synthesized and purified according to the literature [Chem. Commun., 2015, 51, 11777]. Its structural formula is:

[0038]

[0039] 4-Hydroxybenzonitrile (4HCB, CAS: 767-00-0, purity 99%) and 1-bromonaphthalene (CAS: 90-11-9, purity 98%) were purchased from Tianjin Xiens Biochemical Technology Co., Ltd.

[0040] 1-Chloronaphthalene (CAS: 90-13-1, purity 96%) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0041] Analytical grade anhydrous ethanol (CAS: 64-17-5) was purchased from Lianyungang Bohua (Tianjin) Pharmaceutical Chemical Co., Ltd.

[0042] The heating used in the growth process of 2,6-DPA organic semiconductor single crystals is a heating stage from Bibi Technology Co., Ltd., model (SD160).

[0043] The crystal quality was tested using an X-ray diffractometer from Rigaku Corporation, model (RIGAKUSMARTLAB9KW).

[0044] The IV and IT characteristic curves of organic semiconductor single crystals were tested using a semiconductor tester from Detech Corporation, model (B1500A).

[0045] The X-ray source (model 50501, copper target, maximum power 50W, operating current 2μA-2mA, operating voltage 5keV-50keV) from Wiseman High Voltage Power Supply (Xianyang) Co., Ltd. was used to test the direct X-ray detection performance of organic semiconductor single crystal. The X-ray source was 5cm away from the 2,6-DPA organic semiconductor. The dose rate of X-rays could be changed by adjusting the voltage and current of the X-ray tube.

[0046] The X-ray response of organic semiconductor single crystals was tested using a pulsed X-ray source from Gordon (model XRS3, X-ray pulse time 15ns, X-ray energy up to 270keV) and an oscilloscope from LeCroy (model HDO9000).

[0047] The X-ray source dose calibration was performed using a Fluke X-ray quality analyzer, model (RAYSAFEX2).

[0048] Example 1

[0049] A liquid-phase preparation method for 2,6-DPA organic semiconductor single crystals includes the following steps:

[0050] A 2,6-DPA organic semiconductor seed crystal with a length of approximately 1 mm was added to 15 ml of a first saturated solution and allowed to stand at 100°C for 12 hours until the first solvent evaporated, yielding a 2,6-DPA organic semiconductor single crystal. Figure 1 As shown, the first saturated solution is a saturated solution obtained by dissolving 2,6-DPA powder in a first solvent at 100°C. The first solvent is 1-chloronaphthalene.

[0051] The preparation method of 2,6-DPA organic semiconductor seed crystal is as follows: 2,6-DPA powder is dissolved in a second solvent to obtain a saturated solution at 100°C, and the solution is kept at 100°C for 48 hours to allow the second solvent to evaporate, thereby obtaining 2,6-DPA organic semiconductor seed crystal. The second solvent is 1-chloronaphthalene.

[0052] Example 2

[0053] A liquid-phase preparation method for 2,6-DPA organic semiconductor single crystals includes the following steps:

[0054] A 2,6-DPA organic semiconductor seed crystal with a length of approximately 1 mm was added to 10 ml of a first saturated solution and kept at a constant temperature of 100°C for 24 hours until the first solvent evaporated, thus obtaining a 2,6-DPA organic semiconductor single crystal. The first saturated solution was a saturated solution obtained by dissolving 2,6-DPA powder in a first solvent at 100°C. The first solvent was 1-bromonaphthalene.

[0055] The preparation method of 2,6-DPA organic semiconductor seed crystal is as follows: 2,6-DPA powder is dissolved in a second solvent to obtain a saturated solution at 100°C, and the solution is kept at 100°C for 48 hours to allow the second solvent to evaporate, thereby obtaining 2,6-DPA organic semiconductor seed crystal. The second solvent is 1-chloronaphthalene.

[0056] The 2,6-DPA organic semiconductor single crystal obtained in Example 1 has a length of about 1 cm, a width of about 1 cm, and a thickness of about 10 micrometers, which is in the centimeter range. The 2,6-DPA organic semiconductor single crystal obtained in Example 2 has a length of about 5 mm, a width of about 3 mm, and a thickness of about 10 micrometers, which is in the millimeter range.

