CN102692445B - Organic semiconductor gas sensor with organic heterojunction-containing gas-sensitive layer - Google Patents

Abstract

The invention provides an organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction, which utilizes charge transfer between two organic semiconductor materials to form a heterojunction to change the oxidation-reduction potential of the film surface, thereby improving the sensitivity of the sensor to sensitive gases. Response, the organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction provided by the present invention has high sensitivity at room temperature, and the thickness of the gas-sensing layer is small, which effectively shortens the response/recovery time of the device, and is disposable by using a vacuum deposition method. The preparation of the device is completed without subsequent processes such as annealing, which simplifies the preparation process of the device; the organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer provided by the present invention can detect _NO gas with a volume fraction of 5ppm , and the response/reply can be completed within 10 minutes.

Description

Organic semiconductor gas sensor with gas sensing layer containing organic heterojunction

technical field

The invention relates to an organic semiconductor gas sensor whose gas sensitive layer contains an organic heterojunction.

technical background

With the development of organic semiconductor science and technology, scientists have discovered that many organic semiconductor materials have extremely sensitive responses to some toxic and harmful gases, such as _NO2 , and sensors made of such materials have extremely high sensitivity. B.Bott et al. (B.Bott andT.A.Jones Sensors and Actuators 1984, 5, 43) reported that when the organic semiconductor material lead phthalocyanine is above 100°C, the volume fraction is one part per billion in the _NO2 environment The conductance of the medium film will increase significantly. Such sensors usually work in high-temperature environments, which limits their application range. Therefore, it is imperative to develop sensors that can detect at room temperature. M.Passard et al. (M.Passard, A.Pauly, JPBlanc, S.Dogo, JPGermain, C.Maleysson, Thin Solid Films, 1994, 237, 272-276) found that different gas molecules have different redox properties After being adsorbed by the phthalocyanine film, an oxidation or reduction reaction can occur, and free hole carriers or electron carriers are generated in the film, so the conductance of the film is changed. T.Someya et al. (T.Someya, HEKatz, A.Gelperin, AJLovingerand A.Dodabalapur, Applied.Physics.Letter.2002, 81, 3079-3081) researched and proposed that the adsorption position of organic gas-sensitive film and gas is mainly in At the grain boundaries, polycrystalline thin films with relatively large specific surface areas have been extensively studied. However, the surface anisotropy of the polycrystalline film is serious, and the activation energy distribution required for the gas adsorption-desorption process of the active sites on the film surface is wide, and the desorption rate is seriously affected by the slow active sites. These polycrystalline films with large specific surface areas are often realized by thick films (0.5-1 micron), and the diffusion of gas in the film body at room temperature will significantly prolong the response time and recovery time of the sensor. The ultra-thin film can realize fast response at room temperature, and the VOPc ultra-thin film can detect NO ₂ in one hundred thousandth at room temperature, and the sensitivity is obviously increased in high-concentration gases. The surface potential distribution of the ultra-thin film is relatively uniform and concentrated, and the number of grain boundaries is small. At room temperature, the sensitivity of low-concentration gases below 5 parts per million is not high. Therefore, adjusting the redox potential of the surface of organic semiconductor thin films to make it easier to transfer charges between sensitive gases is an effective means to improve the performance of organic semiconductor gas sensors. In 2005, Wang Jun et al. (J.Wang, HBWang, XJYan, HCHang, DHYan, Applied Physics Letters, 2005, 87, 093507) reported the accumulation of free carriers at the interface of two organic semiconductors to form a heterojunction. The accumulation of free carriers leads to higher conductance at the heterojunction interface, and at the same time causes changes in the positions of the conduction and valence bands of the two organic semiconductors at the heterojunction interface. That is, the redox potential of the material can be changed through the heterojunction effect between organic semiconductors, thereby improving the sensitivity of the material to gases. Zhu Feng et al. (F.Zhu, JBYang, D.Song, CHLi, DHYan.Appl.Phys.Lett.2009, 94, 143305) found that in the organic heterojunction prepared by the weak epitaxial growth method, this heterogeneous The change in redox potential caused by the junction effect can penetrate deep into the region of 40 nm near the heterojunction interface.

Contents of the invention

The object of the present invention is to provide an organic semiconductor gas sensor whose gas sensitive layer contains an organic heterojunction.

The principle of the invention is to use charge transfer between two organic semiconductor materials to form a heterojunction, change the redox potential of the film surface, and improve the sensor's response to sensitive gases.

