A small molecule thermoelectric performance additive containing a quaternary ammonium salt group in the side chain and its preparation method and application

Abstract

The invention discloses a small molecule thermoelectric performance additive containing a quaternary ammonium salt group in the side chain, a preparation method and an application thereof, and belongs to the field of organic semiconductor materials. The invention introduces a quaternary ammonium salt group into the small molecule side chain, thereby improving the performance of the existing organic polymer thermoelectric material. The compound provided by the invention has good solubility and high miscibility with the polymer, which is conducive to solution processing of the device.

Description

Technical Field

[0001] The invention relates to the field of organic semiconductor materials, and in particular to a small molecule thermoelectric performance additive containing a quaternary ammonium salt group in a side chain, and a preparation method and application thereof. Background Art

[0002] Thermoelectric effect can realize the mutual conversion of heat energy and electrical energy, and has great potential in waste heat recovery and green refrigeration applications. Compared with inorganic thermoelectric materials, organic polymer thermoelectric materials have a wide range of sources, strong molecular modifiability, good solubility, and can be prepared on a large scale by solution methods such as spraying and roll-to-roll. They also have intrinsic flexibility and other characteristics, which can meet the requirements of wearable devices. However, the performance of current organic polymer thermoelectric materials is still far behind that of inorganic materials, and a method to improve the performance of existing organic polymer thermoelectric materials is urgently needed.

[0003] Quaternary ammonium salts are compounds generated by replacing all four hydrogen atoms in ammonium ions with hydrocarbon groups. In recent years, the research on the construction of organic polymer thermoelectric materials using quaternary ammonium salt compounds has also received more and more attention. However, in most thermoelectric materials reported so far, quaternary ammonium salt compounds are mainly used as main molecules or dopants (Adv. Funct. Mater, 2021, 31, 2010567; J. Am. Chem. Soc., 2014, 136, 13478), and there are relatively few additives used as additives to improve the performance of polymer thermoelectric materials. The development of this type of third component additive can further improve the performance of existing organic polymer thermoelectric materials, which has important research significance and practical value for the development of organic polymer thermoelectric devices. Summary of the invention

[0004] The present invention provides a small molecule thermoelectric performance additive containing a quaternary ammonium salt group in a side chain, and a preparation method and application thereof. The present invention introduces a quaternary ammonium salt group into the small molecule side chain, thereby improving the performance of existing organic polymer thermoelectric materials.

[0005] The present invention first provides a compound, the structural formula of which is shown in Formula I:

[0006]

[0007]

[0008] In the formula I, R and R' are each selected from any one of a C1-C50 straight or branched alkyl group, a C1-C50 alkoxy group, a C7-C50 aralkyl group, and a C5-C50 heteroalkyl group;

[0009] X is selected from any one of hydrogen, fluorine, chlorine, bromine and iodine; X1 is selected from any one of chlorine, bromine and iodine.

[0010] In the above-mentioned compound, the heteroatom in the heteroalkyl group is at least one of oxygen, sulfur and selenium; the number of the heteroatom substitution is 1 to 10;

[0011] In the aralkyl group, the alkyl group is any one of a C1-C50 alkyl group, a C1-C50 alkylcarbonyl group, an acyloxy group, a nitrile group and a C1-C50 alkoxy group; and the number of the alkyl substituents in the aralkyl group is an integer of 1 to 4.

[0012] In the above compounds, in Formula I, R and R' are selected from any one of C1-C16 straight chain or branched chain alkyl groups; R and R' are the same or different;

[0013] Specifically, in the formula I, R and R' are selected from any one of C1-C10 straight chain or branched chain alkyl groups; R and R' are the same or different;

[0014] More specifically, R is n-octyl; R' is methyl; X is selected from any one of hydrogen, fluorine, chlorine, bromine and iodine; and X1 is selected from any one of chlorine, bromine and iodine.

[0015] The present invention also provides a method for preparing the above compound, comprising the following steps:

[0016] Under an inert atmosphere, a compound represented by formula II and a compound represented by formula III are subjected to a substitution reaction in an organic solvent to obtain a compound represented by formula I;

[0017]

[0018] In the formula II and formula III, R, R', X and X1 are the same as those in the compound represented by the above formula I.

