阅读说明：本技术 三胺基甲烷衍生物作为n型掺杂剂在半导体材料中的应用 (Application of triaminomethane derivative as n-type dopant in semiconductor material ) 是由 裴坚 杨驰远 王婕妤 雷霆 丁一凡 卢阳 于 2019-04-22 设计创作，主要内容包括：本发明公开了三胺基甲烷衍生物作为n型掺杂剂在半导体材料中的应用。三胺基甲烷衍生物作为有机半导体、碳纳米管、二维半导体材料等半导体材料的n型掺杂剂,具有高稳定性高、高溶解性和高掺杂能力的优点,与有机半导体材料有良好的混溶性,且掺杂不会破坏聚合物传输电荷的π-π堆积通道,可以加工高性能的掺杂半导体厚膜。将三胺基甲烷衍生物作为n型掺杂剂应用于薄膜晶体管、热电材料、太阳能电池和发光二极管等光电器件中,可以极大的提高半导体材料体相或者界面的电子密度,降低体相或者界面的电阻、接触势垒,提高材料的n型电导率和功率因子。(The invention discloses application of a triaminomethane derivative as an n-type dopant in a semiconductor material. The triaminomethane derivative is used as an n-type dopant of semiconductor materials such as organic semiconductors, carbon nano tubes, two-dimensional semiconductor materials and the like, has the advantages of high stability, high solubility and high doping capacity, has good miscibility with organic semiconductor materials, can not damage a pi-pi stacking channel of polymer transmission charges by doping, and can be used for processing high-performance doped semiconductor thick films. The triamino methane derivative serving as an n-type dopant is applied to photoelectric devices such as thin film transistors, thermoelectric materials, solar cells, light emitting diodes and the like, so that the electron density of a bulk phase or an interface of a semiconductor material can be greatly improved, the resistance and the contact potential barrier of the bulk phase or the interface are reduced, and the n-type conductivity and the power factor of the material are improved.)

1. The application of the triaminomethane derivative as an n-type dopant of a semiconductor material is characterized in that the triaminomethane derivative has a structural general formula shown in a formula I:

wherein R is¹、R²、R³、R⁴、R⁵、R⁶Represents the same or different substituents on the methylene group in the alpha position of the N atom, R¹、R²、R³、R⁴、R⁵、R⁶Are linked to each other to form a ring, or are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group and an aryl group.

2. The use according to claim 1, wherein when R is¹、R²、R³、R⁴、R⁵、R⁶When two or more of them are bonded to each other to form a ring, they are bonded directly to each other to form a ring, or they jointly represent an alkylene group, or they form a heterocyclic ring containing O, N and/or S atoms.

3. The use according to claim 2, wherein R is¹、R²、R³、R⁴、R⁵、R⁶Two or more rings connected to each other have one or more substituents, which are hydroxyl, alkyl, alkoxy, alkenyl, alkynyl, aryl, or ester groups.

4. The use according to claim 1, wherein the alkyl group is a linear or branched alkyl group of C1 to C6, the alkenyl group is a linear or branched alkenyl group of C2 to C6, the alkynyl group is a linear or branched alkynyl group of C2 to C6, and the aryl group is a phenyl, naphthyl, pyridyl, thienyl or pyrrolyl group.

5. Use according to claim 1, wherein the triaminomethane derivative is selected from one of the following compounds:

wherein n is a positive integer.

6. Use according to claim 1, wherein the semiconductor material is an organic semiconductor material, carbon nanotubes or a two-dimensional semiconductor material.

7. Use according to claim 6, wherein the semiconducting material is one of the following polymeric semiconducting materials P1-P8:

wherein the polymerization degree n is a positive integer; r is selected from one of the following groups:

Ar¹selected from one of the following groups:

Ar²is composed of

X¹And X²Each independently is H, Cl, F or CN.

8. Use according to claim 5, wherein the semiconducting material is the following polymer FBDPPV or polymer PNDI 2T:

Technical Field

The invention relates to application of a triamino methane derivative as an n-type dopant of a semiconductor material, belonging to the field of semiconductor functional materials and the field of organic electronics.

