CN104974174A - Linear oligothiophene organic small-molecule semiconductor material - Google Patents

Abstract

The invention discloses an organic small molecule semiconductor material, which includes a Cor group and two structural units, wherein each structural unit includes an FT group, and a 3,4-position modified by an alkoxy group or an alkylthio group. A thiophene unit and an A group, the A group is connected to the Cor group through the thiophene unit and the FT group in turn, wherein the A group is an electron-accepting group unit, and the FT group includes 1 to 12 An oligothiophene short-chain unit formed by combining two modified or unmodified thiophenes, and the Cor group includes a condensed ring π-conjugated unit formed by parallel connection of two or more 5- or 6-membered rings or a derivative unit thereof. The organic small molecular semiconductor material of the invention has the advantages of small spectral band gap, long spectral absorption wavelength and the like, and can be applied to organic semiconductor optoelectronic devices.

Description

A linear oligothiophene organic small molecule semiconductor material

technical field

The invention relates to an organic small molecule semiconductor material, in particular to a linear oligothiophene organic small molecule semiconductor material, which belongs to the field of organic semiconductor materials.

Background technique

Organic semiconductor materials have the advantages of light weight, good flexibility, low production cost, and easy large-scale production. They have become the most eye-catching new technologies and new products with huge market prospects in the field of research and development and the booming organic electronics industry in recent years. .

Organic semiconductor materials mainly include high molecular organic materials and small molecular organic materials. Since the polymer material is a mixture, its structure is uncertain, the dispersion is large, it is not easy to purify, and it is easy to cause differences between material batches. In contrast, organic small molecule semiconductor materials have the advantages of simple and definite structure, easy purification, and good reproducibility in practical applications.

Organic semiconductor materials have a wide range of applications, including organic electroluminescent diodes (OLEDs), organic field effect transistors (OFETs), organic photovoltaic cells (OPVs), chemical sensors, organic semiconductor lasers, and many other categories. It is worth mentioning that small molecule materials of oligothiophene derivatives play an extremely important role in the application of organic semiconductor materials, mainly in the application of organic field effect transistor (OFET) and organic photovoltaic cell (OPV), especially in recent years. Fruitful results have been obtained in the research, and the photoelectric conversion rate of organic photovoltaic devices even exceeds 10%.

Functional modification of linear oligothiophenes is a common approach to construct efficient organic small molecule semiconductors. At present, the functional modification of linear oligothiophenes includes introducing electron-donating conjugated units at the center of linear oligothiophenes and introducing two electron acceptor units at the two α-terminal positions of linear oligothiophenes. This method can form an electron-donor-acceptor structure in the molecule, reduce the spectral band gap of the material, and red-shift the absorption spectrum of the material. However, when the length of the linear oligothiophene conjugated chain is longer, since the distance between the terminal acceptor unit and the conjugated body of the oligothiophene is enlarged, the intramolecular electron-donating-acceptor structure reduces the resistance of the material. The role played by the spectral band gap becomes weaker, and the absorption spectrum of the material cannot be further red-shifted, which limits the application of this method in the development of high-efficiency new materials.

Contents of the invention

Aiming at the deficiencies in the prior art, the main purpose of the present invention is to provide an organic small molecule semiconductor material, which has a lower spectral band gap and a longer spectral absorption wavelength.

To achieve the above object, the technical scheme adopted in the present invention is as follows:

An organic small molecule semiconductor material, comprising a Cor group and two structural units connected to the Cor group, each structural unit includes a FT group, a 3,4-position composed of alkoxy or alkylthio A modified thiophene unit and an A group, the A group is sequentially connected to the Cor group through the 3,4-position modified thiophene unit by alkoxy or alkylthio group and the FT group,

Among them, the A group is an electron-accepting group unit, the FT group includes an oligothiophene short chain unit formed by combining 1 to 12 modified or unmodified thiophenes, and the Cor group includes two or more 5- or 6-membered rings. The condensed ring π-conjugated unit formed in parallel or its derivative unit, the thiophene unit modified by alkoxy or alkylthio at the 3,4-position has the following structural formula:

Wherein, X includes an oxygen atom or a sulfur atom, and R ₁ and R ₂ include a substituted or unsubstituted C1-C20 alkyl group or a C1-C20 heteroalkyl group.