The organic semiconductor gas sensor with an organic heterojunction in the gas-sensing layer provided by the present invention comprises a first organic semiconductor gas sensor with an organic heterojunction in the gas-sensing layer and an organic semiconductor gas sensor with an organic heterojunction in the second gas-sensing layer sensor.

FIG. 1 is a schematic structural view of the first organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction according to the present invention.

(A) The composition of the organic semiconductor gas sensor of the first gas-sensing layer of the present invention containing an organic heterojunction is as follows: the substrate 1, the induction layer 2, the first organic semiconductor layer 3, and the second organic semiconductor layer 4 are connected in sequence, The film of the second organic semiconductor layer 4 is a discontinuous film, and the metal electrode 5 partially covers the second organic semiconductor layer 4 and is partially connected to the first organic semiconductor layer 3; the induction layer 2 and the first organic semiconductor layer 3 There is a weak epitaxial relationship between them. The weak epitaxial relationship is that the force between the material molecules of the induction layer 2 and the material molecules of the first organic semiconductor layer 3 is van der Waals force, and there is an epitaxial relationship between the two molecular crystal lattices. Relationship; a heterojunction is formed between the materials of the first organic semiconductor layer 3 and the second organic semiconductor layer 4 due to charge transfer;

The substrate 1 is an insulating material, which is glass or ceramics, or a composite material formed by covering a layer of insulating material on the surface of a conductive material, which is a heavily doped silicon wafer that is thermally grown to form a layer of silicon dioxide on the surface ; If the root mean square roughness (RMS) of the substrate surface is greater than 1 nm, it needs to be smoothed with an insulating polymer coating such as polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA);

The induction layer 2 is hexabiphenyl (p-6P), 2,7-bis(4-biphenyl)-phenanthrene (BPPh), 2,5-bis(4-1,1':4',1 One of "-terphenyl)-thiophene (3PT) and 2,7-bis(4-4'-fluorobiphenyl)-phenanthrene (F2-BPPh), with a thickness not less than 2 nanometers and not more than 10 Nano;

The first organic semiconductor layer 3 is metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functionalized variants; the metal-containing phthalocyanine is copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), One of cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); functionalized variants of metal-containing phthalocyanines Vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxide phthalocyanine (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), perfluorozinc phthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc); its thickness is not less than 1.5 nanometers and not more than 20 nanometers;

The second organic semiconductor layer 4 is metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functionalized variants; the metal-containing phthalocyanine is copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc) , cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc) and tin phthalocyanine (SnPc); functionalization of metal-containing phthalocyanines The body is vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxytin phthalocyanine (SnOPc), perfluorophthalocyanine One of copper (F ₁₆ CuPc), perfluorozinc phthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc); its thickness is not less than 0.2 nanometers and not more than 1.5 nanometers;

The material of the metal electrode 5 is gold.

Fig. 2 is a schematic structural view of the second organic semiconductor gas sensor with an organic heterojunction in the gas sensing layer according to the present invention.

(B) The composition of the second organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer of the present invention is as follows: the substrate 1, the inductive layer 2, and the first organic semiconductor layer 3 are connected in sequence, and the first organic semiconductor layer 3 is connected with the first organic semiconductor layer. The second organic semiconductor layer 4 and the metal electrode 5 are all connected, and the metal electrode 5 is partially in direct contact with the first organic semiconductor layer 3; there is a weak epitaxial relationship between the induction layer 2 and the first organic semiconductor layer 3; A heterojunction is formed between the organic semiconductor layer 3 and the organic semiconductor layer 4 because of charge transfer; the film of the second organic semiconductor layer 4 is a discontinuous film;

The material and processing method of the substrate 1 are the same as (A); the material of the metal electrode 5 is the same as (A);

The materials and thicknesses of the induction layer 2, the first organic semiconductor layer 3 and the second organic semiconductor layer 4 are the same as (A).

The organic semiconductor gas sensor whose gas-sensing layer contains an organic heterojunction involved in the present invention can be measured by means of a planar diode, that is, the metal electrode 5 is respectively used as the positive and negative electrodes of the diode for measurement. For a composite material in which the substrate is formed by covering a layer of insulating material on the surface of a conductive material, it can also be measured in the form of a transistor, that is, the conductive material is used as the gate electrode of the transistor, and the electrodes 5 are respectively used as the source/drain electrodes of the transistor for measurement.

