WO2023217034A1 - 一种有机场效应晶体管及其制备方法 - Google Patents

一种有机场效应晶体管及其制备方法 Download PDF

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WO2023217034A1
WO2023217034A1 PCT/CN2023/092511 CN2023092511W WO2023217034A1 WO 2023217034 A1 WO2023217034 A1 WO 2023217034A1 CN 2023092511 W CN2023092511 W CN 2023092511W WO 2023217034 A1 WO2023217034 A1 WO 2023217034A1
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organic
effect transistor
layer
conductive layer
single crystal
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李寒莹
林城策
伍瑞菡
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浙江大学
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
    • H10K10/40—Organic transistors
    • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
    • H10K10/462—Insulated gate field-effect transistors [IGFETs]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
    • H10K10/40—Organic transistors
    • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
    • H10K10/462—Insulated gate field-effect transistors [IGFETs]
    • H10K10/466—Lateral bottom-gate IGFETs comprising only a single gate
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
    • H10K10/80—Constructional details
    • H10K10/82—Electrodes
    • H10K10/84—Ohmic electrodes, e.g. source or drain electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/30—Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/40—Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/549—Organic PV cells

Definitions

  • the invention relates to the technical field of organic semiconductor devices, and in particular to an organic field-effect transistor and a preparation method thereof.
  • Organic semiconductor devices have the advantages of low preparation cost, flexibility, light weight, and large-area preparation. They have good application prospects in flexible displays, flexible wearable devices, Internet of Things, and biomedical fields, and have attracted widespread attention.
  • the preparation of high-performance organic semiconductor devices is an important process for realizing the practical use of organic semiconductor devices.
  • organic field-effect transistor OFET
  • OFET organic field-effect transistor
  • carriers As the carrier of current in electronic devices, carriers refer to charge particles that can move freely under the action of an electric field. In semiconductor materials, there are two types of carriers: electrons and holes. Among them, electrons have a negative charge and holes have a positive charge. In OFET applications, both hole and electron transport are important.
  • Carrier mobility (abbreviated as mobility, represented by ⁇ , unit is cm 2 V -1 s -1 ) refers to the mobility rate of carriers under unit electric field intensity.
  • mobility is a key parameter that represents its performance, determining how quickly it turns on or off. The higher the mobility, the faster the OFET turns on or off.
  • the carrier mobility ⁇ can be characterized by hole mobility ( ⁇ p ) and electron mobility ( ⁇ n ) respectively.
  • ⁇ p and ⁇ n can be obtained by the following formula:
  • the p-type transfer characteristic curve and n-type transfer characteristic curve of OFET are measured by a semiconductor analyzer, where L is the length of the OFET channel, W is the width of the OFET channel, and C i is the gate insulating layer capacitance. It can be measured with Measured by a semiconductor parameter analyzer with capacitance analysis function, I DS is the current passing between the source and drain stages when the OFET is working, V G is the voltage applied to the gate, It can be obtained by testing the transfer characteristic curve of a field effect transistor operating in the saturation region.
  • (a) and (b) in Figure 1 are the cross-sectional view and top view of a common OFET structure respectively.
  • W and L can be measured by the ruler in the top view of the OFET taken by an optical microscope; (c) and () in Figure 1 d) are the transfer characteristic curves of p-type OFET and n-type OFET that can be measured by a semiconductor analyzer and the I DS 1/2 -V G curve after the transfer characteristic curve is processed. By calculating the curve I DS 1/2 -V The slope of G can be obtained
  • the mobility of OFET is generally lower than 1cm 2 V -1 s -1 .
  • it is a basic requirement that the mobility of electrons and holes in OFET is not less than 0.1cm 2 V -1 s -1 .
  • the performance of the circuit is greatly affected by the balance of electron and hole transmission, and the one with poorer transmission performance will become a bottleneck that severely limits the circuit's operation. Even if a lot of optimization is done in other aspects to make the hole mobility ( ⁇ p ) and electron mobility ( ⁇ n ) very high respectively, if the balance between hole mobility and electron mobility is poor, the circuit will Performance cannot be further improved. Therefore, improving the balance of hole and electron transport in semiconductor devices is of great significance to improving device performance.
  • the balance of hole and electron transport in semiconductor devices can be expressed by the proximity between ⁇ p and ⁇ n .
  • This balance can be measured by the balance coefficient B.
  • B the closer the hole mobility and electron mobility are, and the hole and electron mobility are closer.
  • the balance coefficient B ⁇ 1. Therefore, the balance coefficient B ⁇ 1 is the condition for balanced hole and electron transport.
  • organic semiconductor materials can be divided into three categories: p-type semiconductor materials (referred to as p-type materials), n-type semiconductor materials (referred to as n-type materials) and bipolar (ambipolar) materials. ) Semiconductor materials (bipolar materials for short). P-type semiconductor materials mainly transport holes ( ⁇ p > 100 ⁇ n) in OFETs; n-type semiconductor materials mainly transport electrons ( ⁇ n > 100 ⁇ p ) in FETs; bipolar semiconductor materials can both transport holes and Electrons can also be transported, and ⁇ p and ⁇ n are close (0.01 ⁇ p / ⁇ n ⁇ 100).
  • P-type semiconductor materials and n-type semiconductor materials are collectively called unipolar semiconductor materials (unipolar materials for short).
  • the judgment criteria for the classification of organic semiconductor materials here are only based on the performance measured after the material is first prepared into OFETs, rather than the performance measured after various modifications or optimizations. If only one of ⁇ p or ⁇ n is measured in the first report, it means that the material is likely to show a single carrier transport performance, and the material is considered to be a unipolar semiconductor material rather than a bipolar type.
  • Semiconductor material For example, commonly used rubrene, pentacene, and pentacene derivatives (eg, TIPS-pentacene) are common p-type materials.
  • the aggregated structure of organic semiconductors has a great influence on the performance of organic electronic devices. According to the orderliness of molecular arrangement, the aggregated structure of organic semiconductors can be divided into single crystal, polycrystalline and amorphous.
  • Organic semiconductor single crystal referred to as organic single crystal
  • the single crystal aggregate state has the highest order, the fewest defects, and no grain boundaries.
  • the scattering effect is minimal when transporting carriers, and the carrier transport performance is the highest. It has been proven that the long-range order of organic single crystals is very conducive to improving carrier mobility and exciton diffusion length, thereby conducive to the improvement of organic electronic properties.
  • bipolar OFETs can be obtained that can transport both holes and electrons.
  • unipolar materials the molecular structure of bipolar materials is more complex and often requires complex modification, chemical connection and screening based on unipolar material molecules, which increases the number of steps in material synthesis and production. and difficulty, which is not conducive to industrial applications. Therefore, bipolar semiconductor materials have fewer material options than unipolar semiconductor materials. For example, (Z.Cai, et al.
  • DPP diketopyrrolopyrrole
  • DPP-F2 dipolar material
  • DPP-F2 dipolar material
  • DPP-F2 molecules are more complex than DPP molecules, more difficult to synthesize and have a more asymmetric structure, which is not conducive to obtaining a single crystal structure. Improper modification may not even result in bipolar materials.
  • bipolar materials are more difficult to obtain than unipolar materials, have smaller material selectivity, and are therefore more difficult to apply in industrialization.
  • the molecular structure of unipolar semiconductor materials (p-type or n-type) is simpler.
  • the simple molecular structure reduces the synthesis cost of unipolar semiconductor materials, and there are more types of materials to choose from, making them more suitable for industrial applications.
  • it also makes unipolar semiconductor materials easier to crystallize and prepare. High-performance OFETs.
  • p-type materials also have greater industrial application advantages than n-type semiconductor materials. This is because p-type materials are generally better than n-type materials in terms of mobility, air stability, and richness of material selection when used in OFETs (Zhao Y, Guo Y, Liu Y. 25th Anniversary Article: Recent Advances in n -Type andAmbipolar Organic Field-Effect Transistors[J].Advanced Materials,2013.
  • p-type materials As the three types of organic semiconductor materials: p-type materials, n-type materials and bipolar materials, p-type materials have the most abundant types, are the most fully researched, and are the most promising to achieve large-scale industrial applications first.
  • Workfunction is an important physical parameter of electrode materials.
  • electrode materials can be divided into high work function electrode materials and low work function electrode materials.
  • the work function of a material is ⁇ 4.5eV
  • it is considered to be a high work function electrode material, such as gold (Au, 5.1eV), platinum (Pt, 5.65eV), copper (Cu, 4.65eV), chromium (Cr, 4.6eV ), indium tin oxide (ITO, 4.8eV), etc.
  • the work function of the material is ⁇ 4.5eV
  • it is considered to be a low work function electrode material, such as calcium (Ca, 2.87eV), cesium (Cs, 2.14eV), barium (Ba, 2.7eV), magnesium (Mg, 3.66eV), aluminum (Al, 4.28eV), silver (Ag, 4.26eV), etc.
  • the work function of the material can be measured by ultraviolet photoelectron spectroscopy (UPS) or Kelvin probe microscopy (KPFM).
  • the degree of matching between the work function of the electrode material and the energy level of the organic semiconductor material will have a great impact on carrier transport in OFETs.
  • a high work function electrode material is used as the source and drain electrode of an OFET, it is beneficial to the hole transport properties of the OFET, but it is not conducive to the electron transport properties of the OFET.
  • a low work function electrode material is used as the source and drain electrode of the OFET, It is conducive to OFET showing electron transport properties, but it is not conducive to OFET showing hole transport properties (J.Fidyk, et al. Polymers (Basel). 12 (2020) 1–14. N.B. Kotadiya, et al. Nat. Mater.17(2018)329–334; Y.Zhou, et al.Science(80-.).336(2012)327–332.
  • the work function of electrode materials is related to the material's ability to lose electrons, that is, its ability to be oxidized.
  • the higher the work function the less likely the material is to be oxidized and the more chemically stable it is when used as an electrode. From this aspect, the higher the work function of the electrode material, the better.
  • high work function electrode materials have good air stability, can extend their service life when used as electrodes, and have advantages in industrial applications.
  • high work function electrode materials are not conducive to the transmission of electrons in OFETs, they are currently commonly used.
  • the following technical problems are as follows: In OFETs composed of p-type materials, using high work function electrode materials as electrodes cannot obtain higher ⁇ p and ⁇ n ; at the same time, ⁇ n cannot be made equivalent to ⁇ p .
  • n-type materials Use p-type materials and n-type materials to transport holes and electrons respectively.
  • n-type materials generally have lower mobility, poor air stability, lagging research, and fewer options, thus limiting the development of applications such as complementary circuits and light-emitting transistors.
  • bipolar materials that can transport holes and electrons simultaneously.
  • the molecular structure of bipolar materials is complex, the synthesis steps are cumbersome, and there are few types of materials to choose from, which increases the cost of industrial application; and the complex molecular structure is not conducive to the crystallization of bipolar material molecules, making it difficult to obtain high-performance materials. Single crystal to improve the mobility of OFET.
  • HM-p-OSC-FET Using high work function electrode materials as source and drain electrodes, and only using p-type materials with a single crystal structure to obtain OFET (this type of OFET is referred to as HM-p-OSC-FET) has great advantages in application.
  • HM- p-OSC-FET is rich in materials (p-type semiconductor materials are mature in research and rich in variety), has excellent performance (single crystal structure is conducive to high-performance carrier transport) and stable electrode performance, and has broad application prospects.
  • HM-p-OSC-FETs due to the weak ability of p-type materials to transport electrons, and the high work function electrode materials are not conducive to the transmission of electrons in OFETs, it is common that HM-p-OSC-FETs have low electron mobility and poor ⁇ p and ⁇ n balance.
  • HM-p-OSC-FET can further expand its application scope and reduce the types of OFETs that need to be used in organic integrated circuits, thus simplifying the circuit design and preparation process and improving circuit integration.
  • the high integration, high performance and industrialization of organic integrated circuits are of great significance.
  • the existing technologies mainly include the following two types:
  • the present invention provides an organic field-effect transistor and a preparation method thereof.
  • the organic field-effect transistor has a simple structure, convenient preparation, and low cost. It only uses relatively well-developed p-type organic semiconductor materials.
  • the organic field effect transistor can exhibit high hole mobility and Electron mobility, and the hole mobility and electron mobility are balanced, so that the balance coefficient B ⁇ 1, overcoming the technical bias that p-type organic semiconductor materials are not conducive to electron transmission and difficult to obtain high electron mobility, and use high work function electrode materials It extends the service life of the electrode in the air environment while ensuring high electron mobility, and overcomes the technical bias that is not conducive to improving electron mobility when high work function conductive materials are used as OFET electrodes. It is used in organic complementary circuits and light-emitting transistors. It has good application prospects.
  • the present invention adopts the following technical solutions:
  • the invention provides an organic field-effect transistor, which sequentially includes a first conductive layer, an organic semiconductor layer, an insulating layer, and a second conductive layer;
  • the first conductive layer is composed of a conductive material with a work function of 4.5 eV or above;
  • the organic semiconductor layer is composed of p-type organic semiconductor single crystal
  • the insulating layer is composed of insulating material
  • the second conductive layer is composed of a material with an electrical conductivity of 1S/m or above;
  • the organic field-effect transistor of the present invention has a specific structure composed of specific materials and preparation methods. All the following conditions must be strictly met to produce an organic field-effect transistor with the technical effects of the present invention: including a first conductive layer, an organic semiconductor in order layer, an insulating layer and a second conductive layer, and the first conductive layer is composed of a conductive material with a work function of 4.5eV or above; the organic semiconductor layer is composed of a p-type organic semiconductor single crystal; the insulating layer is composed of The second conductive layer is made of an insulating material; the second conductive layer is made of a material with a conductivity of 1S/m or more, and the above conditions are indispensable; as can be seen from Comparative Examples 1-11, changing the material of the first conductive layer makes the hole mobility low and the air Poor stability, the device cannot work without the first conductive layer, changing the material of the semiconductor layer makes the device performance worse, the device cannot work without the organic semiconductor layer, the device lacks the insulating layer or changes the thickness of the
  • first conductive layer, insulating layer and second conductive layer are each independently selected from a single layer or a multi-layer film.
  • the organic field-effect transistor satisfies the following requirements: hole mobility ⁇ p ⁇ 0.5cm 2 V -1 s -1 , electron mobility ⁇ n ⁇ 0.5cm 2 V -1 s -1 , and a balance coefficient.
  • the first conductive layer exists as an electrode of the OFET, and generally includes two mutually separated electrodes, a source electrode and a drain electrode, which serve to connect external circuits, bear voltage, and inject holes and electrons into the organic semiconductor layer.
  • the work function of the electrode material that constitutes the first conductive layer has a great relationship with the oxidation resistance of the electrode material: the greater the work function, the stronger the oxidation resistance of the electrode material, and the greater the stability of the electrode material working in the air. good.
  • the work function of the electrode material constituting the first conductive layer is required to be above 4.5 eV.
  • the work function of the electrode material can be calculated based on the ultraviolet photoelectron spectroscopy (UPS) data of the material.
  • UPS ultraviolet photoelectron spectroscopy
  • ⁇ is the work function of the conductive material
  • h ⁇ is the photon energy provided by the instrument, which is 21.22eV
  • E cutoff is the secondary electron cutoff edge data of the material obtained from the UPS spectrum
  • E F is obtained from the UPS spectrum
  • the Fermi edge data of the material is 0 for a conductive sample with good contact with the instrument. Therefore, the work function of the electrode material is 21.22-E cutoff .