Further, the structural formula of the small organic molecule semiconductor material can refer to FIG. 1 .

Further, in the thiophene unit modified by alkoxy or alkylthio at the 3,4-position, R ₁ and R ₂ are connected to each other, and connected to the 3,4-position of the thiophene ring. An oxygen or sulfur atom and adjacent CC bonds on the thiophene ring form a 5- to 8-membered substituted or unsubstituted ring structure.

Compared with the prior art, the present invention has at least the following advantages: the symmetrical two terminal positions of the linear thiophene in the organic semiconductor molecule are formed by an electron-accepting group unit and directly connected with the 3,4-position by an alkoxy group Or a compound unit composed of an alkylthio-modified thiophene unit, by directly connecting the electron-accepting group A with the 3,4-position of alkoxy or alkylthio-modified thiophene unit with strong electron-donating ability, so that the electron donating and accepting The distance between the body units is shortened to the minimum, and the role of the electron-accepting group unit is maximized. On this basis, by introducing a linear conjugated oligothiophene short chain (FT) and a functional conjugated core unit (Cor), the spectral band gap and absorption spectrum of the modified linear oligothiophene unit can be further adjusted, which is more conducive to the material in the Application performance on organic semiconductor devices.

Description of drawings

Fig. 1-1 is the structural formula of organic small molecule semiconductor material of the present invention;

Fig. 1-2 is the structural formula of a kind of annular structure in organic small molecule semiconductor material of the present invention;

Figure 2-1 to Figure 2-10 are the molecular structural formulas of some exemplary compounds of the present invention;

Figures 3a to 3b are the molecular structural formulas of the two oligothiophene organic semiconductor molecules H and J whose structures are compared with each other in the present invention;

Fig. 4 is the absorption spectrum of oligothiophene organic semiconductor molecules H and J shown in Fig. 3a-Fig. 3b;

Fig. 5-Fig. 10 are the synthesis process roadmaps of Examples 1-6 of the present invention respectively.

Detailed ways

In view of the foregoing defects of the prior art, the inventors of the present case have conducted a lot of research and practice, by directly combining a thiophene unit modified by an alkoxy group or an alkylthio group at the 3,4-position with strong electron-donating properties with an electron-accepting group unit The compound units formed by connecting are used as the two terminal groups of linear thiophene, and then a new type of organic semiconductor molecule is constructed, which can reduce the distance between the electron acceptor group unit and the electron donor group unit in the molecule , to enhance the degree of charge separation in the molecule, thereby realizing the absorption spectrum of the red-shifted oligothiophene organic small molecule semiconductor material, and reducing the spectral band gap of the material.

Specifically, the organic small molecule semiconductor material of the present invention has the molecular structural formula shown in Figure 1, wherein, X includes an oxygen atom or a sulfur atom, A is an electron-accepting group unit, and FT includes 1 to 12 modified or unmodified The oligothiophene short chain unit formed by the combination of thiophenes, Cor includes condensed ring π-conjugated units formed by parallel connection of two or more 5- or 6-membered rings or its derivative units, R ₁ and R ₂ include substituted or unsubstituted C1～ A C20 alkyl group or a C1-C20 heteroalkyl group.

In the technical scheme of the present invention, one aspect thereof is to directly link the 3,4-position thiophene units modified by alkoxy or alkylthio groups with strong electron-donating properties to the electron acceptor unit A to form a terminal modification group group.

In one embodiment of the present invention, in the thiophene unit modified by alkoxy or alkylthio group at the 3,4-position, R ₁ and R ₂ are connected to each other, and connected to 3 in the thiophene ring , Two oxygen or sulfur atoms at the 4-position and adjacent CC bonds on the thiophene ring form a 5-8 membered or unsubstituted ring structure.