The preparation method of the organic semiconductor gas sensor with organic heterojunction in the gas sensitive layer of the present invention is as follows:

(1) the first kind of gas sensitive layer that the present invention relates to contains the organic semiconductor gas sensor method of organic heterojunction as follows:

(1) Substrate 1 is an insulating material, which is glass or ceramics, or a composite material formed by covering a layer of insulating material on the surface of a conductive material, which is a heavily doped silicon wafer that forms a layer of silicon dioxide thermally grown on the surface ; If the root mean square roughness (RMS) of the substrate surface is greater than 1 nm, it needs to be smoothed with an insulating polymer coating such as polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA);

(2) vacuum-deposit induction layer 2 on the surface of substrate 1, the thickness is not less than 2 nanometers, not more than 10 nanometers, the material is hexabiphenyl (p-6P), 2,7-bis(4-biphenyl)-phenanthrene ( BPPh), 2,5-bis(4-1,1′:4′,1″-terphenyl)-thiophene (3PT) and 2,7-bis(4-4′-fluorobiphenyl)- One of phenanthrene (F2-BPPh);

(3) Vacuum-deposit the first organic semiconducting layer 3 on the surface of the inducing layer 2, with a thickness not less than 1.5 nanometers and not greater than 20 nanometers; there is a weak epitaxial relationship between the inducing layer 2 and the first organic semiconducting layer 3, so The weak epitaxial relationship is that the force between the material molecules of the induction layer 2 and the material molecules of the organic semiconductor layer 3 is van der Waals force, and there is an epitaxial relationship between the two kinds of molecular crystal lattices; the material of the first organic semiconductive layer 3 are metal-free phthalocyanines (H ₂ Pc) or metal-containing phthalocyanines and their functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), phthalocyanine One of ferrous cyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); the functionalized variant of the metal-containing phthalocyanine is vanadyl phthalocyanine (VOPc) , titanium oxyphthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxytin phthalocyanine (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), perfluoro One of zinc phthalocyanine (F ₁₆ ZnPc) and cobalt phthalocyanine (F ₁₆ CoPc);

(4) Vacuum deposit the second organic semiconductor layer 4 on the surface of the first organic semiconductor layer 3, the film of the second organic semiconductor layer 4 is a discontinuous film; the second organic semiconductor layer 4 and the first organic semiconductor layer 3 materials A heterojunction is formed between them due to charge transfer; the thickness of the second organic semiconductor layer 4 is not less than 0.2 nanometers and not greater than 1.5 nanometers, and the material is metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functional Metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine ( PbPc) and tin phthalocyanine (SnPc); functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), aluminum chlorophthalocyanine (AlClPc), phthalocyanine Tin dichlorocyanine (SnCl ₂ Pc), tin oxytin phthalocyanine (SnOPc), copper perfluorophthalocyanine (F ₁₆ CuPc), zinc perfluorophthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc);

(5) using a drain plate to vacuum-deposit a metal electrode 5 on the surface of the second organic semiconductor layer 4;

Among them, the background vacuum degree is not lower than 8.0×10 ^-4 Pa, the deposition rate of the metal electrode is 20 nm/min, and the deposition rate of other materials is 1 nm/min.

The thickness of the organic semiconductor layer is determined by the product of the deposition rate and the deposition time. When the product of the two is less than the thickness of the monolayer film, the resulting film is a discontinuous film; the material used for the second organic semiconductor layer 4 is formed of The thickness of the monolayer film is greater than 1.5 nanometers, so the film of the second organic semiconductor layer 4 prepared by the above method is a discontinuous film.

(II) The second kind of gas sensitive layer that the present invention relates to contains the organic semiconductor gas sensor manufacturing method of organic heterojunction as follows:

(1) The substrate 1 is an insulating material, which is glass or ceramics, or a composite material formed by covering a layer of insulating material on the surface of a conductive material, which is a layer of silicon dioxide formed by thermal growth on the surface of a heavily doped silicon wafer; If the root mean square roughness (RMS) of the substrate surface is greater than 1 nm, it needs to be smoothed with an insulating polymer coating such as polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA);

(2) Vacuum-deposit induction layer 2 on the surface of the substrate, the thickness of which is not less than 2 nanometers and not more than 10 nanometers, and the material is hexabiphenyl (p-6P), 2,7-bis(4-biphenyl)-phenanthrene (BPPh ), 2,5-bis(4-1,1′:4′,1″-terphenyl)-thiophene (3PT) and 2,7-bis(4-4′-fluorobiphenyl)-phenanthrene One of (F2-BPPh);

