Application of a high power factor CaTiO3-based material in photothermoelectric detectors

Abstract

The present invention provides an application of a CaTiO3-based material with a high power factor in a photothermal-electric detector, belonging to the technical field of photoelectric detection. This material is rich in oxygen vacancies, has a high Seebeck coefficient and high conductivity, and is prepared by heavily doping CaTiO3 with at least one rare earth element at the Ca site. The detector is composed of at least two series-connected CaTiO 3‑δ photothermal-electric detector material units, which are in the shape of a cuboid block and are prepared by a vacuum hot pressing sintering method, and have excellent ultraviolet to far-infrared electromagnetic radiation detection capabilities. The present invention directly uses the high power factor CaTiO 3‑δ material as the photon absorption layer and directly converts the generated heat into an electric signal, and its signal-to-noise ratio is much higher than that of the high-resistance SrTiO3 or BaTiO3 thin film absorption layer material; at the same time, reducing the size of the high power factor CaTiO 3‑δ material does not weaken the electric signal, and connecting small-size samples in series can also double the electric signal and effectively improve the signal-to-noise ratio, which helps to promote the wide application of CaTiO3-based materials in photothermal-electric detectors.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermoelectric detection, and in particular to the application of a high power factor CaTiO3-based material in a photothermoelectric detector. Background Art

[0002] Photodetectors are divided into photon detectors and thermal detectors. Among them, photon detectors are detectors that convert the energy of photons into electrical signals based on physical mechanisms such as electro-optical effect, photoconductivity effect or electrochemical effect. However, its detection band is often limited by the band gap of the material, that is, electrical signals can only be generated when the photon energy is greater than the band gap of the material. Thermal detectors are photodetectors that use thermal effects such as temperature changes or thermal radiation to detect electromagnetic radiation. Unlike photon detectors, thermal detectors cause temperature changes in materials by absorbing radiation energy, and then convert temperature changes into electrical signals. Usually based on physical mechanisms such as pyroelectric effect, thermoelectric effect, thermistor, gas expansion, etc., thermal detectors can be divided into thermoelectric effect radiation detectors, thermoelectric effect radiation detectors, radiation Bohr meters, gas expansion radiation detectors, etc. Among them, thermoelectric effect radiation detectors convert the absorbed light into heat, and then use the Seebeck effect to convert heat into voltage. This type of detector uses p and n type thermoelectric piles to convert the heat generated by the photon absorption layer into electrical signals. This type of detector has high preparation cost, low responsiveness, and a high threshold of detectable laser power density. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a high power factor CaTiO3-based material for use in photothermoelectric detectors. Since the CaTiO3-based material has obvious absorption of electromagnetic waves from ultraviolet to far infrared, and a high power factor can be obtained by preparation. S 2 σ , that is, a high Seebeck coefficient ( S) and high electrical conductivity ( σ ), and by discarding the absorption layer and p- and n-type thermopiles in the thermopile detector, directly using the high power factor CaTiO 3-δ The material acts as a photon absorption layer and directly converts the generated heat into electrical signals. Its signal-to-noise ratio is much higher than that of high-resistance SrTiO3 or BaTiO3 thin film absorption layer materials. In addition, by reducing the high power factor of CaTiO 3-δ The electrical signal will not be weakened due to the size of the material. Connecting small-sized samples in series can increase the electrical signal exponentially and effectively improve the signal-to-noise ratio, which will help promote the widespread application of CaTiO3-based materials in photothermoelectric detectors.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] Application of a high power factor CaTiO3-based material in a photothermoelectric detector, wherein the high power factor CaTiO3-based material is used as a detection material of the photothermoelectric detector, and the chemical formula of the detection material is CaTiO 3-δ ,0< δ ≤0.5, indicating high power factor CaTiO 3-δ Photothermoelectric detector materials are rich in oxygen vacancies.

[0006] Preferably, the high power factor of the detection material S 2 σ By high Seebeck coefficient S and high conductivity σ Joint decision.

[0007] Preferably, the detection material is obtained by heavily doping CaTiO3 and at least one rare earth element at the Ca position.

[0008] Preferably, the rare earth element is one of La, Ce, Dy, Nd, Pm, Sm, Eu, Pr, Er, Tm, and Yb.