Further, the ring structure includes a thiophene unit, and at least one molecular fragment is connected between the oxygen and/or sulfur atoms modified at the 3,4-position of the thiophene unit, and the molecular fragment includes -CH ₂ - _CH2- .

More specifically, the ring structure may have the structural formula shown in Figure 1-2, wherein X is an oxygen atom and/or a sulfur atom, -Y- is a molecular fragment, and the molecular fragment includes -CH ₂ -CH ₂ - .

Further, the thiophene units modified by alkoxy or alkylthio groups at the 3,4-position with strong electron-donating properties in the present invention include the following two types:

(1) There is no cross-connection between the 3,4-position substituting modification groups, forming two independent substituting groups. The modification units R ₁ and R ₂ are independently selected from substituted or unsubstituted C1-C20 alkyl groups or C1-C20 heteroalkyl groups in each case. R ₁ and R ₂ may or may not be the same in principle. However, in the process of the present invention, modifying units having the same structure are actually selected. _In the solution provided by the present invention, the adjustment of the structure _of the R1 and R2 modification units can further adjust the solubility of the material and improve the application effect of the material in the device preparation process. The following are some modified units used in the solutions disclosed by the present invention, but the solutions provided by the present invention are not limited to the following units.

(2) The 3,4-position substituted modification groups R1 and R2 are connected to each other, and form a 5~ 8-membered substituted or unsubstituted ring structures. In order to further illustrate the structure of the units of the present invention, some examples are enumerated below, but the modified structures involved in the present invention are not limited to the following structural units:

In the above technical solution provided by the present invention, the modification of the substituting modification groups on the 5-8 membered ring can further adjust the solubility of the material and improve the application effect of the material in the device preparation process.

In order to further highlight the effect of the present invention, the present invention also selects an electron-accepting group unit, which is directly connected to the above-mentioned thiophene unit modified by alkoxy or alkylthio at the 3,4-position. The selection of the electron-accepting group unit is mainly based on two key factors: the electron-accepting ability and the solubility of the material. In the solution of the present invention, the electron receiving unit can have but not limited to the following structure:

Wherein, R ₃ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl.

More preferably, A has any one of the following structural formulas:

Wherein, R ₃ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl.

In order to increase the degree of conjugation of molecules, in the technical solution of the present invention, the degree of conjugation of material molecules can also be adjusted by introducing oligothiophene short-chain conjugation units (FT). In the series of thiophene short-chain conjugated units, it is also possible to further adjust the solubility of the material by introducing substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkane substituent units, and improve the material in the device preparation process. application effect.

The oligothiophene short-chain conjugate unit (FT) has at least any one of the following structural formulas:

Among them, R ₄ , R ₅ , and R ₆ include hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, m and n are integers from 0 to 2, and m and n cannot be 0, r is 1 or 2, one of R ₇ and R ₈ is hydrogen, the other is substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, q is any between 1-12 an integer.

Further, FT has at least any one of the following structural formulas:

Wherein, R ₉ includes substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, R ₁₀ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl.

In order to further illustrate the structure of the unit of the present invention, some examples thereof are enumerated below, but the modified structures involved in the present invention are not limited to the following structural units:

1. Oligothiophene short-chain conjugated unit with centrosymmetric structure:

Wherein t is a definite integer from 1 to 12.

2. Oligothiophene short-chain conjugated unit with regular structure:

In order to further adjust the spectral band gap and material absorption spectrum performance of the material, in the technical solution of the present invention, the core of the linear oligothiophene unit is also introduced into the π-conjugated functional unit Cor, wherein Cor includes two and A condensed ring π-conjugated unit formed by parallel connection of the above 5 or 6-membered rings or a derivative unit thereof.