Background

Conjugated organic small molecules, conjugated polymers, carbon nanotubes, and two-dimensional material semiconductors represented by graphene, black phosphorus, transition metal dichalcogenide, etc. have attracted much attention of scientists due to their unique properties in light, electricity, magnetism, etc., and have become a research hotspot of novel semiconductor materials in the last two decades. The organic semiconductor, carbon nano tube and two-dimensional semiconductor material based synthesis and functionalized device research relates to multiple disciplines such as chemistry, physics, electronics, materials science and the like, is a leading-edge field of multidiscipline intersection, is full of vitality and opportunity, and is one of important directions for future development of chemistry and material science.

Due to the characteristics of lightness, thinness, flexibility, easy decoration and the like, organic semiconductors, carbon nanotubes and two-dimensional semiconductor materials have wide application prospects in the field of photoelectric materials, and have obtained a series of attractive results, particularly in the fields of solar cells (PV), Light Emitting Diodes (LED), thin film transistors (FET or TFT), thermoelectric generators (TEG) and the like. The thin film transistor has the characteristics of simple and convenient processing, low cost, large-area flexible preparation, easy integration and the like, so that the research on the application aspects of electronic paper, electronic tags, active matrix driving, sensors, memories and the like has shown obvious advantages and is considered to have great market potential. Compared with the traditional inorganic thermoelectric material, the thermoelectric material as a new-generation energy conversion material has the advantages of low cost, environmental friendliness, light weight, large-area preparation and the like; meanwhile, the flexible characteristic of the thermoelectric material also provides possibility for manufacturing bendable and wearable thermoelectric power generation equipment or refrigeration equipment.

In semiconductor devices, doping is extremely critical to improve device performance. Doping can be classified as either p-type doping or n-type doping depending on the presence of the majority carriers after doping. For organic semiconductors, carbon nanotubes, and two-dimensional semiconductor materials, p-type doping and n-type doping agents adjust the hole or electron carrier density of the bulk or interface of the semiconductor material by oxidation or reduction to improve the performance of the semiconductor device. The difficulty of achieving stable n-type doping is much greater than p-type doping, subject to the band structure of the materials and the position of the fermi level. However, n-type doping plays a crucial role in semiconductor devices. For example, in a light emitting diode device, the n-type doping of the semiconductor active light emitting layer can greatly improve the operating current and the light emitting brightness of the device (Lin, X.et. al, coating the thermal ionization with photo-activation of n-doping in organic semiconductors. Nat.Mater.2017,16(12), 1209-1215.). In a Solar cell device, the interface between the electron transport layer and the semiconductor active layer is doped n-Type, which can improve the short-circuit current and the energy conversion efficiency of the device (Wu, Z.H.et. al, n-Type Water/Alcohol-solvent Naphthalene dioxide-Based Conjugated Polymers for High-performance polymer solvent cells, J.Am.chem.Soc.2016 (6), 2004-) 2013.). In the thin film transistor, the n doping is carried out on the interface of the semiconductor active layer and the metal electrode, so that the injection barrier and the contact resistance of a carrier can be reduced, the mobility and the on-off ratio of the device can be improved, and the high-performance and large-area flexible device is guaranteed (Lussem, B.et.al, Doped organic transistors, chem.Rev.2016,116(22), 13714-13751.). In Thermoelectric Materials, the n-doping of semiconductor bodies can effectively adjust the carrier concentration and greatly improve the conductivity and power factor of the Materials (Kroon, R.et. al., Thermoelectric plastics: from design to synthesis, processing and structure-property relationships.Chem.Soc.Rev.2016,45 (22)), 6147-. For carbon nanotubes, graphene and other two-dimensional semiconductor materials, n-type doping plays a very important role in widening material application and improving device performance. For example, n-Type Doping of Graphene can effectively adjust the work function, and is applied to a transparent Cathode electrode (Kwon, s. — j.et.al, Solution-Processed n-Type Graphene Doping for Cathode in incorporated polymer light-Emitting diodes, acs appl.mat. interfaces 2018,10(5), 4874-phase 4881); the n-type doping of the Carbon Nanotube can adjust the carrier concentration and the existence form of the main carrier, and a high-performance Thermoelectric device (Blackburn, j.l. et. al, Carbon-Nanotube-Based Thermoelectric Materials and devices, adv. mater.2018,30(11), 1704386.); similarly, the defect state in the material can be filled up by n-Doping the classical two-dimensional materials such as molybdenum disulfide or Black Phosphorus, the carrier mobility is greatly improved, and a foundation is laid for a High-performance semiconductor device (Xu, Y.; et al, Field-Induced n-Doping of Black Phosphorus for cmos compatible 2D electronic devices with High electronic mobility. adv. Funct. Mater.2017,27(38), 1702211.). In summary, the n-type dopant has irreplaceable effects on the n-type doping of the semiconductor in regulating the carrier type and number of the active layer of the device and improving the carrier injection of the interface of the active layer and the electrode and carrier transport layer. Therefore, the development of high-performance n-type dopants is of great importance in device applications of organic semiconductors, carbon nanotubes, and two-dimensional semiconductor materials.

