KR20170112882A - organic solar cells and manufacturing method thereof - Google Patents

Abstract

According to the present invention, it is possible to improve the morphology of the photoactive layer by mixing an appropriate amount of the second organic semiconductor material in the conjugated low-molecular compound (first organic semiconductor material) which simultaneously includes the electron-exciton and the electron- Battery can be provided.

Description

[0001] The present invention relates to an organic solar cell and a manufacturing method thereof,

The present invention relates to an organic solar cell and a method of manufacturing the same, and more particularly, to an organic solar cell improved in morphology of an electron guide and an electron acceptor in a photoactive layer and a manufacturing method thereof.

The fossil fuels currently used as primary energy sources encountered various problems such as environmental pollution caused by combustion and limitations of the reserves. As a result, research on various renewable energy sources such as hydrogen energy, hydropower, and wind power has been carried out, and many research and development on solar cells using solar energy have been conducted. .

Solar cells can be roughly classified into solar cells using inorganic materials such as silicon and solar cells using organic materials. Thin film solar cells using organic materials are superior to inorganic solar cells using silicon because of their easy processability in the manufacturing process of organic materials. Therefore, it is possible to manufacture low-cost thin films and large-area devices such as spin coating, screen printing, ink jet, And it is possible to manufacture a flexible element by a roll-to-roll process, which is advantageous in realizing an inexpensive process unit price.

Initially, organic solar cells using polymer have been studied with much interest. However, the molecular weight (Mn, Mw) and the molecular weight distribution index (PDI) are different each time the polymerization is repeated and the reproducibility of the completed device is deteriorated.

In order to overcome such a problem, an organic solar cell using a low-molecular compound having excellent reproducibility has attracted attention as an alternative. However, in order to commercialize such an organic solar cell, high efficiency is a first task to be preceded.

Patent Document 1. Korean Patent Laid-Open No. 10-2011-0117966

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic solar cell having a higher efficiency by improving the morphology of a photoactive layer and a method of manufacturing the same.

In order to achieve the above object,

A lower electrode formed on a substrate;

A photoactive layer formed on the lower electrode, the photoactive layer including (a) a p-type organic semiconductor material, (b) an n-type organic semiconductor material, and (c) a solvent; And

And an upper electrode formed on the photoactive layer,

The p-type organic semiconductor material includes (a-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula Thereby providing an organic solar cell.

In the above formulas,

X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other and each independently represents hydrogen or halogen,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ And R < ₆ > are the same or different and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms,

and n is an integer of 1 to 10,000,000.

Wherein R ₁ and R ₂ are the same or different and each independently is a straight-chain alkyl group having 1 to 7 carbon atoms, and R ₃ and R ₄ are the same or different, Wherein R ₃ and R ₄ are the same or different and each independently is a straight chain alkyl group having from 8 to 22 carbon atoms.

In the formula 1, when R ₁ and R ₂ are symmetrical to each other and have the same structure, R ₃ and R ₄ are also symmetrical to each other and have the same structure. In the formula 2, R ₅ and R ₆ are also symmetrical to each other and have the same structure.

Wherein the first organic semiconductor material (a-1) is a low molecular weight compound having a molecular weight of 1000 to 2000 g / mol and the second organic semiconductor material (a-2) is a high molecular weight compound having a molecular weight of 50,000 to 100,000 g / Lt; / RTI >

The first organic semiconductor material (a-1) may be any one selected from low-molecular compounds represented by the following formulas (3) to (7).

The second organic semiconductor material (a-2) may be a polymer compound represented by the following formula (8).

In the above formula

n is an integer of 1 to 10,000,000, and more specifically, a molecular weight of 50,000 to 100,000 g / mol is preferable.

The (b) n- type organic semiconductor material is Methyl (6,6) -phenyl -C61- butyrate (PC ₆₀ BM), (6,6) -phenyl -C61- butynyl rigs Acid methyl ester (C ₆₀ -PCBM) , (6,6) -phenyl -C71- butynyl rigs Acid methyl ester (C ₇₀ -PCBM), (6,6) -phenyl -C77- butynyl rigs Acid methyl ester (C ₇₆ -PCBM), (6,6) -Phenyl-C79-butyric acid methyl ester (C ₇₈ -PCBM), (6,6) -phenyl-C ₈₁ -butylic acid methyl ester (C ₈₀ -PCBM) Rick acid methyl ester _{(C 82 -PCBM), (6,6} ) - phenyl butyric -C85- rigs acid methyl ester (C ₈₄ -PCBM), bis (1- [3- (methoxycarbonyl) propyl] -1 _{phenyl) (bis-C 60 -PCBM)} , 3'- phenyl -3'H- cycloalkyl profile (8,25) (5,6) fullerene -C70- bis -D5h (6) -3'- acid methyl (Bis-C ₇₀ -PCBM), indene-C60-bis-adduct (ICBA), monoindenyl C60 (ICMA), and combinations thereof.

The mixing weight ratio of the (a-1) first organic semiconductor material and (a-2) the second organic semiconductor material may be 1: 0.01-0.04.

The solvent (c) may be a mixed solvent consisting of chlorobenzene and 1,8-diiodoctane.

In the solvent (c), the mixing volume ratio of the chlorobenzene and 1,8-diiodoctane may be 1: 0.002-5.

According to another aspect of the present invention, there is provided a method of manufacturing an organic solar cell including the steps of:

I) forming a lower electrode on a substrate,

(A-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula (2) (b) an n-type organic semiconductor material; And (c) a solvent to prepare a first solution,

III) coating the first solution on the lower electrode to form a photoactive layer and

IV) forming an upper electrode on the photoactive layer.

[Chemical Formula 1]

(2)

In the above formula

X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other and each independently represents hydrogen or halogen,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ And R < ₆ > are the same or different and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms,

and n is an integer of 1 to 10,000,000.

The mixing weight ratio of the (a-1) first organic semiconductor material and (a-2) the second organic semiconductor material may be 1: 0.01-0.04.

The solvent (c) may be a mixed solvent consisting of chlorobenzene and 1,8-diiodoctane.

The mixing volume ratio of chlorobenzene and 1,8-diiodoctane may be 1: 0.002-5.

Step (III) may be performed by a spin coating method.

According to the present invention, it is possible to improve the morphology of the photoactive layer by mixing an appropriate amount of the second organic semiconductor material in the conjugated low-molecular compound (first organic semiconductor material) which simultaneously includes the electron-exciton and the electron- Battery can be provided.

In addition, when the second organic semiconductor material is added to the first organic semiconductor material including the electron-emitter and the electron-emitter at the same time, since it plays a role of preventing the aggregation phenomenon which was a problem of the first organic semiconductor material, As a result, the effect of improving the network structure characteristics of the first organic semiconductor material by improving the morphology of the photoactive layer can be achieved.

In addition, since the organic solar cell according to the present invention can be manufactured so as to exhibit excellent efficiency even at a room temperature process, a high-temperature heat treatment process is not required during the device fabrication process, so that the fabrication process is simplified and costs are reduced, And has a merit of broadening the selection range.

1 is a sectional view showing an organic solar cell 100 according to the present invention.
2 is a schematic view showing a process of manufacturing the organic solar battery 100 according to the present invention.
FIG. 3 is a graph showing JV characteristics for the organic solar cells prepared in Examples 1 to 5 when irradiated with light having an energy of 100 mW / cm 2.
4 is a graph showing external quantum efficiencies (EQE) (%) of the organic solar cells prepared in Examples 1 to 5.
5 is a graph showing JV characteristics of the organic solar cells prepared in Comparative Examples 1 to 5 when irradiated with light having an energy of 100 mW / cm < 2 >.
FIG. 6 is a graph showing external quantum efficiencies (EQE) (%) of organic solar cells prepared in Comparative Examples 1 to 5.
7 is a graph showing JV characteristics of the organic solar cells prepared in Examples 6 to 8 and Comparative Example 3 when irradiated with light having an energy of 100 mW / cm 2.
8 is a TEM (Transmission Electron Microscope) of the photoactive layer prepared according to Example 3 (a) and Comparative Example 3 (b).
9 is energy-filtering transmission electron microscopy (EF-TEM) of the photoactive layer prepared according to Example 3 (a) and Comparative Example 3 (b).
10 is an image (Rq = 0.75 nm) of the surface morphology of the photoactive layer produced according to Example 3 of the present invention through AFM.
11 is an image (Rq = 1.36 nm) of the photoactive layer produced according to Comparative Example 3 of the present invention through AFM.
FIG. 12 is a graph showing JV characteristics of organic solar cells manufactured from Comparative Examples 6 to 10 when irradiated with light of 100 mW / cm 2 energy. FIG.
13 is a graph showing the JV characteristics of the organic solar cell of the organic solar cell manufactured in Comparative Examples 11 to 15 when irradiated with light having an energy of 100 mW / cm < 2 >.
FIG. 14 is a graph showing JV characteristics of organic solar cells prepared in Comparative Examples 16 to 20 when irradiated with light of 100 mW / cm 2 energy. FIG.
15 is a graph showing changes in photoelectric conversion efficiency (PCE) of the organic solar cells of Example 3 and Comparative Example 3 measured at high temperature of 110 ° C for each hour.
FIG. 16 is a graph showing changes in fill factor (FF) of the organic solar cells of Example 3 and Comparative Example 3 measured at high temperature of 110 ° C. for each hour.
17 is a graph showing changes in J _SC of the organic solar cells of Example 3 and Comparative Example 3 measured at high temperature of 110 ° C for each hour.
18 shows the characteristics (the photoelectric conversion efficiency (PCE), the fill factor (FF), the J _SC , and the V (%) of the organic solar cell of Example 9 measured at each time under the conditions of 65, 85% relative humidity _OC ).