  • the first conductive layer is a single layer or a multi-layer film composed of a high work function conductive material (work function above 4.5 eV).
  • the organic semiconductor layer is the core structure in the OFET and is a channel for the transmission of electrons and holes, which plays the role of transporting carriers and conducting current.
  • P-type organic semiconductor materials are generally superior to n-type semiconductor materials in terms of performance, stability and richness of materials, so p-type organic semiconductor materials are selected to construct the organic semiconductor layer.
  • the single crystal aggregate state has the highest order, the fewest defects and grain boundaries, the smallest scattering effect when transporting carriers, and the highest carrier transport performance. It has been proven that the long-range order of organic single crystals is very conducive to improving carrier mobility and exciton diffusion length, thereby conducive to the improvement of organic electronic properties. Therefore, a p-type organic semiconductor single crystal is selected as the organic semiconductor layer.
  • the insulating layer serves in the OFET to isolate the second conductive layer serving as the gate from the first conductive layer and the organic semiconductor layer used to transport charges, preventing the first conductive layer and the organic semiconductor layer from forming a composite structure, and A conductive path is formed between the second conductive layers to ensure that the OFET can work normally (see Figure 4 for the structure). Therefore, the material used for the insulating layer needs to have good insulating properties, that is, the insulating layer is required to be composed of insulating materials.
  • the second conductive layer constitutes the gate of the OFET and has the function of providing gate voltage and controlling the ON or OFF of the OFET.
  • the conductivity of the material constituting the second conductive layer is required to be above 1 S/m.
  • the mobility of OFET is an important parameter that characterizes the opening or closing speed of OFET. Under other conditions being the same, the higher the mobility, the faster the opening or closing speed of OFET, and the better the performance of OFET.
  • Mobility ⁇ can be characterized by hole mobility ⁇ p and electron mobility ⁇ n respectively. In order to ensure the performance of OFET, both ⁇ p and ⁇ n of OFET are required to be ⁇ 0.5cm 2 V -1 s -1 .
  • the balance coefficient B is a parameter that characterizes the proximity of ⁇ p and ⁇ n in OFET.
  • B ⁇ 1 of OFET is required.
  • the organic semiconductor layer is a single crystal thin film composed of organic materials with a HOMO energy level ⁇ -5.5 eV and a band gap width ⁇ 1.8 eV.
  • HOMO energy level is the abbreviation of "highest occupied molecular orbital" and is an important parameter in organic semiconductor materials. Holes are transported at the HOMO energy level of organic semiconductors. Organic semiconductor materials with too low HOMO energy levels are not conducive to hole transport when used in OFETs. Therefore, the HOMO energy level of selected organic materials is required to be ⁇ -5.5eV.
  • the band gap width is the energy difference between the bottom of the guidance band and the top of the valence band, also known as the forbidden band width.
  • a single crystal film is a film composed of a single crystal or a single crystal array. It can be composed of a continuous single crystal with a small thickness, or a single crystal array composed of multiple single crystals.
  • holes and electrons are injected from a first conductive layer into an organic semiconductor layer.
  • the hole and electron injection effects will directly affect the hole mobility and electron mobility measured in OFET.
  • the injection effect of holes and electrons is affected by the matching degree of energy levels between the material of the first conductive layer and the material of the organic semiconductor. When other conditions are the same, the more matched the energy levels are, the better the hole or electron injection effect will be, and the more conducive it will be to the improvement of OFET mobility.
  • OFETs composed of p-type organic semiconductor materials and high work function conductive materials, the hole injection effect is good, but the electron injection effect is very poor. Therefore, OFETs generally exhibit hole mobility much higher than electron mobility. Even electron mobility cannot be measured.
  • the polar organic small molecules adjust the energy level structure at the interface between the first conductive layer and the organic semiconductor layer, and reduce the potential barrier for electrons to be injected from the first conductive layer into the organic semiconductor layer, so that electrons and holes can be injected from the first conductive layer in a more balanced manner.
  • the conductive layer is injected into the organic semiconductor layer.
  • the dipole moment introduced by polar organic small molecules is an important factor in achieving energy level control. In order to achieve effective energy level control, the dipole moment of polar organic small molecules is required to be greater than 1 Debye (D).
  • forming a polar organic small molecule layer between the first conductive layer and the organic semiconductor layer means introducing more polar organic small molecules, which is more conducive to realizing the adjustment of the polar organic small molecules between the first conductive layer and the organic semiconductor layer. Effects of energy level structure between semiconductor layers.
  • the position between the first conductive layer and the organic semiconductor layer refers to the interface where the first conductive layer and the organic semiconductor are in contact with each other.
  • polar organic small molecules The role of polar organic small molecules is to lower the injection barrier for electrons from the first conductive layer into the organic semiconductor layer, making it easier for electrons to enter the organic semiconductor layer from the first conductive layer, thereby achieving balanced hole and electron transport.
  • the polar organic small molecule layer can reduce the electron injection barrier between the first conductive layer and the organic semiconductor layer by more than 0.05 eV.
  • the reduction in the electron injection barrier can be measured by Kelvin Probe Microscopy (KPFM).
  • KPFM Kelvin Probe Microscopy
  • the specific test method is as follows: first, use the first conductive layer material and the organic semiconductor layer material to prepare the conductive layer film and the organic semiconductor layer film respectively, and use KPFM to test the Fermi energy levels EF1 and EF2 on the surface of the conductive layer film and the organic semiconductor layer film respectively; Then use polar organic small molecules to treat the surfaces of the conductive layer film and organic semiconductor layer film respectively (the treatment method is the same as the method of introducing polar organic small molecules into OFET), and then use KPFM to test the conductive layer film and organic semiconductor layer film again.
  • the Fermi levels of the surface are EF1' and EF2'.
  • the molecular weight of the polar organic small molecule with a dipole moment greater than 1D is less than 50 Da.
  • the molecular weight of a small polar organic molecule can be expressed by the number of atoms that make up the small polar molecule. 50Da means that the number of atoms that make up a small polar organic molecule is 50.
  • the freezing point of the polar organic small molecule is less than 25°C under one atmospheric pressure.
  • the freezing point indicates the highest temperature required for a substance to solidify into a solid: if the temperature is lower than the freezing point, the substance is solid; if the temperature is higher than the freezing point, the substance is liquid.
  • the freezing point of a substance is related to the pressure of the environment in which the substance is located.
  • the freezing point of polar organic small molecules is less than 25°C at one atmospheric pressure, which means that this polar organic small molecule must be in a liquid state when the ambient temperature is higher than 25°C in a normal atmospheric pressure environment.
  • the polar organic small molecule is selected from at least one of the polar organic small molecules containing hydroxyl, cyano group, carboxyl, mercapto group, carbonyl, and amide group; as more preferably, the polar organic small molecule is selected from Methanol, ethanol, propanol, isopropyl alcohol, butanol, ethylene glycol, formic acid, acetic acid, propionic acid, acetonitrile, acetaldehyde, ethyl mercaptan, propyl mercaptan, acetone, tetrahydrofuran, N'N-dimethylmethane At least one of the amides.
  • the organic field effect transistor may also include: an insulating substrate and/or packaging layer;
  • the invention also provides a method for preparing an organic field-effect transistor, which includes the following steps:
  • the deposition method of the second conductive layer is selected from one or more of a vapor deposition method and a solution method;
  • the deposition method of the insulating layer is selected from one or more of vapor deposition, solution, atomic layer deposition, and in-situ oxidation;
  • the first conductive layer is composed of a conductive material with a work function of 4.5 eV or above;
  • the organic semiconductor layer is composed of p-type organic semiconductor single crystal
  • the insulating layer is composed of insulating material
  • the second conductive layer is composed of a material with an electrical conductivity of 1S/m or above;
  • the first conductive layer, The deposition sequence of the organic semiconductor layer, insulating layer, and second conductive layer is to select a high work function material as the first conductive layer, a p-type organic semiconductor single crystal as the semiconductor layer, an insulating material to form the insulating layer, and a material with a conductivity of 1S/m or above.
  • the preparation conditions of forming the second conductive layer and controlling the deposition thickness of the first conductive layer are comprehensively and accurately controlled, combined with the treatment of polar organic small molecules and precise control of the treatment time to regulate the p-type organic semiconductor single crystal, forming an overall synergy. Only by functioning can the organic field-effect transistor with high hole mobility and high electron mobility according to the present invention and a balance coefficient ⁇ 1 be prepared.
  • first conductive layer, insulating layer, and second conductive layer are independently selected from single-layer or multi-layer films;
  • the deposition thickness is 30-100 nm; more preferably, the deposition thickness is 100 nm.
  • the second conductive layer can be metal, alloy, conductive metal oxide, inorganic non-metal deposited by vapor deposition method, or metal nanoparticles or conductive polymer deposited by solution method, It can also be highly doped silicon, as well as a superposition of the above materials.
  • the insulating layer can be an insulating metal oxide, non-metal oxide or nitride by chemical vapor deposition, atomic layer deposition, in-situ oxidation, or a polymer deposited by solution or vapor deposition, or It can be self-assembled small molecules obtained by solution method or vapor deposition method, as well as the superposition of the above materials.
  • the surface of the insulating substrate refers to the smooth and flat side of the insulating substrate that has insulating properties.
  • any one surface can be used for material deposition and device preparation; for both For insulating substrates with different surfaces, a surface with better insulation and smaller roughness should be selected for material deposition and device preparation.
  • the second conductive layer, insulating layer, organic semiconductor layer and first conductive layer are all deposited on the same side surface of the insulating substrate; when preparing multiple OFETs, different OFETs can be prepared separately on different surfaces of the same insulating substrate.
  • Both the second conductive layer and the insulating layer may be single-layer or multi-layer structures.
  • oxide layer silicon dioxide
  • polymers and self-assembled small molecule layers can also be modified on the surface of silicon dioxide to form an insulating layer with a multi-layer structure.
  • the p-type organic semiconductor single crystal can be directly deposited on the substrate surface through in-situ growth, or it can be grown elsewhere and then transferred to the substrate surface through transfer. P-type organic semiconductor single crystals can be grown by solution method and gas phase method.
  • step 2) in order to make polar organic small molecules exist on the surface of the p-type organic semiconductor single crystal, it is necessary to first make the polar organic small molecules contact the surface of the organic semiconductor single crystal, and then remove the polarity on the surface of the organic semiconductor single crystal.
  • Organic small molecule liquid Methods for bringing polar organic small molecules into contact with the surface of organic semiconductor single crystals include droplet contact and vapor contact.
  • the droplet contact method refers to adding polar organic small molecule liquid to the surface of organic semiconductor single crystal through dripping, spraying, printing, soaking, rinsing, etc., and making the surface of organic semiconductor single crystal completely covered with polar organic small molecule liquid.
  • the vapor contact method refers to turning polar organic small molecule liquid into vapor through evaporation, and placing the organic semiconductor single crystal in the vapor atmosphere of the polar organic small molecule, so that the organic semiconductor A method of fully contacting the surface of a single crystal with small polar organic molecules.
  • the organic semiconductor single crystal and the polar organic small molecule atmosphere can be separated by spin coating, natural drying, gas purging, etc.; for the vapor contact method, the organic semiconductor single crystal can be removed from the vapor atmosphere, and then The natural drying method enables the atmospheric separation of organic semiconductor single crystals and polar organic small molecules.
  • the first conductive layer can be directly deposited on the surface of the organic semiconductor single crystal by physical vapor deposition (including vacuum evaporation, sputtering, ion plating), chemical vapor deposition, solution printing, etc., or it can be Indirect deposition is performed by transferring an existing film of conductive material to the surface of an organic semiconductor single crystal.
  • the first conductive layer, The deposition sequence of the organic semiconductor layer, insulating layer, and second conductive layer is to select a high work function material as the first conductive layer, a p-type organic semiconductor single crystal as the semiconductor layer, an insulating material to form the insulating layer, and a material with a conductivity of 1S/m or above.
  • the invention discloses an organic field-effect transistor with high hole mobility and high electron mobility and a balance coefficient of ⁇ 1.
  • the present invention also provides an optoelectronic device: the optoelectronic device includes the organic field effect transistor as mentioned above, and the optoelectronic device is selected from the group consisting of light-emitting transistors, memories, sensors, and displays.
  • the present invention also provides an organic circuit: the organic circuit includes the organic field effect transistor as mentioned above, and the organic circuit is selected from at least one of a gate circuit, a combinational logic circuit, a sequential logic circuit, and an amplification circuit. A circuit composed of circuits.
  • the present invention also provides an optoelectronic integrated array, which includes one or more optoelectronic devices as described above and an organic circuit as described above. (As shown in Figure 3).
  • the organic field effect transistor as mentioned above the preparation method of the organic field effect transistor as mentioned above, the optoelectronic device as mentioned above, the organic circuit as mentioned above and the optoelectronic integrated array as mentioned above are used in semiconductor devices. , transportation and logistics, mining and metallurgy, environment, medical equipment, explosion-proof detection, food, water treatment, pharmaceutical, and biological fields.
  • Figure 1 is an OFET structure and transfer characteristic curve.
  • Figure 1 (a) is a cross-sectional view showing the OFET structure
  • Figure 1 (b) is a top view of the OFET. From the top view, the channel length L and channel length can be measured. Track width W;
  • (c) in Figure 1 is the n-type transfer characteristic curve, which can be used to calculate the electron mobility ⁇ n ;
  • (d) in Figure 1 is the p-type transfer characteristic curve, which can be used to calculate the hole mobility ⁇ p ;
  • Figure 2 is a schematic structural diagram of the organic semiconductor molecules DPP (a) and DPP-F2 (b) (Cai, Z., Luo, H., Chen, X., Zhang, G., Liu, Z., & Zhang, D. Chemistry-An Asian Journal, 2014, 9(4), 1068-1075.), it can be seen that the DPP-F2 molecule is obtained after complex modification of DPP;
  • Figure 3 is a schematic diagram of the effect of the optoelectronic integrated array of the present invention.
  • Figure 4 is a schematic structural diagram of an organic field effect transistor, which sequentially includes a first conductive layer, an organic semiconductor layer, an insulating layer and a second conductive layer;
  • Figure 5 shows the measured ultraviolet photoelectron spectrum of gold
  • Figure 6 is (a) an optical microscope photograph and (b) a microscope photograph under orthogonal polarized light of the TIPS-pentacene single crystal array in Example 1;
  • FIG. 7 is an optical microscope photograph of the OFET of Example 1, which can be used to calculate the channel length L and channel width W;
  • (b) in Figure 7 is when the semiconductor layer does not completely cover the electrode restriction area. Situation diagram, W at this time should be based on the actual semiconductor range;
  • Figure 8 is a transfer characteristic curve diagram of Embodiment 1.
  • (a) in Figure 8 is a p-type transfer characteristic curve diagram, which can be used to calculate hole mobility.
  • (b) in Figure 8 is a transfer characteristic in an n channel. Curve graph that can be used to calculate electron mobility;
  • FIG. 9 is an optical microscope photograph of the TIPS-pentacene single crystal in Example 2.
  • Figure 10 is a graph showing the resistance change of the first conductive layer material in Comparative Example 1 and Example 1 before and after being exposed to air.
  • (a) in Figure 10 is the first conductive layer (calcium) of Comparative Example 1 before being exposed to air. The resistance is 22 ⁇ .
  • (b) in Figure 10 is the resistance of the first conductive layer after Comparative Example 1 is exposed to the air for 5 minutes, which is 8810 ⁇ .
  • (c) in Figure 10 is before the Example 1 is exposed to the air.
