KR101778292B1 - Triphenylene derivatives, method of preparation thereof and organic solar cell comprising the same - Google Patents

Abstract

상기 식에서, R₁ 내지 R₄는 명세서에서 정의한 바와 같다.The present invention provides a triphenylene derivative represented by the following general formula (1), a method for producing the same, and an organic solar cell comprising the same,
[Chemical Formula 1]

Wherein R ₁ to R ₄ are as defined in the specification.

Description

TECHNICAL FIELD The present invention relates to a triphenylene derivative, a process for preparing the same, and an organic solar cell comprising the triphenylene derivative,

The present invention provides a triphenylene derivative having a pore transfer characteristic, a method for producing the same, and an organic solar cell comprising the same.

Researches on renewable and clean alternative energy sources such as solar energy, wind power, and hydro power are actively being conducted to solve the global environmental problems caused by the depletion of fossil energy and its use. In particular, there is a growing interest in solar cells, which are current-voltage generating cells that utilize the photovoltaic effect of absorbing light energy from sunlight to generate electrons and holes.

Dye-sensitized solar cell (DSSC) was first developed by Professor Michael Gratzel of the Lausanne University of Technology in Switzerland (1991) and introduced to Nature magazine (Vol. 353, p. 737) .

In the early dye-sensitized solar cell structure, a dye that absorbs light is adsorbed on a porous photo-electrode on a transparent electrode film through which light and electricity pass, and then another conductive glass substrate is placed on top and a simple structure .

The working principle of a dye-sensitized solar cell is as follows. When dye molecules chemically adsorbed on the surface of a porous photocathode absorb solar light, dye molecules generate electron-hole pairs, and electrons are converted into conduction tines of semiconductor oxide used as a porous photocathode Injected and transferred to the transparent conductive film to generate a current. The holes remaining in the dye molecules are transferred to the photocathode by the hole conduction or hole conductive polymer by the oxidation-reduction reaction of the liquid or solid electrolyte, and form a complete solar cell circuit, .

In this dye-sensitized solar cell structure, the transparent conductive film is mainly composed of fluorine doped tin oxide (FTO) or indium doped tin oxide (ITO), and a nanotube having a wide band gap is used as the porous photo cathode. The dyestuff is particularly well absorbed and has a lowest unoccupied molecular orbital (LUMO) energy level of the dye than the energy level of the condiction band of the photocathode material, which facilitates the separation of the exciton produced by the light, Various materials are chemically synthesized and used. The highest efficiency of liquid dye-sensitized solar cells reported so far is 11-12% for about 20 years.

Organic photovoltaics (OPVs), which have been studied extensively since mid-1990, have been used to study organic materials with electron donor (D or often called hole acceptor) characteristics and electron acceptor (A) . When a solar cell made of organic molecules absorbs light, electrons and holes are formed. This is called an exiton. The exciton moves to the DA interface to separate the charge, the electrons move to the electron acceptor, and the hole moves to the electron donor, generating a photocurrent.

Since the distance that the exciton generated from the electron donor can travel normally is very short, about 10 nm, the photoconductivity can not be accumulated thickly, and the efficiency of the photoconductivity is low due to low light absorption. In recent years, however, efficiency has greatly increased with the introduction of the so-called bulk heterojunction (BHJ) concept of increasing the surface area at the interface and the development of donor organic materials having a small band gap that is easy to absorb a wide range of solar light, Organic solar cells with efficiency over 8% have been reported (Advanced Materials, 23 (2011) 4636).

On the other hand, Prof. Mikael Gratel of the Department of Chemistry, Lausanne University of Technology, Switzerland, inventor of the dye-sensitized solar cell, reported that in 1998, instead of the liquid electrolyte, a solid-type hole transporting organic material spiro-OMeTAD (2,2 ', 7,7'-tetrakis We have reported an all-solid dye-sensitized solar cell with an efficiency of 0.74% by using N, N-di- (4-methoxyphenylamino) -9,9'-spirobifluorene. In addition, the ruthenium-based dyestuffs were produced using low-cost pure organic dyes and hole conductors such as P3HT and PEDOT, but the efficiency was still low at 2-7%.

The spiro-OMeTAD has a high hole-transporting efficiency and is widely used as a hole-transporting material of a solar cell that is recently produced. However, spiro-OMeTAD has a spiro-bifluorene core in its chemical structure. To synthesize spiro-OMeTAD, it has a complicated process. Various hole transporting organic compounds have been reported to replace this, but are still difficult to synthesize due to the complicated structure.