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

Low-molecular organic solar cells have a great advantage of being excellent in reproducibility as compared with polymer organic solar cells, and have attracted a lot of research developers. P-DTS (FBTTh ₂ ) ₂ has been developed as a representative light-emitting active layer material used in such a low molecular organic solar cell, and when a device of a conventional structure is manufactured by mixing it with a C ₇₁ fullerene derivative having a high electron affinity, An excellent efficiency of about 7% can be achieved. However, in the case of the above-described light-active layer, the morphology is not optimized due to the coagulation phenomenon between the low-molecular compounds,

Therefore, in the present invention, by mixing an appropriate amount of the second organic semiconductor material in the first organic semiconductor material, which is a low molecular compound constituting the photoactive layer of the low molecular organic solar cell, an aggregation phenomenon, which was a conventional problem of the low molecular compound as the first organic semiconductor material, And optimize the morphology of the photoactive layer, thereby remarkably improving the photoelectric conversion efficiency.

One aspect of the present invention is

A lower electrode formed on a substrate;

A photoactive layer formed on the lower electrode, the photoactive layer including (a) a p-type organic semiconductor material, (b) an n-type organic semiconductor material, and (c) a solvent; And

And an upper electrode formed on the photoactive layer,

The p-type organic semiconductor material includes (a-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula Organic solar cell.

[Chemical Formula 1]

(2)

In the above formula

Wherein X _1, X _2, X ₃ and X _4, and is the same as or different from each other, are each independently hydrogen or halogen, wherein _{R 1, R 2, R 3} , R 4, R 5 And R < ₆ > are the same or different, and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms, and n is an integer of 1 to 10,000,000.

In the formula 1, when R ₁ and R ₂ are symmetrical to each other and have the same structure, R ₃ and R ₄ are also symmetrical to each other and have the same structure. In the formula 2, R ₅ and R ₆ Are preferably symmetrical to each other and have the same structure. The use of the first and second organic semiconductor materials having such a structure is excellent in intermolecular energy transfer.

Wherein R ₁ and R ₂ are the same or different and each independently is a straight chain alkyl group having 1 to 7 carbon atoms, and R ₃ and R ₄ are the same or different and each independently represent a group having 8 to 22 carbon atoms Branched alkyl group,

In formula (2), R ₃ and R ₄ are the same or different, and each independently is a straight-chain alkyl group having 8 to 22 carbon atoms, since the first organic semiconductor material having such a side chain structure and the When the second organic semiconductor material is mixed, molecular accumulation and supramolecular alignment between each other are most improved.

For the above-mentioned effects, X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other in Formula 1, and most preferably independently hydrogen or F.

Hereinafter, the structure of the organic solar battery according to the present invention will be described in detail with reference to FIG.

1 is a cross-sectional view illustrating an organic solar cell 100 according to the present invention. Referring to FIG. 1, a lower electrode 120 formed on a substrate 110, a photoactive layer 130 formed on the lower electrode 120, An upper electrode 140 formed on the photoactive layer 130 is formed in order and a PEIE polymer surface modification layer 120a may be further formed between the lower electrode 120 and the photoactive layer 130. [

Wherein the photoactive layer (130) comprises (a) a p-type organic semiconductor material, (b) an n- 1) a first organic semiconductor material represented by the following formula (1); and (a-2) a second organic semiconductor material represented by the following formula (2).

[Chemical Formula 1]

(2)

In the above formula

Wherein X _1, X _2, X ₃ and X _4, and is the same as or different from each other, are each independently hydrogen or halogen, wherein _{R 1, R 2, R 3} , R 4, R 5 And R < ₆ > are the same or different, and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms, and n is an integer of 1 to 10,000,000.

In the formula 1, when R ₁ and R ₂ are symmetrical to each other and have the same structure, R ₃ and R ₄ are also symmetrical to each other and have the same structure. In the formula 2, R ₅ and R ₆ Are preferably symmetrical to each other and have the same structure. The use of the first and second organic semiconductor materials having such a structure is excellent in intermolecular energy transfer.

Wherein R ₁ and R ₂ are the same or different and each independently is a straight chain alkyl group having 1 to 7 carbon atoms, and R ₃ and R ₄ are the same or different and each independently represent a group having 8 to 22 carbon atoms Branched alkyl group,

In formula (2), R ₃ and R ₄ are the same or different, and each independently is a straight-chain alkyl group having 8 to 22 carbon atoms, since the first organic semiconductor material having such a side chain structure and the When the second organic semiconductor material is mixed, molecular accumulation and supramolecular alignment between each other are most improved.

For the above-mentioned effects, X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other in Formula 1, and most preferably independently hydrogen or F.

According to an embodiment of the present invention, the substrate 110 is formed of a material selected from the group consisting of glass, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyisosulfonate And may preferably be a glass substrate.

According to an embodiment of the present invention, the lower electrode 120 may be an anode or a cathode. The lower electrode 120 may be formed of indium tin oxide (ITO), fluorinated tin oxide (FTO), indium zinc oxide (IZO) And may be any one selected from the group consisting of AZO (Al-doped Zinc Oxide), IZTO (Indium Zinc Tin Oxide), SnO ₂ , ZnO, carbon nanotubes, graphene and silver nanowires. (Indium Tin Oxide).

According to an embodiment of the present invention, a polymer surface modification layer 120a made of PEIE (polyehthylenimine ethoxylated) may be further formed on the lower electrode 120. The polymer surface modification layer 120a is preferably formed to a thickness of 1 to 20 nm.

With the lower electrode 120, the polymer surface modification layer (120a) is PEIE (polyehthylenimine ethoxylated) formed on the polymer, to the lower electrode (120 because of the surface dipole (surface dipole) of an amine group (NH ₂₎ contained in PEIE ) Of the work function. The amine group improves the adhesion between the lower electrode 120 and the photoactive layer 130 by chemical interaction with the photoactive layer 130 formed on the PEIE polymer surface modification layer 120a.

The adhesion between the lower electrode 120 and the photoactive layer 130 can be improved by forming the PEIE polymer surface modification layer 120a on the lower electrode 120, Lowering the work function and making it possible to use it as a cathode.

The photoactive layer 130 according to the present invention is a bulk-heterojunction (BHJ) structure in which an electron-donating substance and an electron-accepting substance are mixed with each other. -Type organic semiconductor material and (c) a solvent.

The (a) p-type organic semiconductor material includes (a-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula .

[Chemical Formula 1]

(2)

In the above formula

Wherein X _1, X _2, X ₃ and X _4, and is the same as or different from each other, are each independently hydrogen or halogen, wherein _{R 1, R 2, R 3} , R 4, R 5 And R ₆ are the same or different and each independently represents a straight or branched alkyl group having 1 to 22 carbon atoms, and n is an integer of 1 to 10,000,000. In Formula 1, R ₁ and R ₂ are mutually symmetrical, When R ₃ and R ₄ have the same structure, R ₃ and R ₄ are also symmetrical to each other and have the same structure. In the formula 2, R ₅ and R ₆ are also symmetrical with each other and have the same structure. The use of the first and second organic semiconductor materials having such a structure is excellent in intermolecular energy transfer.

Wherein R ₁ and R ₂ are the same or different and each independently is a straight chain alkyl group having 1 to 7 carbon atoms, and R ₃ and R ₄ are the same or different and each independently represent a group having 8 to 22 carbon atoms Branched alkyl group,

In formula (2), R ₃ and R ₄ are the same or different, and each independently is a straight-chain alkyl group having 8 to 22 carbon atoms, since the first organic semiconductor material having such a side chain structure and the When the second organic semiconductor material is mixed, molecular accumulation and supramolecular alignment between each other are most improved.

For the above-mentioned effects, X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other in Formula 1, and most preferably independently hydrogen or F.

In other words, the photoactive layer 130 may include (a-1) a first organic semiconductor material represented by Formula 1, and (a-2) a second organic semiconductor material represented by Formula 2; (A-1) a first organic semiconductor material represented by Chemical Formula 1; and (a-2) a first organic semiconductor material represented by Chemical Formula (1) A second organic semiconductor material represented by 2; (b) an n-type organic semiconductor material; And (c) a solvent.

The photoactive layer 130 may be a bulk-hetero junction type layer formed using a solution process, and the solution process may be a spin coating process, an ink-jet printing process, a doctor blade coating process, A doctor blade coating method, an electrospray coating method, a dip coating method, and a screen printing method. Preferably, the method is a spin coating method.

The properties such as homogeneity and morphology of the photoactive layer 130 have the greatest influence on the performance of the organic solar cell. These characteristics are the same as those of the first organic semiconductor material (a-1) and the second organic semiconductor material The mixture weight ratio of the semiconductor material, the type and content of the solvent, and the like, the meaning of these numerical limitations or kinds is very large.

(A-1) the first organic semiconductor material represented by Formula 1 is a low molecular compound having a molecular weight of 1000 to 2000 g / mol, and (a-2) 2 organic semiconductor material is a polymeric compound having a molecular weight of 50,000 to 100,000 g / mol.

The second organic semiconductor material represented by the above formula (a-2) is mixed with the first organic semiconductor material (a-1) in an appropriate amount to form the above-mentioned low molecular compound (a-1) (A-1) the network structure of the first organic semiconductor material represented by the above formula (1) is improved, and the photoelectric conversion efficiency Can be improved by 1% or more.

At this time, the organic solar cell can be improved by up to 1% or more when the photoactive layer according to the present invention is introduced even when the organic solar cell has an optimized low molecular organic solar cell structure in which conventional technologies are concentrated. That is, in the low-molecular organic solar cell having the optimized structure, (a-1) the present invention including the first organic semiconductor material represented by Formula 1 and the second organic semiconductor material represented by Formula (a-2) It is understood that a remarkable effect of further improving the photoelectric conversion efficiency can be achieved.

The first organic semiconductor material (a-1) may be any one selected from low-molecular compounds represented by the following formulas (3) to (7).

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

Preferably, the (a-1) first organic semiconductor material may be a low molecular weight compound represented by the formula (5).

The second organic semiconductor material (a-2) may be a polymer compound represented by the following formula (8).