(3) Vacuum-deposit the first organic semiconducting layer 3 on the surface of the inducing layer 2, there is a weak epitaxial relationship between the inducing layer 2 and the first organic semiconductor layer 3, and the thickness is not less than 1.5 nanometers and not greater than 20 nanometers, the The weak epitaxial relationship is that the force between the material molecules of the induction layer 2 and the material molecules of the first organic semiconductor layer 3 is Van der Waals force, and there is an epitaxial relationship between the two kinds of molecular crystal lattices; the first organic semiconductive layer 3 The materials are metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), One of ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); the functionalized variant of the metal-containing phthalocyanine is vanadyl phthalocyanine (VOPc ), titanium oxyphthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxytin phthalocyanine (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), all One of zinc fluorophthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc);

(4) utilizing a drain board to vacuum-deposit a metal electrode 5 on a part of the surface of the first organic semiconductor layer 3;

(5) vacuum deposit the second organic semiconductor layer 4 on the surface of the first organic semiconductor layer 3 other than the metal electrode 5, and the film of the second organic semiconductor layer 4 is a discontinuous film; the second organic semiconductor layer 4 and the material of the first organic semiconductor layer 3 form a heterojunction due to charge transfer; the thickness of the second organic semiconductor layer 4 is not less than 0.2 nanometers and not greater than 1.5 nanometers, and the material of the second organic semiconductor layer 4 is no Metallic phthalocyanines (H2Pc) or metal-containing phthalocyanines and their functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine ( FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine (VOPc), oxyphthalocyanine Titanium (TiOPc), Aluminum Chlorophthalocyanine (AlClPc), Dichlorotin Phthalocyanine (SnCl ₂ Pc), Tin Oxyphthalocyanine (SnOPc), Copper Perfluorophthalocyanine (F ₁₆ CuPc), Zinc Perfluorophthalocyanine One of (F ₁₆ ZnPc) and perfluorocobalt phthalocyanine (F ₁₆ CoPc);

Among them, the background vacuum degree is not lower than 8.0×10 ^-4 Pa, the deposition rate of the metal electrode is 20 nm/min, and the deposition rate of other materials is 1 nm/min.

The thickness of the organic semiconductor layer is determined by the product of the deposition rate and the deposition time. When the product of the two is less than the thickness of the monolayer film, the resulting film is a discontinuous film. The thickness of the monomolecular film formed by the materials used in the second organic semiconductor layer 4 is greater than 1.5 nanometers, so the film of the second organic semiconductor layer 4 prepared by the above method is a discontinuous film. Since the metal electrode is deposited before the second organic semiconductor layer 4 , part of the second organic semiconductor 4 will be deposited on the surface of the metal electrode when the second organic semiconductor layer 4 is deposited, which has negligible impact on the device.

Beneficial effects: the organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction provided by the present invention includes a first gas-sensing layer containing an organic heterojunction organic semiconductor gas sensor and a second gas-sensing layer containing an organic heterojunction Junction organic semiconductor gas sensors. The organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer provided by the invention utilizes charge transfer between two organic semiconductor materials to form a heterojunction to change the oxidation-reduction potential of the film surface, thereby improving the response of the sensor to sensitive gases. The organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction provided by the present invention has high sensitivity at room temperature, and the thickness of the gas-sensing layer is small, which effectively shortens the response/recovery time of the device, and uses a vacuum deposition method to complete the device at one time The preparation of the device does not require subsequent processes such as annealing, which simplifies the preparation process of the device. The organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer provided by the invention can detect _NO2 gas with a volume fraction of 5 parts per million, and the response/recovery can be completed within 10 minutes.

Description of drawings

FIG. 1 is a schematic structural view of the first organic semiconductor gas sensor with a gas-sensing layer containing an organic heterojunction according to the present invention.

Fig. 2 is a schematic structural view of the second organic semiconductor gas sensor with an organic heterojunction in the gas sensing layer according to the present invention.

Fig. 3 is the response/recovery curve to NO2 gas with a volume fraction of one part per million of the organic semiconductor gas sensor with an organic heterojunction in the gas-sensing layer of the present invention adopting the configuration shown in Fig. 1 at room temperature. Wherein, the substrate is a heavily doped silicon wafer whose surface is thermally oxidized and grown to form SiO ₂ , the induction layer is p-6P with a thickness of 4 nanometers, the organic semiconductor layer 3 is TiOPc with a thickness of 3 nanometers, and the organic semiconductor layer 4 is F ₁₆ CuPc, The thickness is 0.5 nm, and gold is used as the electrode.

