KR101091179B1 - Organic solar cell using morphology controller and method for fabricating the same - Google Patents

Abstract

An organic solar cell and a method of manufacturing the same are provided. The organic solar cell includes a first electrode and a second electrode disposed opposite to each other, and a photoactive layer disposed between the first electrode and the second electrode and mixed with an electron donor material and an electron acceptor material, wherein the electron donor material is disposed at an end thereof. It contains conjugated polymers having hydrophobic functional groups. An organic solar cell manufacturing method includes forming a first electrode on a substrate, and forming a photoactive layer on which the electron donor material and the electron acceptor material containing a conjugated polymer having a hydrophobic functional group at a terminal thereof are mixed on the first electrode. And forming a second electrode on the photoactive layer. According to this, by forming a photoactive layer using a conjugated polymer having a hydrophobic functional group at the end, the contact area between the electron donor material and the electron acceptor material is increased, thereby promoting the separation of excitons at the DA interface, thereby improving the photoelectric conversion efficiency. Can be improved.

Description

Organic solar cell using morphology controller and method for fabricating the same {Organic solar cell using morphology controller and method for fabricating the same}

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

 Recently, as the interest in developing clean alternative energy in the face of environmental problems and high oil prices is increasing, many researches have been conducted on solar cell development. As silicon solar cells, which are mostly commercialized solar cells, have a high manufacturing price and the demand for silicon in the semiconductor industry increases, the price of silicon materials also increases, and it is still less than fossil fuels to replace in terms of economics. In addition, since silicon has a small extinction coefficient, there is a problem in that it must be manufactured in the form of a heavy and thick solar cell for sufficient light absorption. Organic solar cells, on the other hand, have high absorption coefficients of organic molecules used as photoactive layer materials, and thus can absorb solar light even with thin films of hundreds of nanometers. It has good workability, so it can be applied to various fields, and it has various production advantages in terms of economics and technology by making low-temperature atmospheric pressure manufacturing process, inexpensive materials, simple manufacturing process, mass production, and manufacturing large modules. However, since the charge trap density is large, the lifetime and mobility of the charge are low, and the diffusion length is short, so that the light collection efficiency is not good, and thus the photoelectric conversion efficiency is low. Therefore, improvement of photoelectric conversion efficiency is most important for organic solar cells to secure competitiveness in terms of power generation cost.

The technical problem to be solved by the present invention is to provide an organic solar cell having improved photoelectric conversion efficiency by increasing the contact area of the electron donor material and the electron acceptor material of the photoactive layer.

Another technical problem to be solved by the present invention is to provide an organic solar cell manufacturing method with improved photoelectric conversion efficiency.

In order to achieve the above technical problem, an aspect of the present invention provides an organic solar cell. The battery includes a first electrode and a second electrode disposed opposite to each other, and a photoactive layer disposed between the first electrode and the second electrode and mixed with an electron donor material and an electron acceptor material, wherein the electron donor material is hydrophobic at an end thereof. It contains conjugated polymers having functional groups.

The hydrophobic functional group may be an aliphatic or aromatic compound containing fluorine.

The conjugated polymer is at least one selected from the group consisting of polythiophene, polycarbazole, polyfluorene, polysilole, polyphenylene, and derivatives thereof The derivative may be P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1-b; 3, 4-b '] dithiophene) -alt-4,7- (2,1,3-benzothiadiazole)]), PCDTBT (poly [N-9 ″ -hepta-decanyl-2,7-carbazole-alt-5,5 -(4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)]), PFDTBT (poly (2,7- (9- (2'-ethylhexyl) -9-hexyl- fluorene) -alt-5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole))), MEH-PPV (poly- [2-methoxy-5- ( 2'-ethyl-hexyloxy) -1,4-phenylene vinylene]) or MDMO-PPV (poly [2-methoxy-5- (3,7-dimethyloctyloxy) -1,4-phenylene vinylene]).

The conjugated polymer having a hydrophobic functional group at the terminal may be a compound represented by the following formula (1).

<Formula 1>

Wherein n is an integer from 1 to 10,000,000.

The conjugated polymer having a hydrophobic functional group at the terminal may be contained in an amount of 0.5 to 95 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the total electron donor material forming the photoactive layer.

On the other hand, the organic solar cell is interposed between the first electrode and the photoactive layer and the hole transport layer located on the first electrode and the electron transport layer interposed between the second electrode and the photoactive layer and located on the photoactive layer It may further include at least one.

Another aspect of the present invention provides an organic solar cell manufacturing method to achieve the above technical problem. The method includes forming a first electrode on a substrate, forming a photoactive layer on which the electron donor material containing an conjugated polymer having a hydrophobic functional group and an electron acceptor material are mixed on the first electrode, and the photoactive layer. Forming a second electrode on the layer.

