A molecular glass scintillator material and its preparation method and application

Abstract

The present invention discloses a molecular glass scintillator material, a preparation method and an application thereof. The molecular glass scintillator is composited based on a molecular glass main body and an efficient luminescent guest, and a flexible, transparent, large-area X-ray scintillator screen can be prepared on a transparent substrate by a melt casting method. The molecular glass scintillator exhibits efficient radioluminescence, low X-ray detection line and high imaging resolution under X-ray excitation. Compared with the existing technology, the molecular glass scintillator provided by the present invention, as a new type of X-ray scintillator, not only has excellent scintillation and imaging properties, but is also easy to process and low in cost.

Description

Technical Field

[0001] The invention relates to a novel molecular glass scintillator material and its application as a high-efficiency X-ray scintillator screen in the field of X-ray imaging. Background Art

[0002] X-ray scintillators are a type of material that has luminescent properties when excited by X-rays. They can convert high-energy X-rays into low-energy visible light and have great application value in radiation detection, safety testing, and biomedicine. However, most of the X-ray scintillators currently used commercially are based on inorganic materials represented by ceramic scintillators, which usually require extremely high preparation temperatures (≥1700°C), are difficult to prepare over a large area on a flexible substrate, and exhibit low spatial resolution due to their anisotropic crystal properties. Therefore, it is urgent to develop new low-cost, easy-to-process, transparent, and efficient scintillator materials.

[0003] Metal-free pure organic light-emitting materials have outstanding advantages such as abundant raw material reserves, high mechanical flexibility, excellent processing performance, easy synthesis and modification. As a new material in the X-ray scintillator family, it has received widespread attention in recent years. Huang Wei et al. used "bright triplet excitons" to prepare a series of pure organic scintillators based on room temperature phosphorescent materials containing halogen heavy atoms, which exhibited efficient radiative luminescence under X-ray excitation (Nature. Photonics. 2021, 15, 187-192.). Yang Yang et al. developed a scintillator material based on "thermally activated delayed fluorescence (TADF) molecules". Compared with traditional fluorescent materials, TADF materials have an exciton utilization rate of nearly 100%, and thus exhibit efficient radiative luminescence under X-ray excitation (Nature. Materials. 2022, 21, 210-216.). However, although these materials exhibit efficient X-ray luminescence, due to the properties of their crystalline powders, there are certain difficulties in preparing large-area transparent X-ray scintillating screens.

[0004] Therefore, based on the existing technical background, it is very necessary to develop a new type of pure organic scintillator material, which not only has efficient X-ray luminescence, but also has the characteristics of large-area processing, amorphous transparency, and flexibility. Summary of the invention

[0005] The purpose of the present invention is to provide a novel molecular glass scintillator, which exhibits efficient radioluminescence under X-ray excitation, is easy to prepare into a large-area transparent scintillator screen, and exhibits excellent imaging resolution.

[0006] Another object of the present invention is to provide a method for preparing the molecular glass scintillator.

[0007] Another object of the present invention is to provide application of the molecular glass scintillator in the field of X-ray imaging.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A novel molecular glass scintillator is prepared by doping a molecular glass main material with a high-efficiency luminescent guest material to form a film; wherein the molecular glass main material is a compound of any of the following structures:

[0010]

[0011] Wherein, X is N, P, As, Tb or Bi; R 1 is Br or I; R 2 is H, F, Cl, Br, I or CH 3 .

[0012] Among the above molecular glass host materials, the A-type molecular glass host is based on triphenylamine modified with halogen heavy atoms, has a relatively simple structure, and can be obtained through cheap commercial channels. Among them, the molecular glass host of (X=N, R=Br) is preferred.

[0013] The above molecular glass host materials, including type B, type C, type D, and type E molecular glass hosts, are respectively based on benzene ring, triazine ring, triphenylamine and its derivatives, and triphenylbenzene as the central core, with diphenylamine derivatives grafted on the periphery. Since the synthesis of these molecules involves some common chemical reactions, some of which have even been reported in the literature, they can be conventionally synthesized by referring to the synthesis methods in the literature.

[0014] The above-mentioned luminescent guest materials are luminescent guest materials with the property of "thermally activated delayed fluorescence" (referred to as thermally activated delayed fluorescence molecules), luminescent guest materials with the property of "thermoexcitons" (referred to as thermoexciton molecules), traditional fluorescent luminescent guest materials (referred to as traditional fluorescent molecules, which refer to pure fluorescent molecules that completely transition from singlet radiation to the ground state) or metal organic phosphorescent luminescent guest materials (referred to as phosphorescent molecules). Compared with thermoexciton molecules and traditional fluorescent molecules, thermally activated delayed fluorescence molecules and phosphorescent molecules have the advantages of rich structural variety, high exciton utilization, and outstanding device external quantum efficiency, and are preferred luminescent guest materials. Compared with metal organic phosphorescent molecules, thermally activated delayed fluorescence molecules have better structural compatibility with molecular glass host materials and are the most preferred guest luminescent materials. The above-mentioned luminescent guest materials all involve reported molecules, so they can be synthesized with reference to the disclosed methods.