List some of them below, but the modified structures involved in the present invention are not limited to the following structural units:

Among them, X ₁ , X ₂ , and X ₃ are independently selected from any one of atoms such as O, S, Se, Si, N, and C, and the C1-C20 alkyl or C1-C20 Heteroalkyl, R ₁₁ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl. k is a definite integer of 1-6.

More preferably, Cor has any one of the following structural formulas:

Wherein, R ₁₂ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl.

Furthermore, according to the technical scheme provided by the present invention, the molecular structural formulas of some exemplary compounds of the present invention (please refer to Figure 2-1 to Figure 2-10) and the preparation schemes of some key compounds are listed below. The listed compounds are only used as a detailed description of the technical solution of the present invention, and cannot be interpreted as limiting the design concept of the present invention.

In order to illustrate the technical advantages of the scheme of the present invention, the present invention also provides two oligothiophene organic semiconductor molecules H and J whose structures are compared with each other, please refer to Figure 3a-Figure 3b, wherein J corresponds to a compound that does not have an EDOT structure at its end ; H corresponds to a compound having an EDOT structure at its end.

Ultraviolet-visible absorption spectroscopy (UV-vis) is used for testing, and the testing wavelength range is 300nm to 800nm. The two materials H and J are respectively prepared with a concentration of about 1×10 ^-6 mol/L with redistilled chloroform solvent. Chloroform solution is measured, and its absorption spectrogram please refer to Fig. 4, can find out: the compound H of end group modified EDOT is obviously better than the compound J of end group unmodified EDOT. Compared with J, the maximum absorption peak of H is red-shifted from 492nm to 525nm, red-shifted by 33nm; and the molar absorptivity at the maximum absorption peak of H is 8.79×10 ⁴ Lmol ^-1 cm ^-1 , and at the maximum absorption peak of J The molar absorptivity coefficient of the compound is 6.98×10 ⁴ L mol ^-1 cm ^-1 , which shows that after the end group is introduced into the EDOT structure, the light absorptivity is significantly improved. The organic semiconductor small molecule involved in the present invention has a lower spectral band gap and a longer spectral absorption wavelength.

The synthesis and preparation technical scheme of the present invention will be described in further detail below in conjunction with several preferred embodiments.

Embodiment 1 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add A (0.26g, 0.29mmol), tetrakis(triphenylphosphine)palladium (33mg, 28.7μmol), B (0.26g, 0.63mmol), DMF (2mL) into a 25mL single-necked bottle under anhydrous and oxygen-free conditions. The reaction was carried out at 80°C for 20 hours. After the reaction was completed, the solid was collected by precipitation with methanol and purified by column chromatography to obtain the final product C (0.25 g). The yield was 70%. The characterization data of this product C are as follows:

MS (MALDI-TOF): Calcd, 1246.36; Found, 1246.40.

¹ H NMR (CDCl ₃ , 400MHz): δ=9.91(s,2H), δ=7.68(s,2H), δ=7.34(d,2H), δ=7.26(s,2H), δ=6.92( d,2H),δ=4.43(s,8H),δ=2.89～2.83(m,8H),1.72～1.63(m,6H),1.45～1.26(m,28H),0.98～0.86(m,18H ).

Please refer to Figure 5 for the synthetic route of this example.

Embodiment 2 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add C (0.20g, 0.16mmol), 3-ethyl-2-thio-4-thiazolidinedione (57mg, 0.35mmol), 5 drops of piperidine, 15mL dry chloroform, reflux for 4h, water Interextracted with chloroform, dried the organic phase, filtered, spin-dried the solvent, precipitated with methanol, collected the solid, and purified by column chromatography to obtain the target product D (0.19g), with a yield of 76%. . The characterization data of this product D are as follows:

MS (MALDI-TOF): Calcd, 1532.33; Found, 1532.12.