[0019] In the above preparation method, the molar ratio of the compound represented by formula II to the compound represented by formula III is 1:10-20; specifically, it can be 1:10;

[0020] The organic solvent is at least one of toluene, xylene, chlorobenzene and o-dichlorobenzene;

[0021] The inert atmosphere is nitrogen and / or argon atmosphere;

[0022] The temperature of the substitution reaction is 90-110° C., specifically 100° C.; the time is 24-72 hours, specifically 24 hours.

[0023] In the above preparation method, there are steps of suction filtration and washing the solid with chloroform after the substitution reaction.

[0024] The use of the above compounds as universal performance enhancers for organic polymer thermoelectric materials also falls within the protection scope of the present invention.

[0025] In the above application, the organic polymer is a conjugated polymer.

[0026] Specifically, the organic polymer is Among them, n is 10 to 99.

[0027] In the above application, the molar ratio of the compound represented by formula I to the repeating unit of the organic polymer is 1:15 to 45, and can be specifically 1:30.

[0028] The above compound (compound represented by formula I) is used as an additive to improve the thermoelectric properties of organic polymers.

[0029] The improved thermoelectric performance of the organic polymer is p-type thermoelectric performance.

[0030] The organic polymer is a conjugated polymer.

[0031] Specifically, the organic polymer is Among them, n is 10 to 99.

[0032] The present invention has the following beneficial effects:

[0033] (1) The raw materials used in the synthesis are readily available and easy to industrialize;

[0034] (2) The small molecule thermoelectric performance enhancer containing a quaternary ammonium salt group in the side chain of the present invention can improve the p-type thermoelectric performance of existing organic polymer materials;

[0035] (3) The compound itself has good solubility and a high degree of miscibility with polymers, which is conducive to solution processing of devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the preparation method of DPPNMe3Br in Example 1;

[0037] Figure 2 is the DPPNMe3Br in Example 1 1 H-NMR spectrum;

[0038] Figure 3 is the DPPNMe3Br in Example 1 13 C-NMR spectrum;

[0039] Figure 4 To improve the thermoelectric performance of polymer PDPP-EDOT based on DPPNMe3Br of Example 2;

[0040] Figure 5 This is the synthetic route of polymer PDPP-EDOT. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific embodiments. The given examples are only for illustrating the present invention, but not for limiting the scope of the present invention.

[0042] The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0043] The quantitative tests in the following examples were all repeated three times, and the results were averaged.

[0044] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0045] The structural formula of the raw material compound 1 used in the following Example 1 is It was purchased from Shuo Lun Organic Optoelectronics Technology (Beijing) Co., Ltd.

[0046] NMe3 was purchased from Beijing Bailingwei Technology Co., Ltd.

[0047] Example 1

[0048] The specific reaction conditions for the synthesis of the compound shown in Formula I (in Formula I, R is n-octyl, R' is methyl, X is a bromine atom, and X1 is a bromine atom; this compound is defined as DPPNMe3Br) are as follows:

[0049] Chemical reaction flow chart Figure 1 The specific method is as follows: Compound 1 (0.2 mmol) was dissolved in 50 mL toluene, NMe3 (2 mmol) was added, nitrogen was introduced, and the mixture was heated to 100°C for 24 hours to stop the reaction. The solid was filtered and washed with chloroform to obtain DPPNMe3Br (0.178 mmol, yield: 88%).

[0050] The structural confirmation data are as follows: 1 H NMR (400MHz, Dimethylsulfoxide-d6): δ = 8.53 (d, 2H), 7.58 (d, 2H), 3.92 (t, 4H), 3.29 (m, 4H), 3.04 (s, 18H), 1.70-1.59 (m, 8H), 1.35-1.26 (m, 16H).

[0051] Figure 2 and Figure 3 DPPNMe3Br 1 H-NMR spectra and 13 C-NMR spectrum.