  • the resistance of the first conductive layer (gold) is 15 ⁇ .
  • (d) in Figure 10 is the resistance of the first conductive layer after exposure to air for 5 minutes in Example 1, which is 17 ⁇ ;
  • Figure 11 is an optical microscope photograph of the organic semiconductor single crystal in Comparative Example 2. (a) in Figure 11 is a TIPS-pentacene single crystal and a C60 single crystal, and (b) in Figure 11 is a picture that has not been exposed to the TIPS-pentacene solution. C60 single crystal;
  • FIG. 13 is a p-type transfer characteristic curve graph of the OFET in Comparative Example 4;
  • (b) in FIG. 13 is a n-type transfer characteristic graph of the OFET in Comparative Example 4.
  • the thickness of the materials used in the following examples is a thickness selected after optimization, or a commercially available material specification. It is not the only choice, nor is it used to limit the scope of the present invention.
  • the present invention provides an organic field effect transistor, which sequentially includes a first conductive layer, an organic semiconductor layer, an insulating layer, and a second conductive layer.
  • the first conductive layer is composed of a work function of more than 4.5 eV.
  • the organic semiconductor layer is composed of a p-type organic semiconductor single crystal, the insulating layer is composed of an insulating material, and the second conductive layer is composed of a material with a conductivity of 1 S/m or more.
  • the organic semiconductor layer can be selected from any one of condensed aromatic hydrocarbons, sulfur-containing heterocondensed rings, nitrogen-containing heterocondensed rings and their respective derivatives; more preferably, The condensed aromatic hydrocarbon is selected from any one of acene, perylene, diphenylanthracene, and rubrene; the sulfur-containing heterocondensed ring is selected from oligothiophene, benzothiophene, and tetrathiafulval Any one of alkenes; the nitrogen-containing heterofused ring is selected from any one of metal phthalocyanine and metal porphyrin; more preferably, the organic semiconductor layer has a HOMO energy level ⁇ -5.5 eV and a band gap Thin films composed of organic single crystal materials with a width ⁇ 1.8eV.
  • the electrical conductivity of the first conductive layer is greater than 1S/m; preferably, the first conductive layer is selected from the group consisting of a first metal, a first conductive metal oxide, a first conductive metal oxide, and a first conductive metal oxide.
  • the first metal is selected from at least one of a first metal element and a first metal alloy; more preferably, the first metal element is selected from gold, copper , at least one of platinum, chromium, cobalt, and palladium; more preferably, the first metal alloy is selected from an alloy of at least two of gold, copper, platinum, chromium, cobalt, and palladium; more preferably, the first metal alloy
  • the first conductive metal oxide is selected from at least one of indium tin oxide, tungsten oxide, vanadium oxide, and ruthenium oxide; more preferably, the first conductive polymer is selected from poly(3,4-ethylenedioxythiophene ): polystyrene sulfonate;
  • the insulating layer may be selected from at least one of insulating polymers, insulating metal oxides, insulating non-metal oxides or nitrides, and self-assembled small molecules; more preferably , the insulating polymer is selected from polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinyl acetate, polyimide (PI), polyvinylidene fluoride, polyvinylidene fluoride copolymer , polyvinylidene fluoride-trifluoroethylene-chlorofluoroethylene, polystyrene, poly- ⁇ -methylstyrene, polyvinylpyrrolidone, polyvinylphenol, polyparaxylene (parylene), polybenzocyclic At least one of butene, perfluoro (1-butenyl vinyl ether) polymer, and cyanoethyl plulane; more preferably, the insulating metal oxide is selected from aluminum
  • the polymer refers to a cross-linked or non-cross-linked insulating polymer
  • the insulating metal oxide refers to a metal oxide with insulating properties
  • the non-metal oxide or nitride refers to a metal oxide with insulating properties. Properties of non-metallic oxides or nitrides. It should be noted that metal oxide materials can be used in the insulating layer, the first conductive layer and the second conductive layer, but the metal oxide used for the insulating layer is an insulating metal oxide with insulating properties, such as aluminum oxide.
  • titanium oxide, tantalum oxide, hafnium oxide, and the metal oxide used for the first conductive layer or the second conductive layer is a conductive metal oxide with conductive properties, such as indium tin oxide and tungsten oxide, which should be distinguished.
  • the second conductive layer may be selected from at least one of a second metal, a second conductive metal oxide, a second conductive polymer, and a conductive inorganic non-metal; preferably , the second metal is selected from a second metal element or a second metal alloy; preferably, the second metal element is selected from gold, silver, copper, iron, aluminum, zinc, tin, titanium, platinum, chromium, cobalt , at least one of palladium, manganese, nickel, magnesium, lead, and gallium; more preferably, the second metal alloy is selected from gold, silver, copper, iron, aluminum, zinc, tin, titanium, platinum, chromium, An alloy of at least two of cobalt, palladium, manganese, nickel, magnesium, lead, and gallium; more preferably, the second conductive metal oxide is selected from the group consisting of indium tin oxide, tungsten oxide, vanadium oxide, ruthenium oxide, and iron oxide , at least one
  • the polar organic small molecule is selected from at least one of polar organic small molecules containing hydroxyl, cyano, carboxyl, thiol, carbonyl, and amide groups; more preferably, the polar organic small molecule
  • the polar organic small molecules are selected from methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, formic acid, acetic acid, propionic acid, acetonitrile, acetaldehyde, ethyl mercaptan, propyl mercaptan, acetone, tetrahydrofuran, At least one of N'N-dimethylformamide; more preferably, there is a polar organic small molecule layer with a dipole moment greater than 1D between the first conductive layer and the organic semiconductor layer; more preferably, The polar organic small molecule layer can reduce the electron injection barrier between the first conductive layer and the organic semiconductor layer by more than 0.05 eV.
  • the organic field effect transistor may also include: an insulating substrate and/or an encapsulation layer; further, the insulating substrate is a surface insulating substrate, which serves as a supporting structure during the preparation and use of OFETs. exists and can be a rigid or flexible structure. In order to avoid mutual interference when multiple OFETs are prepared on the same substrate, the substrate surface needs to be insulated. In some special cases, when the second conductive layer itself has a certain mechanical strength and can play a supporting role, it does not need to contain an insulating substrate.
  • the second conductive layer when using a heavily doped silicon wafer or a thick copper foil (which can conduct electricity) as the second conductive layer, since the second conductive layer itself is rigid and can play a supporting role, no additional insulating substrate is needed.
  • the oxide layer component is silicon dioxide
  • the conductive part of the heavily doped silicon wafer serves as the second conductive layer
  • the oxide layer on its surface serves as the insulating layer, used as the electrically functional component of the OFET (different from the mechanically functional part that is only used as a support).
  • the insulating substrate is selected from at least one of silicon wafers, glass, ceramics, insulating metal oxides, paper or polymers containing oxide layers; preferably, the polymer can be selected from polyethylene naphthalate At least one of glycol ester, polyethylene terephthalate, polyetheretherketone, polyimide, polycarbonate, polyethersulfone resin, polyarylate, and polycyclic olefin.
  • the encapsulation layer can play a role in protecting the OFET and is made of polymer material.
  • Organic single crystal films can be detected by instruments that analyze fine structures such as optical microscopes with crossed polarizers, atomic force microscopes, scanning electron microscopes, transmission electron microscopes, laser confocal Raman spectrometers, single crystal diffractometers, etc., and can be detected by Kelvin detectors. Needle microscope, ultraviolet photoelectron spectrometer, angle-resolved photoelectron spectrometer, ultraviolet absorption spectroscopy, conductivity method, functional calculation, etc. can analyze the energy level structure of conductive materials and organic semiconductor materials. The energy level structure of conductive materials and organic semiconductor materials can be analyzed through optical microscope, atomic force microscope, scanning electron Microscopes, transmission electron microscopes, etc. can be used to detect the structure of semiconductor devices.
  • Semiconductor parameter analyzers Hall effect testers, scanning probe microscopes, ferroelectric testers, quantum efficiency testers, transient spectrometers, solar cell testers, optoelectronics Detection systems, microfluorescence spectrometers, spectrum testers, conductivity measurement systems and other instruments that can analyze photoelectric properties detect the relevant performance of semiconductor devices.
  • an ultraviolet photoelectron spectrometer was used for characterization.
  • optical microscopes were used for observation.
  • a semiconductor parameter analyzer was used to obtain the characteristic curve of the OFET, and the mobility calculation formula and the balance coefficient calculation formula were used for calculation.
  • heavily doped silicon can be directly used as the second conductive layer.
  • a double-layer structure composed of a 300 nm thick silicon dioxide layer (SiO 2 ) on the surface of the silicon wafer and a PMMA polymer film obtained by spin coating -PMMA) as an insulating layer. TIPS-pentacene single crystal is used as the organic semiconductor layer, and 100nm thick gold obtained by vacuum evaporation is used as the first conductive layer.
  • the work function of gold used as the first conductive layer was tested using ultraviolet photoelectron spectroscopy.
  • a gold film is deposited on a substrate with good electrical conductivity, and then placed in a UV photoelectron spectrometer to measure the UV photoelectron spectrum.
  • the cutoff edge energy E cutoff and the Fermi edge energy E F can be obtained from the spectrum, as shown in Figure 5.
  • the identification and single crystal morphology of organic semiconductor single crystals can be characterized by an optical microscope with crossed polarizers.
  • the highly ordered molecular arrangement in organic semiconductor single crystals causes organic single crystals to exhibit regular edges and regular geometric morphology in appearance, and often exhibit anisotropy in optical and other properties, which can be detected under orthogonally polarized light.
  • Uniform color change was observed.
  • (a) in Figure 6 is a single crystal array composed of multiple TIPS-pentacene single crystals. It has regular edges and regular geometric morphology, and shows (b) in Figure 6 under orthogonal polarized light. The uniform color change shown can therefore be simply identified as an organic single crystal array.
  • the dipole moment of the polar organic small molecule used is the basic object parameter composed of the polar organic small molecule, which can be obtained by simply querying the literature or solvent manual. The results are shown in Table 1.
  • the mobility ⁇ of OFET can be calculated by the following formula:
  • L is the length of the OFET channel
  • W is the width of the OFET channel, which can be obtained from the OFET photo obtained by an optical microscope (as shown in (a) in Figure 7).
  • W should take the actual width of the semiconductor layer (as shown in (b) in Figure 7).
  • C i is the gate insulating layer capacitance, which can be measured by a semiconductor parameter analyzer with capacitance analysis function. It can be obtained by testing the transfer characteristic curve of a field effect transistor operating in the saturation region.
  • the p-type transfer characteristic curve and n-type transfer characteristic curve of the OFET in Example 1 measured by a semiconductor analyzer are shown in (a) and (b) of Figure 8, respectively.
  • the transfer characteristic curve shown in Figure 8 shows an obvious V-shape. The appearance of the V-shaped curve is a sign that OFET can show both hole transport and electron transport. When the curve has no V-shaped characteristics, it can be judged that the obtained OFET can only transmit one type of carriers.
  • Example 2 demonstrates the use of a TIPS-pentacene single crystal with a morphology different from that in Example 1, and its morphology is shown in Figure 9. From the regular edges and regular geometric morphology, it can be simply judged to be a single crystal. It should be noted that whether it is a single crystal array composed of multiple organic semiconductor single crystals in Figure 6 or a single organic semiconductor single crystal in Figure 9, they all fall within the scope of organic semiconductor single crystals.
  • the structure and performance characterization method of the OFET composed of TIPS-pentacene single crystal is the same as that in Example 1. The obtained device related parameters and performance are shown in Table 1.
  • An organic field effect transistor based on p-type organic semiconductor single crystal pentacene single crystal and platinum and its preparation method including the following steps:
  • An organic field effect transistor based on p-type organic semiconductor single crystal rubrene single crystal and platinum and its preparation method including the following steps:
  • the organic field effect transistor and its preparation method include the following steps:
  • An organic field effect transistor based on p-type organic semiconductor single crystal perylene single crystal and gold/tungsten oxide and its preparation method.
  • Example 3 For the preparation method of the organic field effect transistor in Example 11, refer to Example 3.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • Gold/tungsten oxide is deposited by vacuum evaporation.
  • An organic field effect transistor based on p-type organic semiconductor single crystal TIPS-pentacene single crystal and platinum/vanadium oxide and its preparation method.
  • Example 12 The preparation method of the organic field effect transistor in Example 12 is as described in Example 3.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • Example 13 For the preparation method of the organic field-effect transistor in Example 13, refer to Example 6.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • Indium tin oxide is deposited by transfer.
  • Embodiment 14 For the preparation method of the organic field effect transistor in Embodiment 14, refer to Embodiment 8.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • Example 15 The preparation method of the organic field effect transistor in Example 15 is as described in Example 6.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • Example 16 For the preparation method of the organic field effect transistor in Example 16, refer to Example 8.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • An organic field effect transistor and a preparation method thereof An organic field effect transistor and a preparation method thereof.
  • Example 8 For the preparation methods of organic field effect transistors in Examples 17-30, refer to Example 8. The structure and performance characterization methods were the same as those in Example 5. The material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • An organic field effect transistor and a preparation method thereof An organic field effect transistor and a preparation method thereof.
  • Example 8 For the preparation method of organic field-effect transistors in Examples 31-33, refer to Example 8. The structure and performance characterization methods were the same as those in Example 9. The material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • An organic field effect transistor and a preparation method thereof An organic field effect transistor and a preparation method thereof.
  • Example 8 For the preparation method of organic field-effect transistors in Examples 34-36, refer to Example 8. The structure and performance characterization methods were the same as those in Example 5. The material selection formula is shown in Table 2, and the obtained OFET performance is shown in Table 3.
  • An organic field effect transistor based on p-type organic semiconductor single crystal TIPS-pentacene single crystal and calcium and its preparation method including the following steps:
  • Comparative Example 1 uses calcium, a low work function material, as the first conductive layer.
  • the resistance of the first conductive layer increased from the original 22 ⁇ to 8810 ⁇ (as shown in (a) and (b) in Figure 10).
  • the resistance increased 400 times, indicating that calcium acts as When the first conductive layer is used, it is easily oxidized by air, resulting in a decrease in conductivity, that is, poor air stability. Oxidation of electrodes will seriously affect the performance of semiconductor devices.
  • the resistance of the first conductive layer changed from 15 ⁇ to 17 ⁇ , with basically no change (as shown in (c) and (d) in Figure 10 ), It shows that gold has good air stability when used as the first conductive layer.
  • the resistance of the first conductive layer in Comparative Example 1 increased to 50K ⁇ , and the resistance of the first conductive layer in Example 1 became 18 ⁇ , basically unchanged, further demonstrating that high work function materials are
  • the first conductive layer has good air stability and can extend the service life of the electrode in the air environment.
  • Comparative Example 2 uses TIPS-pentacene single crystal (p-type) and C 60 single crystal (n-type) to construct OFET respectively.
  • TIPS-pentacene single crystal p-type
  • C 60 single crystal n-type
  • the only option is to deposit the C60 single crystal first and then deposit the TIPS-pentacene single crystal.
  • the grown double-layer single crystal structure is shown in (a) in Figure 11.
  • the lower layer is C60 single crystal and the upper layer is TIPS-pentacene single crystal. It can be seen that although the TIPS-pentacene solution did not completely dissolve C60, it still caused obvious damage to the surface of the C60 single crystal.