Fig. 4 adopts the second kind of gas sensitive layer of the present invention that adopts the configuration shown in Fig. 2 to contain the organic semiconductor gas sensor of organic heterojunction at room temperature to be 5 parts per million by volume _NO Gas response/ recovery curve. Wherein, the substrate is a heavily doped silicon wafer whose surface is covered with thermally grown SiO ₂ , the induction layer is p-6P with a thickness of 2 nanometers, the organic semiconductor layer 3 is VOPc with a thickness of 2 nanometers, and the organic semiconductor layer 4 is CuPc, The thickness is 1 nm, and gold is used as the electrode.

Detailed ways

Metal-free phthalocyanine (H ₂ Pc), copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc) are used in all the following examples. ), lead phthalocyanine (PbPc), tin phthalocyanine (SnPc), vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), tin dichloride phthalocyanine (SnCl ₂ Pc) , oxytin phthalocyanine (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), perfluorozinc phthalocyanine (F ₁₆ ZnPc), perfluorocobalt phthalocyanine (F ₁₆ CoPc), 2,7-di (4-biphenyl)-phenanthrene (BPPh), 2,5-bis(4-1,1′:4′,1″-terphenyl)-thiophene (3PT), 2,7-bis(4- 4'-fluorobiphenyl)-phenanthrene (F2-BPPh) is a commercial product, which is used after being purified by vacuum sublimation twice after purchase. Glass, pottery, surface thermal oxidation growth forms the heavy weight of silicon dioxide (SiO ₂ ) Doped silicon wafers are used after cleaning. Polymethyl methacrylate (PMMA) and polyvinyl alcohol (PVA) are commercial products and used directly after purchase.

Example 1

The configuration of the first organic semiconductor gas sensor with an organic heterojunction in the gas-sensitive layer of the present invention is shown in Figure 1, and the specific preparation method is as follows:

(1) Substrate 1 is an insulating material, which is glass or ceramics, or a composite material formed by covering a layer of insulating material on the surface of a conductive material, which is a heavily doped silicon wafer that forms a layer of silicon dioxide thermally grown on the surface ; If the root mean square roughness (RMS) of the substrate surface is greater than 1 nm, it needs to be smoothed with an insulating polymer coating such as polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA);

(2) vacuum-deposit induction layer 2 on the surface of substrate 1, the thickness is not less than 2 nanometers, not more than 10 nanometers, the material is hexabiphenyl (p-6P), 2,7-bis(4-biphenyl)-phenanthrene ( BPPh), 2,5-bis(4-1,1′:4′,1″-terphenyl)-thiophene (3PT) and 2,7-bis(4-4′-fluorobiphenyl)- One of phenanthrene (F2-BPPh);

(3) the first organic semiconducting layer 3 is vacuum-deposited on the surface of the inducing layer 2, and there is a weak epitaxial relationship between the inducing layer 2 and the first organic semiconducting layer 3; The force between the material molecules of the organic semiconductor layer 3 is van der Waals force, and there is an epitaxial relationship between the two molecular crystal lattices. The thickness is not less than 1.5 nanometers and not more than 20 nanometers. The material of the first organic semiconducting layer 3 is metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functionalized variants; the metal-containing phthalocyanine is phthalocyanine One of copper (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc) and tin phthalocyanine (SnPc) species; functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), phthalocyanine One of tin oxide (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), zinc perfluorophthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc);

(4) Vacuum deposit the second organic semiconductor layer 4 on the surface of the first organic semiconductor layer 3, the film of the second organic semiconductor layer 4 is a discontinuous film; the second organic semiconductor layer 4 and the first organic semiconductor layer 3 materials A heterojunction is formed between them due to charge transfer; the thickness of the second organic semiconductor layer 4 is not less than 0.2 nanometers and not greater than 1.5 nanometers, and the material of the second organic semiconductor layer 4 is metal-free phthalocyanine (H ₂ Pc) or Metal-containing phthalocyanines and their functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), zinc phthalocyanine ( One of ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), phthalocyanine Aluminum chloride (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxide phthalocyanine (SnOPc), perfluoro copper phthalocyanine (F ₁₆ CuPc), perfluoro zinc phthalocyanine (F ₁₆ ZnPc) and all One of fluorocobalt phthalocyanine (F ₁₆ CoPc);

(5) Utilize the drain plate to vacuum-deposit the metal electrode 5 on the surface of the second organic semiconductor layer 4; the material of the metal electrode 5 is gold;

Among them, the background vacuum degree is not lower than 8.0×10 ^-4 Pa, the deposition rate of the metal electrode is 20 nm/min, and the deposition rate of other materials is 1 nm/min.