Accordingly, the inventors of the present invention have been studying a hole transport material that can replace spiro-OMeTAD, and as described in the present invention, it has been found that a compound having triphenylene as a core structure is simple in synthesis and excellent in hole transport property Thereby completing the present invention.

The present invention provides a triphenylene derivative having a pore transfer property and a process for producing the same.

The present invention also provides an organic solar cell comprising the triphenylene derivative.

In order to solve the above problems, the present invention provides a compound represented by the following formula (1): < EMI ID =

[Chemical Formula 1]

In this formula,

And R ₁ is C _{1 -4} alkyl, C _{1 -4} alkoxy or halogen,

이고,R ₂ to R ₄ are each independently

ego,

q is 0 or 1,

R ₅ and R ₆ are, each independently,

Hydrogen, C _{1 -10} alkyl, C _{1 -4} alkoxy, C _{1 -4} alkylthio, C ₅ or _-8 cycloalkyl or halogen,

Or phenyl or naphthyl, wherein phenyl or naphthyl is unsubstituted or substituted by 1 is C _{1 -4} alkyl, C _{1 -4} alkoxy, each independently selected from the group consisting of C _{1 -4} alkylthio, halogen one to 5 substituents, or

를 형성하고,R _5, R ₆ and R ₅ and R ₆ together with the nitrogen atom to which the

Lt; / RTI >

p is from 0 to 4,

Z is a bond, O, S, NR ₁₁ or CR ₁₂ R ₁₃ ,

R ₇ and R ₈ are each independently hydrogen, C _{1 -4} alkyl, C _{1 -4} alkoxy, C _{1 -4} alkylthio, halogen or NR ₉ R _10, and

And R ₉ and R ₁₀ are each independently hydrogen, C _{1 -4} alkyl or C _{6 -20} aryl,

R ₁₁ is hydrogen, C _{1 -4} alkyl or C _{6 -20} aryl,

R ₁₂ and R ₁₃ is hydrogen, C _{1 -4} alkyl or C _{6 -20} aryl, each independently.

The compound represented by the general formula (1) has a core structure of triphenylene, and substituents of R ₁ are substituted at positions 3, 7 and 11 of triphenylene, and R ₂ to R ₄ are substituted. In particular, R ₂ to R ₄ are characterized by having a substituent containing a nitrogen atom.

The compound represented by the above formula (1) can be used as a hole transporting material, and is characterized in that it is not only effective to the effect of spiro-OMeTAD, which is a hole transporting material, but also has a simple structure and easy synthesis and is advantageous for commercial mass production.

In the above formula (1), preferably, R ₁ is methyl.

Also preferably, R ₂ to R ₄ are the same as each other.

Further preferably, q is 0, which R ₂ to R ₄ structures in the sense that there is phenylene which is connected to the triphenylene in and, R ₂ to R ₄ is a structure of the NR ₅ R ₆ each independently It means to have.

And also preferably, R ₅ and R ₆ is phenyl, said phenyl is substituted by C _{1 -4} alkoxy. More preferably, the phenyl is substituted with methoxy. Most preferably, R < ₅ > and R < ₆ > are 4-methoxyphenyl.

Representative examples of the compound represented by the formula (1) are as follows:

.

.

The present invention also provides a process for preparing a compound represented by the following general formula (1)

[Reaction Scheme 1]

In the above Reaction Scheme 1, the definitions of R ₁ to R ₄ are as defined above.

Step 1 is a step of reacting a compound represented by the formula (2) with zirconium tetrachloride to prepare a compound represented by the formula (3). After the reaction, it is preferable to obtain the compound represented by the general formula (3) by recrystallization from an alcohol (for example, butanol).

Step 2 is a step of preparing a compound represented by the formula (4) by dehydrogenating the compound represented by the formula (3). Pd / C can be used for the dehydrogenation reaction. After the above reaction, it is preferable to obtain the compound represented by the general formula (4) by recrystallization with an alcohol (for example, butanol).

Step 3 is a step of reacting a compound represented by the formula (4) with bromine to prepare a compound represented by the formula (5) wherein Br is substituted. Nitromethane is preferably used as a solvent, and iron powder is preferably used together. After the reaction, the compound represented by the general formula (4) is preferably obtained by recrystallization from 1,2-dichlorobenzene.