[Chemical Formula 8]

In the above formula

n is an integer of 1 to 10,000,000, and more specifically, a molecular weight of 90,000 to 100,000 g / mol is preferable.

The mixing weight ratio of the first organic semiconductor material (a-1) and the second organic semiconductor material (a-2) is preferably 1: 0.01-0.04. -2) If the mixing ratio by weight of the second organic semiconductor material is less than 1: 0.01, the organic solar cell light conversion efficiency improvement effect due to the improvement of the morphology can not be attained. If the ratio is 1: 0.05 or more, It is preferable to perform it within the above-mentioned range.

The solvent (c) is preferably a mixed solvent composed of chlorobenzene and 1,8-diiodoctane. If a solvent other than the mixed solvent is used, as shown in the following Experimental Example, Or less, and the light conversion efficiency is remarkably lowered to a maximum of 2% or less.

The mixing volume ratio of the chlorobenzene and the 1,8-diiodoctane is preferably 1: 0.002-5.

That is, the most preferred structure of the photoactive layer 130 in the organic solar cell according to the present invention is (a-1) the first organic semiconductor material represented by the above Chemical Formula 1; (a-2) a second organic semiconductor material represented by Chemical Formula 2; (b) an n-type organic semiconductor material; And (c) a solvent, wherein (a-1) the mixing ratio by weight of the first organic semiconductor material represented by Formula 1 and (a-2) the second organic semiconductor material represented by Formula 2 is 1: 0.04, and the solvent (c) is a mixed solvent of chlorobenzene and 1,8-diiodoctane, and the mixing ratio of the chlorobenzene and 1,8-diiodoctane is 1: 0.002-5. It can be seen that the light conversion efficiency is remarkably lowered as in the experimental example described later when any of the above ranges deviates from the above-mentioned range.

By introducing the photoactive layer 130 satisfying the above-described constitution of the present invention, it is possible to further improve the light conversion efficiency by at least 0.1% and at most 1%, even if the organic solar cell has an optimized structure.

That is, the ability to improve the light conversion efficiency in addition to the optimized organic solar cell is an effect having significant significance in the art alone. The present invention further improves the efficiency of 1% or more, and thus achieves a remarkable effect .

Furthermore, even if the same structure as the above-described photoactive layer 130 is used, (a-1) the first organic semiconductor material represented by Formula 1; (a-2) If the mixing weight ratio of the second organic semiconductor material represented by the formula (2) is slightly out of the range, the effect of the present invention can not be achieved, -1) a first organic semiconductor material represented by Formula 1; (a-2) There is a problem that the second organic semiconductor material represented by the above-mentioned formula (2) is mixed and used.

The (b) n- type organic semiconductor material is Methyl (6,6) -phenyl -C61- butyrate (PC ₆₀ BM), (6,6) -phenyl -C61- butynyl rigs Acid methyl ester (C ₆₀ -PCBM) , (6,6) -phenyl -C71- butynyl rigs Acid methyl ester (C ₇₀ -PCBM), (6,6) -phenyl -C77- butynyl rigs Acid methyl ester (C ₇₆ -PCBM), (6,6) -Phenyl-C79-butyric acid methyl ester (C ₇₈ -PCBM), (6,6) -phenyl-C ₈₁ -butylic acid methyl ester (C ₈₀ -PCBM) Rick acid methyl ester _{(C 82 -PCBM), (6,6} ) - phenyl butyric -C85- rigs acid methyl ester (C ₈₄ -PCBM), bis (1- [3- (methoxycarbonyl) propyl] -1 _{phenyl) (bis-C 60 -PCBM)} , 3'- phenyl -3'H- cycloalkyl profile (8,25) (5,6) fullerene -C70- bis -D5h (6) -3'- acid methyl May be any one or more selected from the group consisting of esters (Bis-C ₇₀ -PCBM), indene-C60-bis-adduct (ICBA), monoindenyl C60 (ICMA), and combinations thereof, 6,6) -phenyl-C71-butyric acid methyl ester Can be Termini (C ₇₀ -PCBM).

According to an embodiment of the present invention, the upper electrode may be made of MoO ₃ / Ag, Au, Pt, or the like.

An example of the most preferable typical structure of the organic solar cell according to the present invention is that an ITO layer and a PEIE polymer surface modification layer are sequentially formed on a substrate and a polymer compound and a solvent are mixed on the polymer surface modification layer A photoactive layer prepared by coating a solution and a MoO 3 / Ag upper electrode sequentially formed on the substrate.

Another aspect of the invention relates to a method of making an organic solar cell comprising the steps of:

I) forming a lower electrode on a substrate;

(A-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula (2) (b) an n-type organic semiconductor material; And (c) a solvent to prepare a first solution;

III) coating the first solution on the lower electrode to form a photoactive layer; And

IV) forming an upper electrode on the photoactive layer.

The method for producing the organic solar cell of the present invention will be described in more detail as follows.

(I) A lower electrode is formed on a substrate, and the lower electrode may be formed on the substrate by vapor deposition.

The deposition method is not particularly limited as long as it is a deposition method commonly used in the field of solar cell technology. Preferably, the deposition method is selected from the group consisting of a chemical vapor deposition method and a physical vapor deposition method . Of these, a rapid deposition rate, a large-area deposition, and a relatively low-temperature deposition can be formed through a sputtering method.

The substrate may be made of a material selected from, for example, glass, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyisosulfonate (PES). Most preferably, a glass substrate can be applied.

The lower electrode may be an anode or a cathode. The lower electrode may be formed of a material selected from the group consisting of ITO (Indium Tin Oxide), FTO (fluorinated Tin Oxide), IZO (Indium Zinc Oxide), AZO Zinc Tin Oxide), SnO ₂ , ZnO, carbon nanotubes, graphene, and silver nanowires, and may be indium tin oxide (ITO).

After step (I), before step (II), step (I-1) may further comprise forming a PEIE polymer surface modification layer on the lower electrode.

At this time, in order to form the PEIE polymer surface modification layer on the lower electrode, a solution containing the PEIE polymer may be formed on the surface of the lower electrode by spin coating.

When such a PEIE polymer surface modification layer is formed on the lower electrode, since the work function is lowered so that the electrode having a higher work function can also be used as the lower electrode, the life shortening problem caused by the use of the low work function electrode Can be prevented and solved. That is, the effect of improving the lifetime of the organic solar battery can be obtained.

The PEIE polymer surface modification layer may be made of PEIE (polyehthylenimine ethoxylated), and preferably has a thickness of 1 to 20 nm.

The polymer surface modification layer formed on the lower electrode has a function of lowering the work function of the lower electrode due to the surface dipole of the amine group (NH ₂ ) contained in the PEIE, which is a PEIE (polyehthylenimine ethoxylated) polymer . This amine group improves the adhesion between the lower electrode) and the photoactive layer due to chemical interaction with the photoactive layer formed on the PEIE polymer surface modification layer.

The step (I-1) may further include: (I-2) drying the PEIE polymer surface modification layer formed at the step (I-1) at 80 to 130 ° C for 5 to 15 minutes.

(A-1) a first organic semiconductor material represented by the following Chemical Formula 1; and (a-2) a second organic semiconductor material represented by Chemical Formula 2 below; (b) an n-type organic semiconductor material; And (c) a solvent to prepare a first solution (II), and then coating the resultant solution on the lower electrode or the surface modified layer of the PEIE polymer to form a photoactive layer (III).

(A-1) a first organic semiconductor material represented by the following Chemical Formula 1; and (a-2) a second organic semiconductor material represented by Chemical Formula 2 below; (b) an n-type organic semiconductor material; And (c) a solvent to prepare a first solution.

[Chemical Formula 1]

(2)

In the above formula

Wherein X _1, X _2, X ₃ and X _4, and is the same as or different from each other, are each independently hydrogen or halogen, wherein _{R 1, R 2, R 3} , R 4, R 5 And R < ₆ > are the same or different, and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms, and n is an integer of 1 to 10,000,000.

In the formula 1, when R ₁ and R ₂ are symmetrical to each other and have the same structure, R ₃ and R ₄ are also symmetrical to each other and have the same structure. In the formula 2, R ₅ and R ₆ Are preferably symmetrical to each other and have the same structure. The use of the first and second organic semiconductor materials having such a structure is excellent in intermolecular energy transfer.

Wherein R ₁ and R ₂ are the same or different and each independently is a straight chain alkyl group having 1 to 7 carbon atoms, and R ₃ and R ₄ are the same or different and each independently represent a group having 8 to 22 carbon atoms Branched alkyl group,

In formula (2), R ₃ and R ₄ are the same or different, and each independently is a straight-chain alkyl group having 8 to 22 carbon atoms, since the first organic semiconductor material having such a side chain structure and the When the second organic semiconductor material is mixed, molecular accumulation and supramolecular alignment between each other are most improved.

For the above-mentioned effects, X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other in Formula 1, and most preferably independently hydrogen or F.

The characteristics of the photoactive layer are the same as those of the first organic semiconductor material (a-1) and the second organic semiconductor material (a-2) Organic semiconductor materials, and the kind and content of the solvent. Therefore, the components of the photoactive layer are very important for the performance of the organic solar cell.

(a-1) the first organic semiconductor material represented by Formula 1 is a low molecular compound having a molecular weight of 1000 to 2000 g / mol, and the second organic semiconductor material represented by Formula (2) It is a polymer compound having a molecular weight of 100,000 g / mol.

The second organic semiconductor material represented by the above formula (a-2) is mixed with the first organic semiconductor material (a-1) in an appropriate amount to form the above-mentioned low molecular compound (a-1) The aggregation phenomenon of the first organic semiconductor material is inhibited to improve the morphology and the network structure of the first organic semiconductor material represented by the above formula (1) (a-1), so that the organic semiconductor material having high hole mobility and high light absorption rate, A photoelectric conversion efficiency of 1% or more is achieved.

