SnSe2 / doped tin oxide heterostructure double-layer film as well as preparation method and application thereof

Abstract

The invention discloses a SnSe2 / doped tin oxide heterostructure double-layer film as well as a preparation method and application thereof. The SnSe2 / doped tin oxide heterostructure double-layer thin film comprises a doped tin oxide thin film and a SnSe2 thin film deposited on the doped tin oxide thin film. The preparation method comprises the following steps: reacting a tin source and a selenium source at a high temperature, and depositing on a doped tin oxide film at a low temperature; the high temperature is 600-650 DEG C; and the low temperature is 250-300 DEG C. The SnSe2 / doped tin oxide heterostructure double-layer film provided by the invention is of a wide-narrow band gap homotype heterostructure, has relatively high carrier mobility, has certain transmittance in a visible light region, and can be used as a transparent conductive material.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive materials, and in particular to a SnSe2 / doped tin oxide heterostructure double-layer film and a preparation method and application thereof. Background Art

[0002] Transparent conductive oxide films are a type of material that combines transparency and conductivity. They are widely used in solar cells, touch screens and flat panel displays, sensors, light-emitting diodes, smart windows, and energy-saving doors and windows for buildings. Common transparent conductive oxide films include tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO). Among them, ITO has the best performance and is widely used, but its chemical stability and durability are poor, and its performance degrades severely in harsh outdoor environments. At the same time, the element indium has a small reserve in nature and is toxic, which makes ITO expensive and unfavorable to the environment. FTO has excellent chemical stability, durability, and heat resistance, and is pollution-free to the environment. It has large reserves of raw materials, low cost, and is suitable for large-scale coating, but the conductivity of FTO is inferior to that of ITO.

[0003] For semiconductor materials, conductivity is determined by carrier concentration and mobility. In the prior art, element doping, including single element doping and multi-element doping, is one of the means to improve the conductive properties of FTO. Element doping can increase the carrier concentration, but the content of the doping element is limited by the solid solubility, and excessive doping will increase the scattering of ion impurities, thereby reducing the carrier mobility. Therefore, how to improve the carrier mobility under the premise of higher carrier concentration is the key to improving conductivity. Researchers have made many attempts, such as doping graphene, carbon nanotubes, precious metal wires, etc. into FTO films, but they are restricted by problems such as high contact resistance or easy oxidation, and the results are not ideal. Therefore, improving conductivity requires another way. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a SnSe2 / doped tin oxide heterostructure double-layer film and its preparation method and application. The SnSe2 / doped tin oxide heterostructure double-layer film provided by the present invention is a wide and narrow bandgap isotype heterostructure with high carrier mobility, thereby achieving high conductivity.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] On the one hand, the present invention provides a SnSe2 / doped tin oxide heterostructure double-layer film, including a doped tin oxide film and a SnSe2 film deposited on the doped tin oxide film.

[0007] As a preferred embodiment, the doped tin oxide film is a single-element doped or multi-element doped tin oxide film; the single-element doping is fluorine doping; one of the elements in the multi-element doping is fluorine, and the other elements are selected from at least one of niobium, nickel, molybdenum and lanthanum.

[0008] In another aspect, the present invention provides a method for preparing the above-mentioned SnSe2 / doped tin oxide heterostructure double-layer film, comprising the following steps:

[0009] The tin source and the selenium source react at high temperature and are deposited on the doped tin oxide film at low temperature; the high temperature is 600-650°C; the low temperature is 250-300°C.

[0010] As a preferred embodiment, the reaction time at high temperature is 60 to 120 minutes;

[0011] Preferably, the heating rate of the high temperature is 25-35°C / min;

[0012] Preferably, the heating rate of the low temperature is 10-15°C / min.

[0013] As a preferred embodiment, the high temperature reaction and / or low temperature deposition is performed in an atmosphere of an inert carrier gas.

[0014] As a preferred embodiment, the tin source is stannous chloride, such as anhydrous stannous chloride or dihydrated stannous chloride;

[0015] Preferably, the selenium source is elemental selenium.

[0016] As a preferred embodiment, the molar ratio of tin in the tin source to selenium in the selenium source is 1:2 to 2.5.

[0017] In certain specific embodiments, the doped tin oxide film is pre-treated by cleaning; the cleaning specifically comprises: soaking in a standard piranha solution, washing and drying; the washing comprises washing with acetone, water, and ethanol in sequence.

[0018] In some specific embodiments, the high temperature reaction and low temperature deposition are performed in a dual temperature zone tube furnace.

[0019] On the other hand, the present invention provides the use of the above-mentioned SnSe2 / doped tin oxide heterostructure double-layer film in the preparation of conductive materials; such as solar cells, light-emitting diodes, etc.

[0020] Preferably, the invention is used in preparing a transparent conductive material.

