KR100701751B1 - Low Molecular Weight Conjugated Phosphorus Compounds and Device using the Same - Google Patents

Abstract

Provided is a low molecular weight conjugated phosphorus compound having excellent electro-conductivity and stability to apply the room temperature spin coating process thereto. The low molecular weight conjugated phosphorus compound is represented by the formula(1), where X is P or PO, Ar is independently the group represented by the structural formula(1-1) or the structural formula(1-2), R1 is H, C1-10 linear or branched alkyl, C1-10 linear or branched alkoxy, or C1-10 linear or branched alkoxyalkyl, and m is an integer from 2 to 3. The organic thin-film transistor comprises the conjugated phosphorus compound as a channel material. The organic solar cell comprises conjugated phosphorus compound as a hole conducting material. The organo-electroluminescent device comprises the organo-electroluminescent as a luminescent material or a hole conducting material.

Description

Low Molecular Weight Conjugated Phosphorus Compounds and Device using the Same}

The present invention relates to a low molecular conjugated phosphorus compound and a device using the same, and more particularly, to a low molecular conjugated phosphorus compound having linear conjugated chains and a device using the same as an organic semiconductor, a hole transport material or a light emitting material. .

Currently, research on low-molecular weight inorganic materials such as pentacene is accelerated as an organic semiconductor material, and it is divided into a research group focusing on polymer organic materials centered on polythiophene.

Low-molecular organic materials such as pentacene have been reported to have excellent charge mobility and current flashing ratio, but they require expensive vacuum deposition equipment and are difficult to form fine patterns. There is no big advantage.

On the other hand, polythiophene-based polymer organic materials, unlike low-molecular materials, can be formed in solution, and thin films can be formed using screen printing, ink-jet, roll printing, etc. It is reported that there is an advantage in cotton and large area.

However, since the polymer organic materials have different oxidation potentials due to the difference in molecular weight distribution, it is difficult to apply them to devices due to deterioration of stability, while the low molecular weight organic materials have the same oxidation potential. It turned out to be advantageous in terms of.

Conventional light emitting materials are known as low molecular materials such as Alq (tris- (8-hydroxyquinoline) aluminium) and high molecular materials such as polyphenylenevinylene (PPV) and poly-alkylthiophene (PAT). No stable organic materials capable of spin coating at room temperature have been reported.

The present invention is to solve the problems of the prior art as described above, by using a low molecular conjugated phosphorus compound having linear conjugated chains (linear conjugated chains), the room temperature spin coating process is not only possible and stable when the device is applied, An object of the present invention is to provide a low molecular organic material having excellent electrical conductivity.

That is, the present invention relates to a compound having a low molecular weight conjugate represented by the following formula (1).

[Formula 1]

Where

X is P or PO,

Ar is each independently

R ¹ is hydrogen; Linear or branched alkyl groups having 1 to 10 carbon atoms; Linear or branched alkoxy groups having 1 to 10 carbon atoms; And a linear or branched alkoxyalkyl group having 1 to 10 carbon atoms,

m is an integer of 2-3.

According to another aspect of the present invention, the low molecular conjugated phosphorus compound is used as an organic semiconductor, a hole conducting material, or a light emitting material, and is capable of spin coating at room temperature and is stable. To provide a device excellent in electrical conductivity and luminous efficiency.

Hereinafter, the present invention will be described in more detail.

The low molecular conjugated phosphorus compounds of the present invention are represented by the following general formula (1):

Where

X is P or PO,

Ar is each independently

R ¹ is hydrogen; Linear or branched alkyl groups having 1 to 10 carbon atoms; Linear or branched alkoxy groups having 1 to 10 carbon atoms; And a linear or branched alkoxyalkyl group having 1 to 10 carbon atoms,

m is an integer of 2-3.

The low molecular conjugated compound of the present invention has a P or PO at the molecular center and includes a linear conjugated chain as a side chain. Since the low molecular conjugated phosphorus compound of the present invention is a low molecule, it is not only stable by having the same oxidation potential, but also excellent in solubility in organic solvents, and thus can be coated by a conventionally known coating method at room temperature, and exhibits electrical conductivity.

