Intermediate band semiconductor material and preparation method thereof

Abstract

The invention relates to an intermediate band semiconductor material and a preparation method thereof.The chemical formula of the intermediate band semiconductor material is Sr4In2Sb2O5Q5, Q is S or Se, the intermediate band semiconductor material is prepared from reaction raw materials containing the Sr element, the In element, the Sb element, the Q element and the O element through a high-temperature solid-phase reaction method, and the intermediate band semiconductor material has the characteristics of multi-band absorption and large photo-generated current; and the material has relatively high photoelectric response characteristic and excellent photoelectric property.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials, and more specifically to an intermediate-band semiconductor material and its preparation method. Background Technology

[0002] Intermediate-band photoconductor materials possess multiphoton absorption characteristics, enabling them to achieve multiple absorption similar to multi-junction solar cells within a single material. This results in theoretical photoelectric conversion efficiencies far exceeding those of ordinary semiconductors, thus attracting significant attention. However, experimentally synthesized and verified intermediate-band semiconductors are extremely scarce, and the corresponding materials exhibit weak intermediate-band light absorption, a narrow tunable band structure, and band gaps deviating considerably from their optimal values, hindering the full utilization of solar energy. Therefore, exploring and developing novel intermediate-band semiconductors holds significant scientific and applied importance.

[0003] Heteroanionic oxygen-sulfur or oxygen-selenium compounds possess an inherent advantage in forming intermediate-band semiconductor materials. On one hand, the electronegativity difference between O atoms and S or Se atoms leads to the formation of different structural functional regions, thereby inducing the generation of intermediate-band electronic structures. On the other hand, modification of specific structural functional regions can tune the energy range of the corresponding intermediate band while simultaneously enhancing its light absorption intensity, making it possible to achieve large intermediate-band light absorption and optimal band structure combinations. However, currently, research and inventions related to heteroanionic intermediate-band semiconductors are largely lacking. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides a type of heteroanion intermediate band semiconductor material and its preparation method. This material has a unique chain-like crystal structure, a simple preparation process, multi-band absorption, large photocurrent characteristics, large photoelectric response characteristics, and excellent photoelectric performance.

[0005] To achieve the above-mentioned objectives of this invention, this invention proposes a method for preparing intermediate band semiconductor materials, comprising:

[0006] S1, the reaction raw materials containing Sr, In, Sb, O and Q elements are mixed in an element molar ratio of 4:2:2:5:5 and ground evenly;

[0007] S2, the grinding product in S1 is gradually heated from room temperature to a first temperature within a predetermined time, and then naturally cooled to room temperature after being kept at that temperature for a certain time.

[0008] Where Q is either S or Se.

[0009] Preferably, in S1, the reaction raw materials are SrO, In2O3 powder, Sb2O3 powder and Sb2O3 powder.

[0010] Preferably, in step S2, the grinding product is gradually heated from room temperature to the first temperature within 10 hours, the first temperature being 700℃~900℃, and then naturally cooled to room temperature after being kept at that temperature for at least 12 hours.

[0011] Preferably, in step S1, the reaction raw materials further include a flux.

[0012] Preferably, in step S2, the grinding product in step S1 is gradually heated from room temperature to a first temperature over a predetermined period of time, held at that temperature for a certain period of time, and then cooled uniformly to a second temperature, and then naturally cooled to room temperature. The second temperature is the crystallization temperature of the flux.

[0013] Preferably, the flux is an alkali metal halide.

[0014] Preferably, it further includes:

[0015] S3, take the product from S2 and grind it thoroughly;

[0016] S4, the grinding product in S3 is gradually heated from room temperature to a first temperature within a predetermined time, and then naturally cooled to room temperature after being kept at that temperature for a certain time.

[0017] The present invention also proposes an intermediate-band semiconductor material with the chemical formula Sr4In2Sb2O5Q5, wherein Q is S or Se.

[0018] Preferably, the intermediate-band semiconductor material belongs to the monoclinic crystal system, with Sr4In2Sb2O5S5 belonging to the P21 / c space group and Sr4In2Sb2O5Se5 belonging to the C2 / m space group.