N-type doping of organic semiconductors, carbon nanotubes, two-dimensional semiconductor materials is essentially a controlled reduction of the material while stably retaining the reduced state of the semiconductor in the aggregate and solid states. Therefore, the n-type dopant having good performance needs to satisfy the following conditions: 1. the reducibility of the material is stronger, or a strong reducing substance can be generated in a doping reaction so as to ensure good n-doping capability; 2. the n doping of the semiconductor is stable, and the de-doping is not easy to occur, so that the service life of the semiconductor device is ensured; 3. it also requires a certain chemical stability and less severe conditions of use in order to ensure storage and processability. The n-type dopants currently used in the above semiconductors can be mainly classified into low ionization energy compounds, vaporizable organic salts, active carbon-carbon bond compounds and active carbon-hydrogen bond compounds according to their chemical structure characteristics, as shown in the following table:

wherein the low ionization energy compound mainly comprises alkali metal lithium, sodium, calcium and potassium, alkali metal nitride lithium and sodium nitride, and low valence metal complex Cr₂(hpp)₄、W₂(hpp)₄Cobaltocene (CoCp)₂) Rhodium metallocenes (RhCp)₂) Organic reducing agents such as bisdithiolopentacene (TTN), tetrakis (dimethylamino) ethylene (TDAE), etc. These n-type dopants, which are highly reducing, are inherently sensitive to air, are not easily stored, have poor solution processability, can only be used for doping semiconductors by vacuum evaporation (diffusion) and inert matrix dispersion methods, and are susceptible to dedoping after doping semiconductors. The evaporable organic salt compounds are generally conjugated quaternary ammonium halide anion salts, mainly comprising crystal violet (CrystalViolet), Pyronin (Pyronin B), dimethylbenzimidazole salts (o-MeO-DMBI-I), tetrabutylammonium fluoride (TBAF). The dopant has good stability, but the processing mode for doping the semiconductor is basically limited to vacuum evaporation, and only tetrabutylammonium fluoride (TBAF) has certain solution processability. The active carbon-carbon bond compound mainly comprises a dimeric (dimethylbenzimidazole) derivative (2-Cy-DMBI)₂Dimeric cyclopentadienyl rhodium (RhCp)₂)₂Dimeric (pentamethylcyclopentadienyl triethylphenylrhodium) (Cp Ru (TEB))₂The compound can be doped with semiconductors in a vacuum evaporation or solution processing mode, has strong doping capability but poor stability and is sensitive to air, light and temperature. The active carbon-hydrogen bond compound comprises leuco-Crystal Violet (DPDPDPH), dihydropyridine derivative (DPDPDPH),The dimethyl dihydroimidazole pyridine derivative (N-DMBI) can be used for doping a semiconductor in a vacuum evaporation or solution processing mode, and has stronger doping capability; in particular, for N-DMBI, it is currently the best performing organic N-type dopant due to its very strong doping capability. The stability of the active carbon-hydrogen bond compound is stronger than that of a homologous active carbon-carbon bond compound, the active carbon-hydrogen bond compound is basically stable to air, but is still sensitive to light and temperature, and the active carbon-hydrogen bond compound is unstable in processing solvents such as chloroform and trichloroethylene which are commonly used for processing semiconductors by a solution method. In summary, n-type dopants suitable for organic semiconductors while satisfying strong doping properties, good processability, high chemical stability, and high stability of the doped devices are still under development.