More specifically, the low molecular conjugated compound represented by Chemical Formula 1 is preferably selected from the group represented by the following Chemical Formulas 2 to 5.

On the other hand, as a method for synthesizing the low molecular conjugated phosphorus compounds of the present invention, chemical or electrochemical oxidative synthesis, which is a typical polymerization method of heteroaromatic compounds, and condensation synthesis using an organic transition metal compound such as nickel or palladium may be used. It synthesize | combines according to the reaction path shown by following Reaction Formula 1.

In Scheme 1, R ¹ is the same as defined in Formula 1.

Toluene, dimethoxy ether, tetrahydrofuran, dimethylformamide, water, and the like may be used as the solvent used in the reaction, and the reaction is preferably carried out at a temperature of −80 to 40 ° C. under a nitrogen atmosphere for 1 to 24 hours.

The low molecular conjugated phosphorus compound of the present invention synthesized according to the reaction scheme as described above may be made to facilitate the solution process by adjusting the substituent. Therefore, it can be coated with a conventionally known coating method at room temperature, specifically, it can be formed into a thin film by screen printing, printing, spin coating, spin casting, dipping or ink spraying.

On the other hand, another aspect of the present invention relates to a device using the low molecular conjugated phosphorus compound as an organic semiconductor, a hole conducting material or a light emitting material.

In detail, the device may be an organic thin film transistor (OTFT), an organic field effect transistor (OFET), an organic solar photovoltaic cell, or an organic light emitting device.

In addition, the low molecular conjugated phosphorus compounds of the present invention can be applied to organic semiconductor layers of OTFTs and OFETs, hole transport layers of organic photovoltaic cells or light emitting layers and hole transport layers of OLEDs by conventional processes known in the art.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

Example  One: Low molecular weight Conjugate  Preparation of Phosphorus Compound (1)

2-hexyl-5,2 ': 5', 2 "-terthiophene (2-hexyl-5,2 ': 5', 2")-terthiophene (3 g, 9.04 mmol) in 150 ml THF solvent under nitrogen atmosphere. Dissolved. The mixture was cooled to -70 ° C and butyllithium (6 ml, 1.6 M) was added dropwise. The mixture was stirred at 0 ° C for 1.5 h and cooled to -60 ° C. After addition of phosphorous bromide (0.43 g, 2 mmol), the mixture was stirred at room temperature overnight. After 50 ml of methylene chloride was added, the organic phase was washed sequentially with aqueous NH ₄ Cl solution (20 ml) and water, and then dried over MgSO ₄ . The solvent was evaporated and purified by column chromatography to give an orange solid (0.7 g, yield = 35%).

The UV absorbance in the neutral and iodine doped state of the final compound thus synthesized was measured, and the result is shown in FIG. 1. As can be seen in FIG. 1, the conjugated nitrogen compound of the present invention absorbed UV in a wide wavelength range.

¹ H-NMR (CDCl ₃ ) d (ppm) 7.30 (dd, 1H), 7.15 (dd, 1H), 7.10 (d, 1H), 7.00 (2d, 2H), 6.70 (d, 1H), 2.80 (t , 2H), 1.70 (qt, 2H), 1.40 (m, 6H), 0.90 (t, 3H)

Example  2: Low molecular weight Conjugate  Preparation of Phosphorus Compound (2)

3 ', 4'-ethylenedioxy-5-hexyl-2,2': 5 ', 2 "-terthiophene (3,4-ehylenedioxy-5-hexyl-2,2': 5 ', 2")- terthiophene (2 g, 5.13 mmol) was dissolved in 80 ml THF solvent under nitrogen atmosphere. The mixture was cooled to -70 ° C and butyllithium (3.42 ml, 1.6 M) was added dropwise. The mixture was stirred at 0 ° C for 1.5 h and cooled to -60 ° C. Phosphorous bromide (0.31 g, 1.14 mmol) was added and the mixture was stirred at room temperature overnight. After adding 200 ml of methylene chloride, the organic phase was washed sequentially with aqueous NH ₄ Cl solution (150 ml) and water, and then dried over MgSO ₄ . The solvent was evaporated and purified by column chromatography to give a yellow solid (0.52 g, yield = 38%).