The first organic semiconductor material (a-1) may be any one selected from low-molecular compounds represented by the following formulas (3) to (7).

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

Preferably, the (a-1) first organic semiconductor material may be a low molecular weight compound represented by the formula (5).

The second organic semiconductor material (a-2) may be a polymer compound represented by the following formula (8).

[Chemical Formula 8]

In the above formula

n is an integer of 1 to 10,000,000, and more specifically, a molecular weight of 50,000 to 100,000 g / mol is preferable.

The mixing weight ratio of the first organic semiconductor material (a-1) and the second organic semiconductor material (a-2) is preferably 1: 0.01-0.04. -2) If the mixing ratio by weight of the second organic semiconductor material is less than 1: 0.01, the organic solar cell light conversion efficiency improvement effect due to the improvement of the morphology can not be attained. If the ratio is 1: 0.05 or more, It is preferable to perform it within the above-mentioned range.

The solvent (c) is preferably a mixed solvent composed of chlorobenzene and 1,8-diiodoctane. If a solvent other than the mixed solvent is used, as shown in the following Experimental Example, Or less, and the light conversion efficiency is remarkably lowered to a maximum of 2% or less.

The mixing volume ratio of the chlorobenzene and the 1,8-diiodoctane is preferably 1: 0.002-5.

That is, in the method for manufacturing an organic solar cell according to the present invention, the first solution for preparing the photoactive layer is most preferably composed of (a-1) the first organic semiconductor material represented by Chemical Formula 1; (a-2) a second organic semiconductor material represented by Chemical Formula 2; (b) an n-type organic semiconductor material; And (c) a solvent, wherein (a-1) the mixing ratio by weight of the first organic semiconductor material represented by Formula 1 and (a-2) the second organic semiconductor material represented by Formula 2 is 1: 0.04, and the solvent (c) is a mixed solvent of chlorobenzene and 1,8-diiodoctane, and the mixing ratio of the chlorobenzene and 1,8-diiodoctane is 1: 0.002-5. It is confirmed that the performance of the organic solar cell manufactured through the above range and configuration is significantly lowered as in the experiment example described later.

When the organic solar battery according to the present invention is manufactured, the organic solar battery having the optimized structure can further improve the light conversion efficiency by at least 0.1% and at most 1%.

(A-1) a first organic semiconductor material represented by the above-mentioned formula (1), even if it has the same composition as the above-mentioned first solution; (a-2) If the mixing weight ratio of the second organic semiconductor material represented by Formula 2 is slightly out of order, the effect of the present invention can not be achieved, and the light conversion efficiency of the organic solar cell (A-1) a first organic semiconductor material represented by Formula 1; (a-2) There is a problem that the second organic semiconductor material represented by the above-mentioned formula (2) is mixed and used.

The (b) n- type organic semiconductor material is Methyl (6,6) -phenyl -C61- butyrate (PC ₆₀ BM), (6,6) -phenyl -C61- butynyl rigs Acid methyl ester (C ₆₀ -PCBM) , (6,6) -phenyl -C71- butynyl rigs Acid methyl ester (C ₇₀ -PCBM), (6,6) -phenyl -C77- butynyl rigs Acid methyl ester (C ₇₆ -PCBM), (6,6) -Phenyl-C79-butyric acid methyl ester (C ₇₈ -PCBM), (6,6) -phenyl-C ₈₁ -butylic acid methyl ester (C ₈₀ -PCBM) Rick acid methyl ester _{(C 82 -PCBM), (6,6} ) - phenyl butyric -C85- rigs acid methyl ester (C ₈₄ -PCBM), bis (1- [3- (methoxycarbonyl) propyl] -1 _{phenyl) (bis-C 60 -PCBM)} , 3'- phenyl -3'H- cycloalkyl profile (8,25) (5,6) fullerene -C70- bis -D5h (6) -3'- acid methyl May be any one or more selected from the group consisting of esters (Bis-C ₇₀ -PCBM), indene-C60-bis-adduct (ICBA), monoindenyl C60 (ICMA), and combinations thereof, 6,6) -phenyl-C71-butyric acid methyl ester Can be Termini (C ₇₀ -PCBM).

Next, (III) the first solution is coated on the lower electrode to form a photoactive layer. Specifically, the photoactive layer may be formed by coating the first solution on the lower electrode or the PEIE polymer surface modification layer .

The coating method may be carried out by any one method selected from the group consisting of spin coating, nozzle coating, spray coating, inkjet and slit coating. Preferably by spin coating.

(III) forming an upper electrode on the photoactive layer. An upper electrode may be formed on the photoactive layer by a conventional method.

According to an embodiment of the present invention, the upper electrode may be made of MoO ₃ / Ag, Au, Pt, or the like.

The organic solar cell manufactured as described above includes the photoactive layer formed using the first solution, so that a solar cell having high photoelectric conversion efficiency can be manufactured through a simpler manufacturing process.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. It is natural that it belongs to the claims.

In addition, the experimental results presented below only show representative experimental results of the embodiments and the comparative examples, and the respective effects of various embodiments of the present invention which are not explicitly described below will be specifically described in the corresponding part.

Synthetic example  1. A compound represented by the general formula (3) DTS -0F); 7,7 '-( 4,4- Bis - Ethylhexyl ) -4H- 3, < / RTI > 2-b: 4,5-b '] dithiophene -2,6- Dill ) Bis (4- (5'- Hexyl - [2,2'- Vitio Phen] -5-yl) benzo [c] [1,2,5] thiadiazole)

[Reaction Scheme 1]

The 15 ml reaction tube was evacuated and flame-dried three or more times to remove water inside the glass. Compound 10 (0.55 g, 1.18 mmol) and compound 11 (0.40 g, 0.54 mmol) were added, respectively, and vacuum and venting were repeated three times to make the inside of the bulb nitrogen atmosphere. The purified toluene (5.4 ml) and Pd (PPh ₃ ) ₄ (0.062 g, 0.05 mmol) were added thereto and stirred in a microwave. The solvent was removed from the resulting mixture by using a rotary evaporator, and then subjected to column chromatography using hexane and chloroform to obtain 0.504 g of a compound represented by the formula (3) in a yield of 86%. The above reaction process is shown in Scheme 1 above.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.19 (t, 2H), 8.00 (d, 2H), 7.78 (m, 4H), 7.16 (d, 2H), 7.09 (d, 2H), 6.71 (d , 2H), 2.81 (t, 4H), 1.68 (m, 4H), 1.38 ~ 1.09 (m, 34H), 0.92 ~ 0.81 (m, 18H).

Synthesis Example 2. Synthesis of Compound (4)

2-1) Synthesis of the compound represented by the formula (14); 4- (4,4-bis (2-ethylhexyl) -4H-silolo [ 3,2-b: 4,5-b '] dithiophene Yl) -5- Floro -7- (5'- Hexyl - [2,2'- Batiotopen ] -5-yl) benzo [ c] [1,2,5] thiadiazole

[Reaction Scheme 2]

The 15 ml reaction tube was vacuumed and flame-dried more than 3 times to remove moisture inside the glass. Compound 12 (0.87 g, 1.51 mmol) and compound 13 (0.60 g, 1.25 mmol) were added, respectively, and vacuum and venting were repeated three times to make the inside of the bulb nitrogen atmosphere. The resulting solution was mixed with purified toluene (7.4 ml) and Pd (PPh ₃ ) ₄ (0.071 g, 0.06 mmol), and the mixture was stirred in microwave and then stirred at 160 ° C for 1 hour to complete the reaction. The solvent was removed using a rotary evaporator under reduced pressure, and the residue was subjected to column chromatography using hexane and chloroform to obtain 0.85 g of the compound represented by the formula (14) in a yield of 82.6%. The above reaction process is shown in Reaction Scheme 2 above.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.28 (t, 1H), 8.03 (d, 1H), 7.73 (d, 1H), 7.27 (d, 1H), 7.19 (d, 1H), 7.12 (d 1H), 7.08 (d, 1H), 6.73 (d, 1H), 2.82 (t, 2H), 1.70 (m, 2H), 1.47-0.97 (m, 28H) 0.96-0.76 (m, 15H).

2-2) a compound represented by the formula (4) (DTS-1F); Benzo [c] [1, < / RTI > 2, 5-fluoro-7- (5 ' -hexyl-pyrimidin- [2,2'-bithiophen] -5-yl) benzo [c] [1,2,5] thiadiazole) Synthesis

[Reaction Scheme 3]

The 15 ml reaction tube was vacuumed and flame-dried more than 3 times to remove moisture inside the glass. Compound 10 (0.26 g, 0.56 mmol) and compound 15 (0.53 g, 0.54 mmol) were added, respectively, and vacuum and venting were repeated three times to make the inside of the bulb nitrogen atmosphere. Put it refined toluene (7.7 ㎖) and _{Pd (PPh 3) 4 (0.031} g, 0.02 mmol) was stirred in a microwave (microwave), the reaction was terminated by stirring for 1 hour at 160 ℃. The resulting mixture was subjected to column chromatography using hexane and chloroform to remove the solvent by using a reduced pressure rotator to obtain 0.461 g of compound (DTS-1F) represented by the formula (4) in 71% yield. The above reaction process is shown in the above-mentioned Scheme 3.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.33 (t, 1H), 8.20 (t, 1H), 8.03 ~ 8.01 (m, 2H), 7.82 (m, 2H), 7.70 (d, 1H), 7.18 4H), 1.74-1.67 (m, 4H), 1.42-1.05 (m, 2H), 7.17-7.10 (m, 34H), 0.92-0.80 (m, 18H).