¹ H NMR (CDCl ₃ , 400MHz): δ=7.90～7.70(s,2H), δ=7.70～7.50(s,2H), δ=7.50～7.30(d,2H), δ=7.30～7.10(s ,2H),δ=7.10～6.85(d,2H),δ=4.50～4.30(s,8H),δ=4.30～4.10(q,4H),δ=2.90～2.80(m,8H),1.80～ 1.60(m,6H), 1.50～1.20(m,28H), 1.00～0.80(m,24H).

Please refer to Figure 6 for the synthetic route of this example.

Embodiment 3 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add B (0.43g, 1.03mmol), malononitrile (0.14g, 2.06mmol), 5 drops of piperidine, 10mL dry chloroform into a 50mL single-necked bottle, reflux for 4h, inter-extract water and chloroform, dry the organic phase, filter, spin Dry the solvent and recrystallize from ethanol to obtain the final product E (0.40g), with a yield of 83%. The characterization data for this product E are as follows:

MS (MALDI-TOF): Calcd, 462.01; Found, 461.95.

¹ H NMR(CDCl ₃ ,400MHz):δ=7.84(s,1H),δ=7.15(s,1H),δ=4.45～4.41(m,4H),δ=2.56(t,2H),1.62～ 1.55 (m, 2H), 1.37～1.33 (m, 6H), 0.90 (t, 3H).

Please refer to Figure 7 for the synthetic route of this example.

Embodiment 4 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add A (0.13g, 0.16mmol), tetrakis(triphenylphosphine)palladium (19mg, 16.4μmol), E (0.16g, 0.35mmol), DMF (5mL) into a 25mL single-necked bottle under anhydrous and oxygen-free conditions, in The reaction was carried out at 80°C for 20 hours. After the reaction was completed, the solid was collected by precipitation with methanol and purified by column chromatography to obtain the final product F (0.25 g), with a yield of 90%. The characterization data of this product F are as follows:

MS (MALDI-TOF): Calcd, 1210.39; Found, 1210.13.

¹ H NMR (CDCl ₃ , 400MHz): δ=7.83(s,2H), δ=7.49(s,2H), δ=7.36(s,2H), δ=4.47(s,8H), δ=4.21( d,4H), δ=2.89(t,4H), 1.86～1.80(m,2H), 1.71～1.52(m,12H), 1.45～1.37(m,12H), 1.35～1.31(m,8H), 1.04(t,6H),0.95(t,6H),0.89(t,6H).

Please refer to Figure 8 for the synthetic route of this example.

Embodiment 5 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add B (0.46g, 1.10mmol), n-octyl cyanoacetate (0.33g, 1.67mmol), 5 drops of piperidine, 10mL of dry chloroform into a 50mL single-necked bottle, reflux for 4h, inter-extract water and chloroform, and dry the organic phase. After filtration, the solvent was spin-dried, and recrystallized from ethanol to obtain the final product G (0.47g), with a yield of 72%. The characterization data of this product G are as follows:

MS (MALDI-TOF): Calcd, 593.13; Found, 593.05.

¹ H NMR (CDCl ₃ , 400MHz): δ=8.37(s,1H), δ=7.13(s,1H), δ=4.42～4.39(m,4H), δ=4.26(t,2H), δ= 2.55(t,2H), 1.77～1.70(m,2H), 1.60～1.56(m,2H), 1.37～1.28(m,16H), 0.92～0.87(m,6H).

Please refer to Figure 9 for the synthetic route of this example.

Embodiment 6 The synthesis and preparation process of the organic small molecule semiconductor material can be:

Add A (0.13g, 0.17mmol), tetrakis(triphenylphosphine)palladium (21mg, 17.5μmol), G (0.23g, 0.38mmol), DMF (3mL) into a 25mL single-necked bottle under anhydrous and anaerobic conditions, in The reaction was carried out at 80°C for 20 hours. After the reaction was completed, the solid was collected by precipitation with methanol and purified by column chromatography to obtain the final product H (0.25 g), with a yield of 73%.

The characterization data of this product H are as follows:

MS (MALDI-TOF): Calcd, 1472.63; Found, 1472.37.