Disclosure of Invention

Aiming at the problems of few structures and poor performance of high-performance n-type dopants which are suitable for organic semiconductors, carbon nanotubes and two-dimensional semiconductor materials at present, the invention aims to provide an n-type dopant with a brand-new chemical structure. The n-type dopant has the advantages of simple chemical structure, quick and simple synthesis, strong doping property, good processability, high chemical stability and high stability of a doped device. After the representative n-type polymer semiconductor material FBDPPV is doped, the highest conductivity (more than 20S/cm) and power factor (more than 50 muW/mK) of the current n-type polymer semiconductor material can be obtained²). The strategy has extremely important significance for practical device application of the n-type low-dimensional semiconductor.

In a first aspect of the present invention, a triaminomethane (triaminomethane) derivative having a general structural formula shown in formula I below is provided as an n-type dopant for an organic semiconductor, a carbon nanotube, or a two-dimensional semiconductor material:

wherein R is¹、R²、R³、R⁴、R⁵、R⁶Represents the same or different substituents on the methylene group in the alpha position of the N atom, R¹、R²、R³、R⁴、R⁵、R⁶Two or more of which may be linked to each other to form a ring, or each may be independently selected from a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group and an aryl group.

When R is¹、R²、R³、R⁴、R⁵、R⁶When two or more of them are bonded to each other to form a ring, they may be bonded directly to each other to form a ring, or they may be bonded to each other to form an alkylene group (e.g., methylene, ethylene, etc.), or they may form a heterocyclic ring containing O, N and/or S atoms. The ring formed may have one or more substituents thereon, which may be hydroxyl, alkyl, alkoxy, alkenyl, alkynyl, aryl, ester groups, and the like. Wherein when R is¹、R²、R³、R⁴、R⁵、R⁶In the case where two or more of them are connected to form a fused ring structure of a three-to eight-membered ring, the substituents on the rings are preferably hydroxyl, acetal group, or acyloxy group.

When R is¹、R²、R³、R⁴、R⁵、R⁶When not linked to a ring, it is preferably a hydrogen atom, a linear or branched alkyl group (e.g., methyl, ethyl, propyl, isopropyl, etc.) having from C1 to C6, a linear or branched alkenyl group (e.g., vinyl, propenyl, etc.) having from C2 to C6, a linear or branched alkynyl group (e.g., ethynyl, propynyl, etc.) having from C2 to C6, or an aryl group such as phenyl, naphthyl, pyridyl, thienyl, pyrrolyl, etc.

The design principle of the triaminomethane compound as an n-type dopant is as follows:

(1) three tertiary nitrogen atoms are arranged around a carbon-hydrogen bond in the center of a molecule, and the strength of the carbon-hydrogen bond in the center can be weakened by utilizing the orbital interaction (anomeric effect) of a nitrogen atom lone pair electron and a carbon-hydrogen bond reverse bond orbit, and simultaneously, the charge density of a hydrogen atom is greatly improved, so that the hydrogen atom becomes an active carbon-hydrogen bond compound, can provide negative hydrogen ions when reacting with a semiconductor, and becomes an n-type dopant with high doping capacity;

(2) all nitrogen atoms in molecules are tertiary nitrogen atoms, and methylene substituted by alkyl is saturated, so that the electrical enrichment property of the nitrogen atoms can be increased, the charge density of central hydrogen atoms is further improved, and the n-type doping reaction activity is improved. The introduction of the hydrocarbyl can also obviously improve the solubility and the processability of the triamino methane in an organic solvent, simultaneously improve the miscibility of counter ions (shown as a formula II) generated after n doping with an organic semiconductor and a polymer semiconductor alkyl side chain, and greatly weaken phase separation caused by doping reaction so as to improve the electrical property of the material and the stability of a device.

(3) All substituents R¹～R⁶The active nitrogen atoms and carbon-hydrogen bonds in the methylene group and the center are separated, the active center does not contain conjugated structures such as double bonds, benzene rings and the like, and the stability of the triamino methane in visible light and near ultraviolet light environments can be remarkably improved;

(4) the triaminomethane is converted into the guanidine positive ion (formula II) with alkyl substitution after being doped, has extremely high chemical stability, and R¹～R⁶The substitution of (a) may further stabilize the guanidine cation by a hyperconjugation effect. Meanwhile, the positive ions have a certain volume due to the substitution of the hydrocarbyl, are not easy to diffuse and migrate, have strong interaction with alkyl side chains of the semiconductor, and are favorable for stabilizing the stability of the doped device.