The thickness of the organic semiconductor layer is determined by the product of the deposition rate and the deposition time. When the product of the two is less than the thickness of the monolayer film, the resulting film is a discontinuous film; the material used for the second organic semiconductor layer 4 is formed of The thickness of the monolayer film is greater than 1.5 nanometers, so the film of the second organic semiconductor layer 4 prepared by the above method is a discontinuous film.

Fig. 3 is that adopting the configuration shown in Fig. 1 is the first kind of organic semiconductor gas sensor whose gas-sensitive layer contains organic heterojunction involved in the present invention at room temperature to the volume fraction of _NO2 gas response/ recovery curve. Wherein, the substrate is a heavily doped silicon wafer whose surface is thermally oxidized and grown to form SiO ₂ , the induction layer is p-6P with a thickness of 4 nanometers, the organic semiconductor layer 3 is TiOPc with a thickness of 3 nanometers, and the organic semiconductor layer 4 is F ₁₆ CuPc, The thickness is 0.5 nm, and gold is used as the electrode. Compared with the reference device, the reference device has no response, the sensitivity of the first organic semiconductor gas sensor adopting the structure shown in Figure 1 is 17, the response time is 2.5 minutes, and the recovery time is 7 minutes. The response time is the time required from the start of NO2 supply to the sensor current value reaching 50% of the peak value, and the recovery time is the time required from the stop of NO2 supply to the sensor current value decreasing to 50% of the peak value. Therefore, the use of the organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer of the present invention can effectively improve the sensitivity of the device and shorten the response/recovery time of the device.

Table 1 shows the composition of the first organic semiconductor gas sensor with an organic heterojunction in the gas-sensing layer prepared by the above-mentioned process and the given conditions in Table 1, and the device when the volume fraction of _NO2 is 5ppm parameter.

Table 1

Note: SiO ₂ refers to the heavily doped silicon wafer formed by thermal oxidation on the surface. The data marked with * after the sensitivity and _response /recovery time are measured by transistors, and the rest are measured by planar diodes. The data obtained by the measurement method.

Example 2

The method for making the second gas-sensing layer of the present invention with the structure shown in Figure 2 contains an organic heterojunction organic semiconductor gas sensor is as follows:

(1) The substrate 1 is an insulating material, which is glass or ceramics, or a composite material formed by covering a layer of insulating material on the surface of a conductive material, which is a layer of silicon dioxide formed by thermal growth on the surface of a heavily doped silicon wafer; If the root mean square roughness (RMS) of the substrate surface is greater than 1 nm, it needs to be smoothed with an insulating polymer coating such as polymethyl methacrylate (PMMA) or polyvinyl alcohol (PVA);

(2) Vacuum-deposit induction layer 2 on the surface of the substrate, the thickness of which is not less than 2 nanometers and not more than 10 nanometers, and the material is hexabiphenyl (p-6P), 2,7-bis(4-biphenyl)-phenanthrene (BPPh ), 2,5-bis(4-1,1′:4′,1″-terphenyl)-thiophene (3PT) and 2,7-bis(4-4′-fluorobiphenyl)-phenanthrene One of (F2-BPPh);

(3) Vacuum deposition of the first organic semiconducting layer 3 on the surface of the inducing layer 2, there is a weak epitaxial relationship between the inducing layer 2 and the first organic semiconductor layer 3, and the weak epitaxial relationship is the material molecules of the inducing layer 2 and The force between the material molecules of the first organic semiconductor layer 3 is van der Waals force, and there is an epitaxial relationship between the two molecular crystal lattices; the thickness of the first organic semiconductor layer 3 is not less than 1.5 nanometers and not greater than 20 nanometers, The materials are metal-free phthalocyanine (H ₂ Pc) or metal-containing phthalocyanine and its functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), One of ferrous phthalocyanine (FePc), zinc phthalocyanine (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); the functionalized variant of the metal-containing phthalocyanine is vanadyl phthalocyanine (VOPc ), titanium oxyphthalocyanine (TiOPc), aluminum chloride phthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxytin phthalocyanine (SnOPc), perfluorocopper phthalocyanine (F ₁₆ CuPc), all One of zinc fluorophthalocyanine (F ₁₆ ZnPc) and cobalt perfluorophthalocyanine (F ₁₆ CoPc);