¹ H NMR (CDCl ₃ , 400MHz): δ=8.37(s,2H), δ=7.48(s,2H), δ=7.33(s,2H), δ=4.45(s,8H), δ=4.26( t,4H),δ=4.21(d,4H),δ=2.88(t,4H),δ=1.87～1.81(m,2H),1.72～1.52(m,16H),1.42～1.41(m,16H ) 1.36～1.25(m,24H), δ=1.04(t,6H), δ=0.95(t,6H), δ=0.91～0.87(m,12H).

Please refer to Figure 10 for the synthetic route of this example.

The above described and illustrated embodiments should not be interpreted as limiting the design concept of the present invention. Those who have the same knowledge in the technical field of the present invention can improve and change the technical idea of the present invention in various forms, and such improvements and changes should be understood as belonging to the protection scope of the present invention.

Claims (9)

1. A small organic molecule semiconductor material is characterized in that it comprises a Cor group and two structural units connected with the Cor group, each structural unit comprises a FT group, and a 3,4-position is formed by alkoxy A thiophene unit modified by a group or an alkylthio group and an A group, the A group is sequentially passed through the thiophene unit modified by an alkoxy group or an alkylthio group at the 3,4-position and the FT group and the Cor group group connection, Among them, the A group is an electron-accepting group unit, the FT group includes an oligothiophene short chain unit formed by combining 1 to 12 modified or unmodified thiophenes, and the Cor group includes two or more 5- or 6-membered rings. The condensed ring π-conjugated unit formed in parallel or its derivative unit, the thiophene unit modified by alkoxy or alkylthio at the 3,4-position has the following structural formula: Wherein, X includes an oxygen atom or a sulfur atom, and R ₁ and R ₂ include a substituted or unsubstituted C1-C20 alkyl group or a C1-C20 heteroalkyl group. 2. according to the described organic small molecule semiconductor material of claim 1, it is characterized in that, in the thiophene unit that described 3,4-position is modified by alkoxy group or alkylthio group, R ₁ and R ₂ are connected with each other, And with the two oxygen or sulfur atoms connected to the 3,4-position of the thiophene ring and the adjacent CC bonds on the thiophene ring to form a 5-8-membered substituted or unsubstituted ring structure. 3. The organic small molecule semiconductor material according to claim 2, characterized in that the ring structure includes a thiophene unit, and is modified in the 3,4-position oxygen and/or sulfur atom of the thiophene unit. There is at least one molecular fragment comprising _{-CH2 -} CH2-. 4. organic small molecule semiconductor material according to claim 1, is characterized in that described A group has any one in following structural formula at least: Wherein, R ₃ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl. 5. The small organic molecule semiconductor material according to claim 4, characterized in that the A group has any one of the following structural formulas: Wherein, R ₃ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl. 6. The organic small molecule semiconductor material according to claim 1, characterized in that the FT group has at least any one of the following structural formulas: Among them, R ₄ , R ₅ , and R ₆ include hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, m and n are integers from 0 to 2, and m and n cannot be 0, r is 1 or 2, one of _R7 and _R8 is hydrogen, the other is substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, q is between 1-12 any integer. 7. The organic small molecule semiconductor material according to claim 1 or 6, characterized in that the FT group has at least any one of the following structural formulas: Wherein, R ₉ includes substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, R ₁₀ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl. 8. The organic small molecule semiconductor material according to claim 1, characterized in that the Cor group has at least any one of the following structural units: Among them, X ₁ , X ₂ , and X ₃ are at least independently selected from any one of O, S, Se, Si, N, and C atoms and the C1-C20 alkyl or C1-C20 Heteroalkyl, R ₁₁ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl, k is an integer of 1-5. 9. The organic small molecule semiconductor material according to claim 1 or 8, characterized in that the Cor group has any one of the following structural formulas: Wherein, R ₁₂ includes hydrogen, substituted or unsubstituted C1-C20 alkyl or C1-C20 heteroalkyl.