¹ H-NMR (CDCl ₃ ) d (ppm) 7.27 (dd, 1H), 7.17 (dd, 1H), 7.02 (d, 1H), 6.68 (d, 1H), 4.35 (m, 4H), 2.78 (t , 2H), 1.66 (qt, 2H), 1.35 (m, 2H), 1.29 (m, 4H), 0.86 (m, 3H, CH ₃ )

Example  3: Low molecular weight Conjugate  Preparation of Phosphorus Compound (3)

Trirs (5 "-hexyl-2-terthienyl) phosphine (80 mg, 0.078 mmol) was dissolved in 30 ml THF solvent and hydrogen peroxide (35% aqueous solution) Added. The mixture was stirred at room temperature for 15 hours. Then, 100 ml of methylene chloride was added, and then the organic phase was washed with water and then dried over MgSO ₄ . The solvent was evaporated and purified by column chromatography to give an orange solid (77 mg, yield = 95%).

¹ H-NMR (CDCl ₃ ) d (ppm) 7.60 (dd, 1H), 7.20 (dd, 1H), 7.10 (d, 1H), 7.00 (2d, 2H), 6.70 (d, 1H), 2.70 (t , 2H), 1.70 (qt, 2H), 1.30 (m, 6H), 0.90 (t, 3H),

Example  4: Low molecular weight Conjugate  Preparation of Phosphorus Compound (4)

Tris (3 ', 4'-ethylenedioxy-5 "-hexyl-2-terthienyl) phosphine (80 mg, 0.067 mmol) (tirs (3', 4'-ethylenedioxy-5" -hexyl-2-terthienyl Except for using) phosphine) was carried out in the same manner as in Preparation Example 3 to obtain a brown solid (60mg, yield = 74%).

¹ H-NMR (CDCl ₃ ) d (ppm) 7.52 (dd, 1H), 7.23 (dd, 1H), 7.05 (d, 1H), 6.69 (d, 1H), 4.36 (m, 4H), 2.79 (t , 2H), 1.67 (qt, 2H), 1.34 (m, 2H), 1.30 (m, 4H), 0.88 (t, 3H)

As described above, the low-molecular conjugated phosphorus compound of the present invention is a novel low-molecular organic semiconductor capable of stable spin coating at room temperature, and is stable, and has excellent electrical conductivity and luminous efficiency. It can be used for Transistor, Organic Solar Photovoltaic Cell, and Organic Light Emitting Device (OLED).

1 is a spectrum showing a comparison of the UV absorbance of the neutral and iodine doped low molecular conjugated phosphorus compound synthesized in Preparation Example 1 of the present invention.

Claims (8)

A low molecular conjugated phosphorus compound represented by Formula 1 below:  [Formula 1] Where X is P or PO, Ar is each independently R ¹ is hydrogen; Linear or branched alkyl groups having 1 to 10 carbon atoms; Linear or branched alkoxy groups having 1 to 10 carbon atoms; And a linear or branched alkoxyalkyl group having 1 to 10 carbon atoms, m is an integer of 2-3. The compound of claim 1, wherein the compound which is a low molecular conjugate represented by Chemical Formula 1 is selected from the group represented by the following Chemical Formulas 2 to 5. [Formula 2] [Formula 3] [Formula 4] [Formula 5] An organic thin film transistor comprising the compound of claim 1 as a channel material. The organic thin film transistor of claim 3, wherein the channel material is thinned by screen printing, printing, spin coating, spin casting, dipping, or ink spraying. An organic photovoltaic cell comprising the conjugated phosphorus compound of claim 1 as a hole conducting material. The organic photovoltaic cell of claim 5, wherein the hole transport material is thinned by screen printing, printing, spin coating, spin casting, dipping, or ink spraying. An organic electroluminescent device comprising the conjugated phosphorus compound of claim 1 as a light emitting material or a hole transporting material. The organic electroluminescent device according to claim 7, wherein the light emitting material or the hole transporting material is thinned by screen printing, printing, spin coating, spin casting, dipping, or ink spraying.