(4) Utilize the drain plate to vacuum-deposit the metal electrode 5 on the surface of the first organic semiconductor layer 3; the material of the metal electrode 5 is gold;

(5) vacuum deposit the second organic semiconductor layer 4 on the surface of the first organic semiconductor layer 3 other than the metal electrode 5, and the film of the second organic semiconductor layer 4 is a discontinuous film; the second organic semiconductor layer 4 and the material of the first organic semiconductor layer 3 form a heterojunction due to charge transfer, the thickness of the second organic semiconductor layer 4 is not less than 0.2 nanometers and not more than 1.5 nanometers, and the material is metal-free phthalocyanine (H ₂ Pc ) or metal-containing phthalocyanines and their functionalized variants; metal-containing phthalocyanines are copper phthalocyanine (CuPc), nickel phthalocyanine (NiPc), cobalt phthalocyanine (CoPc), ferrous phthalocyanine (FePc), phthalocyanine One of zinc (ZnPc), lead phthalocyanine (PbPc), and tin phthalocyanine (SnPc); functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine (VOPc), titanium oxyphthalocyanine (TiOPc), Aluminum chlorophthalocyanine (AlClPc), dichlorotin phthalocyanine (SnCl ₂ Pc), tin oxide phthalocyanine (SnOPc), copper perfluorophthalocyanine (F ₁₆ CuPc), zinc perfluorophthalocyanine (F ₁₆ ZnPc ) and one of perfluorocobalt phthalocyanine (F ₁₆ CoPc);

Among them, the background vacuum degree is not lower than 8.0×10 ^-4 Pa, the deposition rate of the metal electrode is 20 nm/min, and the deposition rate of other materials is 1 nm/min.

The thickness of the organic semiconductor layer is determined by the product of the deposition rate and the deposition time. When the product of the two is less than the thickness of the monolayer film, the resulting film is a discontinuous film. The thickness of the monomolecular film formed by the materials used in the second organic semiconductor layer 4 is greater than 1.5 nanometers, so the film of the second organic semiconductor layer 4 prepared by the above method is a discontinuous film. Since the metal electrode is deposited before the second organic semiconductor layer 4 , part of the second organic semiconductor 4 will be deposited on the surface of the metal electrode when the second organic semiconductor layer 4 is deposited, which has negligible impact on the device.

Fig. 4 shows the response/recovery curve of the organic semiconductor gas sensor with the structure shown in Fig. 2 and the gas-sensing layer containing an organic heterojunction when the volume fraction of nitrogen dioxide is 5ppm. Wherein, the substrate is a heavily doped silicon wafer whose surface is covered with thermally grown SiO ₂ , the induction layer is p-6P with a thickness of 2 nanometers, the organic semiconductor layer 3 is VOPc with a thickness of 2 nanometers, and the organic semiconductor layer 4 is CuPc, The thickness is 1 nm, and gold is used as the electrode. Compared with the reference device, the reference device has no response, the sensitivity of the organic semiconductor gas sensor using the gas-sensing layer containing the organic heterojunction provided by the present invention is 10, the response time is 2.5 minutes, and the recovery time is 7 minutes. The response time is the time required from the start of NO2 supply to the sensor current value reaching 50% of the peak value, and the recovery time is the time required from the stop of NO2 supply to the sensor current value decreasing to 50% of the peak value. Therefore, the use of the organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer of the present invention can effectively improve the sensitivity of the device and reduce the response/recovery time of the device.

Table 2 shows the composition of the second organic semiconductor gas sensor with an organic heterojunction in the gas-sensitive layer prepared by the above-mentioned process and the given conditions in Table 2 and the device when the volume fraction of _NO2 is 5 ppm parameter.

Table 2

Note: SiO ₂ refers to heavily doped silicon wafers formed by thermal oxidation on the surface to form silicon dioxide (SiO ₂ ). Those marked with * after the sensitivity and response/recovery time are the data obtained by transistor measurement, and the rest are not marked The data obtained by using the planar diode measurement method.