Synthesis Example 3. Synthesis of Compound Represented by Chemical Formula 5

3-1) Synthesis of the compound represented by the formula (16) (4- (6-bromo-4,4-bis (2-ethylhexyl) -4H-silolo [3,2- (5'-hexyl- [2,2'-bithiophen] -5-yl) benzo [c] [1,2,5] thiadiazole) synthesis

[Reaction Scheme 4]

(0.81 g, 0.99 mmol) and chloroform (76 ml) were added to a 250 ml reaction tube and the mixture was stirred under ice-cooling at 0 ° C while blocking the light. Then, an-bromosuccinimide (0.18 g, 1.04 mmol) was added thereto several times and reacted at room temperature for 16 hours, and then extracted with water and dichloromethane in a separating funnel. Among them, the dichloromethane layer was removed with a rotary evaporator to obtain a product. The product was purified by column chromatography using hexane and chloroform to obtain 0.85 g of the compound represented by the formula (16) in 94% yield. The above reaction process is shown in Scheme 4 above.

¹ H NMR (400 MHz, CDCl ₃ ):? = 8.26 (t, IH), 8.03 (d, IH), 7.72 (M, 1H), 6.72 (d, 1H), 2.82 (t, 2H), 1.68 (m, 2H), 1.45-0.98 (m, 28H) 0.92-0.77

3-2) Synthesis of the compound represented by the formula (17) (4- (4,4-bis (2-ethylhexyl) -6- (trimethylstannyl) -4H-silolo [3,2- (5'-hexyl- [2,2'-bithiophen] -5-yl) benzo [c] [1,2,5] biphenyl- ≪ / RTI >

[Reaction Scheme 5]

(0.81 g, 0.90 mmol) and hexamethyldithine (1.48 g, 4.53 mmol) were added to a 15-ml reaction tube, respectively. Vacuum and venting were repeated three times, It was made into atmosphere. The purified toluene (12.9 ml) and Pd (PPh ₃ ) ₄ (0.052 g, 0.04 mmol) were added thereto, and the mixture was stirred in a microwave. The mixture was stirred at 160 ° C for 1 hour to complete the reaction. Extract the resulting mixture with diethyl ether using a separatory funnel and wash thoroughly with distilled water. Among them, the diethyl ether layer was washed with a rotary evaporator to remove the solvent, and after the mixture was obtained, washing with methanol was carried out at 40 ° C until the hexamethyldithine disappeared and then dried sufficiently 0.83 g of the compound represented by the Compound 17 was obtained in a yield of 94%. The above reaction process is shown in the above Scheme 5.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.29 (t, 1H), 8.02 (d, 1H), 7.72 (d, 1H), 7.18 (d, 1H), 7.13 (s, 1H), 7.11 (s 2H), 1.70 (m, 2H), 1.60-1.17 (m, 24H), 1.03-0.77 (m, 19H), 0.46 (s, 9H).

3-3) The compound represented by the formula (18) (4- Bromo -5,6- Diplo -7- (5'- Hexyl - [2,2'-bar this Thiophen-5-yl) Benzo [c] [1, 2, 5] Thiadiazole ) synthesis.

[Reaction Scheme 6]

The 15 ml reaction tube was vacuumed and flame-dried more than 3 times to remove moisture inside the glass. The compound (0.46 g, 1.26 mmol) represented by Compound 19 and the compound represented by Compound 20 (0.26 g, 0.64 mmol) were added, respectively, and vacuum and venting procedures were repeated three times to make the inside of the bulb nitrogen atmosphere . The purified toluene (13 ml) and Pd (PPh ₃ ) ₄ (0.037 g, 0.03 mmol) were added thereto, and the mixture was stirred in a microwave, followed by stirring at 160 ° C for 1 hour to terminate the reaction. The solvent was removed from the resulting mixture using a rotary evaporator, and the residue was subjected to column chromatography using hexane and chloroform to obtain 194 mg of a compound represented by the formula (18) in a yield of 61%. The above reaction process is shown in Scheme 6 above.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.17 (d, 1H), 7.21 (d, 1H), 7.14 (d, 1H), 6.73 (d, 1H), 2.82 (t, 2H), 1.74 ~ 1.66 (m, 2H), 1.41-1.32 (m, 6H), 0.88 (t, 3H).

3-4) A compound represented by the formula 6 (DTS-3F; 4- (4,4-bis (2-ethylhexyl) -6- (5-fluoro- 7- (5'- Yl] -4H-silolo [3,2-b: 4,5-b '] dithi [pi] (5'-hexyl- [2,2'-bithiophen] -5-yl) benzo [c] [1,2,5] ≪ / RTI >

[Reaction Scheme 7]

The 15 ml reaction tube was vacuumed and flame-dried more than 3 times to remove moisture inside the glass. The compound (0.26 g, 0.56 mmol) represented by Compound 18 and the compound represented by Compound 17 (0.53 g, 0.54 mmol) were added, and the vacuum and venting processes were repeated three times to make the inside of the bulb nitrogen atmosphere . Put it refined toluene (7.7 ㎖) and _{Pd (PPh 3) 4 (0.031} g, 0.02 mmol) was stirred in a microwave (microwave), the reaction was terminated by stirring for 1 hour at 160 ℃. The resulting mixture was subjected to column chromatography using hexane and chloroform to remove the solvent by using a reduced pressure rotator to obtain 0.461 g of a compound (DTS-3F) represented by the formula (6) in 71% yield. The above reaction process is shown in Scheme 7 above.

^{1 H NMR (400MHz, 60 ℃} , C 2 D 2 Cl 4): δ = 8.37 (m, 2H), 8.23 (d, 1H), 8.06 (d, 1H), 7.74 (d, 1H), 7.26 (d 2H), 2.88-2.84 (m, 4H), 1.79-1.71 (m, 4H), 7.28 (d, ), 1.62-1.03 (m, 34H), 0.97-0.87 (m, 18H).

Synthesis Example 4. Synthesis of Compound (7,7 '- (4,4-bis (2-ethylhexyl) -4H-silolo [3,2-b: 4,5- b'] dithiophene- Benzo [c] [1,2,5] triazolo [4,5-b] thiophene- Thiadiazole)) Synthesis

[Reaction Scheme 8]

The 15 ml reaction tube was vacuumed and flame-dried more than 3 times to remove moisture inside the glass. The compound (0.18 g, 0.37 mmol) represented by Compound 11 and the compound (0.13 g, 0.18 mmol) represented by Compound 18 were respectively added and vacuum and venting procedures were repeated three times to make the inside of the chitosan nitrogen atmosphere . Purified toluene (9 ml) and Pd (PPh ₃ ) ₄ (0.024 g, 0.03 mmol) were added thereto, and the mixture was stirred in a microwave. The mixture was stirred at 160 ° C for 1 hour to complete the reaction. The obtained mixture was subjected to column chromatography using hexane and chloroform to obtain a compound represented by the formula (7) in a yield of 170 mg (74%).

_{^{1 H NMR (400MHz, CDCl 3}} ): δ = 8.34 (t, 2H), 8.13 (d, 2H), 7.15 (d, 2H), 7.09 (d, 2H), 6.69 (d, 2H), 2.79 (t , 4H), 1.73-1.65 (m, 4H), 1.41-1.07 (m, 34H), 0.92-0.88 (m, 18H).

Manufacturing example  1-4. Photoactive layer  For manufacturing Blending  solution.

The first organic semiconductor material, the second organic semiconductor material, and the fullerene compound are mixed in an appropriate amount and mixed in a solvent to prepare a blending solution for the production of the photoactive layer.

1) Preparation of the first organic semiconductor material.

Any one selected from the compounds represented by formulas (3) to (7) prepared from Synthesis Examples 1 to 4 was used.

Hereinafter, the first organic semiconductor materials used for the experimental classification are represented by chemical formulas 3, 4, 5, 6, and 7.

2) Preparation of the second organic semiconductor material.

Lot number purchased from NanocleTech. YY7010 (compound represented by the following formula (8)) was used as a second organic semiconductor material.

[Chemical Formula 8]

The molecular weight of the second organic semiconductor material used herein is not particularly limited to a molecular weight of 50,000 to 100,000 g / mol, but in order to clearly evaluate the influence of the parameters in the present experiment, The compound having a molecular weight of 93000 g / mol was used.

In the following Experimental Examples, unless otherwise indicated, the chemical formula 8 means that the compound represented by Chemical Formula 8 having a molecular weight of 93000 g / mol was used as the second organic semiconductor material.

3) Blending  Preparation of solution

The first organic semiconductor material, the second organic semiconductor material, and the fullerene compound were added to a mixed solvent (1 ml) mixed with chlorobenzene and 1,8-diiodooxane in a ratio of 99.6: 0.4, Or more to prepare a blending solution.

At this time, the types and mixing ratios of the first organic semiconductor material, the second organic semiconductor material, the fullerene compound, and the solvent are prepared as shown in Table 1 below.

The first organic semiconductor material The second organic semiconductor material Fullerene compound menstruum Production Example 1 (3)
(DTS (BTTh ₂ ) ₂ )
19.4 mg 8
0.4 mg PC ₇₁ BM
13.2 mg 1 ml Production Example 2 Formula 4
(DTS (FBTTh ₂ ) (BTTh ₂ ))
19.4 mg Production Example 3 Formula 5
(p-DTS (FBTTh ₂ ) ₂ )
19.4 mg Production Example 4 6
(DTS (DFBTTh ₂ ) (FBTTh ₂ ))
19.4 mg Production Example 5 Formula 7
DTS (DFBTTh ₂ ) ₂
19.4 mg

Manufacturing example  6 to 8. Photoactive layer  For manufacturing Blending  solution.

Formula 5 compounds _{(p-DTS (FBTTh 2)} 2) represented by the compound of the formula 8 (PCDTBT) and florene-based compounds by mixing (PC ₇₁ BM) in an appropriate solvent ratios (chlorobenzene and 1,8 -DTTS (FBTTh ₂ ) ₂ : PCDTBT: PC ₇₁ BM blending solution was prepared by blending the solution with 1 ml of a mixed solvent of diisooctodioctane and diisooctodioctane in a ratio of 99.6: 0.4.