According to the above design principle, R¹～R⁶Are all preferably R first¹And R⁶、R²And R³、R⁴And R⁵Are respectively connected to form a ring and jointly represent methylene, and the specific structure is as follows:

in the triamino methane (named TAM) structure, the formation of six-membered condensed rings can stabilize the trans conformation of all nitrogen atom lone pair electrons and central carbon-hydrogen bonds, and the triamino methane has very high n doping capacity according to the design principle (1); the formation of six-membered fused rings can also effectively stabilize positive ions, and according to the design principle (4), the product after the triamino methane is doped has very strong stability. Meanwhile, the triamino methane has extremely high molecular symmetry, and is favorable for large-scale synthesis preparation and application.

Secondly preferred, R²And R³、R⁴And R⁵Are each linked to form a ring, and jointly represent a methylene group, R¹And R⁶Directly connected to form a ring, and the concrete structure is as follows:

in the triaminomethane structure (named TAM)₅₆₆) In the middle, the five-membered and six-membered condensed rings can also stabilize the trans conformation of all nitrogen atom lone pair electrons and central carbon-hydrogen bonds, and the triamino methane also has very high n doping capacity according to the design principle (1); the formation of five-membered and six-membered fused rings can also effectively stabilize positive ions, and according to the design principle (4), the product after the triamino methane is doped also has strong stability. Meanwhile, the triamino methane also has higher molecular symmetry and is easy to synthesize, prepare and apply.

Again preferred, R¹And R⁶Directly linked to form a ring, R³And R⁴Directly linked to form a ring, R⁵And R⁶Directly connected to form a ring, and the concrete structure is as follows:

in the triaminomethane (named TAM)_3T) In the structure, the electron density of nitrogen atoms can be greatly improved by forming an aziridine structure, and the triamino methane also has higher n-doping capacity according to the design principle (2); however, the lack of a fused ring structure makes the positive ions generated after doping thereof inferior to the aforementioned TAM and TAM₅₆₆The structure is stable. The triamino methane also has extremely high molecular symmetry, and is favorable for large-scale synthesis preparation and application.

Then, R¹～R⁶Are each preferably a hydrogen atom, preferred triaminomethanesThe specific structure of the alkane is as follows:

in the triaminomethane (named TAM)_Me) In the structure, R does not form a cyclic structure¹～R⁶The smaller steric hindrance and the hyperconjugation effect between the two can also increase the electron density of nitrogen atoms and stabilize positive ions generated after doping. According to design principles (2) and (4), the triaminomethane should also have a strong n-doping capability. The triamino methane also has extremely high molecular symmetry, and is favorable for large-scale synthesis preparation and application.

Specific structures of the remaining preferred triaminomethanes are exemplified below:

n in the above structural formula represents a positive integer, preferably a positive integer of 5 to 200.

According to the design principle (3), all the triaminomethanes should have the stability in the visible light and near ultraviolet light environments, and the stability is proved by experiments (see example four). Compared with the existing N-type organic dopant N-DMBI with the best performance, the triamino methane compound has extremely high chemical stability and light stability. In particular, the triaminomethane-based compound is soluble in water and exhibits extremely high stability in an aqueous solution.

The triaminomethane compound shown in the formula I can be used as an n-type dopant of semiconductor materials such as organic semiconductors, carbon nanotubes, two-dimensional semiconductor materials and the like, and includes but is not limited to the following polymer semiconductor materials P1-P8 (wherein the polymerization degree n is a positive integer, and the preferable value range is 5-200):

among them, the substituent of the polymer P1 is preferably X¹＝H，X²(ii) F, R ═ 4-octadecyldialkyl, Ar¹A preferred P1 has the structure:

the triamino methane and the polymer (named as FBDPPV, the preferable value range of the polymerization degree n is 10-100) are mixed and processed to form a film, so that the conductivity of the polymer can be remarkably improved (from 10)^-6The S/cm is increased to 0.5-21S/cm), the Seebeck coefficient of the doped FBDPPV is tested under the temperature gradient environment, and-60 to-405 mu V K can be obtained^-1The seebeck coefficient of (a) proves that triaminomethane can effectively n-dope a polymer semiconductor.