[0009] The present invention also provides a photothermoelectric detector using the above-mentioned high power factor CaTiO3-based material in a photothermoelectric detector, which comprises at least two CaTiO3-based materials connected in series. 3-δ The photothermoelectric detector material unit is composed of the CaTiO 3-δ The photothermoelectric detector material unit is made of CaTiO3 and at least one rare earth element heavily doped at the Ca position, wherein the CaTiO 3-δ The shape of the photothermoelectric detector material unit is a rectangular block.

[0010] Preferably, the CaTiO 3-δ The preparation method of the photothermoelectric detector material unit is as follows: CaTiO3 and an oxide of at least one rare earth element are mixed; then the mixture is sintered in a vacuum hot pressing sintering furnace, and the CaTiO3 is cut to obtain 3-δ Photothermoelectric detector materials unit.

[0011] Preferably, the CaTiO 3-δ The photothermoelectric detector material unit is prepared by sintering in a vacuum hot pressing sintering furnace: the vacuum degree is 0.1~1Pa, the pressure is 5~20MPa, the temperature is 1400~1600℃, and the insulation time is 2~4h.

[0012] Preferably, the photothermal detector is based on the photothermal effect and Seebeck effect of CaTiO3-based materials with high power factor and is used for detecting light from ultraviolet to far infrared spectra.

[0013] Preferably, the method for using the photothermoelectric detector is as follows: connect the red and black test leads of the source meter to the rectangular block of CaTiO 3-δ The photothermoelectric detector material units are in direct contact, and the light source of the measured band directly irradiates the surface of the detection sample. One side of the detection sample is illuminated, resulting in a temperature difference, which is converted into a voltage signal with a high signal-to-noise ratio based on the Seebeck effect.

[0014] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] (1) The present invention adopts CaTiO with high power factor 3-δ As the core component of the detector, the material directly utilizes its excellent photothermal effect and Seebeck effect to convert the absorbed photon energy into electrical signals, which significantly improves the signal-to-noise ratio and responsiveness of the detector. Compared with traditional high-resistance oxide thin film materials, such as SrTiO3 or BaTiO3, the detector of the present invention exhibits higher sensitivity and lower noise level under the same conditions. At the same time, the detector of the present invention has a wide-band detection capability from ultraviolet to far infrared, covering a wider range of electromagnetic radiation and meeting the needs of different application scenarios.

[0016] (2) The present invention introduces rare earth elements into CaTiO3 by heavily doping rare earth elements, which significantly improves the electrical properties of the material and provides a material basis for the preparation of high-performance photothermoelectric detectors. At the same time, in terms of structural design, the present invention abandons the complex structure of traditional thermopile detectors and directly utilizes high power factor CaTiO 3-δ The material is used as a photon absorbing layer and multiple CaTiO 3-δ The photothermoelectric detector material unit achieves signal enhancement. This simplified structural design not only improves the reliability and stability of the photothermoelectric detector, but also facilitates integration and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 The high power factor CaTiO 3-δ Schematic diagram of the structure of the material photothermoelectric detector;

[0019] Figure 2 The CaTiO prepared in Example 1 of the present invention 3-δ Sample and La prepared in Example 2 0.2 Ca0.8 TiO 3-δ UV-Vis-NIR absorption spectra of samples;

[0020] Figure 3 The infrared emissivity diagram of the samples provided in Example 1 and Example 2 of the present invention in different bands; wherein, Figure 3 (a) is CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ Infrared emissivity graph of the sample in the 3~5μm band; Figure 3 (b) is CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ Infrared emissivity graph of the sample in the 8~14μm band;

[0021] Figure 4 The performance parameter curves of the samples provided in Example 1 and Example 2 of the present invention at different temperatures; wherein, Figure 4 (a) is CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ Seebeck coefficient curves of samples at different temperatures; Figure 4 (b) is CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ Conductivity curves of samples at different temperatures; Figure 4 (c) is CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ Power factor curves of samples at different temperatures;

[0022] Figure 5 The CaTiO prepared in Example 1 of the present invention 3-δ The voltage response curve of the sample's photothermoelectric detector at room temperature and under illumination of light sources of different wavelengths; Figure 5 (a) is the voltage response curve under 365nm ultraviolet light source; Figure 5 (b) is the voltage response curve under 780nm laser light source irradiation; Figure 5(c) is the voltage response curve under 808nm laser light source irradiation; Figure 5 (d) is the voltage response curve under 850nm laser light source irradiation; Figure 5 (e) is the voltage response curve under 980nm laser light source irradiation; Figure 5 (f) is the voltage continuous response curve under 850nm laser light source irradiation;