The conjugated polymer having a hydrophobic functional group at the terminal may be a compound represented by the following formula (1).

<Formula 1>

Wherein n is an integer from 1 to 10,000,000.

The forming of the photoactive layer may include applying a mixed solution of an electron donor material and an electron acceptor material containing a conjugated polymer having a hydrophobic functional group at an end thereof onto a first electrode, and forming the first electrode coated with the mixed solution. And putting the substrate into a container containing the solvent of the mixed solution, and may include solvent assisted annealing.

The step of applying the mixed solution is spin coating, dip coating, ink-jet printing, spray coating, screen printing, drop casting Or by a method of doctor blade.

Further, after performing the solvent assisted annealing step, the method may further include thermal annealing.

As described above, according to the present invention, by forming a photoactive layer using a conjugated polymer having a hydrophobic functional group at the terminal, the crystallinity of the electron acceptor material is improved, while the crystallinity of the electron donor material is maintained to maintain the crystallinity of the electron donor material. Increasing the contact area of the material, thereby promoting the separation of excitons at the DA interface to improve the photoelectric conversion efficiency.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout.

1 is a cross-sectional view showing an organic solar cell according to an embodiment of the present invention.

As shown in FIG. 1, an organic solar cell according to an exemplary embodiment of the present invention may include a substrate 10, a first electrode 20, a photoactive layer 30, and a second electrode 40. have.

The substrate 10 is used to support an organic solar cell, a transparent glass substrate or poly ethylene terephthlate (PET), polyethersulphone (PES), polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), or PAR Polyarylate) may be used a transparent plastic substrate. But it is not limited thereto.

The first electrode 20 is positioned on the substrate 10, and preferably made of a transparent material so that light passing through the substrate 10 reaches the photoactive layer 30 to be described later. In addition, the first electrode 20 is a conductive material having a high work function and low resistance. In this case, the material forming the first electrode 20 may be Al-doped Zinc Oxide (AZO), Indium Tin Oxide (ITO), Fluorine-doped Tin Oxide (FTO), Indium Zinc Oxide (IZO), or the like. It may be selected from the group consisting of a mixture.

The photoactive layer 30 is positioned on the first electrode 20. The photoactive layer 30 has a bulk heterojunction structure in which an electron donor (D) material and an electron acceptor (A) material are mixed, and excitons generated from the electron donor material by receiving light. (exciton) acts as a photoelectric conversion layer that generates current by separating electrons and holes. More specifically, when the organic solar cell is irradiated with light, an electron donor material absorbs light to form an electron-hole pair (exciton) in an excited state, and the electron-hole pair diffuses in an arbitrary direction and then electron donor The electron acceptor material interface (DA interface) is encountered. In this case, since the electron affinity of the electron acceptor material is greater than that of the electron donor material, electrons move toward the electron acceptor material having a high electron affinity, and holes remain in the electron donor material and are separated into respective charges. The separated electrons and holes are collected and moved to each electrode by the difference in concentration between the internal electric field and the accumulated charge formed by the work function difference between the anode (first electrode) and the cathode (second electrode). Through it flows in the form of current. Therefore, as the DA interface in the photoactive layer 30 increases, the DA interface exists at a close distance from the electron-hole pair generated by light, and the electron-hole pairs can be effectively separated into electrons and holes. Can improve the photoelectric conversion efficiency. According to the present invention, by using a conjugated polymer having a hydrophobic functional group at its end as part or all of the electron donor material, it is possible to cause nano phase phase separation with a relatively hydrophilic electron acceptor material. It can improve the crystallinity of the material. Therefore, throughout the specification of the present invention, the hydrophobic functional group should be understood to refer to an atomic group having a relatively strong hydrophobicity than the electron donor material to the extent that can cause phase separation of the electron donor material and the electron acceptor material. The hydrophobic functional group may be, for example, an aliphatic or aromatic compound containing fluorine. The conjugated polymer may include polythiophene, polycarbazole, polyfluorene, polysilole, polyphenylene, or derivatives thereof. P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1-b; 3,4-b '] dithiophene) -alt-4,7- (2,1,3-benzothiadiazole)]), PCDTBT (poly [N-9 "-hepta-decanyl-2,7-carbazole-alt-5,5- (4 ', 7') -di-2-thienyl-2 ', 1', 3'-benzothiadiazole)]), PFDTBT (poly (2,7- (9- (2'-ethylhexyl) -9-hexyl-fluorene) -alt-5, 5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole))), MEH-PPV (poly- [2-methoxy-5- (2'-ethyl-hexyloxy) -1,4-phenylene vinylene]) or MDMO-PPV (poly [2-methoxy-5- (3,7-dimethyloctyloxy) -1,4-phenylene vinylene]). However, it is not limited to the above materials. As one example, the conjugated polymer having a hydrophobic functional group at the terminal may be a compound represented by the following formula (1).