The mixture ratio of the low-molecular compound (p-DTS (FBTTh ₂ ) ₂ ) represented by Chemical Formula 5, the compound represented by Chemical Formula 8 (PCDTBT), the fluorene compound (PC ₇₁ BM) and the solvent is specifically shown in Table 2 below .

The first organic semiconductor material The second organic semiconductor material Fullerene compound
(PC ₇₁ BM) menstruum Production Example 6 Formula 5
(p-DTS (FBTTh ₂ ) ₂ )
19.6 mg 8
(PCDTBT)
0.2 mg 13.2 mg 1 ml Production Example 7 Formula 5
(p-DTS (FBTTh ₂ ) ₂ ) 19.4 mg 8
(PCDTBT)
0.4 mg 13.2 mg 1 ml Production Example 8 Formula 5
(p-DTS (FBTTh ₂ ) ₂ )
18.81 mg 8
(PCDTBT)
0.99 mg 13.2 mg 1 ml

Example  1 to 5. Preparation of Organic Solar Cells.

The structure of the produced organic solar cell is as follows.

: ITO / PEIE / photoactive layer / MoO ₃ / Ag

The organic solar cell having the above-described structure was produced through the following process. First, a substrate coated with an ITO layer as a lower electrode was used on a glass substrate. The substrate coated with the ITO layer to be used as the lower electrode (hereinafter referred to as ITO bottom electrode) was sequentially washed with isopropyl alcohol for 10 minutes, acetone for 10 minutes, and isopropyl alcohol for 10 minutes, followed by drying .

The PEIE polymer was diluted with 0.2 wt% of 2-methoxyethanol on the cleaned and dried ITO lower electrode to prepare a PEIE polymer solution (0.2 wt%), which was spin-coated at 6000 rpm for 60 seconds The surface modified PEIE polymer layer was coated and dried at 100 ° C for 10 minutes to form a 5 nm thick PEIE polymer surface modified layer.

Any of the blending solutions prepared in Preparation Examples 1 to 5 was coated on the surface of the polymeric surface modification layer of PEIE to a thickness of 80 nm using a spin coating method to form a photoactive layer. The spin coating conditions were performed at 3000 rpm for 60 seconds.

Next, MoO ₃ was deposited to a thickness of 4 nm to form an upper electrode on the photoactive layer, and an aluminum electrode was deposited to a thickness of 100 nm on the MoO ₃ .

Examples 6 to 8. Preparation of Organic Solar Cells.

The photoactive layer was prepared in the same manner as in Example 1 except that the blending solution prepared in Preparation Examples 6 to 8 was used instead of the blending solution prepared in Production Example 1. [

In Example 6, instead of the blending solution prepared in Production Example 1, a photoactive layer was formed using the blending solution prepared in Production Example 6. In Example 7, instead of the blending solution prepared in Production Example 1, The photoactive layer was formed by using the blending solution prepared in Production Example 8 instead of the blending solution prepared in Production Example 1. In Example 8, the photoactive layer was formed using the blending solution prepared in Production Example 8 instead of the blending solution prepared in Production Example 1. [

Example  9. Manufacture of organic solar cells.

Example 9 was prepared in the same manner as in Example 1 except that the organic solar cell was manufactured under the conditions of 65 ° C and 85% relative humidity (RH).

Comparative Example  1 to 5. Preparation of Organic Solar Cells. PCDTBT Not mixed)

During the production of the organic solar cell of Examples 1 to 5, only 19.8 mg of the low-molecular compound (Formula 3-7) and 13.2 mg of PC ₇₁ BM without mixing PCDTBT in the photoactive layer were dissolved in a solvent (chlorobenzene: 1, Except that a low molecular weight compound (Formula 3-7): PC ₇₁ BM solution prepared by adding the compound of Formula 1 to 1 ml of polyoxyethylene-6, 8-diiodooxane 99.6: 0.4 was used.

Specifically, Comparative Example 1 uses the low molecular weight compound represented by Formula 3, Comparative Example 2 uses the low molecular weight compound represented by Formula 4, Comparative Example 3 uses the low molecular weight compound represented by Formula 5, Is a low molecular weight compound represented by the formula (6), and Comparative Example 5 is a low molecular weight compound represented by the formula (7).

Comparative Example  6 to 20. Preparation of organic solar cell (control of solvent type, mixing ratio, etc.)

The structure of the produced organic solar cell is as follows.

: ITO / PEIE / photoactive layer / MoO ₃ / Ag

The organic solar cell having the above-described structure was produced through the following process. First, a substrate coated with an ITO layer as a lower electrode was used on a glass substrate. The substrate coated with the ITO layer to be used as the lower electrode (hereinafter referred to as ITO bottom electrode) was sequentially washed with isopropyl alcohol for 10 minutes, acetone for 10 minutes, and isopropyl alcohol for 10 minutes, followed by drying .

The PEIE polymer was diluted with 0.2 wt% of 2-methoxyethanol on the cleaned and dried ITO lower electrode to prepare a PEIE polymer solution (0.2 wt%), which was spin-coated at 2500 rpm for 10 seconds The surface modified PEIE polymer layer was coated and dried at 100 ° C for 10 minutes to form a 5 nm thick PEIE polymer surface modified layer.

Each of the blending solutions prepared in the ratio shown in Table 3 below was coated on the PEIE polymer surface modification layer to a thickness of 80 nm by spin coating to form a photoactive layer. The spin coating conditions were carried out at 1000 rpm for 60 seconds.

Next, MoO ₃ was deposited to a thickness of 4 nm to form an upper electrode on the photoactive layer, and an aluminum electrode was deposited to a thickness of 100 nm on the MoO ₃ .

The first organic semiconductor material
Formula 5
(p-DTS (FBTTh ₂ ) ₂ ) The second organic semiconductor material Fullerene compound
PC ₆₁ BM menstruum Comparative Example 6 20 mg 0 mg P3HT 20 mg 1 ml of a 1: 1 mixed solvent of o-xylene and 1-methyl-naphthalene Comparative Example 7 15 mg 5 mg P3HT Comparative Example 8 10 mg 10 mg P3HT Comparative Example 9 5 mg 15 mg P3HT Comparative Example 10 0 mg 20 mg P3HT Comparative Example 11 20 mg 8
PCDTBT
0 mg Comparative Example 12 15 mg 8
PCDTBT
5 mg Comparative Example 13 10 mg 8
PCDTBT
10 mg Comparative Example 14 5 mg 8
PCDTBT
15 mg Comparative Example 15 0 mg 8
PCDTBT
20 mg Comparative Example 16 20 mg 8
PCDTBT
0 mg 20 mg 1 ml of a mixed solvent in which chlorobenzene and 1,8-diiodoctane were mixed at 99.6: 0.4 Comparative Example 17 15 mg 8
PCDTBT
5 mg Comparative Example 18 10 mg 8
PCDTBT
10 mg Comparative Example 19 5 mg 8
PCDTBT
15 mg Comparative Example 20 0 mg 8
PCDTBT
20 mg

Experimental Example  1. Comparison of performance of organic solar cell by mixing weight.

In order to confirm the performance of the organic solar cell according to the types of the first organic semiconductor material and the second organic semiconductor material, the characteristics of the organic solar cells prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were measured and compared.

3 shows the JV characteristics of the organic solar cells prepared in Examples 1 to 5 when irradiated with light having a specific energy of 100 mW / cm < 2 >, and the organic solar cells prepared in Comparative Examples 1 to 5 The JV characteristic for the battery is shown in Fig.

FIG. 4 is a graph showing the external quantum efficiencies (EQE) (%) of the organic solar cells prepared in Examples 1 to 5, and FIG. 6 is a graph showing the external quantum efficiencies And external quantum efficiencies (EQE) (%).

The respective parameters for the organic solar cells of Examples 1 to 5 and Comparative Examples 1 to 5 measured from Figures 3 to 6 are summarized in Table 4 below.

V _oc
(V) J _sc
(MA / cm2) J _{sc , EQE}
(MA / cm2) FF (%) PCE
(%) Example 1 0.75 4.21 5.01 40.68 1.28 Example 2 0.70 80.28 9.83 54.53 3.17 Example 3 0.80 15.37 14.37 66.36 8.13 Example 4 0.79 13.73 12.84 62.75 6.84 Example 5 0.86 11.71 11.51 69.82 7.06 Comparative Example 1 0.78 4.00 5.56 34.32 1.06 Comparative Example 2 0.70 8.47 9.30 52.20 3.07 Comparative Example 3 0.79 14.63 13.69 59.64 6.68 Comparative Example 4 0.78 12.83 12.67 64.10 6.37 Comparative Example 5 0.87 11.33 11.25 68.75 6.78

Referring to FIGS. 3 to 6 and Table 4, the organic solar cells of Examples 1 to 5 have an open circuit voltage (V _OC ) of 0.7 to 0.86 V on average, a J _SC of 4.21 to 15.37 mA / A fill factor of 5.01 to 66.36, and a PCE (%) of 1.28 to 8.13%. In particular, the optimized organic solar cell of Example 3 exhibited a J _SC of 15.37 mA / cm 2, an open circuit voltage (V _OC ) of 0.80 V, a fill factor of 66.36, and a PCE of 8.13% .

On the other hand, the organic solar cells of Comparative Examples 1 to 5 having the photoactive layer without the polymer compound 8 represented by the formula (8) had an open circuit voltage (V _OC ) of 0.70 to 0.87 V, an average open circuit voltage of 4.0 to 14.63 mA / Of J _SC , a fill factor of 34.32 to 68.75, and a PCE of 1.06 to 6.68%.

Among them, Comparative Example 3, which is a control group of the organic solar cell of Example 3, has an open circuit voltage (V _OC ) of 0.79 V, a J _SC of 14.63 mA / cm 2, a fill factor of 59.64, PCE < / RTI >

That is, when the polymer compound (PCDTBT) of the formula (8) was present, PCE (%) increased from 0.1% to 1.0% at least. The organic solar cell used in the experiment of the present invention had a high efficiency of 7% since it was already manufactured to achieve the maximum efficiency. However, it was confirmed that by mixing the first organic semiconductor material, the second organic semiconductor material and the fullerene compound in the photoactive layer as provided in the present invention, a remarkable effect of 1% or more was attained. The efficiency increase of about 0.1% in such an optimized organic solar cell is meaningful in the art.