[0019] Preferably, the intermediate band semiconductor material has a chain-like structure, consisting of [In2Q5]. 4- Chain and [Sr4Sb2O5] 4+ The chain structure consists of In and Q forming a tetrahedral coordination, and Sb and O forming a triangular pyramidal coordination, [InQ4]. 5- Tetrahedrons are connected by sharing vertices.

[0020] The material proposed in this invention is a type of heteroanion intermediate-band semiconductor material with typical multi-band absorption characteristics and an optical band gap between 1.4 eV and 2.8 eV. This material exhibits significant photoelectric response characteristics, indicating that it is a promising new photoelectric conversion material that can be used in fields such as photoelectric detection, photocatalysis, and photochemical cells. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram illustrating the crystal structure of Sr4In2Sb2O5S5 obtained in Embodiment 1 of the present invention;

[0023] Figure 2 The schematic diagram shows the powder X-ray diffraction pattern of the polycrystalline sample of Sr4In2Sb2O5S5 obtained according to Example 2 of the present invention.

[0024] Figure 3 The schematic representation shows the ultraviolet-visible-near-infrared diffuse reflectance spectrum of the polycrystalline sample of Sr4In2Sb2O5S5 obtained according to Example 2 of the present invention;

[0025] Figure 4 This schematic diagram illustrates the crystal structure of Sr4In2Sb2O5Se5 obtained in Embodiment 3 of the present invention.

[0026] Figure 5 The schematic diagram shows the powder X-ray diffraction pattern of the polycrystalline sample of Sr4In2Sb2O5Se5 obtained according to Example 4 of the present invention.

[0027] Figure 6 The illustration shows the photoelectric response of a thin film device prepared from a polycrystalline sample of Sr4In2Sb2O5Se5 obtained according to Example 4 of the present invention. Detailed Implementation

[0028] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0029] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims.

[0030] like Figure 1 The image shows an intermediate-band semiconductor material according to an embodiment of the present invention. The intermediate-band semiconductor material has the chemical formula Sr4In2Sb2O5Q5, where Q is S or Se. The intermediate-band semiconductor material belongs to the monoclinic crystal system, with Sr4In2Sb2O5S5 belonging to the P21 / c space group and Sr4In2Sb2O5Se5 belonging to the C2 / m space group. The intermediate-band semiconductor material has a chain-like structure composed of [In2Q5]. 4- Chain and [Sr4Sb2O5] 4+ The chain structure consists of In and Q forming a tetrahedral coordination, and Sb and O forming a triangular pyramidal coordination, [InQ4]. 5- Tetrahedrons are connected by sharing vertices.

[0031] The crystallographic data of the Sr4In2Sb2O5Q5 single crystal sample of this invention are shown in the table below.

[0032]

[0033] Table 1 Crystallographic data of Sr4In2Sb2O5Q5

[0034] The Sr4In2Sb2O5Q5 of this invention exhibits typical multi-band absorption characteristics, with an optical band gap between 1.4 eV and 2.8 eV. It also has a large photoelectric response characteristic, indicating that it is a promising new photoelectric conversion material.

[0035] This invention also provides a method for preparing the intermediate band semiconductor material as described above, comprising:

[0036] S1. The reaction raw materials containing Sr, In, Sb, O and Q elements are placed under vacuum, mixed in an element molar ratio of 4:2:2:5:5, and then ground evenly.

[0037] S2. Under vacuum, the grinding product from step S1 is gradually heated from room temperature to a first temperature of 700℃~900℃ over 10 hours. After holding at this temperature for at least 12 hours, it is naturally cooled to room temperature.

[0038] Preferably, the reaction raw materials are SrO, In2O3 powder, Sb2O3 powder and Sb2O3 powder.

[0039] Preferably, the reaction raw materials also include a flux, which can promote crystal growth.

[0040] Preferably, the flux can be an alkali metal halide, such as NaI, KCl, KBr, KI, etc.

[0041] Preferably, the ground product is gradually heated from room temperature to a first temperature and held at that temperature for a certain period of time, then cooled at a uniform rate to a second temperature, which is the crystallization temperature of the flux, and then naturally cooled to room temperature.

[0042] Preferably, the method for preparing the above-mentioned intermediate band semiconductor material further includes:

[0043] S3, Take the product from step S2 and grind it thoroughly;

[0044] S4. Under vacuum, the grinding product from step S3 is gradually heated from room temperature to a first temperature over 10 hours, held at that temperature for a certain period of time, and then naturally cooled to room temperature.