[0021] The above technical solution has the following beneficial effects:

[0022] The SnSe2 / doped tin oxide heterostructure double-layer film provided by the present invention is composed of two semiconductors with wide and narrow band gaps. Among them, SnSe2 is an n-type semiconductor with a narrow band gap (1-2eV), and tin oxide is an n-type semiconductor with a wide band gap (3-4eV). Donor impurities (fluorine element) are doped into the tin oxide wide band gap semiconductor, so it has an electronic barrier. No doping is performed in the SnSe2 narrow energy gap semiconductor (i.e., an intrinsic semiconductor), so there is an electronic potential well. Since the potential well depth between the SnSe2 / doped tin oxide heterostructure is large, the electrons therein can move close to the heterojunction interface in the potential well, so that the electrons flow from the wide band gap side to the narrow band gap side, forming a high-mobility "two-dimensional electron gas" (2-DEG). At the same time, there is no scattering effect of ionized impurities on the SnSe2 intrinsic semiconductor side, so these two-dimensional electron gases have a higher mobility moving in the plane direction. These synergistic enhancement effects make the SnSe2 / doped tin oxide heterostructure double-layer film have a higher conductivity.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. In the prior art, the synthesis methods of SnSe2 include hydrothermal method, chemical vapor deposition method, etc.; among them, the SnSe2 prepared by the hydrothermal method is in powder form and has agglomeration phenomenon; the chemical vapor deposition method can obtain a thin film product, but the reaction time of this method is long and a low-pressure environment is required; in addition, since the generation conditions of SnSe2 and SnSe are similar, it is difficult to obtain high-purity SnSe2. The doped tin oxide-SnSe2 heterogeneous structure composite material in the present invention is deposited in a dual-temperature zone tubular furnace with a certain gradient. At the same time, due to the excess of selenium source, the deposited SnSe2 film has a high purity and is basically free of Se elemental substance, SnSe and other impurities.

[0025] 2. The electrical conductivity of the SnSe2 / doped tin oxide heterostructure double-layer film provided by the present invention is better than that of the single-layer doped tin oxide film; wherein, SnSe2 is a two-dimensional layered material with graphene-like properties, and can be prepared into various heterostructures along the vertical plane direction without lattice mismatch; in addition, Se reserves are abundant and environmentally friendly.

[0026] 3. The preparation method provided by the present invention can prepare SnSe2 with a small film thickness, ensuring high conductivity while having a certain transmittance, so it can be used to prepare a transparent conductive film. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a device for preparing a doped tin oxide-SnSe2 heterostructure composite material according to Example 1 of the present invention.

[0028] Figure 2It is the XRD spectrum of the SnSe2 thin film prepared in Examples 1-3 of the present invention.

[0029] Figure 3 It is the Raman spectrum of the SnSe2 thin film prepared in Examples 1-3 of the present invention.

[0030] Figure 4 This is a SEM image of the SnSe2 thin film prepared in Example 1 of the present invention.

[0031] Figure 5a-5c This is the EDS element distribution diagram of the SnSe2 film prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following embodiments are only some embodiments of the present invention, rather than all embodiments. Therefore, the detailed description in the embodiments of the present invention provided below is not intended to limit the scope of the present invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0033] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0034] Embodiment 1:

[0035] This embodiment provides a SnSe2 / doped tin oxide heterostructure double-layer film, and the preparation device is as follows Figure 1 As shown, the specific steps include:

[0036] Prepare a 10mm×10mm FTO glass substrate, place the FTO glass substrate in a standard piranha solution for 1 hour to remove organic impurities on the surface; ultrasonically clean it in an acetone solution for 20 minutes, ultrasonically clean it in deionized water for 10 minutes, and ultrasonically clean it in anhydrous ethanol for 10 minutes; dry it; place the cleaned FTO glass substrate in the low temperature zone heating center of a dual-temperature zone tube furnace;

[0037] Weigh 0.379 g SnCl2 (0.002 mol) and 0.332 g Se powder (0.0042 mol) and place them in two quartz boats respectively, and then place them in the high temperature zone heating center of a dual temperature zone tube furnace;

[0038] Seal the quartz tube of the dual-temperature zone tube furnace with a flange, pass high-purity argon gas for 1 h to exhaust the air in the quartz tube, then adjust the high-purity argon flow rate to 80 mL / min and maintain this flow rate during the preparation process;

[0039] The temperature of the heating center of the high-temperature zone is set to 600℃, and the temperature of the heating center of the low-temperature zone is set to 300℃; the temperature is raised from the initial temperature of 20℃, and the heating time is set to 20min; after reaching the target temperature, the temperature is kept for 90min; after the insulation is completed, the heating is stopped, and the substrate is allowed to cool to room temperature with the furnace to obtain a SnSe2 / FTO heterostructure double-layer film.

[0040] In this embodiment, the thickness of the SnSe2 film deposited on the FTO substrate is about 200-300 nm.