  • (b) in Figure 11 shows the complete C60 single crystal surface. It can be seen that the surface is very smooth and flat. The surface of C60 single crystal becomes rough after TIPS-pentacene growth. This will seriously affect the interface between the two semiconductors, resulting in poor performance of the resulting OFET.
  • Comparative Example 3 used the TIPS-pentacene polycrystalline film obtained by spin coating as the organic semiconductor layer to construct TIPS-pentacene.
  • the polycrystalline film has a rough surface and is composed of many crystal grains. The grain boundaries between grains will seriously hinder carrier transport.
  • (b) in Figure 12 is the p-type transfer characteristic curve of the obtained OFET.
  • Comparative Example 4 used TIPS-pentacene single crystals without polar organic small molecule treatment to prepare OFETs, as shown in Figure 4 13 is the p-type transfer characteristic curve and n-type transfer characteristic curve of the OFET in Comparative Example 4.
  • the OFET obtained from it still has a high hole mobility (1.93cm 2 V -1 s -1 )
  • the electron migration The rate ⁇ electricity is low, only 1.08 ⁇ 10 -2 cm 2 V -1 s -1
  • the calculated balance coefficient B 2.25, which does not meet the requirement of B to 1. It shows that the existence of polar organic small molecules plays an important role in improving the electron mobility of OFETs with p-type organic semiconductor single crystal as the semiconductor layer and high work function conductive material as the first conductive layer.
  • the insulating layer using an insulating material is a necessary structure of the organic field effect transistor
  • Comparative Example 5 compared with Example 2, the 300 nm parylene insulating layer (insulating material) was replaced with 300 nm gold (conductive material). ). Since there is no insulating layer, the device is always in a short-circuit state and cannot work properly. It is explained that the insulating layer composed of insulating material is a necessary structure of the organic field effect transistor.
  • Comparative Example 6 is compared with Example 2 in that 50 nm aluminum (conductive material) is replaced by 50 nm aluminum oxide (insulating material). Material, the resistivity is about 0.004S/m, [1] Bai Xiaoping, Chen Yan. Research on the influence of alumina filler conductivity on the performance of cast bodies [J]. Electrical Manufacturing, 2014 (11): 62-65.). Since it does not have a second conductive layer that can conduct electricity, the device produced cannot provide a gate voltage for controlling the turning on and off of the organic field effect transistor, and cannot work normally. It is explained that the second conductive layer composed of conductive material is a necessary structure of the organic field effect transistor.
  • the preparation method of the organic field-effect transistor of Comparative Example 7 is similar to that of Example 1. The only difference is that the thickness of the deposited first conductive layer is 15 nm.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the preparation method of the organic field-effect transistor of Comparative Example 8 is similar to that of Example 1. The only difference is that the thickness of the deposited first conductive layer is 1500 nm.
  • the structure and performance characterization methods are the same as those in Example 1.
  • the first conductive layer In order to illustrate the influence of the thickness of the first conductive layer on the performance of the organic field effect transistor, metals with thicknesses less than 30 nm and greater than 1000 nm were selected as the first conductive layer in Comparative Example 7 and Comparative Example 8 respectively.
  • Comparative Example 7 due to the small thickness of the first conductive layer and the influence of the morphology of the underlying organic semiconductor layer, the first conductive layer is discontinuous and cannot function as an electrode, and the device cannot operate normally.
  • Comparative Example 8 due to the thickness of the first conductive layer being too large, the electrodes were in contact with each other and short-circuited, and the device also failed to operate normally. It means that the thickness of the first conductive layer needs to be controlled within the range of 30-1000nm.
  • Example 9 The preparation method of the organic field-effect transistor of Comparative Example 9 is similar to that of Example 1, with the only difference being that there is no first conductive layer.
  • the structure and performance characterization methods are the same as those in Example 1.
  • Example 10 The preparation method of the organic field-effect transistor in Comparative Example 10 is similar to that of Example 1. The only difference is that there is no organic semiconductor layer. The structure and performance characterization methods are the same as those in Example 1.
  • the preparation method of the organic field-effect transistor in Comparative Example 11 is similar to that of Example 1. The only difference is that the organic semiconductor layer is an n-type organic semiconductor single crystal. The structure and performance characterization methods are the same as those in Example 1.
  • the organic field-effect transistor of the present invention is composed of specific materials and preparation methods to form a specific structure. All the following conditions must be strictly met to produce an organic field-effect transistor with the technical effects of the present invention: It includes a first conductive layer, an organic semiconductor layer, an insulating layer, and a second conductive layer in sequence, and the first conductive layer is composed of a conductive material with a work function of 4.5 eV or more; the organic semiconductor layer is composed of a p-type organic semiconductor single layer.
  • the insulating layer is made of insulating material; the second conductive layer is made of a material with a conductivity of 1S/m or more, and the above conditions are indispensable; it can be seen from Comparative Examples 1-11 that changing the first conductive layer
  • the material makes the hole mobility low and the air stability poor.
  • the device cannot work without the first conductive layer.
  • Changing the material of the semiconductor layer makes the device performance worse.
  • the device cannot work without the organic semiconductor layer.
  • the insulating layer is missing or the thickness of the first conductive layer is changed. Short circuit occurs in devices with equal parameters.
  • the present invention can exert an overall synergy to produce the organic field effect transistor composed of a single p-type organic semiconductor material of the present invention, so that the first conductive layer has good air stability. properties, further achieving the performance of hole mobility ⁇ p and electron mobility ⁇ n ⁇ 0.5cm 2 V -1 s -1 at the same time, and the balance coefficient B ⁇ 1.
  • Inability to work in the comparative example refers to abnormal situations such as short circuit, inability to control the opening and closing of transistors, inability to transmit electrons, etc. due to changes in material types and parameters, lack of a certain layer, etc., resulting in the device being unable to work normally.

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Abstract

本发明提供一种有机场效应晶体管及其制备方法，所述的有机场效应晶体管依次包括第一导电层、有机半导体层、绝缘层、第二导电层；所述的第一导电层由功函数4.5eV以上的导电材料构成；所述的有机半导体层由p型有机半导体单晶构成；所述的绝缘层由绝缘材料构成；所述的第二导电层由电导率大于1S/m的材料构成；进一步的，所述的有机场效应晶体管同时满足：空穴迁移率μp≥0.5cm2V-1s-1，电子迁移率μn≥0.5cm2V-1s-1，且满足平衡系数B≤1，所述平衡系数B的计算公式为：B＝|lg(μp/μn)|，所述的有机场效应晶体管表现出高且平衡的空穴迁移率和电子迁移率，在有机互补电路和发光晶体管等中具有很好的应用前景。

Description

一种有机场效应晶体管及其制备方法 技术领域
本发明涉及有机半导体器件技术领域，具体涉及一种有机场效应晶体管及其制备方法。
背景技术
有机半导体器件具有制备成本低、柔性、质轻、可大面积制备的优点，在柔性显示、柔性可穿戴设备、物联网、生物医疗领域具有很好的应用前景，受到了人们的广泛关注。高性能有机半导体器件的制备是实现有机半导体器件实用化的重要过程。在有机半导体器件中，有机场效应晶体管(Organic field-effect transistor，OFET)是一类常见且重要的基本元件，是有机集成电路中最重要的组成单元。
载流子作为电子器件中电流的载体，是指可以在电场作用下自由移动的电荷微粒。在半导体材料中，载流子类型分为两种：电子(electron)和空穴(hole)，其中，电子带负电荷，空穴带正电荷。在OFET的应用中，空穴和电子的传输均很重要。
载流子迁移率(简称迁移率，用μ表示，单位为cm2V-1s-1)是指载流子在单位电场强度下的迁移速率。对于OFET，迁移率是表示其性能的关键参数，决定了其开启或关闭速度的快慢。迁移率越高，意味着OFET的开启或关闭速度越快，应用于逻辑电路时，得到的电路逻辑运算速度也就越快。根据载流子类型的不同，载流子迁移率μ可分别用空穴迁移率(μp)和电子迁移率(μn)来表征。μp和μn可以通过下列公式获得：

通过半导体分析仪测得OFET的p型转移特性曲线和n型转移特性曲线，其中，L为OFET沟道的长度，W为OFET沟道宽度，Ci为栅极绝缘层电容，可通过带有电容分析功能的半导体参数分析仪测得，IDS为OFET工作时，经过源漏级之间的电流，VG为施加在栅极上的电压，可通过测试在饱和区工作的场效应晶体管的转移特性曲线得到。图1中的(a)和(b)分别为常见的OFET结构的截面图和俯视图，W和L可以在光学显微镜拍摄的OFET的俯视图中通过标尺量得；图1中的(c)和(d)分别为可通过半导体分析仪测得的p型OFET和n型OFET的转移特性曲线以及转移特性曲线处理后的IDS 1/2-VG曲线，通过计算曲线IDS 1/2-VG的斜率即可得到
对于OFET而言，载流子迁移率越高越好。OFET的迁移率普遍低于1cm2V-1s-1。为了实现OFET的实用化，OFET中电子和空穴的迁移率均不低于0.1cm2V-1s-1是基本要求。
在互补电路、发光晶体管等常见应用中，不仅需要OFET的空穴和电子的传输同时存在，还需要μp和μn足够高，且两种载流子传输之间的平衡性较好。单独使用只能传输空穴的p型OFET，或者单独使用只能传输电子的n型OFET，均无法得到互补电路。
此外在互补电路中，电路的性能受电子和空穴传输平衡的影响很大，传输性能较差的一方将成为严重限制电路工作的瓶颈。即使在其他方面做很多的优化，使空穴迁移率(μp)和电子迁移率(μn)分别都很高，但如果空穴迁移率和电子迁移率之间的平衡性较差，电路性能也无法得到进一步提升。因此，提高半导体器件中空穴和电子传输的平衡性对于提高器件性能有着非常重大的意义。
半导体器件中空穴和电子传输的平衡性可以用μp和μn之间的接近程度来表示，两者越接近，则空穴和电子传输之间的平衡性越好。这种平衡性可以用平衡系数B衡量，B的计算公式为B＝|lg(μp/μn)|，B越小，表示空穴迁移率和电子迁移率之间越接近，空穴和电子传输之间平衡性越好；10倍以内的迁移率差距属于可接受的平衡范围，即在0.1μp≤μn≤10μp的范围内，认为空穴和电子传输的达到平衡的标准，此时，平衡系数B≤1。因此平衡系数B≤1为空穴和电子传输平衡的条件。
按照在场效应晶体管中传输载流子能力的不同，可以将有机半导体材料分为三类：p型半导体材料(简称p型材料)，n型半导体材料(简称n型材料)和双极型(ambipolar)半导体材料(简称双极型材料)。p型半导体材料在OFET中主要传输空穴(μp＞100μn)；n型半导体材料在FET中主要传输电子(μn＞100μp)；双极型半导体材料在FET中既可以传输空穴，也可以传输电子，且μp与μn接近(0.01≤μp/μn≤100)。p型半导体材料和n型半导体材料统称为单极型(unipolar)半导体材料(简称单极型材料)。为了方便区分，此处关于有机半导体材料分类的判断标准仅依据该种材料被首次制备成OFET后测得的性能，而不是经过各种改性或优化后测得的性能。若在首次报道中仅测得μp或μn中的一种，则说明该种材料易表现出单一的载流子传输性能，认为该种材料为单极型半导体材料，而不是双极型半导体材料。例如，常用的红荧烯、并五苯，以及并五苯衍生物(例如，TIPS-pentacene)均为常见的p型材料。
有机半导体的聚集态结构对于有机电子器件的性能有很大的影响。按照分子排列的有序性，有机半导体的聚集态结构可分为单晶(single crystal)、多晶和无定型。有机半导体单晶简称为有机单晶(organic single crystal)，在三种形态中具有最高的有序性。对于同一有机半导体材料而言，单晶聚集态具有最高的有序性、最少的缺陷，并且没有晶界，传输载流子时散射作用最小，载流子的传输性能最高。已被证明，有机单晶的长程有序性非常有利于提高载流子的迁移率(carrier mobility)和激子扩散长度(excitions diffusion length)，从而有利于有机电子性能的提高。
单独使用仅由p型材料构成的p型OFET或仅由n型材料构成的n型OFET无法得到互补电路。使用双极型材料可以得到既能传输空穴，也能传输电子的双极型OFET。但是与单极型材料相比，双极型材料分子结构更为复杂，常需要在单极型材料分子的基础上进行复杂的修饰、化学连接及筛选才能得到，增加了材料合成与生产的步骤与难度，不利于产业应用。因此，双极型半导体材料相比于单极型半导体材料而言，可选择的材料更少。例如，(Z.Cai,et al.Chem.-An Asian J.9(2014)1068–1075.)DPP(diketopyrrolopyrrole)是一种p型材料(结构见该文图2中的(a))，通过对DPP分子进行复杂的修饰后，才得到了具有双极型材料DPP-F2(含E-(1,2-difluoro-vinyl)基团的diketopyrrolopyrrole衍生物)(结构见该文图2中的(b))。DPP-F2分子相比DPP分子更加复杂，更难合成且结构更加不对称，不利于获得单晶结构。不当的修饰甚至无法得到双极型材料。因此，双极型材料比单极型材料更难获得，材料选择性更小，因而更难以应用于产业化中。相较于双极型半导体材料，单极型半导体材料(p型或n型)的分子结构更为简单。简单的分子结构一方面降低了单极型半导体材料的合成成本，可供选择的材料种类更多，使其更适合产业化应用，另一方面也使得单极型半导体材料更容易结晶，制得高性能的OFET。
而在单极型半导体材料中，p型材料相较于n型半导体材料也具有更大的产业化应用优势。这是因为p型材料在用于OFET时，在迁移率大小、空气稳定性、材料选择丰富性方面普遍优于n型材料(Zhao Y,Guo Y,Liu Y.25th Anniversary Article:Recent Advances in n-Type andAmbipolar Organic Field-Effect Transistors[J].Advanced Materials,2013.
综上所述，在p型材料、n型材料和双极型材料三类有机半导体材料中，p型材料的种类最丰富、研究最充分、最有望首先实现大规模的产业化应用。
高功函金属用于有机场效应晶体管时存在以下的优势和问题：
功函数(workfunction，缩写为WF，简称功函)是电极材料的一个重要物理参数。材料的功函数是指材料真空能级(VL)与费米能级(EF)之间的能量差(WF＝VL-EF)。根据材料功函数的高低，可以将电极材料分为高功函电极材料和低功函电极材料。当材料的功函数≥4.5eV时，认为其是高功函电极材料，如金(Au,5.1eV)、铂(Pt,5.65eV)、铜(Cu,4.65eV)、铬(Cr,4.6eV)、氧化铟锡(ITO,4.8eV)等；当材料的功函数＜4.5eV时，认为其是低功函电极材料，如钙(Ca,2.87eV)、铯(Cs,2.14eV)、钡(Ba,2.7eV)、镁(Mg,3.66eV)、铝(Al,4.28eV)、银(Ag,4.26eV)等。材料的功函数可通过紫外光电子能谱仪(UPS)或开尔文探针显微镜(KPFM)测得。
电极材料的功函和有机半导体材料的能级之间的匹配程度会对OFET中载流子的传输产生较大影响。高功函电极材料用作OFET的源漏电极时，有利于OFET表现出空穴传输性质，但不利于OFET表现出电子传输性质；相反，低功函电极材料用作OFET的源漏电极时，有利于OFET表现出电子传输的性质，但不利于OFET表现出空穴传输的性质(J.Fidyk,et al.Polymers(Basel).12(2020)1–14.N.B.Kotadiya,et al.Nat.Mater.17(2018)329–334；Y.Zhou,et al.Science(80-.).336(2012)327–332.