[0045] The product is ground and then subjected to a secondary reaction to ensure complete reaction of the raw materials.

[0046] The intermediate-band semiconductor material provided by this invention is a type of heteroanion intermediate-band semiconductor material, which can be applied to the technical fields of manufacturing photoelectric detection devices, photocatalysts, or photovoltaic conversion devices.

[0047] Example 1

[0048] 0.1243 g of SrO powder, 0.0977 g of In₂S₃ powder, 0.0679 g of Sb₂S₃ powder, 0.0292 g of Sb₂O₃ powder, and 1.5 g of KI powder were weighed in an Ar glove box and placed in an agate mortar. The mixture was thoroughly ground and mixed, then transferred to a quartz tube with an inner diameter of 1 cm. The tube was then vacuumed to 0.1 Pa and sealed. The sealed quartz tube was placed in a muffle furnace, and the following heating and cooling program was set: slowly heating from room temperature to 800℃ over 10 hours, holding at 800℃ for 48 hours, then cooling to 550℃ over 36 hours, and finally allowing it to cool naturally to room temperature. The product was removed from the quartz tube, washed three times with deionized water, washed with acetone, and dried to obtain a single crystal sample of Sr₄In₂Sb₂O₅S₅, with the structure shown below. Figure 1 As shown.

[0049] In this embodiment, SrO powder, In2S3 powder, Sb2S3 powder, and Sb2O3 powder were used as reactants and mixed in an elemental molar ratio of 4:2:2:5:5. KI was added as a flux to promote crystal growth. First, the reactants and flux were thoroughly mixed and ground uniformly. Then, the mixture was slowly heated from room temperature to a first temperature in a vacuum environment and held at that temperature. The first temperature was the reaction temperature of the heteroanion intermediate-band semiconductor material, ranging from 700℃ to 900℃, and the holding time was not less than 12 hours. In this embodiment, the temperature was set at 800℃ for 48 hours. Subsequently, the mixture was cooled to 550℃ for 36 hours to allow the heteroanion intermediate-band semiconductor material to crystallize from the KI melt. Finally, after natural cooling to room temperature, the product was washed with deionized water and acetone to remove the flux and dried to obtain a Sr4In2Sb2O5S5 single crystal sample.

[0050] Example 2

[0051] Weigh out 0.1243g of SrO powder, 0.0977g of In₂S₃ powder, 0.0679g of Sb₂S₃ powder, and 0.0292g of Sb₂O₃ powder in an Ar-filled glove box. Place them in an agate mortar and grind them thoroughly until homogeneous. Transfer the mixture to a quartz tube with an inner diameter of 1cm, evacuate to 0.1Pa, and seal. Place the sealed quartz tube in a muffle furnace and set the following heating and cooling program: slowly raise the temperature from room temperature to 850℃ over 10 hours, hold at 850℃ for 24 hours, and then allow it to cool naturally to room temperature. Remove the product from the quartz tube, grind it thoroughly, transfer it to a quartz tube with an inner diameter of 1cm, evacuate to 0.1Pa, and seal. Place the sealed quartz tube in a muffle furnace and set the following heating and cooling program: slowly raise the temperature from room temperature to 850℃ over 10 hours, hold at 850℃ for 24 hours, and then allow it to cool naturally to room temperature. The product was removed from the quartz tube to obtain a polycrystalline sample of Sr4In2Sb2O5S5.

[0052] In this embodiment, SrO powder, In2S3 powder, Sb2S3 powder, and Sb2O3 powder are used as reactants and mixed in an elemental molar ratio of 4:2:2:5:5, without the addition of flux. First, the reactants are mixed and ground uniformly, then slowly heated from room temperature to a first temperature in a vacuum environment and held at that temperature. The first temperature is the reaction temperature of the heteroanion intermediate zone semiconductor material, ranging from 700℃ to 900℃, and the holding time is not less than 12 hours. In this embodiment, the temperature is 850℃ for 24 hours. After the first reaction of the reactants is completed, the reaction product is removed, thoroughly ground, and then reintroduced into a quartz tube for a second reaction. This ensures that all reactants added to the quartz tube undergo a complete reaction, ultimately yielding a polycrystalline Sr4In2Sb2O5S5 sample.