Experimental Example  2. Comparison of characteristics of organic solar cell (2)

The characteristics of the organic solar cells of Examples 6 to 8 and Comparative Example 3 were compared and compared in order to confirm the performance of the organic solar cell according to the mixing ratio of the first organic semiconductor material and the second organic semiconductor material.

The J-V characteristics of the organic solar cells prepared in Examples 6 to 8 and Comparative Example 3 when irradiating with light having a specific energy of 100 mW / cm 2 are shown in FIG.

The respective parameters for the organic solar cells of Examples 6 to 8 and Comparative Example 3 measured from Fig. 7 are summarized in Table 5 below.

V _oc
(V) J _sc
(mA / cm ² ) FF
(%) PCE _max
(%) Comparative Example 3 0.79 14.63 59.64 6.68 Example 6 0.81 14.23 61.41 7.10 Example 7 0.80 15.37 66.36 8.13 Example 8 0.70 10.08 46.38 3.29

Referring to Table 5 and FIG. 7, the organic solar cell of Example 7 having the photoactive layer with the mixed weight ratio of the first organic semiconductor material and the second organic semiconductor material of 1: 0.02 had J _SC of 15.37 mA / cm 2, 0.80 V , An open circuit voltage (V _OC ), a fill factor of 66.36, and a PCE of 8.13%.

On the contrary, the organic solar cell of Comparative Example 3 having a photoactive layer without the PCDTBT, which is a polymer compound of Chemical Formula 8, has J _SC of 14.63 mA / cm 2, an open circuit voltage (V _OC ) of 0.79 V, (fill factor), and PCE of 6.68%.

Further, in Example 8 (having a photoactive layer in which a polymer compound of Chemical Formula 8, which is a second organic semiconductor material, was added in an excessive amount, the mixing ratio by weight of the first organic semiconductor material and the second organic semiconductor material (PCDTBT of Chemical Formula 8) (J _SC) of 10.08 mA / cm 2, an open circuit voltage (V _OC ) of 0.70 V, a fill factor of 46.38, and a PCE of 3.29%.

In summary, the organic solar cell according to the present invention is characterized in that in the photoactive layer, the mixed weight ratio of the first organic semiconductor material and the second organic semiconductor material gradually increases from 1: 0.01 to 1: 0.02, PCE was increased, but it was confirmed that the efficiency was significantly lowered to 3% at a ratio of 1: 0.05 or more.

As a result, it can be seen that, in the organic solar cell according to the present invention, when the mixing weight ratio of the first organic semiconductor material and the second organic semiconductor material is 1: 0.01-0.04, the highest efficiency can be obtained, 1 (p-DTS (FBTTh ₂ ) ₂ ) represented by the formula (5) is used as the organic semiconductor material, excellent efficiency of 7% or more and maximum 8.13% can be achieved.

On the other hand, when the mixing ratio of the first organic semiconductor material to the second organic semiconductor material in the photoactive layer is 1: 0.05 or more, the efficiency is reduced by about 2.5 times or more. As a result, It is preferable that the first organic semiconductor material and the second organic semiconductor material are mixed in the weight ratio range.

Experimental Example  3. Comparison of characteristics of organic solar cell (3) - Morphology

In order to compare the morphology of the photoactive layer of the organic solar cell according to the presence or absence of the second organic semiconductor material, the photoactive layer prepared according to Example 3 and Comparative Example 3 was subjected to TEM (transmission electron microscope) and energy-filtering transmission electron microscopy.

8 is a TEM (Transmission Electron Microscope) of a photoactive layer prepared according to Example 3 (a) and Comparative Example 3 (b) And energy-filtering transmission electron microscopy (EFTEM) of the photoactive layer thus fabricated.

Referring to FIG. 8, it can be seen that the photoactive layer prepared according to Example 3 is formed more uniformly than the photoactive layer prepared according to Comparative Example 3.

In Figure 9, the green portion represents the Si atom and the red portion represents the C atom, where the Si atom is expected to be p-DTS (FBTTh ₂ ) ₂ used as a low molecular compound, which is the first organic semiconductor material, and the C atom The second organic semiconductor material, the fullerene compound, and the like constituting the photoactive layer can not be expected to represent any one substance. Accordingly, the photoactive layer prepared according to Example 3 has a higher molecular weight than the photoactive layer prepared according to Comparative Example 3 by adding the polymer compound as the second organic semiconductor material, so that the green portion is evenly dispersed .

Experimental Example  4. Comparison of characteristics of organic solar cell (3) - Morphology

In order to compare the morphology of the photoactive layer of the organic solar cell according to the presence or absence of the second organic semiconductor material, the photoactive layer prepared according to Example 3 and Comparative Example 3 was photographed with AFM (Atomic Force Microscope).

FIG. 10 is an image (Rq = 0.75 nm) obtained by observing the surface morphology of the photoactive layer according to Example 3 of the present invention through AFM, FIG. 11 is a graph showing the result of comparing the photoactive layer prepared according to Comparative Example 3 of the present invention with AFM (R q = 1.36 nm)

10 and 11, it can be seen that the surface morphology of the photoactive layer produced according to Embodiment 3 is formed to be sharp compared with the surface morphology of the photoactive layer prepared according to Comparative Example 3. [ This embodiment to the optically active layer produced according to the third high molecular compound (PCDTBT) of formula (8) the second by addition of an organic semiconductor material, the first full aggregation of the organic semiconductor material _{(p-DTS (FBTTh 2)} 2) , or agglomeration It is believed that the phenomenon is suppressed and prevented to improve the morphology of the photoactive layer.

Experimental Example  5. Comparison of characteristics of organic solar cell (5)

The characteristics of the organic solar cells of the organic solar cells of Comparative Examples 6 to 20 were measured and compared in order to confirm the performance of the organic solar cells according to the grains.

FIG. 12 is a graph showing JV characteristics of an organic solar cell manufactured from Comparative Examples 6 to 10 when irradiated with light of 100 mW / cm 2 energy, and FIG. 13 is a graph showing JV characteristics of 100 mW / / Cm < 2 > energy, the JV characteristics of the organic solar cell of the organic solar cell prepared in Comparative Examples 11 to 15 were measured. The JV characteristics of the organic solar cell prepared in Comparative Examples 16 to 20 were measured.

V _oc
(V) J _sc
(MA / cm2) FF (%) PCE _max
(%) Comparative Example 6 0.71 2.65 37.01 0.69 Comparative Example 7 0.72 3.22 30.38 0.71 Comparative Example 8 0.67 2.59 31.33 0.55 Comparative Example 9 0.67 1.62 34.06 0.37 Comparative Example 10 0.67 1.36 39.97 0.36 Comparative Example 11 0.57 3.11 44.13 0.78 Comparative Example 12 0.76 7.32 36.36 1.62 Comparative Example 13 0.86 5.37 33.59 1.55 Comparative Example 14 0.88 2.50 32.05 0.71 Comparative Example 15 0.91 1.46 30.88 0.41 Comparative Example 16 0.72 13.04 44.37 4.14 Comparative Example 17 0.76 5.07 31.53 1.22 Comparative Example 18 0.73 2.19 33.29 0.53 Comparative Example 19 0.80 0.98 37.87 0.30 Comparative Example 20 0.83 0.67 44.15 0.25

Referring to Figs. 12-14 and Table 6, the organic solar cell prepared in Comparative Examples 6 to 10 and the organic solar cell according to the present invention (typically, Example 3) can be used as a second organic semiconductor material constituting the photoactive layer, , And the first organic semiconductor material.

In the organic solar cell prepared in Comparative Examples 6 to 10, the mixing weight ratio of the first organic semiconductor material and the second organic semiconductor material is 1: 0.3-3.

Due to these differences, the organic solar cells prepared in Comparative Examples 6 to 10 exhibited a J _SC of 1.62-3.22 mA / cm 2, an open circuit voltage (V _OC ) of 0.67-0.72 V, a fill factor of 30.38-37.01 factor, PCE of less than 1%.

It can be seen that the organic solar cell of the present invention is significantly lowered in comparison with the organic solar cell of the present invention, the J _SC is 5 times, the filling rate (FF) is 2 times, and PCE is 11 times or more lower.

The organic solar cell prepared in Comparative Examples 11 to 15 had a mixed weight ratio (1: 0.3-3) of the organic semiconductor material according to Example 3 of the present invention and the first organic semiconductor material and the second organic semiconductor material constituting the photoactive layer, And the type of solvent.

Due to these differences, the organic solar cells prepared from Comparative Examples 11 to 15 exhibited a J _SC of 1.46-7.32 mA / cm 2, an open circuit voltage (V _OC ) of 0.57-0.91 V, a fill of 30-44 factor, and PCE of 0.78-2%.

The performance was slightly improved as compared with the organic solar cells of Comparative Examples 6 to 10, but it was still significantly lower than that of the organic solar cell according to the present invention. In particular, it can be seen that the PCE has decreased by at least 4 times and up to 11 times.

The organic solar cells prepared in Comparative Examples 16 to 20 differ only in the mixing weight ratio (1: 0.3-3) of the organic solar cell prepared in Example 3 of the present invention, the first organic semiconductor material and the second organic semiconductor material, The organic solar cell of Comparative Example 16, to which the second organic semiconductor material was not added, was best measured with 4% PCE.

Accordingly, in the organic solar cell according to the present invention, when the mixing weight ratio of the first organic semiconductor material and the second organic semiconductor material is 1: 0.01-0.04, excellent efficiency of about 8% can be achieved, 2 Organic semiconductor material (polymer compound) shows a remarkable decrease in performance when the weight ratio is slightly increased.