另一方面，电极材料，特别是金属材料的功函与材料失去电子的能力，即被氧化的能力有关。功函越高，材料越不容易被氧化，用作电极时化学稳定性就越强。从这一方面看，电极材料的功函越高越好。
综上所述，高功函电极材料空气稳定性好，用作电极时能延长使用寿命，在产业化应用中具有优势，但是由于高功函电极材料不利于OFET中电子的传输，目前普遍存在如下技术问题：在由p型材料构成的OFET中，使用高功函电极材料作为电极，无法得到较高的μp和μn；同时，无法使μn与μp相当。
综上所述，要实现互补电路及发光晶体管的良好应用，必须要实现OFET中高空穴迁移率和高电子迁移率的共存，以及空穴迁移率与电子迁移率的平衡性较好。目前有如下三种实现方式：
1.分别使用p型材料和n型材料来传输空穴和电子。但是n型材料相较于p型材料普遍存在迁移率较低、空气稳定性较差，研究滞后，选择更少，因而限制了互补电路和发光晶体管等应用的发展。
2.使用能同时传输空穴和电子的双极型材料。但是双极型材料的分子结构复杂，合成步骤繁琐，可供选择的材料种类少，提高了产业化应用的成本；且复杂的分子结构不利于双极型材料分子的结晶，难以得到高性能的单晶来提高OFET的迁移率。
3.在仅使用p型材料的OFET中，使用有利于电子传输的低功函电极材料作为源漏电极，来提高其中的电子迁移率。但是低功函电极材料的空气稳定性差，在空气中容易被氧化而影响性能。
使用高功函电极材料作为源漏电极，同时仅使用单晶结构的p型材料来获得OFET(这类OFET简称为HM-p-OSC-FET)，在应用上具有很大的优势，HM-p-OSC-FET取材丰富(p型半导体材料研究成熟，种类丰富)、性能优异(单晶结构有利于高性能的载流子传输)且电极性能稳定,具有广阔的应用前景。但是由于p型材料传输电子的能力较弱，且高功函电极材料不利于OFET中电子的传输，因此普遍存在HM-p-OSC-FET的电子迁移率低，且μp和μn平衡性差的技术问题。在HM-p-OSC-FET中实现高的μn，可以进一步扩大其应用范围，减少有机集成电路中需要利用的OFET的种类，从而简化电路设计和制备的工艺，提高电路集成度，对于实现有机集成电路的高度集成化、高性能化和产业化具有重大的意义。
针对HM-p-OSC-FET难以获得高电子迁移率以及平衡的μp和μn的问题，现有技术主要有以下2种：
现有技术1：在p型有机半导体单晶的基础上另外沉积可以传输电子的n型半导体材料，形成双层异质结的结构。(参见参考文献1：Y.Zhang,et al.Journal of the American Chemical Society.132(2010)11580–11584和参考文献2：Fan C,et al.Advanced Materials,2013,25(40).)但是该类方案存在以下问题：，1)需要分别沉积两种材料，工艺复杂，不好控制；2)上层材料中的载流子传输发生在异质结界面处，该界面难以调控，容易因为材料之间结合不好而产生各种缺陷，影响载流子传输的性能，使空穴和电子迁移率下降；3)另外，该方法中依旧用到了n型半导体材料，因此仍需研究n型半导体的性质，而无法充分利用p型半导体种类多，性能好的优势。(X.Zhu,et al.Small.15(2019)1–8.
现有技术2：使用带有反应基团的长链烷烃(自组装分子单层，SAM)修饰电极来改变电极材料的功函数。(Cheng X,et al.Advanced Functional Materials,19.15(2009):2407-2415.)但这种方法存在以下问题：1)必须通过反应基团和电极的反应来实现，仅适用于先沉积电极后沉积半导体的情况；2)先沉积电极的方案会影响半导体单晶的生长，难以得到高质量的有机单晶和高迁移率的OFET。上述案例中的FET的空穴和电子迁移率仅为10－3cm2V-1s-1的水平。3)自组装单分子层的反应复杂，难以控制，容易因为产生多层修饰层、或修饰不完全等原因影响效果；4)目前仅被用于由双极型材料构成的OFET中改善载流子传输的平衡性，未被用于p型材料构成的OFET中来提高电子迁移率。
综上所述，现有技术未见仅采用p型有机半导体材料和使用高功函电极材料而获得高空穴迁移率和电子迁移率，且空穴迁移率和电子迁移率平衡，使得平衡系数B≤1的有机场效应晶体管。
发明内容
针对现有技术的不足，本发明提供了一种有机场效应晶体管及其制备方法，所述有机场效应晶体管结构简单、制备方便、成本低廉，仅使用了发展较为充分的p型有机半导体材料，以及在空气中稳定的高功函电极材料，而避免了使用发展较为滞后的n型材料，以及容易被空气氧化的低功函电极材料，所述有机场效应晶体管可以表现出高空穴迁移率和电子迁移率，且空穴迁移率和电子迁移率平衡，使得平衡系数B≤1，克服了p型有机半导体材料不利于传输电子、难以获得高电子迁移率的技术偏见，使用高功函电极材料在保证高电子迁移率的前提下延长了电极在空气环境中使用寿命，克服了高功函导电材料用作OFET电极时不利于电子迁移率提高的技术偏见，在有机互补电路和发光晶体管等中具有很好的应用前景。
为了解决本发明的现有问题，本发明采用以下技术方案：
本发明提供了一种有机场效应晶体管，所述的有机场效应晶体管依次包括第一导电层、有机半导体层、绝缘层、第二导电层；
所述的第一导电层由功函数4.5eV以上的导电材料构成；
所述的有机半导体层由p型有机半导体单晶构成；
所述的绝缘层由绝缘材料构成；
所述的第二导电层由电导率1S/m以上的材料构成；
本发明的有机场效应晶体管是由特定的材料和制备方法组成了特定结构，必须严格满足以下的所有条件才能制得具有本发明技术效果的有机场效应晶体管：依次包括第一导电层、有机半导体层、绝缘层、第二导电层，且所述的第一导电层由功函数4.5eV以上的导电材料构成；所述的有机半导体层由p型有机半导体单晶构成；所述的绝缘层由绝缘材料构成；所述的第二导电层由电导率1S/m以上的材料构成，以上条件缺一不可；通过对比例1-11可知，改变第一导电层材料使得空穴迁移率低、空气稳定性差，缺少第一导电层器件无法工作，改变半导体层的材料使得器件性能变差，缺少有机半导体层器件无法工作，缺少绝缘层或者改变第一导电层厚度等参数器件发生短路，因此可知本发明只有同时满足以上条件，才能发挥整体协同作用制得本发明的使用单一p型有机半导体材料构成的有机场效应晶体管，达到第一导电层具有良好的空气稳定性，进一步的能达到空穴迁移率μp和电子迁移率μn同时≥0.5cm2V-1s-1，且平衡系数B≤1的性能。
进一步的，所述的第一导电层、绝缘层、第二导电层分别独立选自单层或多层薄膜。
优选的，所述的有机场效应晶体管同时满足：空穴迁移率μp≥0.5cm2V-1s-1，电子迁移率μn≥0.5cm2V-1s-1，且满足平衡系数B≤1，所述平衡系数B的计算公式为：B＝|lg(μp/μn)|；
其中，所述第一导电层作为OFET的电极存在，一般包含源极和漏极两个相互分离的电极，起到连接外部电路、承担电压、向有机半导体层内注入空穴和电子的作用。构成第一导电层的电极材料的功函数，与电极材料的抗氧化性有很大的关系：功函数越大，电极材料的抗氧化性越强，电极材料在空气中工作的稳定性就越好。为了保证空气稳定性，要求构成第一导电层的电极材料功函在4.5eV以上。电极材料的功函可以根据材料的紫外光电子能谱(UPS)数据计算得到。计算公式为：Φ＝hν-(Ecutoff-EF)。其中Φ即为导电材料的功函数；hν为仪器提供的光子能量，为21.22eV；Ecutoff为从UPS谱图中得到的材料的二次电子截止边数据；EF为从UPS谱图中得到的材料的费米边数据，对于与仪器具有良好接触的导电样品，费米边数据为0。因此，电极材料的功函数为21.22-Ecutoff。优选的，所述的第一导电层为高功函导电材料(功函数4.5eV以上)构成的单层或多层薄膜。
所述有机半导体层是OFET中的核心结构，是电子和空穴传输的通道，起到传输载流子、导通电流的作用。p型有机半导体材料在性能、稳定性和取材丰富性方面普遍优于n型半导体材料，因此选用p型有机半导体材料构建有机半导体层。对于同一有机半导体材料而言，单晶聚集态具有最高的有序性、最少的缺陷和晶界，传输载流子时散射作用最小，载流子的传输性能最高。已被证明，有机单晶的长程有序性非常有利于提高载流子的迁移率(carrier mobility)和激子扩散长度(excitions diffusion length)，从而有利于有机电子性能的提高。因此选择p型有机半导体单晶作为有机半导体层。
所述绝缘层在OFET中起到将作为栅极的第二导电层和用于传输电荷的第一导电层、有机半导体层隔绝开，防止第一导电层、有机半导体层形成的复合结构，和第二导电层之间形成导电通路，以保证OFET能正常工作的作用(结构见图4)。因此，用于绝缘层的材料需要具有较好的绝缘性质，即要求绝缘层由绝缘材料构成。
所述第二导电层构成了OFET的栅极，起到提供栅极电压、控制OFET开启或关闭的功能。为了保证第二导电层较好的导电性，要求构成第二导电层的材料的电导率在1S/m以上。OFET的迁移率是表征OFET开启或关闭速度的重要参数，在其他条件相同的情况下，迁移率越高，表示OFET的开启或关闭的速度越快，OFET的性能越好。迁移率μ可分别用空穴迁移率μp和电子迁移率μn来表征。为了保证OFET的性能，要求OFET的μp和μn均≥0.5cm2V-1s-1。平衡系数B是表征OFET中μp和μn接近程度的参数。平衡系数的计算公式为：B＝|lg(μp/μn)|。B越小，表示空穴迁移率和电子迁移率之间越接近，空穴和电子传输之间平衡性越好；理想情况下，B＝0时，μp＝μn，空穴传输和电子传输之间完全平衡。为了保证OFET在互补电路、发光晶体管等常见应用中能充分发挥性能，要求OFET的B≤1。
进一步的，所述的有机半导体层为HOMO能级≥-5.5eV，带隙宽度≥1.8eV的有机材料构成的单晶薄膜。HOMO能级是“最高占据分子轨道”的简称，是有机半导体材料中的一个重要参数。空穴在有机半导体的HOMO能级传输，HOMO能级过低的有机半导体材料用于OFET时不利于空穴的传输，因此要求选择的有机材料HOMO能级≥-5.5eV。带隙宽度是指导带底与价带顶之间的能量差，也称为禁带宽度。合适的带隙宽度，保证了其有机半导体的本征特性，可以实现场效应调控。单晶薄膜是由单晶或者单晶阵列构成的薄膜，可以由一片连续的厚度较小的单晶构成，也可以是由多个单晶组成的单晶阵列构成。
进一步的，所述的第一导电层和有机半导体层中存在偶极矩大于1德拜(D)的极性有机小分子；优选的，所述的第一导电层和有机半导体层之间存在偶极矩大于1德拜(D)的极性有机小分子层；优选的，所述的极性有机小分子层可以使第一导电层和有机半导体层之间的电子注入势垒降低0.05eV以上。
在OFET中，空穴和电子从第一导电层注入到有机半导体层中。空穴和电子注入效果的好坏将直接影响OFET中测得的空穴迁移率和电子迁移率。空穴和电子的注入效果受第一导电层的材料和有机半导体的材料能级匹配程度的影响。其他条件相同的情况下，能级越匹配，空穴或电子注入的效果越好，越有利于OFET迁移率的提高。对于由p型有机半导体材料和高功函导电材料构成的OFET而言，空穴注入效果较好，而电子注入效果很差，因此，OFET一般表现出空穴迁移率远高于电子迁移率，甚至无法测得电子迁移率的情况。极性有机小分子起到了调节第一导电层和有机半导体层界面处能级结构，降低电子从第一导电层注入有机半导体层的势垒，从而使电子和空穴能够更加平衡地从第一导电层注入到有机半导体层的作用。极性有机小分子引入的偶极矩是实现能级调控的重要因素，为了实现有效的能级调控，要求极性有机小分子的偶极矩大于1德拜(D)。偶极矩的单位为[德拜，D]，1D＝3.33×10-30库伦·米。
优选的，在第一导电层和有机半导体层之间形成极性有机小分子层则意味着引入更多的极性有机小分子，更加有利于实现极性有机小分子调节第一导电层和有机半导体层之间能级结构的效果。所述的第一导电层和有机半导体层之间是指位置上位于第一导电层和有机半导体相互接触的界面处。
极性有机小分子的作用是降低电子从第一导电层进入有机半导体层的注入势垒，使电子更容易从第一导电层进入有机半导体层，从而实现平衡的空穴和电子传输。优选的，所述的极性有机小分子层可以使第一导电层和有机半导体层之间的电子注入势垒降低0.05eV以上。
电子注入势垒的降低可以通过开尔文探针显微镜(KPFM)测得。具体测试方法如下：首先使用第一导电层材料和有机半导体层材料分别制备导电层薄膜和有机半导体层薄膜，使用KPFM分别测试导电层薄膜和有机半导体层薄膜表面的费米能级EF1和EF2；再用极性有机小分子分别处理导电层薄膜和有机半导体层薄膜的表面(处理方法与向OFET中引入极性有机小分子的方法相同)，随后再次用KPFM测试导电层薄膜和有机半导体层薄膜表面的费米能级EF1'和EF2'。注入势垒降低量Δ通过公式Δ＝(EF1'-EF1)+(EF2-EF2')进行计算。
进一步的，所述的偶极矩大于1D的极性有机小分子的分子量小于50Da。极性有机小分子的分子量可以用构成极性小分子的原子个数表示。50Da表示构成1个极性有机小分子的所有原子的个数为50个。
进一步的，所述的极性有机小分子在一个大气压下凝固点小于25℃。凝固点表示物质凝固成为固体所需的最高温度：温度低于凝固点，物质为固体；温度高于凝固点，物质为液体。物质的凝固点与物质所处环境的压强有关。极性有机小分子在一个大气压下凝固点小于25℃，表示这种极性有机小分子在正常的大气压强环境中，在环境温度高于25℃以上时，必定为液体状态。
进一步的，所述的极性有机小分子选自含有羟基、氰基、羧基、巯基、羰基、酰胺基的极性有机小分子中的至少一种；作为更优选，极性有机小分子选自甲醇、乙醇、丙醇、异丙醇、丁醇、乙二醇、甲酸、乙酸、丙酸、乙腈、乙醛、乙硫醇、丙硫醇、丙酮、四氢呋喃、N’N-二甲基甲酰胺中的至少一种。
进一步的，所述的有机场效应晶体管还可以包括：绝缘衬底和/或封装层；
本发明还提供一种有机场效应晶体管的制备方法，包括如下步骤：
1)在绝缘衬底表面依次沉积第二导电层和绝缘层，在绝缘层上沉积有机半导体层；所述第二导电层的沉积方法选自气相沉积法、溶液法的一种或多种；所述绝缘层的沉积方法选自气相沉积法、溶液法、原子层沉积法、原位氧化法的一种或多种；
2)将所述沉积有第二导电层、绝缘层和有机半导体层的绝缘衬底置于极性有机小分子氛围中处理10s～2h，使极性有机小分子液体或蒸气与有机半导体层表面充分接触，随后将沉积有第二导电层、绝缘层和有机半导体层的绝缘衬底与极性有机小分子氛围分离；
3)在有机半导体层表面沉积厚度为30～1000nm的第一导电层作为电极，得到所述有机场效应晶体管；
所述的第一导电层由功函数4.5eV以上的导电材料构成；
所述的有机半导体层由p型有机半导体单晶构成；
所述的绝缘层由绝缘材料构成；
所述的第二导电层由电导率1S/m以上的材料构成；
由于p型材料不利于传输电子，且高功函电极材料不利于OFET中电子的注入，使得p型有机场效应晶体管的电子迁移率低、μp和μn平衡性差，本发明对第一导电层、有机半导体层、绝缘层、第二导电层的沉积顺序，选择高功函材料作为第一导电层、p型有机半导体单晶作为半导体层、绝缘材料构成绝缘层、电导率1S/m以上的材料构成第二导电层、控制第一导电层的沉积厚度这些制备条件进行整体性的精确调控，配合极性有机小分子处理及精确控制处理时间对p型有机半导体单晶的调控作用，形成整体协同作用，才能制备得到本发明所述高空穴迁移率和高电子迁移率，且平衡系数≤1的有机场效应晶体管。