[0053] The polycrystalline Sr4In2Sb2O5S5 sample obtained in Example 2 was ground and then subjected to powder X-ray diffraction testing. The results are as follows: Figure 2 As shown, the obtained powder X-ray diffraction pattern is consistent with the theoretical X-ray diffraction pattern of the Sr4In2Sb2O5S5 crystal obtained from single-crystal structure analysis, proving that the obtained polycrystalline sample has high purity.

[0054] The light absorption characteristics of the Sr4In2Sb2O5S5 polycrystalline sample obtained in Example 2 were measured using a UV-Vis-NIR diffuse reflectance spectrometer. The results are as follows: Figure 3 As shown, its optical band gap is 1.8eV and 2.8eV, which can make full use of the ultraviolet and visible light portions of the solar spectrum.

[0055] Example 3

[0056] 0.1243 g of SrO powder, 0.14 g of In2Se3 powder, 0.0961 g of Sb2Se3 powder, 0.0292 g of Sb2O3 powder, and 1.5 g of KI powder were weighed into an agate mortar and ground thoroughly until homogeneous. The mixture was then transferred to a quartz tube with an inner diameter of 1 cm, and the tube was vacuumed to 0.1 Pa before sealing. The sealed quartz tube was placed in a muffle furnace, and the following heating and cooling program was set: slowly increasing the temperature from room temperature to 750℃ over 10 hours, holding at 750℃ for 48 hours, then cooling to 550℃ over 36 hours, and finally allowing it to cool naturally to room temperature. The product was removed from the quartz tube, washed three times with deionized water, washed with acetone, and dried to obtain a single crystal sample of Sr4In2Sb2O5Se5, the structure of which is shown below. Figure 4 As shown.

[0057] In this embodiment, SrO powder, In2Se3 powder, Sb2Se3 powder, and Sb2O3 powder were used as reactants and mixed in an elemental molar ratio of 4:2:2:5:5. KI was added as a flux to promote crystal growth. First, the reactants and flux were thoroughly mixed and ground until homogeneous. Then, the mixture was slowly heated from room temperature to a first temperature in a vacuum environment and held at that temperature. The first temperature was the reaction temperature of the heteroanion intermediate-band semiconductor material, ranging from 700℃ to 900℃, and the holding time was not less than 12 hours. In this embodiment, the temperature was held at 750℃ for 48 hours, followed by cooling to 550℃ for 36 hours to allow the heteroanion intermediate-band semiconductor material to crystallize from the KI melt. After natural cooling to room temperature, the product was washed with deionized water and acetone to remove the flux and dried to obtain a Sr4In2Sb2O5Se5 single crystal sample.

[0058] Example 4

[0059] Weigh out 0.1243g of SrO powder, 0.14g of In₂Se₃ powder, 0.0961g of Sb₂Se₃ powder, and 0.0292g of Sb₂O₃ powder in an agate mortar within an Ar-filled glove box. Grind and mix thoroughly, then transfer to a quartz tube with an inner diameter of 1cm. Vacuum the tube to 0.1Pa and seal it. Place the sealed quartz tube in a muffle furnace and set the following heating and cooling program: slowly increase the temperature from room temperature to 750℃ over 10 hours, hold at 750℃ for 24 hours, and then allow it to cool naturally to room temperature. Remove the product from the quartz tube, grind it thoroughly, transfer it to a quartz tube with an inner diameter of 1cm, vacuum the tube to 0.1Pa, and seal it. Place the sealed quartz tube in a muffle furnace and set the following heating and cooling program: slowly increase the temperature from room temperature to 750℃ over 10 hours, hold at 750℃ for 24 hours, and then allow it to cool naturally to room temperature. The product was removed from the quartz tube to obtain a polycrystalline sample of Sr4In2Sb2O5Se5.