Step 4 is a step of preparing a compound represented by the formula (1), and a compound to be reacted with a compound represented by the formula (5) may be appropriately selected according to the structure of R ₂ to R ₄ .

의 화합물과 반응시킨다. 이때, 톨루엔을 용매로 사용하는 것이 바람직하며, 또한 Pd(PPh₃)₄를 촉매로, K₂CO₃를 염기로 사용하는 것이 바람직하다.
First, when q is 0 in R ₂ to R ₄ , a compound represented by Chemical Formula 5 and a compound represented by NHR ₅ R ₆ are reacted. At this time, toluene is preferably used as a solvent, and sodium tertiary butoxide, palladium acetate and tributylphosphine are preferably used together. When q is 1 in R ₂ to R ₄ ,

Lt; / RTI > At this time, it is preferable to use toluene as a solvent, and it is preferable to use Pd (PPh ₃ ) ₄ as a catalyst and K ₂ CO ₃ as a base.

When R ₂ to R ₄ are mutually the same, it is preferable to use an excessive amount of a compound to be reacted with a compound represented by the formula (5). When R ₂ to R ₄ are different from each other, a compound represented by the formula The compound can be appropriately selected and reacted sequentially.

Also, the present invention provides a hole transport layer comprising the compound represented by the above formula (1). The present invention also provides an organic solar cell including the hole transport layer.

The organic solar battery according to the present invention may include a first electrode, a second electrode, a photoactive layer, and a hole transporting layer containing a compound represented by Formula 1.

The first electrode may be an anode, and the second electrode may be a cathode. The first electrode may be a cathode, and the second electrode may be an anode. The anode may be a transparent material having excellent conductivity, but is not limited thereto. Specifically, it may be indium tin oxide (ITO), tin oxide (SnO ₂ ), fluorine doped tin oxide (FTO), and zinc oxide (ZnO), but is not limited thereto. The cathode may be a metal having a small work function, but is not limited thereto. Specifically, it may be a metal such as lithium, magnesium, or an alloy thereof, or a multi-layered material such as Al: Li, Al: BaF ₂ , or Al: BaF ₂ : Ba.

The hole transport layer and the electron transport layer material are materials that increase the probability that electrons and holes are efficiently transferred to the photoactive layer, thereby transferring generated charges to the electrode. The hole transport layer includes the compound represented by Formula 1 according to the present invention. In addition to the hole transport layer, an electron transport layer may be further included. Examples of the material that can be used for the electron transport layer include aluminum trihydroxyquinolinate (Alq ₃ ), PBD (2- (4-bipheyl) 5-phenyl-1,3,4-oxadiazole, TPQ (1,3,4-tris [(3-phenyl-6-trifluoromethyl) qunoxaline-2-yl] benzene) and triazole derivatives.

The material used for the photoactive layer is not particularly limited as long as it is a material that generates electron-hole pairs by receiving sunlight. For example, an AMX ₃ organic hybrid organic perovskite compound (wherein A is an ammonium salt, M is a divalent metal ion, and X is a halogen ion). Examples thereof, may be _{CH 3 NH 3 PbI 3, CH} 3 NH 3 PbI (3-x) Cl x, CH 3 NH 3 PbI (3-x) for _x Br.

As an example of the method of manufacturing the organic solar cell, there is a method of manufacturing an organic solar battery, which comprises preparing a substrate, forming an anode on one region of the substrate, forming a hole transporting layer on the anode, Forming a photoactive layer on the photoactive layer, and forming a cathode on the photoactive layer. In addition, a step of forming an electron transport layer between the photoactive layer and the cathode may be added.

Compounds having a core structure of triphenylene represented by the above formula (1) according to the present invention are easier to synthesize than spiro-OMeTAD and can be used as a hole transport material since they are easy to synthesize and have excellent hole transporting properties.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited thereto.

Example

Step 1) Preparation of compound 2

4-Methylcyclohexanone (40 g) and zirconium tetrachloride (4 g) were mixed and refluxed overnight. The mixture was cooled to room temperature, hot chloroform (100 mL) was added, and the solid was filtered. The solvent of the filtered solution was removed, and then recrystallized in butanol to obtain Compound 2 (23 g).