Claims (5)

1. The organic semiconductor gas sensor whose gas-sensing layer contains organic heterojunction, is characterized in that, comprises the organic semiconductor gas sensor that the first gas-sensing layer contains organic hetero-junction and the second gas-sensing layer contains organic hetero-junction Organic semiconductor gas sensor; (A) The composition of the organic semiconductor gas sensor with organic heterojunction in the first gas sensitive layer is as follows: substrate (1), induction layer (2), first organic semiconductor layer (3), second The organic semiconductor layers (4) are connected in sequence, the film of the second organic semiconductor layer (4) is a discontinuous film, and the metal electrode (5) partly covers the second organic semiconductor layer (4) and connects with the first organic semiconductor layer (3) Correspondingly, there is a partial connection; there is a weak epitaxial relationship between the induction layer (2) and the first organic semiconductor layer (3), and the weak epitaxial relationship is that the material molecules of the induction layer (2) and the first organic semiconductor layer (3) The force between the material molecules is van der Waals force, and there is an epitaxial relationship between the two molecular crystal lattices; between the first organic semiconductor layer (3) and the second organic semiconductor layer (4) Due to charge transfer, a heterojunction is formed; (B) the composition of the organic semiconductor gas sensor with an organic heterojunction in the second gas sensitive layer is as follows: substrate (1), induction layer (2), first organic semiconductor layer (3 ) are connected in sequence, the first organic semiconductor layer (3) is connected with the second organic semiconductor layer (4), and the metal electrode (5), and the metal electrode (5) is in direct contact with the first organic semiconductor layer (3) ; there is a weak epitaxial relationship between the induction layer (2) and the first organic semiconductor layer (3); between the first organic semiconductor layer (3) and the second organic semiconductor layer (4) due to charge transfer And a heterojunction is formed; the thin film of the second organic semiconductor layer (4) is a discontinuous thin film. 2. The organic semiconductor gas sensor containing an organic heterojunction in the gas-sensitive layer according to claim 1, characterized in that, said substrate (1) is an insulating material, which is glass or pottery, or is on the surface of a conductive material A composite material formed by covering a layer of insulating material, which is a heavily doped silicon wafer with a layer of silicon dioxide thermally grown on the surface; if the root mean square roughness of the substrate surface is greater than 1 nanometer, it needs to be coated with an insulating polymer The layer is smoothed, and the insulating polymer coating is polymethyl methacrylate or polyvinyl alcohol; the induction layer (2) is hexabiphenyl, 2,7-bis(4-biphenyl) -Phenanthrene, 2,5-bis(4-1,1':4',1"-terphenyl)-thiophene) and 2,7-bis(4-4'-fluorobiphenyl)-phenanthrene One; the first organic semiconductor layer (3) is metal-free phthalocyanine or metal-containing phthalocyanine and functionalized variants thereof; metal-containing phthalocyanine is copper phthalocyanine, nickel phthalocyanine, cobalt phthalocyanine, phthalocyanine One of ferrocyanine, zinc phthalocyanine, lead phthalocyanine, and tin phthalocyanine; functionalized variants of metal-containing phthalocyanines are vanadyl phthalocyanine, oxytitanium phthalocyanine, aluminum phthalocyanine chloride, dichlorophthalocyanine One of tin, oxytin phthalocyanine, perfluorophthalocyanine copper, perfluorophthalocyanine zinc and perfluorophthalocyanine cobalt; the second organic semiconductor layer (4) is metal-free phthalocyanine or containing Metallic phthalocyanines and functionalized variants thereof; metal-containing phthalocyanines being one of copper phthalocyanine, nickel phthalocyanine, cobalt phthalocyanine, ferrous phthalocyanine, zinc phthalocyanine, lead phthalocyanine and tin phthalocyanine; containing Functionalized variants of metallic phthalocyanines are vanadyl phthalocyanine, oxytitanyl phthalocyanine, chloroaluminum phthalocyanine, dichlorotin phthalocyanine, oxytin phthalocyanine, copper perfluorophthalocyanine, zinc perfluorophthalocyanine, and One of the perfluorinated cobalt phthalocyanines. 3. The organic semiconductor gas sensor with an organic heterojunction in the gas sensitive layer according to claim 1 or 2, characterized in that the thickness of the inductive layer (2) is not less than 2 nanometers and not greater than 10 nanometers. 4. The gas-sensing layer containing organic heterojunction organic semiconductor gas sensor according to claim 1 or 2, characterized in that the thickness of the first organic semiconductor layer (3) is not less than 1.5 nanometers, not more than 20 nanometers . 5. The gas-sensing layer containing an organic heterojunction organic semiconductor gas sensor according to claim 1 or 2, characterized in that the thickness of the second organic semiconductor layer (4) is not less than 0.2 nanometers, not more than 1.5 nanometers .