[0060] In this embodiment, SrO powder, In2Se3 powder, Sb2Se3 powder, and Sb2O3 powder are used as reactants and mixed in an elemental molar ratio of 4:2:2:5:5, without the addition of flux. First, the reactants are mixed and ground uniformly. Then, in a vacuum environment, the temperature is slowly increased from room temperature to a first temperature and held. The first temperature is the reaction temperature of the heteroanion intermediate-band semiconductor material, ranging from 700℃ to 900℃, and the holding time is not less than 12 hours. In this embodiment, the temperature is 750℃ for 24 hours. After the first reaction of the reactants is completed, the reaction product is removed, thoroughly ground, and then placed back into a quartz tube for a second reaction to ensure that all reactants added to the quartz tube undergo a complete reaction, resulting in a polycrystalline Sr4In2Sb2O5Se5 sample.

[0061] The polycrystalline Sr4In2Sb2O5Se5 sample obtained in Example 4 was ground and then subjected to powder X-ray diffraction testing. The results are as follows: Figure 5 As shown, the obtained powder X-ray diffraction pattern is consistent with the theoretical X-ray diffraction pattern of Sr4In2Sb2O5Se5 crystal obtained from single-crystal structure analysis, proving that the obtained polycrystalline sample has high purity.

[0062] The Sr4In2Sb2O5Se5 polycrystalline sample obtained in Example 4 was ground and placed into a Φ10 stainless steel mold, then cold-pressed under 10 MPa pressure. The molded sample was then vacuum-sealed in a quartz tube and sintered in a muffle furnace at 750℃ for 2 hours. After removing the sample, it was cut into thin slices 6 mm long, 3 mm wide, and 0.5 mm high using a diamond wire cutter. Silver electrodes were then attached to both ends of the slices to construct a photoelectric response device. A 10V voltage was applied to the device, and visible light was used to irradiate it to detect changes in current density. The specific structure is as follows... Figure 6 As shown, this device exhibits a significant current enhancement under visible light illumination.

[0063] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an intermediate band semiconductor material, characterized in that, include: S1, the reaction raw materials containing Sr, In, Sb, O and Q elements are mixed in an element molar ratio of 4:2:2:5:5 and ground evenly; S2, the grinding product in S1 is gradually heated from room temperature to a first temperature within a predetermined time, and then naturally cooled to room temperature after being kept at that temperature for a certain time. Where Q is either S or Se.

2. The method for preparing intermediate band semiconductor material according to claim 1, characterized in that, In S1, the reaction raw materials are SrO, In2O3 powder, Sb2O3 powder and Sb2O3 powder.

3. The method for preparing intermediate band semiconductor material according to claim 1, characterized in that, In step S2, the grinding product is gradually heated from room temperature to the first temperature within 10 hours. The first temperature is 700℃~900℃. After holding at the temperature for no less than 12 hours, it is naturally cooled to room temperature.

4. The method for preparing intermediate band semiconductor material according to claim 1, characterized in that, In step S1, the reaction raw materials also include a flux.

5. The method for preparing intermediate band semiconductor material according to claim 4, characterized in that, In step S2, the grinding product from step S1 is gradually heated from room temperature to a first temperature over a predetermined period of time, held at that temperature for a certain period of time, and then cooled at a uniform rate to a second temperature, and then naturally cooled to room temperature. The second temperature is the crystallization temperature of the flux.

6. The method for preparing intermediate band semiconductor material according to claim 4, characterized in that, The flux is an alkali metal halide.

7. The method for preparing intermediate band semiconductor material according to any one of claims 1-6, characterized in that, Also includes: S3, take the product from S2 and grind it thoroughly; S4, the grinding product in S3 is gradually heated from room temperature to a first temperature within a predetermined time, and then naturally cooled to room temperature after being kept at that temperature for a certain time.

8. An intermediate-band semiconductor material, characterized in that, The chemical formula is Sr4In2Sb2O5Q5, where Q is S or Se.

9. The intermediate band semiconductor material according to claim 8, characterized in that, The intermediate-band semiconductor material belongs to the monoclinic crystal system, with Sr4In2Sb2O5S5 belonging to the P21 / c space group and Sr4In2Sb2O5Se5 belonging to the C2 / m space group.

10. The intermediate band semiconductor material according to claim 8, characterized in that, The intermediate band semiconductor material has a chain-like structure, consisting of [In2Q5]. 4- Chain and [Sr4Sb2O5] 4+ The chain consists of, In forms a tetrahedral coordination with Q, and Sb forms a triangular pyramidal coordination with O, [InQ4]. 5- Tetrahedrons are connected by sharing vertices.

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