[0023] Figure 6 The high power factor La prepared in Example 2 of the present invention 0.2 Ca 0.8 TiO 3-δ The voltage response curve of the sample's photothermoelectric detector at room temperature and under illumination of light sources of different wavelengths; Figure 6 (a) is the voltage response curve under 365nm ultraviolet light source; Figure 6 (b) is the voltage response curve under 780nm laser light source irradiation; Figure 6 (c) is the voltage response curve under 808nm laser light source irradiation; Figure 6 (d) is the voltage response curve under 850nm laser light source irradiation; Figure 6 (e) is the voltage response curve under 980nm laser light source irradiation; Figure 6 (f) is the voltage continuous response curve under 850nm laser light source irradiation;

[0024] Figure 7 The low resistance La prepared in Example 3 of the present invention 0.2 Ca 0.8 TiO 3-δ The voltage response curve of the sample's photothermoelectric detector connected in different ways at room temperature and under 808nm laser irradiation; Figure 7 (a) is the voltage response curve of the single-arm sample; Figure 7 (b) is the voltage response curve of two identical samples connected in series. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] like Figure 1As shown, the present invention provides a photothermoelectric detector using a CaTiO3-based material with a high power factor, which comprises at least two CaTiO3-based materials connected in series. 3-δ The photothermoelectric detector material unit is composed of the CaTiO 3-δ The photothermoelectric detector material unit is made of CaTiO3 and at least one rare earth element heavily doped at the Ca position, wherein the CaTiO 3-δ The shape of the photothermoelectric detector material unit is a rectangular block. 3-δ The preparation method of the photothermoelectric detector material unit is as follows: CaTiO3 and at least one rare earth element oxide are mixed; then sintering is performed in a vacuum hot pressing sintering furnace, the vacuum degree is 0.1~1Pa, the pressure is 5~20MPa, the temperature is 1400~1600℃, and the heat preservation time is 2~4h, thereby obtaining the CaTiO 3-δ Photothermoelectric detector material unit. The above-mentioned photothermoelectric detector is based on the photothermal effect and Seebeck effect of the high power factor CaTiO3-based material and is used to detect the infrared spectrum from ultraviolet to far infrared. At the same time, refer to Figure 1 The photothermoelectric detector provided has a simple structure. Compared with the traditional electric pile detector, it directly omits the photon absorption layer and the pn type thermoelectric pile, and directly converts the high power factor CaTiO 3-δ The base material acts as a photon absorption layer and directly converts the generated heat into electrical signals. The response intensity can be increased by series connection, which is simple and can multiply the electrical signal and effectively improve the signal-to-noise ratio.

[0027] In addition, the method of using the above-mentioned photothermoelectric detector is as follows: connect the red and black test leads of the source meter to the rectangular block of CaTiO 3-δ The photothermoelectric detector material units are in direct contact, and the light source of the measured band directly irradiates the surface of the detection sample. One side of the detection sample is illuminated, resulting in a temperature difference, which is converted into a voltage signal with a high signal-to-noise ratio based on the Seebeck effect.

[0028] It can be seen that the present invention also provides an application of a high power factor CaTiO3-based material in a photothermoelectric detector, wherein the high power factor CaTiO3-based material is used as a detection material of the photothermoelectric detector, and the chemical formula of the detection material is CaTiO 3-δ ,0< δ ≤0.5, indicating high power factor CaTiO 3-δ Photothermoelectric detector materials are rich in oxygen vacancies.

[0029] Specifically, the high power factor of the detection material S 2 σ By high Seebeck coefficient Sand high conductivity σ The detection material is obtained by heavily doping CaTiO3 and at least one rare earth element at the Ca position. The rare earth element is one of La, Ce, Dy, Nd, Pm, Sm, Eu, Pr, Er, Tm, Yb, etc. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] In this example, CaTiO 3-δ The sample preparation process is as follows: 18.58 g of CaTiO3 (purity ≥ 99.5%) is weighed, the weighed CaTiO3 is placed in a graphite mold, and then sintered in a vacuum hot pressing sintering furnace, wherein the vacuum degree is 1 Pa, the pressure is 10 MPa, and the temperature is kept at 1500 ° C for 3 hours to obtain CaTiO 3-δ Sample. The prepared material sample was then cut into a rectangular block structure with a size of 1.6 mm × 1.3 mm × 12 mm (length × width × height).