The substituent of the polymer P4 is preferably R ═ 2-octyldecyl, Ar¹A preferred P4 has the following structure:

the triamino methane and the polymer (named as PNDI2T, the preferable value range of the polymerization degree n is 10-100) are mixed and processed to form a film, and the conductivity of the polymer can be remarkably improved (from 10)^-8Lifting S/cm to 10^-3S/cm) demonstrating that triaminomethane can effectively n-dope polymeric semiconductors, see examples five to twelve.

The preferred Triaminomethane (TAM) doped FBDPPV and PNDI2T films were analyzed by grazing incidence X-ray diffraction (GIWAXS) and, as a result, it was found, as shown in fig. 6, that the doping of the polymer with triaminomethane did not disrupt the original molecular chain stacking of the polymer, and in particular, the pi-pi stacking in the charge transport channel direction of the polymer molecular chains. Even if the impurity content ratio reaches triaminomethane to polymer of 1:1, no phase separation occurs. In contrast to the typical active carbon hydrogen bond dopant dimethyldihydroimidazolium pyridine derivative (N-DMBI), it disrupts the polymer pi-pi stacking and phase separation upon doping of the above polymers. This demonstrates the passage of R¹～R⁶The introduction of the alkyl can effectively reduce the interaction of the dopant on the ion and the conjugated main chain of the polymer and increase the interaction of the dopant on the ion and the alkyl side chain of the polymer, thereby avoiding the damage of doped polymer pi-pi accumulation and the phase separation. Therefore, the triaminomethane has excellent miscibility with the organic semiconductor, and can realize uniform doping of the organic semiconductor. See example thirteen.

In thermoelectric devices such as thermoelectric generators, the thickness of the semiconductor layer is of great importance for maintaining the temperature difference and increasing the output power, and the thickness of doped Organic thermoelectric materials reported in the literature is often in the nanometer level, which greatly limits the practical application of Organic semiconductor materials in thermoelectric devices (Russ b.et.al, Organic thermoelectric materials for energy harnessing and temperature control nat. rev. mater.2016,1(10), 1-14; Kim s.j.et.al, a portable thermoelectric generator fabricated glass fiber energy. The triaminomethane doped organic semiconductor has excellent solution processability, the doping reaction can be conveniently regulated and controlled by temperature, and the doped organic semiconductor film shows high uniformity in a solid state, so that the triaminomethane can be used for preparing the doped organic semiconductor with high electrical property, high stability and thickness of 10 microns. In contrast, N-DMBI doped organic semiconductor films can exhibit higher electrical performance only at the 10nm level.

Therefore, the triaminomethane compound can be used as an n-type dopant of semiconductor materials such as organic semiconductors, carbon nanotubes, two-dimensional semiconductor materials and the like, including but not limited to application in photoelectric devices such as thin film transistors, thermoelectric materials, solar cells, light emitting diodes and the like, and proves that the triaminomethane compound can greatly improve the electron density of a semiconductor material bulk phase or an interface, reduce the resistance and the contact potential barrier of the bulk phase or the interface, and improve the n-type conductivity and the power factor of the material.

In a second aspect of the present invention, there is provided a method for synthesizing, storing and doping a triaminomethane (triaminomethane) derivative.

According to the substituent R¹～R⁶The triaminomethane compound shown in the formula I can be prepared by adopting one of the following methods:

(1) the preparation method is directly prepared by the condensation reaction of amine and N, N-dimethylformamide dimethyl acetal:

(2)R¹～R⁶when two or more fused ring structures are formed, the compound can be prepared by nucleophilic substitution reaction of substituted guanidine and halogenated hydrocarbon or sulfonate, and then reduction by sodium borohydride or lithium aluminum hydride:

the synthesis method is controlled to be a reaction of 1-2 steps, does not need metal catalysis and anaerobic reaction conditions, does not relate to complex oxidant and reducing agent, uses low-toxicity solvents such as alcohols and ethers as reaction solvents, controls the reaction temperature at 0-100 ℃, and can be suitable for large-scale production.