[0057] The 2,6-DPA organic semiconductor single crystals obtained in Examples 1 and 2 were both plate-shaped, yellowish-green in color, and exhibited good transparency. Figure 2 and Figure 3 As shown. XRD tests were performed on the 2,6-DPA organic semiconductor single crystals obtained in Examples 1 and 2, as shown. Figure 4 and Figure 5 As shown, all diffraction peaks are consistent with the calculation results of the CCDC card (CCDC1044209), and all exhibit diffraction peaks of the [1 0 0] cluster, indicating that the crystal has good crystallinity and the molecules grow in a manner perpendicular to the horizontal direction (e.g., Figure 6 (As shown). Compared to Example 2, the 2,6-DPA organic semiconductor single crystal obtained in Example 1 exhibited stronger diffraction peaks, indicating that it had better crystal quality.

[0058] The 2,6-DPA organic semiconductor single crystal prepared in Example 1 exhibits good crystal quality, fast growth rate, and large crystal size. The direct X-ray detection performance of the 2,6-DPA organic semiconductor single crystal prepared in Example 1 is discussed. X-rays acting on the 2,6-DPA organic semiconductor single crystal generate photoelectrons, which further generate a large number of secondary electrons and corresponding holes. Since the 2,6-DPA organic semiconductor single crystal is a p-type semiconductor, electrons are captured by electron energy levels, and holes flow from the positive electrode to the negative electrode under bias voltage. Under a certain bias voltage, the current exhibits a regular change with the X-ray dose rate. Therefore, the X-ray dose rate can be quantitatively reflected by the current value under a certain bias voltage.

[0059] Horizontal and vertical X-ray direct detectors were constructed using the 2,6-DPA organic semiconductor single crystal prepared in Example 1, and the following tests were performed:

[0060] X-ray direct detectors can be structured as either a vertical photoconductive structure or a horizontal photoconductive structure.

[0061] Vertical photoconductive structure such as Figure 7 As shown, the vertical photoconductive structure consists of an electrode fabricated on both the upper and lower surfaces of a 2,6-DPA organic semiconductor single crystal. The electrodes are 100 nm thick gold electrodes, fabricated on the 2,6-DPA organic semiconductor single crystal by vapor deposition (the gold deposition rate is...). This forms a sandwich structure of one electrode / 2,6-DPA organic semiconductor single crystal / electrode.

[0062] The horizontal photoconductive structure employs a coplanar electrode configuration, as shown in the example below. Figure 8 As shown, the horizontal photoconductive structure consists of two electrodes fabricated on one surface of a 2,6-DPA organic semiconductor single crystal. The electrodes are 100 nm thick gold electrodes, fabricated on the 2,6-DPA organic semiconductor single crystal via vapor deposition (the gold deposition rate is...). The horizontal photoconductive structure is constructed using a bottom contact method.

[0063] The X-ray direct detectors constructed using both vertical and horizontal photoconductive structures in this invention exhibit significant responses to X-rays, such as... Figure 9 As shown, the current increases linearly with the increase of the bias voltage at both ends. The horizontal photoelectric structure X-ray direct detector exhibits lower dark current, and at the same dose rate of X-ray irradiation, it displays a higher electrical signal value. This is because the 2,6-DPA organic semiconductor single crystal has better charge transport capability in the (10 0) plane, indicating that the horizontal photoelectric structure X-ray direct detector has better X-ray direct detection performance. The following descriptions will focus on the various indicators of the higher-performance horizontal photoelectric structure X-ray direct detector.

[0064] The X-ray direct detector with a horizontal photoconductive structure constructed in this invention can operate at a relatively low bias voltage, such as... Figure 10 As shown, under a bias voltage of 5V, the current of the X-ray direct detector increases with the increase of the X-ray dose rate (nGy). air s -1 -mGy air s -1 () showed a significant increase.

[0065] based on Figure 10The device current values ​​under different X-ray dose rates were fitted, and the results showed that the square of the X-ray direct detector current has a good linear relationship with the dose rate (e.g., Figure 11 As shown in the figure, this is caused by the large injection effect. This regularity provides a basis for detecting X-ray dose rate using the direct X-ray detector of this invention.

[0066] The relationship between the sensitivity and dose rate of X-ray direct detectors and the fitting results are as follows: Figure 12 As shown, the sensitivity of the X-ray direct detector gradually decreases with increasing dose rate, and remains above 10. 4 μC Gy air -1 s -1 It is comparable to inorganic semiconductor single-crystal devices, breaking the record for X-ray detectors based on organic semiconductor single-crystals.

[0067] like Figure 13 As shown, the X-ray direct detector exhibits good response to high-energy (270 keV) X-rays, with a response time of approximately 20 μs and a recovery time of approximately 300 μs. Under continuous irradiation with high-dose-rate X-rays, the X-ray direct detector demonstrates good stability, such as... Figure 14 As shown, at 442mGy air s -1 Approximately 300 Gy in total air Under irradiation, the current of the X-ray direct detector is 97% of its initial value.