进一步的，所述的第一导电层、绝缘层、第二导电层分别独立选自单层或多层薄膜；
优选的，步骤3)中，所述沉积厚度为30～100nm；更优选的，所述沉积厚度为100nm。
所述步骤1)中，所述第二导电层可以是通过气相沉积法沉积的金属、合金、导电金属氧化物、无机非金属，也可以是通过溶液法沉积的金属纳米粒子、导电聚合物，还可以是高掺杂的硅，以及上述材料的叠加。绝缘层可以是通过化学气相沉积法、原子层沉积法、原位氧化法的绝缘金属氧化物、非金属氧化物或氮化物，也可以是通过溶液法、气相沉积法沉积得到的聚合物，还可以是通过溶液法或气相沉积法得到的自组装小分子，以及上述材料的叠加。所述绝缘衬底表面是指绝缘衬底上，具有绝缘性质，且光滑平整的一面。对于两个表面(因为所用的绝缘衬底一般厚度较小，所以只考虑两个主要表面，而不考虑侧面)相同的绝缘衬底，可选任何一表面用于材料沉积和器件制备；对于两个表面不同的绝缘衬底，应当选择绝缘性更好、粗糙度更小的表面用于材料沉积和器件制备。在同一个完整的OFET结构中，第二导电层、绝缘层、有机半导体层和第一导电层均沉积在绝缘衬底的同一侧表面上；而制备多个OFET时，不同的OFET可以分别制备在同一绝缘衬底的不同表面上。
第二导电层和绝缘层均可以为单层或多层结构。当使用表面含有氧化层的重掺杂硅时，可以不使用绝缘衬底，而直接使用重掺杂硅的导电部分作为第二导电层，使用重掺杂硅表面的氧化层(二氧化硅)作为绝缘层，在二氧化硅表面还可以修饰聚合物、自组装小分子层形成多层结构的绝缘层。p型有机半导体单晶可以通过原位生长的方式直接沉积在衬底表面，也可以先在其他地方生长，再通过转移的方法转移到衬底表面。p型有机半导体单晶可通过溶液法、气相法生长得到。
所述步骤2)中，为了使p型有机半导体单晶表面存在极性有机小分子，需要先使极性有机小分子先与有机半导体单晶表面接触，再除去有机半导体单晶表面的极性有机小分子液体。使极性有机小分子与有机半导体单晶表面接触的方法有液滴接触法和蒸气接触法。液滴接触法是指将极性有机小分子液体通过滴加、喷雾、打印、浸泡、冲洗等方法添加到有机半导体单晶的表面，并且使有机半导体单晶表面完全被极性有机小分子液体覆盖，以达到两者充分接触的目的；蒸气接触法是指将极性有机小分子液体通过蒸发的方式成为蒸气，将有机半导体单晶放置在极性有机小分子的蒸气氛围中，使有机半导体单晶表面与极性有机小分子充分接触的方法。对于液滴接触法，可通过旋涂、自然干燥、气体吹扫等方式使有机半导体单晶和极性有机小分子氛围分离；对于蒸气接触法，可通过将有机半导体单晶移出蒸气氛围，再自然干燥的方法使有机半导体单晶和极性有机小分子氛围分离。
所述步骤3)中，第一导电层可以通过物理气相沉积法(包括真空蒸镀、溅射、离子镀)、化学气相沉积、溶液打印法等方法直接沉积在有机半导体单晶表面，也可以通过将现有的导电材料膜转移到有机半导体单晶表面的方式进行间接沉积。
由于p型材料不利于传输电子，且高功函电极材料不利于OFET中电子的注入，使得p型有机场效应晶体管的电子迁移率低、μp和μn平衡性差，本发明对第一导电层、有机半导体层、绝缘层、第二导电层的沉积顺序，选择高功函材料作为第一导电层、p型有机半导体单晶作为半导体层、绝缘材料构成绝缘层、电导率1S/m以上的材料构成第二导电层、控制第一导电层的沉积厚度这些条件进行整体性的精细调控，配合极性有机小分子处理及精确控制处理时间对p型有机半导体单晶的调控作用，才能制备得到本发明所述高空穴迁移率和高电子迁移率，且平衡系数≤1的有机场效应晶体管。
本发明还提供一种光电器件：所述的光电器件包括如前所述的有机场效应晶体管，所述的光电器件选自发光晶体管、存储器、传感器、显示器。
本发明还提供一种有机电路：所述的有机电路包括如前所述的有机场效应晶体管，所述的有机电路选自门电路、组合逻辑电路、时序逻辑电路、放大电路中的至少一种电路组合而成的电路。
本发明还提供一种光电集成阵列，所述的光电集成阵列包含一个或多个如前所述的光电器件和如前所述的有机电路。(如图3所示)。
进一步的，如前所述的有机场效应晶体管、如前所述的有机场效应晶体管制备方法、如前所述的光电器件、如前述的有机电路以及如前所述的光电集成阵列在半导体器件、交通物流、采矿冶金、环境、医疗器械、防爆检测、食品、水处理、制药、生物领域的用途。
与现有技术相比，本发明的有益效果在于：
1)克服技术偏见，首次利用p型有机半导体单晶和高功导电材料获得了高空穴迁移率和电子迁移率，且空穴迁移率和电子迁移率平衡的有机场效应晶体管，使得空穴迁移率μp≥0.5cm2V-1s-1，电子迁移率μn≥0.5cm2V-1s-1，且满足平衡系数B≤1，；
2)使用了研究成熟、种类丰富、性能优异的p型有机半导体单晶材料，使有机场效应晶体管能在方便取材的情况下获得高空穴迁移率和高电子迁移率，并且空穴和电子传输的达到平衡，克服了p型有机半导体材料不利于传输电子、难以获得高电子迁移率的技术偏见；
3)使用了在空气中稳定性好的高功函导电材料作为电极，在延长电极在空气环境中使用寿命的前提下获得了高的电子迁移率，克服了高功函导电材料用作OFET电极时，不利于电子迁移率提高的技术偏见。
附图说明
图1为OFET结构以及转移特性曲线图，图1中的(a)为表示OFET结构的截面图；图1中的(b)为OFET的俯视图，从俯视图中可以测量得到沟道长度L和沟道宽度W；图1中的(c)为n型转移特性曲线图，可用于计算电子迁移率μn；图1中的(d)为p型转移特性曲线图，可用于计算空穴迁移率μp；
图2为有机半导体分子DPP(a)和DPP-F2(b)的结构示意图(Cai,Z.,Luo,H.,Chen,X.,Zhang,G.,Liu,Z.,&Zhang,D.Chemistry–An Asian Journal,2014，9(4),1068-1075.)，可以看出DPP-F2分子是经过对DPP进行复杂的修饰后得到的；
图3为本发明的光电集成阵列效果示意图；
图4为有机场效应晶体管的结构示意图，依次包含第一导电层、有机半导体层、绝缘层和第二导电层；
图5为测得的金的紫外光电子能谱图；
图6为实施例1的TIPS-pentacene单晶阵列的(a)光学显微镜照片和(b)正交偏振光下的显微镜照片图；
图7中的(a)为实施例1的OFET的光学显微镜照片图，可用于计算沟道长度L和沟道宽度W；图7中的(b)为半导体层未完全覆盖电极限制区域时的情况图，此时的W应该以实际的半导体范围为准；
图8为实施例1的转移特性曲线图，图8中的(a)为p型转移特性曲线图，可用于计算空穴迁移率，图8中的(b)为n沟道下的转移特性曲线图，可用于计算电子迁移率；
图9为实施例2的TIPS-pentacene单晶光学显微镜照片图；
图10为对比例1和实施例1中的第一导电层材料在经过空气暴露前后的电阻变化图，图10中的(a)为对比例1暴露在空气中之前第一导电层(钙)的电阻，为22Ω，图10中的(b)为对比例1暴露在空气中5分钟后第一导电层的电阻，为8810Ω，图10中的(c)为实施例1暴露在空气中之前第一导电层(金)的电阻，为15Ω，图10中的(d)为实施例1暴露在空气中5分钟后第一导电层的电阻，为17Ω；
图11为对比例2中有机半导体单晶的光学显微镜照片图，图11中的(a)为TIPS-pentacene单晶和C60单晶，图11中的(b)为未接触过TIPS-pentacene溶液的C60单晶；
图12中的(a)为对比例3中的TIPS-pentacene多晶薄膜光学显微镜照片图，图12中的(b)为对比例3中OFET的转移特性曲线图；
图13中的(a)为对比例4中的OFET的p型转移特性曲线图；图13中的(b)为对比例4中的OFET的n型转移特性曲线图。
具体实施方式
下面结合实施例和附图详细说明本发明。需要说明的是，以下实施例仅用于说明本发明而不用于限制本发明的范围。此外应理解，在阅读了本发明讲授的内容之后，本领域技术人员可以对本发明作各种改动或修改，这些等价形式同样落于本申请所附权利要求书所限定的范围。
需要说明的是，以下实施例中所用材料的厚度为经过优化后选定的厚度，或商业上可获得的材料规格，并非唯一选择，亦不用于限制本发明的范围。
如图4所示，本发明提供了一种有机场效应晶体管，依次包括第一导电层、有机半导体层、绝缘层、第二导电层，所述的第一导电层由功函数4.5eV以上的导电材料构成，所述的有机半导体层由p型有机半导体单晶构成，所述的绝缘层由绝缘材料构成，所述的第二导电层由电导率1S/m以上的材料构成，进一步的能达到所述的有机场效应晶体管同时满足：空穴迁移率μp≥0.5cm2V-1s-1，电子迁移μn≥0.5cm2V-1s-1，且满足平衡系数B≤1，所述平衡系数B的计算公式为：B＝|lg(μp/μn)|。
进一步的，在本发明的一个实施例中，所述有机半导体层可以选自稠环芳烃、含硫杂稠环、含氮杂稠环及其各自的衍生物的任意一种；更优选的，所述稠环芳烃选自并苯、二萘嵌苯、二苯基蒽、红荧烯中的任意一种；所述含硫杂稠环选自寡聚噻吩、苯并噻吩、四硫富瓦烯中的任意一种；所述含氮杂稠环选自金属酞菁、金属卟啉中的任意一种；更优选的，所述的有机半导体层为HOMO能级≥-5.5eV，带隙宽度≥1.8eV的有机单晶材料构成的薄膜。
进一步的，在本发明的一个实施例中，所述第一导电层的电导率大于1S/m；优选的，所述第一导电层选自第一金属、第一导电金属氧化物、第一导电聚合物中的至少一种；更优选的，所述第一金属选自第一金属单质、第一金属合金中的至少一种；更优选的，所述第一金属单质选自金、铜、铂、铬、钴、钯中的至少一种；更优选的，所述第一金属合金选自金、铜、铂、铬、钴、钯中的至少两种的合金；更优选的，所述第一导电金属氧化物选自氧化铟锡、氧化钨、氧化钒、氧化钌中的至少一种；更优选的，所述第一导电聚合物选自聚(3,4-乙烯二氧噻吩)：聚苯乙烯磺酸盐；
进一步的，在本发明的一个实施例中，所述绝缘层可以选自绝缘聚合物、绝缘金属氧化物、绝缘非金属氧化物或氮化物、自组装小分子中的至少一种；更优选的，所述的绝缘聚合物选自聚甲基丙烯酸甲酯(PMMA)、聚乙烯醇(PVA)、聚乙酸乙烯酯、聚酰亚胺(PI)、聚偏氟乙烯、聚偏氟乙烯共聚物、聚偏氟乙烯-三氟乙烯-氯氟乙烯、聚苯乙烯、聚-α-甲基苯乙烯、聚乙烯吡咯烷酮、聚乙烯基苯酚、聚对二甲苯(派瑞林)、聚苯并环丁烯、全氟(1-丁烯基乙烯基醚)聚合物、氰乙基普鲁烷中的至少一种；更优选的，所述绝缘金属氧化物选自氧化铝、氧化钛、氧化钽、氧化铪中的至少一种；更优选的，所述的绝缘非金属氧化物或氮化物选自二氧化硅、氮化硅中的至少一种；更优选的，所述自组装小分子选自含硅烷基的自组装小分子、含磷酸基的自组装小分子、含硫醇基的自组装小分子中的至少一种；优选的，所述绝缘层为单层或多层薄膜。
其中，所述的聚合物是指交联或者非交联的绝缘聚合物，所述绝缘金属氧化物是指具有绝缘性质的金属氧化物，所述的非金属氧化物或氮化物是指具有绝缘性质的非金属氧化物或氮化物。需要说明的是，在绝缘层、第一导电层以及第二导电层中，均可使用金属氧化物材料，但是用于绝缘层的金属氧化物为具有绝缘性质的绝缘金属氧化物，如氧化铝、氧化钛、氧化钽、氧化铪，而用于第一导电层或第二导电层的金属氧化物为具有导电性质的导电金属氧化物，如氧化铟锡、氧化钨，应当注意区分。
进一步的，在本发明的一个实施例中，所述第二导电层可以选自第二金属、第二导电金属氧化物、第二导电聚合物、导电无机非金属中的至少一种；优选的，所述第二金属选自第二金属单质或第二金属合金；优选的，所述第二金属单质选自金、银、铜、铁、铝、锌、锡、钛、铂、铬、钴、钯、锰、镍、镁、铅、镓中的至少一种；更优选的，所述第二金属合金选自金、银、铜、铁、铝、锌、锡、钛、铂、铬、钴、钯、锰、镍、镁、铅、镓中的至少两种的合金；更优选的，所述第二导电金属氧化物选自氧化铟锡、氧化钨、氧化钒、氧化钌、氧化铁、氧化镍、氧化锌、氧化银中的至少一种；更优选的，所述第二导电聚合物选自聚(3，4-乙烯二氧噻吩)：聚苯乙烯磺酸；更优选的，所述导电无机非金属选自硅、石墨、碳纤维、碳纳米管中的至少一种。更优选的，所述第二导电层为单层或多层薄膜。
在本发明的一个实施例中，所述的极性有机小分子选自含有羟基、氰基、羧基、巯基、羰基、酰胺基的极性有机小分子中的至少一种；更优选的，所述极性有机小分子选自甲醇、乙醇、丙醇、异丙醇、丁醇、乙二醇、甲酸、乙酸、丙酸、乙腈、乙醛、乙硫醇、丙硫醇、丙酮、四氢呋喃、N’N-二甲基甲酰胺中的至少一种；更优选的，所述的第一导电层和有机半导体层之间存在偶极矩大于1D的极性有机小分子层；更优选的，所述的极性有机小分子层可以使第一导电层和有机半导体层之间的电子注入势垒降低0.05eV以上。
进一步的，所述的有机场效应晶体管还可以包括：绝缘衬底和/或封装层；进一步的，所述的绝缘衬底为表面绝缘的衬底，在OFET的制备和使用过程中作为支撑结构存在，可以是刚性或者柔性的结构。为了避免多个OFET制备在同一衬底上产生相互干扰，衬底表面需要绝缘。在一些特殊情况下，当第二导电层本身具有一定的力学强度，可以起到支撑作用时，可以不含有绝缘衬底。例如使用重掺杂的硅片或者较厚的铜箔(可以导电)作为第二导电层时，由于第二导电层本身为刚性，可以起到支撑作用，因此可以不额外使用绝缘衬底。需要注意的是，当使用表面含有绝缘的氧化层(氧化层成分为二氧化硅)的重掺杂硅片时，存在两种情况。第一种情况为，重掺杂硅片的导电部分作为第二导电层，其表面的氧化层作为绝缘层，作为OFET的电学功能组成部分(区分于仅用作支撑的力学功能部分)使用。第二种情况为，仅将含有氧化层的重掺杂硅片作为绝缘衬底使用，在绝缘衬底上另外沉积导电材料、绝缘材料来形成第二导电层和绝缘层。上述两种情况均为常见情况。所述的绝缘衬底选自含有氧化层的硅片、玻璃、陶瓷、绝缘金属氧化物、纸张或聚合物中的至少一种；优选的，所述的聚合物可以选自聚萘二甲酸乙二醇酯、聚对苯二甲酸乙二醇酯、聚醚醚酮、聚酰亚胺、聚碳酸酯、聚醚砜树脂、聚芳脂、聚环烯烃中的至少一种。所述封装层可以起到保护OFET的作用，为聚合物材料。
可以通过带有正交偏振片的光学显微镜、原子力显微镜、扫描电子显微镜、透射电子显微镜、激光共聚焦拉曼光谱仪、单晶衍射仪等分析精细结构的仪器检测有机单晶薄膜，可以通过开尔文探针显微镜、紫外光电子能谱仪、角分辨光电子能谱仪、紫外吸收光谱、电导率法、泛函数计算等分析导电材料和有机半导体材料的能级结构，可以通过光学显微镜、原子力显微镜、扫描电子显微镜、透射电子显微镜等检测半导体器件结构，可以通过半导体参数分析仪、霍尔效应测试仪、扫描探针显微镜、铁电测试仪、量子效率测试仪、瞬态谱仪、太阳能电池测试仪、光电探测系统、显微荧光光谱仪、光谱测试仪、电导测量系统等可以分析光电性能的仪器检测半导体器件的相关性能。
为了表征第一导电层的功函数，使用紫外光电子能谱仪进行表征。为了表征有机半导体单晶的形貌，使用光学显微镜进行观测。为了表征制得的OFET的空穴迁移率、电子迁移率和平衡系数，使用半导体参数分析仪获取OFET的特性曲线，并利用迁移率计算公式和平衡系数计算公式进行计算。
实施例1
一种基于p型有机半导体单晶6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在二氧化硅表面旋涂PMMA溶液得到10nm的PMMA聚合物膜；在沉积有PMMA聚合物膜的硅片表面通过溶液法沉积TIPS-pentacene单晶。