[0015] The luminescent guest material having the property of "thermally activated delayed fluorescence" is preferably a compound of any of the following structures:

[0016]

[0017] Among them, R is

[0018] R 1 -CH 3 -OCH 3

[0019] The luminescent guest material having the property of "hot exciton" is preferably a compound having any of the following structures:

[0020]

[0021] Among them, R is

[0022] R 1 -OH-CN-OCH 3

[0023] R 2 for

[0024] The conventional fluorescent guest material is preferably a compound of any of the following structures:

[0025]

[0026] From this, R is R 1 H, Cl, Br, I, CH 3 or OCH 3 .

[0027] The metal organic phosphorescent guest material is preferably a compound of any of the following structures:

[0028]

[0029] The doping molar ratio of the molecular glass host material and the luminescent guest material described in the present invention is: 100 / 1 to 1 / 1; preferably, the doping molar ratio of the molecular glass host material and the luminescent guest material is 100 / 1, 50 / 1, 10 / 1, 5 / 1, 3 / 1 or 1 / 1; further preferably, the doping molar ratio of the molecular glass host material and the luminescent guest material is 10 / 1 or 5 / 1, and the most preferred molar ratio is 5 / 1.

[0030] Preferably, the above-mentioned film forming method is to form a film by melt casting on a transparent substrate, and the melting temperature is 100-300° C. It mainly depends on the melting points of the molecular glass host material and the luminescent guest material.

[0031] Preferably, the transparent substrate includes a quartz glass substrate, a tempered glass substrate, or a transparent resin substrate; most preferably, the transparent substrate is a quartz glass substrate.

[0032] Preferably, the thickness of the molecular glass scintillator obtained after the film formation is 0.5 to 5 mm; most preferably, the thickness of the molecular glass scintillator is 1 mm.

[0033] The preparation method of the molecular glass scintillator comprises doping the molecular glass main material with the luminescent guest material and processing it into a film by melt casting using a transparent substrate; the melting temperature is 100 to 300°C, and the doping molar ratio of the molecular glass main material and the luminescent guest material is 100 / 1 to 1 / 1.

[0034] The molecular glass scintillator material of the present invention is used for X-ray scintillation and imaging as follows: (1) X-ray scintillation: under X-ray irradiation, the radioluminescence properties of the molecular glass are tested, and the minimum detection line is calculated; (2) X-ray imaging: an X-ray imaging system is built, and the imaging spatial resolution is calculated using the modulation transfer function (MTF) method based on the hypotenuse imaging results, and several objects are selected as imaging objects to collect imaging photos.

[0035] The X-ray imaging device of the present invention is schematically shown as follows: it mainly comprises: an X-ray source, an imaging object, a molecular glass scintillator film, a commercial digital camera, Fig.12 The imaging object includes industrial products and biological tissues, preferably industrial products.

[0036] The invention exhibits efficient radioluminescence under X-ray excitation, and the X-ray detection line is 10-1000nGy / s, and the lowest detection line currently obtained is 77nGy / s

[0037] The present invention exhibits high imaging resolution during X-ray imaging, wherein the X-ray imaging resolution is 5-50 lp / mm (MTF=0.2), and the highest imaging resolution currently obtained is 33.6 lp / mm.

[0038] The molecular glass scintillator can be used in X-ray imaging. The present invention can be prepared into a flexible, transparent, large-area X-ray imaging scintillator screen by a traditional melt casting method. X-ray imaging of industrial products in real life can obtain high-quality imaging photos, which has broad application prospects in medical diagnosis and treatment, safety inspection and non-destructive testing.

[0039] Compared with the existing technology, the present invention has the following advantages and beneficial effects:

[0040] (1) The molecular glass scintillator of the present invention can be easily prepared into a flexible, transparent, large-area scintillating film by conventional melt casting processing means, and exhibits efficient radiant luminescence under X-ray excitation.