[0068] The 2,6-DPA organic semiconductor single crystal in the horizontal photoconductive X-ray direct detector was replaced with a 4HCB organic semiconductor single crystal. The 4HCB organic semiconductor single crystal was obtained by a slow evaporation method at room temperature. The specific steps were as follows: 4HCB powder was dissolved in anhydrous ethanol at room temperature to prepare a saturated solution at room temperature. The saturated solution was placed in a weighing bottle and covered with a sealing film, leaving a small hole in the sealing film to allow the anhydrous ethanol to evaporate slowly. After standing at room temperature for 10 days, the 4HCB organic semiconductor single crystal was obtained.

[0069] Dark current and IV curves of X-ray direct detectors based on 2,6-DPA organic semiconductor single crystals and 4HCB organic semiconductor single crystals (horizontal photoconductive structure) are shown in the figure. Figure 15As shown, under the same X-ray direct detector construction, the performance of the X-ray direct detector using the 2,6-DPA organic semiconductor single crystal of the present invention is significantly better than that of the previously reported 4HCB organic semiconductor single crystal. Specifically, the 2,6-DPA organic semiconductor single crystal of the present invention has a lower dark current, and under the same intensity of X-ray irradiation, the X-ray direct detector current is significantly higher than that of the 4HCB organic semiconductor single crystal, thus exhibiting a larger gain value and a smaller detection limit.

[0070] like Figure 16 As shown, the IT curve at a bias voltage of 5V also demonstrates that the 2,6-DPA organic semiconductor single-crystal direct X-ray detector of this invention has a lower dark current. Taking the dose rate corresponding to a current value three times the dark current (signal-to-noise ratio = 3) as the detection limit (LoD) of the X-ray direct detector, the 2,6-DPA organic semiconductor single crystal of this invention exhibits a lower detection limit, approximately 50 nGy. air s -1 It is an order of magnitude lower than that of 4HCB organic semiconductor single crystal X-ray direct detectors (the detection limit of the control group, 4HCB organic semiconductor single crystal X-ray direct detector, is approximately 750 nGy). air s -1 ).

[0071] The 2,6-DPA organic semiconductor single crystal of this invention can also achieve direct X-ray detection under lower voltage driving conditions, such as... Figure 17 As shown, the detection limit of the X-ray direct detector remains at 50 nGy under a voltage drive of 1V. air s -1 This demonstrates good low-voltage drive performance.

[0072] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A liquid-phase preparation method for 2,6-DPA organic semiconductor single crystals, characterized in that, Includes the following steps: 2,6-DPA organic semiconductor seed crystals are added to a first saturated solution and kept at a constant temperature for 12-48 hours until the first solvent evaporates to obtain 2,6-DPA organic semiconductor single crystals. The first saturated solution is a saturated solution obtained by dissolving 2,6-DPA powder in a first solvent at 80-120°C. The first solvent is naphthalene, 1-chloronaphthalene, 1-bromonaphthalene, 1-methylnaphthalene, 1-ethylnaphthalene, or 2-ethylnaphthalene.

2. The liquid-phase preparation method according to claim 1, characterized in that, The constant temperature for static settling is 80-120℃.

3. The liquid-phase preparation method according to claim 1 or 2, characterized in that, The preparation method of the 2,6-DPA organic semiconductor seed crystal is as follows: 2,6-DPA powder is dissolved in a second solvent to obtain a saturated solution at 80-120°C, and the solution is kept at a constant temperature of 80-120°C for 24-48 hours to allow the second solvent to evaporate, thereby obtaining the 2,6-DPA organic semiconductor seed crystal, wherein the second solvent is 1-chloronaphthalene or 1-bromonaphthalene.

4. The 2,6-DPA organic semiconductor single crystal obtained by the liquid-phase preparation method according to any one of claims 1 to 3.

5. The application of 2,6-DPA organic semiconductor single crystal prepared by the liquid-phase preparation method according to any one of claims 1 to 3 in the structure of X-ray direct detector.

6. The application according to claim 5, characterized in that, The X-ray direct detector structure is a vertical photoconductive structure or a horizontal photoconductive structure, wherein the vertical photoconductive structure is formed by fabricating an electrode on the upper surface and the lower surface of a 2,6-DPA organic semiconductor single crystal; The horizontal photoconductive structure consists of two electrodes fabricated on one surface of a 2,6-DPA organic semiconductor single crystal. The electrode is a gold electrode.

7. The application according to claim 6, characterized in that, The electrode was prepared on the 2,6-DPA organic semiconductor single crystal by vapor deposition.

Images