[0041] Example 2

[0042] The preparation process of the SnSe2 / doped tin oxide heterostructure double-layer film in this embodiment is the same as that in Embodiment 1, except that the temperature of the heating center of the high temperature zone is set to 650° C. In this embodiment, the thickness of the SnSe2 film deposited on the FTO substrate is 100-200 nm.

[0043] Example 3

[0044] The preparation process of the SnSe2 / doped tin oxide heterostructure double-layer film in this embodiment is the same as that in Embodiment 1, except that the temperature of the heating center in the low temperature zone is set to 250° C. In this embodiment, the thickness of the SnSe2 film deposited on the FTO substrate is 100-200 nm.

[0045] Figure 2 The XRD patterns of the SnSe2 films prepared in Examples 1-3 are as follows: Figure 2 It can be seen that when the temperature in the low temperature zone is 300℃, and the high temperature zone is 600℃ and 650℃, the obtained thin film sample is SnSe2, and almost no other substances are contained; among them, when the temperature in the high temperature zone is 600℃, the peak of the (001) crystal plane of the sample is sharper, indicating that the crystallization quality of SnSe2 is better; therefore, 600℃ in the high temperature zone is a more suitable reaction temperature. When the low temperature zone is 250℃, the sample contains not only SnSe2 but also Se, indicating that Se can be deposited at 250℃, which is not conducive to obtaining high-purity SnSe2.

[0046] Figure 3 The Raman spectrum of the SnSe2 thin film prepared in Example 1-3. g The peak position is at 117 cm -1 , A 1g The peak position is at 187 cm -1 In the figure, the two peaks of the Raman spectra of the three embodiments are all near the above value, and the peak positions shift with the reaction temperature. This shows that the thickness of the SnSe2 film prepared by the present invention is affected by the reaction temperature.

[0047] Figure 4This is a SEM scanning image of the SnSe2 film prepared in Example 1. It can be seen that SnSe2 has a layered morphology and a thickness of 200-300 nm.

[0048] Figure 5a This is the EDS image of the SnSe2 film prepared in Example 1, the central part is SnSe2; Figure 5b yes Figure 5a The corresponding Se element distribution diagram, Figure 5c yes Figure 5a Corresponding Sn element distribution diagram. It can be seen from the figure that Se elements are basically concentrated in the SnSe2 area.

[0049] The sheet resistance of the SnSe2 / doped tin oxide heterostructure double-layer films prepared in Examples 1-3 is shown in Table 1. It can be seen that the sheet resistance of the double-layer films has decreased to varying degrees compared with the simple FTO substrate, and the double-layer films prepared at 300°C in the low temperature zone and 600°C in the high temperature zone are the lowest.

[0050] Table 1

[0051] Example 1 Example 2 Example 3 Low temperature area / ℃ 300 300 250 High temperature area / ℃ 600 650 600 Surface resistance / Ω / □ 16.0 16.4 16.3 Decline rate / % 11.1 8.9 9.4

[0052] The sheet resistance of a single-layer FTO substrate is 18Ω / □.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A SnSe2 / doped tin oxide heterostructure double-layer film, characterized in that: The invention comprises a doped tin oxide film and a SnSe2 film deposited on the doped tin oxide film.

2. The SnSe2 / doped tin oxide heterostructure double-layer film according to claim 1, characterized in that: The doped tin oxide film is a single-element doped or multi-element doped tin oxide film; the single-element doping is fluorine doping; one of the elements in the multi-element doping is fluorine, and the other elements are selected from at least one of niobium, nickel, molybdenum and lanthanum.

3. The method for preparing the SnSe2 / doped tin oxide heterostructure double-layer film according to any one of claims 1-2, characterized in that: The following steps are involved: The tin source and the selenium source react at high temperature and are deposited on the doped tin oxide film at low temperature; the high temperature is 600-650°C; the low temperature is 250-300°C.

4. The preparation method according to claim 3, characterized in that: The reaction time at high temperature is 60 to 120 minutes; Preferably, the high temperature heating rate is 25-35°C / min; Preferably, the heating rate of the low temperature is 10-15°C / min.

5. The preparation method according to claim 3, characterized in that: The high temperature reaction and / or low temperature deposition is performed in an atmosphere of an inert carrier gas.

6. The preparation method according to claim 3, characterized in that: The tin source is stannous chloride; Preferably, the selenium source is elemental selenium.

7. The preparation method according to claim 3, characterized in that: The molar ratio of tin in the tin source to selenium in the selenium source is 1:2 to 2.

5.

8. The preparation method according to claim 3, characterized in that: The doped tin oxide film is pre-treated by cleaning; the cleaning specifically includes: soaking in a standard piranha solution, washing and drying; the washing includes washing with acetone, water, and ethanol in sequence.

9. The preparation method according to claim 3, characterized in that: The high temperature reaction and low temperature deposition are carried out in a double temperature zone tube furnace.

10. Use of the SnSe2 / doped tin oxide heterostructure double-layer film according to any one of claims 1-2 in the preparation of conductive materials; Preferably, the invention is used in preparing a transparent conductive material.

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