(2)向沉积有TIPS-pentacene单晶的硅片滴加乙醇，使乙醇铺满晶体表面；旋涂除去乙醇液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
本实施例中，重掺杂的硅可直接作为第二导电层，硅片表面的300nm厚的二氧化硅层(SiO2)和旋涂得到的PMMA聚合物膜构成的双层结构(SiO2-PMMA)作为绝缘层。TIPS-pentacene单晶作为有机半导体层，真空蒸镀得到的100nm厚的金作为第一导电层。
利用紫外光电子能谱对用作第一导电层的金的功函进行测试。先将金薄膜沉积在导电性能良好的基底上，放入紫外光电子能谱仪中测得紫外光电子能谱。从谱图上可以得到截止边能量Ecutoff和费米边能量EF,如图5所示。金属的功函Φ可用下列公式计算得到：Φ＝hν-(Ecutoff-EF)。其中hv为仪器发射的紫外光能量，为21.22eV，对于与仪器电接触良好的金属样品而言，EF＝0。从图5中得到的紫外光电子能谱图结合公式可以计算得到，金的功函为Φ＝21.22-16.14＝5.08eV。利用KPFM测试注入势垒变化，用乙醇处理有机半导体单晶及金表面前后，电子注入势垒降低了0.1eV。
有机半导体单晶的判定和单晶形貌可以通过带有正交偏振片的光学显微镜进行表征。有机半导体单晶中高度有序的分子排列使得有机单晶在外观上表现出规整的边缘、规则的几何形貌，并且常表现出光学等性质上的各向异性，可在正交偏振光下观察到均匀颜色变化。图6中的(a)是由多根TIPS-pentacene单晶构成的单晶阵列，具有规整的边缘和规则的几何形貌，且在正交偏振光下表现出了图6中的(b)所示的均匀颜色变化，因此可简单判定为有机单晶阵列。
所使用的极性有机小分子的偶极矩为极性有机小分子构成的基本物体参数，可通过文献或溶剂手册简单地查询得到。结果见表1所示。
OFET的迁移率μ可通过下列公式计算得到：
其中，L为OFET沟道的长度，W为OFET沟道宽度，可通过光学显微镜得到的OFET照片获得(如图7中的(a)所示)。当半导体层未完全覆盖电极之间的区域时，W应取半导体层的实际宽度(如图7中的(b)所示)。Ci为栅极绝缘层电容，可通过带有电容分析功能的半导体参数分析仪测得，可通过测试在饱和区工作的场效应晶体管的转移特性曲线得到。通过半导体分析仪测得的实施例1中OFET的p型转移特性曲线和n型转移特性曲线分别如图8中的(a)和(b)所示。利用转移特性曲线获得曲线，再根据曲线的斜率可以得到p型和n型下的最后结合OFET的相关参数，可以计算得到μp＝0.85cm2V-1s-1，μn＝1.05cm2V-1s-1；
根据μp和μn，可以用B＝|lg(μp/μn)|计算得到该OFET的平衡参数B＝0.09。另外需要注意的是，图8所示的转移特性曲线表现出明显的V形，V型曲线的出现是OFET既能表现出空穴传输，又能表现出电子传输的一个标志。当曲线无V型特征时，可判断得到的OFET仅能传输一种类型的载流子。
实施例2
一种基于p型有机半导体单晶6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片表面沉积50nm铝作为第二导电层；随后利用气相沉积法在衬底表面沉积300nm聚对二甲苯(派瑞林)薄膜；在派瑞林表面通过溶液法沉积TIPS-pentacene单晶。
(2)向沉积有TIPS-pentacene单晶的硅片滴加甲醇，使甲醇铺满晶体表面；用氮气吹扫衬底表面除去残留的甲醇液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
实施例2中展示了利用不同于实施例1中形貌的TIPS-pentacene单晶，其形貌如图9所示。从规整的边缘和规则的几何形貌可以简单判断为单晶。需要注意的是，不论是图6中的由多根有机半导体单晶构成的单晶阵列，还是图9中的单个有机半导体单晶，都属于有机半导体单晶的范围。由TIPS-pentacene单晶构成的OFET的结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例3
一种基于p型有机半导体单晶并五苯单晶和铂的有机场效应晶体管及其制备方法，包括以下步骤：
(1)在表面平整的玻璃绝缘衬底表面沉积50nm铝作为第二导电层；随后利用原子层沉积法在沉积了铝的绝缘衬底表面沉积30nm氧化铝薄膜；将衬底放入磷酸基的自组装小分子溶液中，使自组装小分子与氧化铝表面反应，形成自组装层。将通过物理气相传输法生长得到的并五苯单晶通过显微探针操作转移到衬底表面。
(2)将表面沉积有并五苯单晶的玻璃放置在充满丙酮蒸气氛围的密闭容器中，放置2h，使丙酮分子和并五苯单晶表面充分接触。取出衬底，在空气中静置2分钟干燥。
(3)利用真空溅射的方法在晶体表面沉积100nm的铂作为第一导电层。制得基于并五苯单晶为半导体层，铂为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例4
一种基于p型有机半导体单晶红荧烯单晶和铂的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片表面沉积2nm钛和50nm金作为第二导电层；随后利用溶液法在沉积有钛和金的硅片表面沉积200nm含有交联聚苯乙烯单体，再通过热交联的方式使单晶交联，得到交联聚苯乙烯绝缘层；利用物理气相传输法生长得到红荧烯单晶，通过显微探针操作将单晶转移到绝缘层表面。
(2)将沉积有红荧烯单晶的衬底浸泡在乙硫醇中，浸泡10s后迅速取出。自然干燥衬底。
(3)利用真空溅射的方法在晶体表面沉积100nm的铂作为第一导电层。制得基于红荧烯单晶为半导体层，铂为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例5
一种基于p型有机半导体单晶四硫富瓦烯单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)以表面平整的聚酰亚胺柔性薄膜为绝缘衬底，在衬底表面沉积30nm金作为第二导电层；随后利用溶液法在衬底表面沉积300nm聚乙烯醇薄膜，利用溶液法再沉积20nm PMMA薄膜。利用物理气相传输法生长得到四硫富瓦烯单晶，通过显微探针操作将单晶转移到沉积了第二导电层和绝缘层的衬底表面。
(2)通过喷雾的方法将乙醛液滴喷在四硫富瓦烯单晶表面，在喷雾的同时进行旋涂，使喷雾液滴能够均匀地分布在单晶表面，与单晶表面充分接触，并能迅速干燥。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于四硫富瓦烯单晶为半导体层，金为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例6
一种基于p型有机半导体单晶酞菁铜单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)以玻璃为绝缘衬底，在玻璃上沉积氧化铟锡作为第二导电层利用溶液热交联法在衬底表面沉积500nm聚酰亚胺薄膜。利用物理气相传输法生长得到酞菁铜单晶，通过显微探针操作将单晶转移到聚酰亚胺薄膜表面。
(2)将甲酸滴在酞菁铜单晶表面，使液体铺满单晶表面，旋涂使甲酸液滴干燥。
(3)利用真空蒸镀的方法在晶体表面沉积30nm的金作为第一导电层。制得基于酞菁铜单晶为半导体层，金为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例7
一种基于p型有机半导体单晶2,7-二辛基[1]苯并噻吩[3,2-b][1]苯并噻吩(C8-BTBT)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)在玻璃表面沉积50nm银，在沉积了银的玻璃表面旋涂分散有氧化钛纳米例子的PMMA溶液得到500nm的氧化钛/PMMA混合绝缘层。通过溶液法在衬底表面直接生长C8-BTBT单晶阵列。
(2)将丙醇液滴滴加在C8-BTBT单晶上，使液体铺满单晶表面，旋涂使丙醇液滴干燥。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于C8-BTBT单晶为半导体层，金为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例8
一种基于p型有机半导体单晶苝单晶和铜的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片，(硅片上有300nm厚的二氧化硅)。在二氧化硅表面旋涂含有交联剂的聚乙烯基吡咯烷酮溶液，热交联后得到50nm交联聚乙烯基吡咯烷酮薄膜；在交联聚乙烯基吡咯烷酮薄膜上通过溶液法生长苝单晶阵列。
(2)向沉积有苝单晶的硅片滴加四氢呋喃，使四氢呋喃铺满晶体表面；旋涂除去二甲亚砜液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的铜作为第一导电层。制得基于苝单晶为半导体层，金为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例9
一种基于p型有机半导体单晶TIPS-pentacene单晶和PEDOT:PSS的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取表面平整的柔性聚酯薄膜作为绝缘衬底，在聚酯薄膜表面通过溶液打印的方法沉积PEDOT：PSS薄膜。在衬底通过溶液旋涂法沉积厚度为200nm的聚乙烯基苯酚薄膜，随后再旋涂含有交联剂的PMMA溶液，通过热交联的方法得到厚度为100nm的交联PMMA薄膜。在PMMA薄膜表面通过溶液法生长TIPS-pentacene单晶阵列。
(2)向沉积有TIPS-pentacene单晶的衬底滴加乙腈，使乙腈铺满晶体表面；旋涂除去乙腈液体。
(3)利用溶液打印的方法在晶体表面沉积PEDOT：PSS作为第一导电层。制得基于TIPS-pentacene为半导体层，PEDOT：PSS为源漏电极的OFET
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例10
一种基于p型有机半导体单晶2,9-二癸基二萘-[2,3-b:2,3-f]噻吩[3,2-b]噻吩(C10-DNTT)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取玻璃作为绝缘衬底，在衬底表面通过真空蒸镀的方法沉积金作为第二导电层。通过溶液旋涂的方法在金表面沉积200nm的聚偏氟乙烯共聚物作为绝缘层。通过溶液法生长得到C10-DNTT单晶阵列，再通过模板转印的方法将C10-DNTT单晶阵列转移到沉积有金和聚偏氟乙烯共聚物的绝缘衬底表面。
(2)向沉积有C10-DNTT单晶阵列的衬底滴加甲醇，使甲醇铺满晶体表面；旋涂除去甲醇液体。
(3)利用真空沉积的方法在晶体表面沉积1000nm金作为第一导电层。制得基于C10-DNTT单晶为半导体层，金为源漏电极的OFET。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
实施例11
一种基于p型有机半导体单晶苝单晶和金/氧化钨的有机场效应晶体管及其制备方法。
实施例11的有机场效应晶体管制备方法参照实施例3。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。金/氧化钨通过真空蒸镀的方法沉积。
实施例12
一种基于p型有机半导体单晶TIPS-pentacene单晶和铂/氧化钒的有机场效应晶体管及其制备方法。
实施例12的有机场效应晶体管制备方法参照实施例3。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例13
一种基于p型有机半导体单晶并四苯单晶和氧化铟锡的有机场效应晶体管及其制备方法。
实施例13的有机场效应晶体管制备方法参照实施例6。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。氧化铟锡通过转移的方法沉积。
实施例14
一种基于p型有机半导体单晶2,8-二氟-5,11-双[2-(三乙基硅基)乙炔基]-蒽并二噻吩单晶和钴的有机场效应晶体管及其制备方法。
实施例14的有机场效应晶体管制备方法参照实施例8。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例15
一种基于p型有机半导体单晶红荧烯单晶和钯的有机场效应晶体管及其制备方法。
实施例15的有机场效应晶体管制备方法参照实施例6。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例16
一种基于p型有机半导体单晶酞菁铜单晶和铬金合金的有机场效应晶体管及其制备方法。
实施例16的有机场效应晶体管制备方法参照实施例8。结构和性能表征方法与实施例1的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例17-实施例30
一种有机场效应晶体管及其制备方法。
实施例17-30的有机场效应晶体管制备方法参照实施例8。结构和性能表征方法与实施例5的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例31-实施例33
一种有机场效应晶体管及其制备方法。
实施例31-33的有机场效应晶体管制备方法参照实施例8。结构和性能表征方法与实施例9的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
实施例34-实施例36
一种有机场效应晶体管及其制备方法。
实施例34-36的有机场效应晶体管制备方法参照实施例8。结构和性能表征方法与实施例5的方法相同。材料选择配方如表2所示，得到的OFET性能如表3所示。
对比例1
一种基于p型有机半导体单晶TIPS-pentacene单晶和钙的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在二氧化硅表面旋涂PMMA溶液得到10nm的PMMA聚合物膜修饰衬底；通过溶液法沉积TIPS-pentacene单晶。
(2)向沉积有TIPS-pentacene单晶的衬底滴加乙醇，使乙醇铺满晶体表面；旋涂除去乙醇液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的钙作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
为了说明使用高功函材料作为第一导电层的优点，对比例1使用了低功函材料钙作为第一导电层。将OFET转移至空气中放置5分钟后，第一导电层的电阻从原来的22Ω增加至8810Ω(如图10中的(a)和(b)所示)，电阻增加了400倍，说明钙作为第一导电层时，容易被空气氧化造成导电性下降，即空气稳定性差。电极的氧化将严重影响半导体器件的性能。作为对比，将实施例1中的OFET转移至空气中放置5分钟后，第一导电层的电阻从15Ω变为17Ω，基本不发生变化(如图10中的(c)和(d)所示)， 说明金作为第一导电层时具有良好的空气稳定性。当在空气中的放置时间延长至2h，对比例1的第一导电层电阻增加至50KΩ，实施例1中的第一导电层电阻变为18Ω，基本不发生变化，进一步说明高功函材料作为第一导电层具有良好的空气稳定性，能够延长电极在空气环境中使用寿命。