In addition, the organic solar cell according to the present invention has a deteriorated performance depending on the kind of the solvent as well as the mixing weight ratio of the first organic semiconductor material and the second organic semiconductor material in the photoactive layer.

Specifically, the performance of the organic solar cell of Comparative Examples 16 to 20 using the same solvent as in Example 3 of the present invention was slightly increased to 4%. However, the organic solar cells of Comparative Examples 6 to 15, And the efficiency is remarkably lower than -2%.

Experimental Example 6: Thermal Stability Analysis

In order to confirm the performance of the organic solar cell according to the present invention at a high temperature of 110 ° C, the characteristics of the organic solar cell of Example 3 and Comparative Example 3 were measured and compared.

Specifically, in this experiment, the organic solar cell of Example 3 and the organic solar cell of Comparative Example 3 were placed in an oven heated to 110 ° C, respectively, and then exposed for 20 minutes, 40 minutes, 60 minutes, 80 minutes, Example 3 and Comparative Example 3 An organic solar cell was taken out, and photoelectric conversion efficiency (PCE), fill factor (FF) and J _SC were measured. The characteristics (the photoelectric conversion efficiency (PCE), the fill factor (FF), and J _{SC )} of the organic solar cells of Example 3 and Comparative Example 3 measured at high temperature of 110 ° C for each hour are _shown in FIGS. Respectively.

FIG. 15 is a graph showing changes in photoelectric conversion efficiency (PCE) of the organic solar cells of Example 3 and Comparative Example 3 measured at high temperature of 110 ° C for each hour. FIG. FIG. 17 is a graph showing changes in fill factor (FF) of the organic solar cells of Example 3 and Comparative Example 3 measured for each hour. And the J _SC change of the organic solar cell of Comparative Example 3 is measured.

As shown in FIGS. 15, 16 and 17, it can be confirmed that the organic solar cell of Example 3 maintains PCE, fill factor (FF), and J _{SC up} to 20 minutes, The maximum PCE decreased by 40%, the fill factor decreased by 10%, and the J _SC decreased by 20-30% until 40-120 minutes.

On the other hand, unlike the present invention, when the second organic semiconductor material is not included (the photoactive layer is formed using the same solvent as in the present invention), the performance of the organic solar cell of Comparative Example 3 is significantly lowered At 20 minutes, PCE decreased by 10%, FF (fill factor) decreased by 10-20%, and J _SC decreased by 10%. In addition, the performance is drastically deteriorated until 40-120 minutes, and it is seen that the numerical value is reduced by half compared to the initial performance.

Comparing the performance after exposure to a high temperature of 110 ° C for 120 minutes, the organic solar cell of Comparative Example 3 was lowered to 0.2, which was three times lower than that of the organic solar cell of Example 3, and the charging rate (FF) was 1.3 times , And J _SC decreased to 0.4, which is more than 2 times.

Accordingly, when the second organic semiconductor material is not included in the photoactive layer in the organic solar cell according to the present invention, it can be confirmed that the lifetime characteristics are significantly lowered in an environment exposed to high temperatures even though the same solvent is used. Specifically, the organic solar cell according to the present invention has an advantage that PCE, FF, and J _SC can be maintained at 80 to 60% of the initial performance when exposed to a high temperature environment of 100 to 200 ° C for 40 to 150 minutes.

On the other hand, when the second organic semiconductor material is not included, the performance of PCE, FF, and J _SC is lowered to 60% or less and 20% 1.3 times higher than other organic solar cells, and up to 3 times lower.

Experimental Example  7. Long term stability analysis

In order to confirm that the long-term performance of the organic solar cell according to the present invention is stably maintained, the performance change of the organic solar cell manufactured in Example 9 with time was measured.

Specifically, in this experiment, the organic solar cell of Example 9 was subjected to photoelectric conversion efficiency (PCE), charge factor (FF), fill factor (J) for 0 hours to 1000 hours under the conditions of 65 ° C. and 85% relative humidity _{SC , and} V _OC were measured.

(Photoelectric conversion efficiency (PCE), fill factor (FF), J _SC , and V _OC ) of the organic solar cell of Example 9 measured under the conditions of 65 ° C. and 85% relative humidity (RH) Is shown in Fig.

18 shows the characteristics (the photoelectric conversion efficiency (PCE), the fill factor (FF), the J _SC , and the photoelectric conversion efficiency) of the organic solar cell of Example 9 measured at each time under the conditions of 65 ° C and 85% relative humidity V _OC ).

As shown in FIG. 18, it was confirmed that the organic solar cell prepared in Example 9 maintained PCE, fill factor (FF), and J _SC for up to 700 hours, and the performance deteriorated little by little after that.

However, even after 800 hours, it can be seen that the PCE and FF have decreased to a maximum of 10% or less. In addition, it can be seen that J _SC and V _OC do not decrease until 1000 hours, but maintain their initial performance. As a result, it was confirmed that the organic solar cell according to the present invention has a very excellent stability that the long-term stability is maintained for up to 1000 to 1500 hours in a normal environment having 85% relative humidity.

100: organic solar cell 110: substrate
120: lower electrode 120a: PEIE polymer surface modification layer
130: photoactive layer 130a: MoO3 layer
140: upper electrode

Claims (13)

A lower electrode formed on a substrate;
A photoactive layer formed on the lower electrode, the photoactive layer including (a) a p-type organic semiconductor material, (b) an n-type organic semiconductor material, and (c) a solvent; And
And an upper electrode formed on the photoactive layer,
(A-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula (2) Features Organic solar cell.
[Chemical Formula 1]

(2)

In the above formula
X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other and each independently represents hydrogen or halogen,
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ And R < ₆ > are the same or different and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms,
and n is an integer of 1 to 10,000,000. The method according to claim 1,
In Formula 1,
R ₁ and R ₂ are the same or different and each independently represents a straight chain alkyl group having 1 to 7 carbon atoms,
R ₃ and R ₄ are the same or different and each independently represents a branched chain alkyl group having 8 to 22 carbon atoms,
Wherein R ₃ and R ₄ are the same or different and each independently represents a linear alkyl group having 8 to 22 carbon atoms. 3. The method of claim 2,
In Formula 1,
When R ₁ and R ₂ are symmetrical to each other and have the same structure as each other,
R ₃ and R ₄ are also symmetrical to each other and have the same structure,
In Formula 2, R ₅ and R ₆ are also symmetrical with each other and have the same structure. The method according to claim 1,
In Formula 1,
Wherein X ₁ , X ₂ , X ₃ and X ₄ are the same or different and each independently hydrogen or F. The method according to claim 1,
Wherein the first organic semiconductor material (a-1) is a low molecular weight compound having a molecular weight of 1000 to 2000 g / mol and the second organic semiconductor material (a-2) is a high molecular weight compound having a molecular weight of 50,000 to 100,000 g / Wherein the organic solar cell is an organic solar cell. The method according to claim 1,
Wherein the first organic semiconductor material (a-1) is any one selected from low-molecular compounds represented by the following general formulas (3) to (7).
(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

The method according to claim 1,
The (b) n- type organic semiconductor material is Methyl (6,6) -phenyl -C61- butyrate (PC ₆₀ BM), (6,6) -phenyl -C61- butynyl rigs Acid methyl ester (C ₆₀ -PCBM) , (6,6) -phenyl -C71- butynyl rigs Acid methyl ester (C ₇₀ -PCBM), (6,6) -phenyl -C77- butynyl rigs Acid methyl ester (C ₇₆ -PCBM), (6,6) -Phenyl-C79-butyric acid methyl ester (C ₇₈ -PCBM), (6,6) -phenyl-C ₈₁ -butylic acid methyl ester (C ₈₀ -PCBM) Rick acid methyl ester _{(C 82 -PCBM), (6,6} ) - phenyl butyric -C85- rigs acid methyl ester (C ₈₄ -PCBM), bis (1- [3- (methoxycarbonyl) propyl] -1 _{phenyl) (bis-C 60 -PCBM)} , 3'- phenyl -3'H- cycloalkyl profile (8,25) (5,6) fullerene -C70- bis -D5h (6) -3'- acid methyl Wherein the organic photovoltaic cell is at least one selected from the group consisting of Bis-C ( _70- PCBM), indene-C60-bisaduct (ICBA), monoindenyl C60 (ICMA) and combinations thereof. The method according to claim 1,
Wherein the weight ratio of the first organic semiconductor material (a-1) to the second organic semiconductor material (a-2) is 1: 0.01-0.04. The method according to claim 1,
The solvent (c) is a mixed solvent composed of chlorobenzene and 1,8-diiodoctane,
Wherein the mixing ratio of the chlorobenzene to the 1,8-diiodoctane is 1: 0.002-5. I) forming a lower electrode on a substrate;
(A-1) a first organic semiconductor material represented by the following formula (1) and (a-2) a second organic semiconductor material represented by the following formula (2) (b) an n-type organic semiconductor material; And (c) a solvent to prepare a first solution;
III) coating the first solution on the lower electrode to form a photoactive layer; And
IV) forming an upper electrode on the photoactive layer.
[Chemical Formula 1]

(2)

In the above formula
X ₁ , X ₂ , X ₃ and X ₄ are the same or different from each other and each independently represents hydrogen or halogen,
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ And R < ₆ > are the same or different and each independently represents a linear or branched alkyl group having 1 to 22 carbon atoms,
and n is an integer of 1 to 10,000,000. 11. The method of claim 10,
Wherein the mixing weight ratio of the first organic semiconductor material (a-1) to the second organic semiconductor material (a-2) is 1: 0.01-0.04. 11. The method of claim 10,
The solvent (c) is a mixed solvent composed of chlorobenzene and 1,8-diiodoctane,
Wherein a mixing volume ratio of the chlorobenzene and the 1,8-diiodoctane is 1: 0.002-5. 11. The method of claim 10,
Wherein the step (III) is performed by a spin coating method.

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