Step 2) Preparation of compound 3

Compound 2 (15 g) and 10% Pd / C (1.5 g) prepared in the above step 1 were refluxed in a triethylene glycol dimethyl ether solvent under argon until gas evolution ceased. After cooling to room temperature, chloroform was added and the mixture was refluxed, followed by filtration to remove the solvent. The compound 3 (11 g) was obtained by recrystallization from butanol.

Step 3) Preparation of compound 4

Compound (3) (8.7 g) prepared in Step 2 and iron powder (0.64 g) were placed in a flask equipped with aluminum foil. Nitromethane (250 mL) was added thereto and bromine (15.4 g) was added dropwise. After refluxing for 11 hours, the mixture was cooled to room temperature. Diethyl ether was added thereto, and the resultant solid was filtered, and the solid was washed with diethyl ether and methanol. And recrystallized in 1,2-dichlorobenzene to obtain Compound 4 (11.2 g).

Step 4) Preparation of Compound 1

(5.0 g), bis (4-methoxyphenyl) amine (8.1 g), sodium tertiary butoxide (4.1 g), palladium acetate (0.22 g), 50% tributylphosphine (0.53 mL) and toluene (35 mL) was refluxed under an argon atmosphere for 24 hours. After cooling to room temperature, ammonium chloride solution was added and extracted with methylene chloride. The extracted organic layer was dried over magnesium sulfate, filtered and the solvent was removed. The residue was purified by column chromatography to obtain 5.9 g of the title compound.

¹ H NMR (CDCl ₃ , standard TMS): 7.94 (3 H, s), 7.74 (3 H, s), 6.74 (12 H, d), 6.52 , s)

Experimental Example : Manufacture and Evaluation of Solar Cells

The end portion of the FTO substrate having a size of 25 mm × 25 mm was etched to partially remove the FTO. 0.1 M of _{[(CH 3) 2 CHO]} 2 Ti in the _{(C 5 H 7 O 2)} 2 (titanium diisopropoxide bis (acetylacetonate)) 1- butanol solution for 10 seconds and 2000 rpm to 700 rpm at 60-second FTO substrates 40 nm thick, and sintered at 500 ° C for 15 minutes to form a TiO ₂ layer as an N-type material.

A solution of 40 wt% of GBL was prepared by adding CH ₃ NH ₃ I (methylammonium iodide) and PbI ₂ (lead (II) iodide) to GBL (gamma-butyrolactone) at a molar ratio of 1.2: Respectively. The solution was coated on the previously prepared TiO ₂ layer at 500 rpm for 5 seconds, 1000 rpm for 40 seconds, and 5000 rpm for 30 seconds and dried at 100 ° C for 10 minutes to form a light absorbing layer.

On the light absorbing layer, a compound prepared in Example or a comparative example, spiro-OMeTAD (2,2 ', 7,7'-tetrakis (N, N-di (4- methoxyphenyl) amino) -9,9'-spirobifluorene ) Was spin-coated at 6000 rpm for 30 seconds to form a hole transporting layer. The electrode was formed by vacuum deposition of Au using a thermal evaporator.

The short-circuit current density, open-circuit voltage, performance index and power generation efficiency of the solar cell were measured. The results are shown in Table 1 below.

Hole transport layer Short circuit current density
(mA / cm 2) Open-circuit voltage (V) Performance Index (%) Power generation efficiency (%) Example 17.01 1.124 75.18 14.4 Comparative Example
(spiro-OMeTAD) 17.77 1.093 73.71 14.3

As shown in Table 1, it is characterized not only by the effect of spiro-OMeTAD, which is a hole-transferring material, but also because it is simpler in structure and easier to synthesize than spiro-OMeTAD.

Claims (9)

A compound represented by the following formula (1):
[Chemical Formula 1]

In this formula,
R ₁ is C _1-4 alkyl,
R ₂ to R ₄ are each independently

ego,
q is 0,
R ₅ and R ₆ are each independently phenyl substituted by C _1-4 alkoxy.
The method according to claim 1,
And R < ₁ > is methyl.
The method according to claim 1,
And R ₂ to R ₄ are the same as each other.
delete delete The method according to claim 1,
R < ₅ > and R < ₆ > are phenyl substituted by methoxy,
The method according to claim 1,
Wherein said compound is a compound having the structure:

.
A hole transport layer comprising a compound according to any one of claims 1 to 3, 6 and 7.
An organic solar battery comprising the hole transport layer of claim 8.