[0032] Using the above-mentioned CaTiO 3-δ The process of sample preparation for photothermoelectric detector is as follows: directly connect the red and black pen of source meter (model: 2450, Keithley) to the CaTiO 3-δ The sample is in contact, and the light source in the measured wavelength band is directly irradiated on the CaTiO 3-δ The surface of the sample. Figure 4 and Figure 5 The high resistance and low power factor CaTiO prepared in this embodiment 3-δ The voltage response curves of the sample's photothermoelectric detector under room temperature and different wavelength light sources show that due to CaTiO 3-δ The sample has a higher resistance and a lower power factor, so the sample provided in this embodiment has a low signal-to-noise ratio when converting electrical signals.

[0033] Example 2

[0034] In this embodiment, a high power factor La 0.2 Ca 0.8 TiO 3-δ The sample preparation process is as follows: 18.58 g of CaTiO3 (purity ≥ 99.5%) and 5.54 g of La2O3 (purity ≥ 99.99%) are weighed, the weighed CaTiO3 and La2O3 are fully mixed and put into a graphite mold, and then sintered in a vacuum hot pressing sintering furnace, wherein the vacuum degree is 1 Pa, the pressure is 10 MPa, and the temperature is kept at 1500 ° C for 3 hours to obtain a high power factor La 0.2 Ca0.8 TiO 3-δ Sample. The prepared material sample was then cut into a rectangular block structure with a size of 1.6 mm × 1.3 mm × 12 mm (length × width × height).

[0035] Using the above high power factor La 0.2 Ca 0.8 TiO 3-δ The process of sample preparation of photothermoelectric detector is as follows: directly connect the red and black pen of the source meter (model: 2450, Keithley) to the high power factor La 0.2 Ca 0.8 TiO 3-δ The sample is in contact with the light source in the measured wavelength band, which is directly irradiated with a high power factor La 0.2 Ca 0.8 TiO 3-δ The surface of the sample. Figure 6 The low resistance and high power factor La prepared in this embodiment 0.2 Ca 0.8 TiO 3-δ The voltage response curves of the sample's photothermoelectric detector under room temperature and different wavelength light sources show that due to La 0.2 Ca 0.8 TiO 3-δ The sample has lower resistance and higher power factor, so the power factor of the material can be effectively improved by doping with rare earth elements, so that the sample provided in this embodiment has a higher signal-to-noise ratio when converting electrical signals.

[0036] Example 3

[0037] In this embodiment, a high power factor La 0.2 Ca 0.8 TiO 3-δ The sample preparation process is as follows: 18.58 g of CaTiO3 (purity ≥ 99.5%) and 5.54 g of La2O3 (purity ≥ 99.99%) are weighed, the weighed CaTiO3 and La2O3 are fully mixed and put into a graphite mold, and then sintered in a vacuum hot pressing sintering furnace, wherein the vacuum degree is 1 Pa, the pressure is 10 MPa, and the temperature is kept at 1500 ° C for 3 hours to obtain a high power factor La 0.2 Ca 0.8 TiO 3-δ Sample. The prepared material sample was then cut into a rectangular block structure with a size of 1.6 mm × 1.3 mm × 7 mm (length × width × height).

[0038] Using the above high power factor La 0.2 Ca 0.8 TiO 3-δThe process of sample preparation of photothermoelectric detector is as follows: directly connect the red and black pen of the source meter (model: 2450, Keithley) to the high power factor La 0.2 Ca 0.8 TiO 3-δ The sample is in contact with the light source in the measured wavelength band, which is directly irradiated with a high power factor La 0.2 Ca 0.8 TiO 3-δ The surface of the sample.