[0041] (2) The molecular glass X-ray scintillator screen of the present invention has very high imaging resolution and has potential application value in medical diagnosis and treatment, safety inspection and industrial non-destructive testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a luminescence spectrum of the molecular glass scintillator prepared in Example 1 under X-ray irradiation;

[0043] Figure 2 is the X-ray detection line diagram of the molecular glass scintillator prepared in Example 1;

[0044] Figure 3 These are photos of the molecular glass scintillator prepared in Example 1 under natural light and X-ray irradiation;

[0045] Figure 4 This is an X-ray imaging resolution diagram of the molecular glass scintillator prepared in Example 1;

[0046] Figure 5 This is an X-ray imaging photograph of the molecular glass scintillator prepared in Example 1;

[0047] Figure 6 This is a real photo of the large-sized molecular glass scintillator screen prepared in Example 1;

[0048] Figure 7 These are photos of the molecular glass scintillator prepared in Example 2 under natural light and X-ray irradiation;

[0049] Figure 8 This is a luminescence spectrum of the molecular glass scintillator prepared in Example 2 under X-ray irradiation;

[0050] Fig. 9 This is a luminescence spectrum of the molecular glass scintillator prepared in Example 3 under X-ray irradiation;

[0051] Fig.10 This is a luminescence spectrum of the molecular glass scintillator prepared in Example 4 under X-ray irradiation;

[0052] Fig.11 This is a luminescence spectrum of the molecular glass scintillator prepared in Example 5 under X-ray irradiation;

[0053] Fig.12 Schematic diagram of an X-ray imaging device. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0055] Example 1

[0056] The molecular structures of the molecular glass host (TB) and the fluorescent guest (DT) used are shown below:

[0057]

[0058] TB and DT were both from commercial sources, of which TB was purchased from Henan Alpha Chemical Co., Ltd. and DT was purchased from Xi'an Biolight Optoelectronics Technology Co., Ltd. The preparation process of molecular glass scintillator film based on TB and DT (DT@TB) is as follows:

[0059] Take TB (1 mmol, 0.4 g) and mix it evenly with DT (0.2 mmol, 0.1 g;) (0.1 mmol, 0.05 g) (0.02 mmol, 0.01 g) (0.01 mmol, 0.005 g) in four quartz tubes according to different molar ratios (5 / 1, 10 / 1, 50 / 1, 100 / 1), completely melt it in an oven at 120°C, and naturally cool it to room temperature to obtain the final molecular glass scintillator.

[0060] The radioluminescence properties of these molecular glass scintillators were tested. Figure 1 As shown in the figure, these four molecular glass scintillators have a characteristic emission peak at about 500nm, showing bright green luminescence, and with the increase of the fluorescent guest doping content, the radiant luminescence intensity also increases significantly. Taking the molecular glass scintillator with the highest radiant luminescence intensity and a host-guest 5 / 1 molar ratio as an example, the X-ray detection limit of this molecular glass scintillator was tested and calculated. Figure 2 As shown, the minimum detection limit of X-rays of this molecular glass is only 77nGy / s, which is 71 times lower than the standard medical detection line (5.5μG / s).

[0061] Furthermore, in this example, we prepared a scintillator screen based on the above molecular glass scintillator (host and guest are compounded in a molar ratio of 5 / 1) on a transparent quartz glass substrate by melt casting. Similarly, TB (1mmol, 0.4g) and DT (0.2mmol, 0.1g) were uniformly mixed, then spread on a quartz sheet (diameter: 35mm; thickness: 0.5mm) with a polytetrafluoroethylene sealing ring, heated and melted on a hot plate at 120°C, and naturally cooled to room temperature to obtain the final molecular glass scintillator screen.

[0062] Figure 3As shown in Figure 4, the molecular glass scintillator screen shows good transparency and bright luminescence under X-ray excitation. Furthermore, the spatial resolution of the molecular glass scintillator screen is characterized by slant edge imaging and modulation transfer function (MTF) fitting. As shown in Figure 4, at MTF = 0.2, the spatial resolution of the molecular glass scintillator screen is as high as 33.6lp / mm, which is more than twice that of the currently commercially used (CsI:TI) X-ray scintillator. Figure 5 The X-ray imaging photo of the molecular glass scintillator screen is shown in Figure 1. It can be seen that the internal structure of the hollow metal label and the small electronic chip placed in the plastic resin box is clearly presented.

[0063] Based on the characteristics of the molecular glass main material, such as flexibility, transparency, and large-area processing, in this embodiment, the same melt casting method is used to further prepare an A4-sized scintillator screen based on the molecular glass scintillator. Figure 6 As shown, the molecular glass scintillating screen exhibits good transparency, and the molecular glass scintillating screen based on a transparent and flexible PET substrate exhibits good flexibility.