The pure triaminomethane compound is stable to sunlight and air, can absorb moisture reversibly in humid air, and is stable to water. The triamino methane without alkene and alkyne groups is stable to near ultraviolet light, and can be stored for a long time after being sealed. The triamino methane containing alkene and alkyne groups can be stored for a long time by being sealed in a dark place. Triaminomethane is dissolved and stabilized in a pure halogenated solvent such as dichloromethane, chloroform, trichloroethylene, tetrachloroethane, chlorobenzene, o-dichlorobenzene, and solution processing can be carried out using the above halogenated solvent. In addition to the above halogenated solvents, the triaminomethane can be solution processed using at least one of the following common solvents:

(1) protic solvents such as water, methanol, ethanol, isopropanol, and ethylene glycol;

(2) ether solvents such as diethyl ether, tetrahydrofuran, and ethylene glycol dimethyl ether;

(3) nonpolar solvents such as n-hexane, n-octane, cyclohexane, toluene, and p-xylene;

(4) dipolar solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, pyridine, and N-methylimidazole.

In addition to solution processing, triaminomethane with molecular weight less than 190g/mol is also suitable for processing by vacuum evaporation, vacuum diffusion and other modes.

The invention designs a novel triaminomethane compound and provides an efficient synthesis method of the compound. The invention also proves that the triaminomethane can be used as a high-efficiency n-type dopant applied to organic semiconductors, carbon nano tubes and two-dimensional semiconductor materials. As an organic n-type dopant, triaminomethane has the following advantages: (1) high stability, high solubility and high doping ability; (2) the compatibility with an organic semiconductor is good, and the doped pi-pi stacking channel which can not damage the charge transmission of the polymer is avoided; (3) high performance doped semiconductor thick films can be processed. Therefore, the result can be widely applied to the electronic field, including the fields of solar cells (PV), Light Emitting Diodes (LED), Thin Film Transistors (TFT), thermoelectric generators (TEG), and the like.

Drawings

FIG. 1 shows representative triaminomethanes TAM (a) and a comparative dopant N-DMBI (b) in deuterated trichloromethane¹H-NMR nuclear magnetic resonance spectrum, and nuclear magnetic spectrum over time, to demonstrate high stability of TAM in solution.

FIG. 2 shows representative triaminomethanes TAM (a) and the comparative dopant N-DMBI (b) in deuterated benzenes¹H-NMR nuclear magnetic resonance spectrum, and nuclear magnetic spectrum under light over time to demonstrate high stability of TAM in solution.

FIG. 3 shows TAM in deuterated water¹H-NMR nuclear magnetic resonance spectrum to show the solubility and high stability of TAM in water.

Fig. 4 is a schematic diagram of a four-probe conductivity test using a dopant-doped organic semiconductor of the present invention as an active layer material.

Fig. 5 is a schematic diagram of a Seebeck coefficient test performed by using the dopant-doped organic semiconductor of the present invention as an active layer material.

FIG. 6 is a grazing incidence X-ray diffraction (GIWAXS) analysis of Triaminomethane (TAM) and dimethyldihydroimidazopyridine derivative (N-DMBI) doped FBDPPV, PNDI2T films, wherein a is the TAM doped FBDPPV film, b is the N-DMBI doped FBDPPV film, c is the TAM doped PNDI2T film, and d is the N-DMBI doped PNDI2T film.

Fig. 7 is a graph of uv-vis-nir absorption spectra of representative triaminomethane compounds TAM mixed with organic semiconductors fbdppv (a) and PNDI2T (b) at different temperatures to show that the triaminomethane doping can be conveniently controlled with temperature.

Fig. 8 is a graph of the optimum conductivity as a function of film thickness for a representative triaminomethane based compound TAM and a comparative dopant N-DMBI doped FBDPPV (a), and the conductivity as a function of time in air for an unencapsulated TAM doped FBDPPV of 10 μm thickness (b), to demonstrate that triaminomethane can process high performance, high stability N-type organic semiconductor films.

Detailed Description

The invention will now be described in further detail by way of examples with reference to the accompanying drawings, without in any way limiting the scope of the invention.