[0039] According to the above examples 1-2, the performance of the samples prepared was tested. Figure 2 , the CaTiO prepared in Example 1 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ The sample has obvious absorption of ultraviolet, visible and near-infrared light between 400nm and 2000nm. Figure 3 (a) and (b) in Example 1, CaTiO 3-δ Sample and La prepared in Example 2 0.2 Ca 0.8 TiO 3-δ The samples have high infrared emissivity in the 3-5 μm and 8-14 μm bands. Since the infrared emissivity is equal to the absorptivity, the samples prepared in the two embodiments have obvious absorption in both mid-infrared and far-infrared. Figure 4 In (a), (b) and (c), rare earth element doping can effectively increase the CaTiO 3-δ The power factor of the material. In addition, high conductivity can effectively reduce the noise of electrical signals, so high power factor can enhance the signal-to-noise ratio of the material's response.

[0040] in addition, Figure 5 (a), (b), (c), (d), (e) and (f) and Figure 6 (a), (b), (c), (d), (e) and (f) are response curves of the samples of Examples 1 to 2 under illumination of different wavelengths, wherein: Figure 5 (a) and Figure 6 (a) is the response curve under 365nm ultraviolet light. Due to the high wavelength frequency of 365nm ultraviolet light, there may be a certain photoelectric effect. Figure 7 In (a) and (b), by connecting La 0.2 Ca 0.8 TiO 3-δ The sample, the response signal of the photothermoelectric detector to the light source is multiplied.

[0041] Therefore, the present invention abandons the absorption layer and the p-type and n-type thermopiles in the thermopile detector and directly utilizes the high power factor CaTiO 3-δ The material acts as a photon absorption layer and directly converts the generated heat into electrical signals. Its signal-to-noise ratio is much higher than that of high-resistance SrTiO3 or BaTiO3 thin film materials. In addition, by reducing the high power factor of CaTiO 3-δ The electrical signal will not be weakened due to the size of the material. Connecting small samples in series can multiply the electrical signal and effectively improve the signal-to-noise ratio.

[0042] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0043] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. Application of a high power factor CaTiO3-based material in a photothermoelectric detector, characterized in that: The high power factor CaTiO3-based material is used as the detection material of the photothermoelectric detector. The chemical formula of the detection material is CaTiO 3-δ ,0< δ ≤0.5, indicating high power factor CaTiO 3-δ The photothermoelectric detector material is rich in oxygen vacancies; the detection material is obtained by heavily doping CaTiO3 and at least one rare earth element at the Ca position; The photothermoelectric detector according to the application of the high power factor CaTiO3-based material in the photothermoelectric detector comprises at least two CaTiO3-based materials connected in series. 3-δ The photothermoelectric detector material unit is composed of the CaTiO 3-δ The photothermoelectric detector material unit is made of CaTiO3 and at least one rare earth element heavily doped at the Ca position, wherein the CaTiO 3-δ The shape of the photothermoelectric detector material unit is a rectangular block; the rare earth element is one of La, Ce, Dy, Nd, Pm, Sm, Eu, Pr, Er, Tm, and Yb; The CaTiO 3-δ The preparation method of the photothermoelectric detector material unit is as follows: CaTiO3 and an oxide of at least one rare earth element are mixed; then the mixture is sintered in a vacuum hot pressing sintering furnace, and the CaTiO3 is cut to obtain 3-δ Photothermoelectric detector material unit; the CaTiO 3-δ The photothermoelectric detector material unit is prepared by sintering in a vacuum hot pressing sintering furnace: the vacuum degree is 0.1~1Pa, the pressure is 5~20MPa, the temperature is 1400~1600℃, and the insulation time is 2~4h.

2. The use of a high power factor CaTiO3-based material in a photothermoelectric detector according to claim 1, characterized in that: The high power factor of the detection material S 2 σ By high Seebeck coefficient S and high conductivity σ Joint decision.

3. The use of a high power factor CaTiO3-based material in a photothermoelectric detector according to claim 1, characterized in that: The photothermal electric detector is based on the photothermal effect and Seebeck effect of the CaTiO3-based material with a high power factor and is used for detecting the spectrum from ultraviolet to far infrared.

4. The use of a high power factor CaTiO3-based material in a photothermoelectric detector according to claim 3, characterized in that: The method for using the photothermoelectric detector is as follows: connect the red and black test leads of the source meter to the rectangular block of CaTiO 3-δ The photothermoelectric detector material units are in direct contact, and the light source of the measured band directly irradiates the surface of the detection sample. One side of the detection sample is illuminated, resulting in a temperature difference, which is converted into a voltage signal with a high signal-to-noise ratio based on the Seebeck effect.

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