[0064] Example 2

[0065] The molecular structures of the molecular glass host (TI) and the fluorescent light-emitting guest (DT) used are shown below:

[0066]

[0067] The molecular glass host material was synthesized according to the synthesis route of the TI reference (DOI: 10.1002 / ejoc.202101397), and its structure was confirmed by NMR characterization, which is consistent with the results reported in the literature ( 1 H NMR (DMSO-d 6 )δ(ppm)7.56(d,J=8.8Hz,4H),7.34-7.23(m,2H),7.11-7.03(m,1H),6.75(d,J=8.8Hz,4H). 13 C NMR (CDCl 3 )δ(ppm)147.29,138.37,129.60,125.85,124.95,124.66,124.04,85.91.) As a comparative experiment of Example 1. Based on the same method, a molecular glass scintillator (DT@TI) with a molar ratio of TI and DT doping of 5 / 1 was prepared. Figure 7 As shown in Figure 2, the molecular glass scintillator with TI as the main molecular glass also exhibits high transparency and green luminescence under X-ray excitation. The radioluminescence properties of the molecular glass scintillator were further tested. Figure 8 Compared with the molecular glass scintillator DT@TB in Example 1, the molecular glass scintillator DT@TI prepared in this example exhibits significantly lower radiative luminescence intensity. The reason for this may be that the iodine heavy atoms in the molecular glass host TI have a serious quenching effect on the thermally activated delayed fluorescence of the luminescent guest DT, resulting in reduced luminescence efficiency. Inefficient radiative luminescence properties are not conducive to high-quality X-ray imaging. This example, as a control experiment, proves that the selection of the molecular glass host material has an important influence on the scintillation performance of the final molecular glass scintillator.

[0068] Example 3

[0069] The main molecular glass used is TB, and the fluorescent guest material is a type of luminescent molecule with thermoexciton properties (TPy). Its molecular structure is shown below:

[0070]

[0071] TB (1mmol, 0.4g) and PY (0.2mmol, 0.074g) were uniformly mixed, and quartz glass (diameter: 35mm, thickness: 0.5mm) was used as the substrate. The mixture was melted on a hot plate at 150°C and naturally cooled to room temperature to obtain the final molecular glass scintillator film (PY@TB). The film thickness was 1mm. The radiation luminescence spectrum of the molecular glass scintillator under X-ray excitation was tested. Fig. 9 As shown, PY@TB exhibits a characteristic emission peak at 477 nm, showing bright sky-blue luminescence.

[0072] Example 4

[0073] The main molecular glass used is TB, and the fluorescent guest material is a traditional fluorescent molecule (DPA). Its molecular structure is shown below:

[0074]

[0075] TB (1mmol, 0.4g) and DPA (0.2mmol, 0.066g) were uniformly mixed, and quartz glass (diameter: 35mm, thickness: 0.5mm) was used as the substrate. The mixture was melted on a hot plate at 130℃ and cooled naturally to room temperature to obtain the final molecular glass scintillator film (DPA@TB). The film thickness was 1mm. The radiation luminescence spectrum of the molecular glass scintillator under X-ray excitation was tested. Fig.10 As shown, DPA@TB exhibits a characteristic emission peak at 446 nm, showing bright deep blue luminescence.

[0076] Example 5

[0077] The molecular glass used is TB as the main body and Ir-4 as the metal organic phosphorescent guest. Its molecular structure is as follows:

[0078]

[0079] TB (1mmol, 0.4g) and Ir-4 (0.01mmol, 0.0059g) were uniformly mixed, and quartz glass (diameter: 35mm, thickness: 0.5mm) was used as the substrate. The mixture was melted on a hot plate at 150°C and naturally cooled to room temperature to obtain the final molecular glass scintillator film (Ir-4@TB). The film thickness was 1mm. The radiation luminescence spectrum of the molecular glass scintillator under X-ray excitation was tested. Fig.11 As shown, Ir-4@TB exhibits a characteristic emission peak at 540 nm, showing bright yellow-green luminescence.

Claims

1. A molecular glass scintillator material, Features: The scintillator material is prepared by doping a molecular glass main material with a high-efficiency luminescent guest material to form a film; wherein the molecular glass main material is a compound of any of the following structures: or ; The luminescent guest material is: 。 2. The molecular glass scintillator material according to claim 1, Features: The doping molar ratio of the molecular glass main material and the luminescent guest material is 100 / 1 to 1 / 1.

3. The molecular glass scintillator material according to claim 2, Features: The doping molar ratio of the molecular glass host material and the luminescent guest material is 100 / 1, 50 / 1, 10 / 1, 5 / 1, 3 / 1 or 1 / 1.

4. The molecular glass scintillator material according to claim 1, Features: The film-forming method is to form a film by melting and casting a transparent substrate, and the melting temperature is 100-300°C.

5. A method for preparing the molecular glass scintillator material according to claim 1, Features The molecular glass main material is doped with the fluorescent luminescent guest material and processed into a film by a transparent substrate through a melting casting method; the melting temperature is: 100-300°C.

6. Use of the molecular glass scintillator material according to claim 1 in X-ray imaging, wherein the use is for the purpose of non-disease diagnosis and treatment methods.

Images