对比例2
一种基于p型有机半导体单晶TIPS-pentacene单晶和n型有机半导体单晶富勒烯(C60)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片表面沉积50nm铝作为第二导电层；随后利用气相沉积法在沉积了铝的硅片表面沉积300nm聚对二甲苯(派瑞林)薄膜；在派瑞林薄膜表面通过溶液法沉积C60单晶，再通过溶液法沉积TIPS-pentacene单晶。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得C60和TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
为了说明仅使用一种p型半导体单晶作为半导体层构建OFET的优势，对比例2分别使用TIPS-pentacene单晶(p型)和C60单晶(n型)构建OFET。首先，当用溶液法沉积两种单晶时，对单晶沉积的顺序有要求，因为可溶解C60的苯类溶剂对TIPS-pentacene都有较高的溶解度，若先沉积TIPS-pentacene单晶，则生长C60单晶的过程会严重破坏下层的TIPS-pentacene单晶，因此只能选择先沉积C60单晶，再沉积TIPS-pentacene单晶的过程。生长得到的双层单晶结构如图11中的(a)所示，下层为C60单晶，上层为TIPS-pentacene单晶。可以看出，虽然TIPS-pentacene的溶液没有完全溶解C60，但是仍然对C60单晶的表面产生了明显的破坏。图11中的(b)为完整的C60单晶表面，可以看出，表面非常光滑平整。而经历过TIPS-pentacene生长后的C60单晶表面变得粗糙。这将严重影响两种半导体之间的界面，使最终得到的OFET性能较差。
结构与性能的表征方法与实施例1的方法相同。获得的器件相关参数及性能如表1所示。
对比例3
一种基于p型有机半导体6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)多晶薄膜和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片表面沉积50nm铝作为第二导电层；随后利用气相沉积法在沉积了铝的硅片表面沉积300nm聚对二甲苯(派瑞林)薄膜；通过溶液旋涂的方法沉积TIPS-pentacene多晶薄膜。
(2)向沉积有TIPS-pentacene多晶薄膜的衬底滴加甲醇，使甲醇铺满多晶薄膜表面；用氮气吹扫衬底表面除去残留的甲醇液体。
(3)利用真空蒸镀的方法在多晶薄膜表面沉积100nm的金作为第一导电层。制得基于
TIPS-pentacene多晶薄膜为半导体层，金为源漏电极的OFET。
为了说明使用有机单晶作为有机半导体层的优势，对比例3使用了旋涂得到的TIPS-pentacene多晶薄膜作为有机半导体层构建TIPS-pentacene。从图12中的(a)可以看出，与有机单晶规则平整的外观不同，多晶薄膜表面粗糙，由很多晶粒构成。晶粒之间的晶界将严重阻碍载流子的传输。从图12中的(b)为得到的OFET的p型转移特性曲线，可以看出，由TIPS-pentacene多晶薄膜构成的OFET的空穴迁移率较低，仅为0.367cm2V-1s-1，且转移特性曲线与实施例1中有明显区别，无法看到V型的转折，由此可判断得到的OFET无电子传输性能(电子迁移率为0)。因此平衡系数B为无穷大， 无法达到B到1的要求。
对比例4
一种基于p型有机半导体单晶6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在二氧化硅表面旋涂PMMA溶液得到10nm的PMMA聚合物膜；在PMMA薄膜表面通过溶液法沉积TIPS-pentacene单晶。
(2)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
为了说明极性有机小分子的存在对于实现高电子迁移率和空穴、电子迁移率平衡的重要性，对比例4使用了未经过极性有机小分子处理的TIPS-pentacene单晶制备OFET，图13为对比例4中OFET的p型转移特性曲线和n型转移特性曲线，从中可得到的OFET虽然仍具有较高的空穴迁移率(1.93cm2V-1s-1)，但电子迁移率μ电较低，仅为1.08×10-2cm2V-1s-1，计算得到平衡系数B＝2.25，未达到B到1的要求。说明极性有机小分子的存在对于提高以p型有机半导体单晶为半导体层，高功函导电材料为第一导电层的OFET的电子迁移率具有重要的作用。
对比例5
一种基于p型有机半导体单晶6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片上沉积50nm铝作为第二导电层；随后利用气相沉积法在沉积了铝的硅片表面沉积300nm金；通过溶液法沉积TIPS-pentacene单晶。
(2)向沉积有TIPS-pentacene单晶的衬底滴加乙醇，使乙醇铺满晶体表面；用氮气吹扫衬底表面除去残留的乙醇液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
为了说明使用绝缘材料的绝缘层是所述有机场效应晶体管的必要结构，对比例5与实施例2相比，将300nm的派瑞林绝缘层(绝缘材料)替换成了300nm的金(导电材料)。由于不具有绝缘层，制得的器件一直处于短路状态，无法正常工作。说明由绝缘材料构成的绝缘层，是所述有机场效应晶体管的必要结构。
对比例6
一种基于p型有机半导体单晶6,13-双(三异丙基硅烷基乙炔基)并五苯(TIPS-pentacene)单晶和金的有机场效应晶体管及其制备方法，包括以下步骤：
(1)取厚度为525μm的p型重掺杂<100>硅片(硅片上有300nm厚的二氧化硅)。在硅片表面沉积50nm氧化铝；随后利用气相沉积法在衬底表面沉积300nm派瑞林绝缘层；在派瑞林绝缘层上通过溶液法沉积TIPS-pentacene单晶。
(2)向沉积有TIPS-pentacene单晶的衬底滴加乙醇，使乙醇铺满晶体表面；用氮气吹扫衬底表面除去残留的乙醇液体。
(3)利用真空蒸镀的方法在晶体表面沉积100nm的金作为第一导电层。制得基于TIPS-pentacene单晶为半导体层，金为源漏电极的OFET。
为了说明使用由导电材料构成的第二导电层是所述有机场效应晶体管的必要结构，对比例6与实施例2相比，将50nm的铝(导电材料)替换成了50nm的氧化铝(绝缘材料，电阻率约为0.004S/m,[1]白晓萍,陈燕.氧化铝填料电导率对浇注体性能影响的研究[J].电气制造,2014(11):62-65.)。由于不具有可以导电的第二导电层，制得的器件无法提供栅压用于控制有机场效应晶体管的开启和关闭，无法正常工作。说明由导电材料构成的第二导电层，是所述有机场效应晶体管的必要结构。
对比例7
对比例7的有机场效应晶体管制备方法参照实施例1，唯一不同的是沉积的第一导电层厚度为15nm。结构和性能表征方法与实施例1的方法相同。
对比例8
对比例8的有机场效应晶体管制备方法参照实施例1，唯一不同的是沉积的第一导电层厚度为1500nm。结构和性能表征方法与实施例1的方法相同。
为了说明第一导电层厚度对所述有机场效应晶体管性能的影响，对比例7和对比例8分别选择了厚度小于30nm和大于1000nm的金属作为第一导电层。对比例7中，由于第一导电层厚度太小，且下方有机半导体层形貌的影响，第一导电层不连续，无法起到电极的作用，器件无法正常工作。对比例8中，由于第一导电层厚度太大，电极之间相互接触发生短路，器件同样无法正常工作。说明第一导电层的厚度需控制在30-1000nm范围之内。
对比例9
对比例9的有机场效应晶体管制备方法参照实施例1，唯一不同的是没有第一导电层。结构和性能表征方法与实施例1的方法相同。
对比例10
对比例10的有机场效应晶体管制备方法参照实施例1，唯一不同的是没有有机半导体层。结构和性能表征方法与实施例1的方法相同。
对比例11
对比例11的有机场效应晶体管制备方法参照实施例1，唯一不同的是有机半导体层为n型有机半导体单晶。结构和性能表征方法与实施例1的方法相同。
表1.实施例1-10、对比例1-8相关参数及性能

表2.实施例11-36材料选择

表3.实施例11-36性能测试

通过实施例和对比例的分析，本发明的有机场效应晶体管是由特定的材料和制备方法组成了特定结构，必须严格满足以下的所有条件才能制得具有本发明技术效果的有机场效应晶体管：依次包括第一导电层、有机半导体层、绝缘层、第二导电层，且所述的第一导电层由功函数4.5eV以上的导电材料构成；所述的有机半导体层由p型有机半导体单晶构成；所述的绝缘层由绝缘材料构成；所述的第二导电层由电导率1S/m以上的材料构成，以上条件缺一不可；通过对比例1-11可知，改变第一导电层材料使得空穴迁移率低、空气稳定性差，缺少第一导电层器件无法工作，改变半导体层的材料使得器件性能变差，缺少有机半导体层器件无法工作，缺少绝缘层或者改变第一导电层厚度等参数器件发生短路，因此可知本发明只有同时满足以上条件，才能发挥整体协同作用制得本发明的使用单一p型有机半导体材料构成的有机场效应晶体管，达到第一导电层具有良好的空气稳定性，进一步的达到空穴迁移率μp和电子迁移率μn同时≥0.5cm2V-1s-1，且平衡系数B≤1的性能。对比例中无法工作是指由于改变材料种类和参数、缺少某一层而制得的器件发生短路、无法控制晶体管的开启和关闭、无法传输电子等异常情况，使得器件无法正常工作。

Claims (20)

  1. 一种有机场效应晶体管，其特征在于，所述的有机场效应晶体管依次包括第一导电层、有机半导体层、绝缘层、第二导电层；
    所述的第一导电层由功函数4.5eV以上的导电材料构成；
    所述的有机半导体层由p型有机半导体单晶构成；
    所述的绝缘层由绝缘材料构成；
    所述的第二导电层由电导率1S/m以上的材料构成。
  2. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述的有机场效应晶体管同时满足：空穴迁移率μp≥0.5cm2V-1s-1，电子迁移率μn≥0.5cm2V-1s-1，且满足平衡系数B≤1，所述平衡系数B的计算公式为：B＝|lg(μp/μn)|。
  3. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述的有机半导体层为HOMO能级≥-5.5eV，带隙宽度≥1.8eV的有机单晶材料构成的薄膜。
  4. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述第一导电层的电导率大于1S/m。
  5. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述绝缘层选自绝缘聚合物、绝缘金属氧化物、绝缘非金属氧化物或氮化物、自组装小分子中的至少一种。
  6. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述第二导电层选自第二金属、第二导电金属氧化物、第二导电聚合物、导电无机非金属中的至少一种。
  7. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述有机半导体层选自稠环芳烃、含硫杂稠环、含氮杂稠环及其各自的衍生物的任意一种。
  8. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述的第一导电层和有机半导体层中存在偶极矩大于1D的极性有机小分子；所述的极性有机小分子的分子量小于50Da。
  9. 根据权利要求8所述的有机场效应晶体管，其特征在于，所述的极性有机小分子在一个大气压下凝固点小于25℃。
  10. 根据权利要求8所述的有机场效应晶体管，其特征在于，所述的极性有机小分子选自含有羟基、氰基、羧基、巯基、羰基、酰胺基的极性有机小分子中的至少一种。
  11. 根据权利要求8所述的有机场效应晶体管，其特征在于，所述极性有机小分子选自甲醇、乙醇、丙醇、异丙醇、丁醇、乙二醇、甲酸、乙酸、丙酸、乙腈、乙醛、乙硫醇、丙硫醇、丙酮、四氢呋喃、N’N-二甲基甲酰胺中的至少一种。
  12. 根据权利要求1所述的有机场效应晶体管，其特征在于，所述的第一导电层和有机半导体层之间存在偶极矩大于1D的极性有机小分子层。
  13. 根据权利要求12所述的有机场效应晶体管，其特征在于，所述的极性有机小分子层可以使第一导电层和有机半导体层之间的电子注入势垒降低0.05eV以上。
  14. 根据权利要求1所述的有机场效应晶体管，其特征在于，还包括：绝缘衬底和/或封装层。
  15. 一种有机场效应晶体管的制备方法，其特征在于，包括如下步骤：
    1)在绝缘衬底表面依次沉积第二导电层和绝缘层，在绝缘层上沉积有机半导体层；所述第二导电层的沉积方法选自气相沉积法、溶液法的一种或多种；所述绝缘层的沉积方法选自气相沉积法、溶液法、原子层沉积法、原位氧化法的一种或多种；
    2)将所述沉积有第二导电层、绝缘层和有机半导体层的绝缘衬底置于极性有机小分子氛围中处理10s～2h，使极性有机小分子液体或蒸气与有机半导体层表面充分接触，随后将沉积有第二导电层、绝缘层和有机半导体层的绝缘衬底与极性有机小分子氛围分离；
    3)在有机半导体层表面沉积厚度为30～1000nm的第一导电层作为电极，得到所述有机场效应晶体管；
    所述的第一导电层由功函数4.5eV以上的导电材料构成；
    所述的有机半导体层由p型有机半导体单晶构成；
    所述的绝缘层由绝缘材料构成；
    所述的第二导电层由电导率1S/m以上的材料构成。
  16. 一种光电器件，其特征在于，所述的光电器件包含如权利要求1-14任一项所述的有机场效应晶体管或如权利要求15所述的制备方法制备的有机场效应晶体管。
  17. 根据权利要求16所述的光电器件，其特征在于，所述的光电器件选自发光晶体管、存储器、传感器、显示器。
  18. 一种有机电路，其特征在于，所述的有机电路包含权利要求1-14任一项所述的有机场效应晶体管或如权利要求15所述的制备方法制备的有机场效应晶体管。
  19. 一种光电集成阵列，其特征在于，所述的光电集成阵列包含一个或多个如权利要求16-17所述的光电器件和如权利要求18所述的有机电路。
  20. 如权利要求1-14任一项所述的有机场效应晶体管、权利要求15所述的制备方法制得的有机场效应晶体管、权利要求16-17所述的光电器件、权利要求18所述的有机电路、权利要求19所述的光电集成阵列在半导体器件、交通物流、采矿冶金、环境、医疗器械、防爆检测、食品、水处理、制药、生物领域的用途。
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