[0052] Example 2

[0053]

[0054] The small molecule DPPNMe3Br prepared in Example 1 was dissolved in dimethyl sulfoxide at room temperature, and the solution concentration was 4 mg / mL. 10 μL of the above DPPNMe3Br solution was mixed with 300 μL of the o-dichlorobenzene solution of the polymer PDPP-EDOT (its concentration was 4 mg / mL) to make the molar ratio of the compound DPPNMe3Br to the polymer PDPP-EDOT repeating unit be 1:30 (the repeating unit is the smallest unit with the same chemical composition in the polymer, and its amount of substance can be obtained by dividing the mass of the polymer by the relative molecular mass of the repeating unit) to obtain a mixed solution. The above mixed solution was drop-coated on a glass substrate containing a gold electrode by a pipette gun, and the solution was drained at 60°C in a vacuum drying oven. The resulting film thickness was about 2 microns. After heating at 120°C for 1 hour, it can be used for thermoelectric performance testing.

[0055] The above-mentioned 4 mg / mL polymer PDPP-EDOT solution in o-dichlorobenzene was drop-coated on the glass substrate containing the gold electrode by a pipette, and the solution was dried in a vacuum oven at 60°C. The resulting film thickness was about 2 microns. After heating at 120°C for 1 hour, it can be used for thermoelectric performance testing.

[0056] The thermoelectric performance test method is as follows:

[0057] The conductivity (σ) and Seebeck test (S) are performed on the same film substrate. The conductivity is tested in a vacuum environment using a four-probe method. The Seebeck coefficient can be calculated by S = ΔV / ΔT, where ΔV is the thermal voltage between the two electrodes of the device when a temperature difference of ΔT is applied. ΔT is introduced by a semiconductor heating module, and ΔV is measured in a vacuum by a commercial voltmeter. The temperature difference is measured by an infrared camera. Thermoelectric performance (PF) can be calculated from the conductivity and the Seebeck coefficient by the following formula

[0058] PF=σS 2

[0059] Results Figure 4 ,Depend on Figure 4 It can be seen that DPPNMe3Br makes the thermoelectric performance of polymer PDPP-EDOT at 130℃ increase from 94μWm -1 K -2 Increased to 571μWm -1 K -2 .

[0060] The synthesis method of the above polymer PDPP-EDOT is as follows:

[0061] The synthetic route of polymer PDPP-EDOT is as follows: Figure 5As shown, the specific method is as follows: Compound 2 (150 mg, 0.16 mmol) (preparation method refers to Wang, Z, Liu, Z, Ning, L, et al., Charge Mobility Enhancement for Conjugated Dpp-Selenophene Polymer by Simply Replacing One Bulky Branching Alkyl Chain with Linear One at Each Dpp Unit. Chemistry of Materials) was added to a Schlenk tube. 2018,30:3090.), 5,7-bis(trimethyltinyl)-2,3-dihydrothiophene[3,4-b][1,4]dioxane (74.8mg, 0.16mmol) (Beijing Inokai Technology Co., Ltd.), tri(dibenzylideneacetone)dipalladium (3.0mg, 0.0032mmol) (Beijing Inokai Technology Co., Ltd.) and tri(o-methylphenyl)phosphine (7.6mg, 0.025mmol) (Beijing Inokai Technology Co., Ltd.) were dissolved in a mixed solvent of toluene (9mL) and N,N-dimethylformamide (1mL). Oxygen in the system was removed by circulating freeze extraction. The reaction system was stirred in a nitrogen atmosphere for 3 hours at 110°C. The system was then poured into methanol and stirred for 30 minutes, filtered and the solid was collected. The obtained solid was subjected to Soxhlet extraction with methanol, acetone, n-hexane and chloroform in sequence (oil bath temperature was 100°C, time was 12 hours, and solvent amount was 80 mL) to remove existing oligomers and other impurities. The insoluble dark blue solid was collected and vacuum dried at 50°C for 48 hours to obtain the purified polymer PDPP-EDOT.

[0062] In the structural formula of the polymer PDPP-EDOT, n is 10-99.

Claims

1. Application of a compound as a universal performance enhancer for organic polymer thermoelectric materials; The compound is ; The organic polymer is ,in, n is 10~99.

2. The use according to claim 1, characterized in that: In the application, the molar ratio of the compound to the repeating units of the organic polymer is 1:15-45.

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