<Formula 1>

Wherein n is an integer from 1 to 10,000,000.

When the conjugated polymer having a hydrophobic functional group at the terminal is used as part of the electron donor material, the conjugated polymer may be contained in an amount of 0.5 to 95 parts by weight based on 100 parts by weight of the total electron donor material constituting the photoactive layer 30, preferably 1 to It may be contained in 10 parts by weight.

2A and 2B are schematic diagrams showing the structure of the photoactive layer before and after the conjugated polymer having a hydrophobic functional group at its end is introduced into the photoactive layer, respectively.

2A and 2B, the crystallinity of the electron donor material 32 before and after the introduction of the conjugated polymer having a hydrophobic functional group at the terminal is the same, but the electron after the introduction of the conjugated polymer having the hydrophobic functional group at the terminal is introduced. The crystallinity of the acceptor material 34 is improved. Accordingly, since the contact area of the electron donor material 32 and the electron acceptor material 34, that is, the DA interface is increased, separation of the electron-hole pairs generated in the electron donor material 32 is facilitated, thereby increasing the photoelectric conversion efficiency. I can bring it.

In general, in the region where the electron donor material and the electron acceptor material coexist, the electron acceptor material enters between the electron donor materials, thereby adversely affecting the crystallinity of the electron donor material. Therefore, an increase in the crystallinity of the electron acceptor material leads to a decrease in the crystallinity of the electron donor material and low hole mobility, resulting in a decrease in the efficiency of the organic solar cell. According to the present invention, however, the hydrophobic functional group introduced at the terminal of the conjugated polymer, which is the electron donor material, can effectively inhibit the inflow of the electron acceptor material into the electron donor material, thereby increasing the crystallinity of the electron acceptor material while increasing the crystallinity of the electron donor material. Can be maintained to improve the efficiency of the battery. It is a kind of hydrophobic functional group located at the end of conjugated polymer, which promotes nano-level fine phase separation between electron donor material and electron acceptor material, improving the crystallinity of electron acceptor material and preventing the electron acceptor material from decreasing crystallinity. It is the result of playing the role of a morphology controller.

The electron acceptor material includes at least one of a fullerene (C ₆₀ ), a fullerene derivative, a perylene, a polybenzimidazole (PBI), and a PTCBI (3,4,9,10-perylene-tetracarboxylic bis-benzimidazole). The fullerene derivative may be PCBM ((6,6) -phenyl-C ₆₁ -butyric acid-methylester) or PCBCR ((6,6) -phenyl-C ₆₁ -butyric acid cholesteryl ester). However, it is not limited to the above materials.

In addition, a hole transport layer HTL may be interposed between the first electrode 20 and the photoactive layer 30. The hole transport layer is a layer for easily transferring holes generated in the photoactive layer 30 to be described later to the first electrode 20, for example, MTDATA, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) It can be formed using a material such as poly (styrenesulfonate).

Referring back to FIG. 1, the second electrode 40 is positioned on the photoactive layer 30. The second electrode 40 is disposed to face the first electrode 20 and a material having a low work function is used. The difference in work function between the first electrode 20 and the second electrode 40 forms an electric field to transfer the charge separated at the D-A interface of the photoactive layer 30. The material forming the second electrode 40 includes, but is not limited to, a metal such as Al, Ca, Mg, K, Ti, Li, or an alloy thereof.

An electron transport layer ETL may be interposed between the photoactive layer 30 and the second electrode 40. The hole transport layer is a layer to facilitate the transfer of electrons generated in the photoactive layer 30 to the second electrode 40, for example, BCP (2,9-Dimethyl-4,7-diphenyl-1 10-phenanthroline), LiF and the like can be used to form.

In the method of manufacturing an organic solar cell according to another embodiment of the present invention, first forming the first electrode 20 on the substrate 10, then forming the photoactive layer 30, and finally, the second electrode 40. It may include the step of forming).

The forming of the first electrode 20 on the substrate may be performed by thermal evaporation, e-beam evaporation, RF (Radio Frequency) sputtering, or magnetron sputtering. Can be appropriately selected and performed.

The photoactive layer 30 may be formed by mixing an electron donor material containing an conjugated polymer having a hydrophobic functional group and an electron acceptor material in an organic solvent, and then applying a mixed solution onto the first electrode 20. Can be done. As a result, the photoactive layer 30 is formed in the form of a bulk heterojunction.

The conjugated polymer having a hydrophobic functional group at the terminal may be a compound represented by the following formula (1).

<Formula 1>

Wherein n is an integer from 1 to 10,000,000.

The coating of the mixed solution on the first electrode 20 may include spin coating, dip coating, ink-jet printing, spray coating, and screen printing. It can be carried out by a solution process appropriately selected from the method of printing, drop casting or doctor blade.

In the forming of the photoactive layer 30, the mixed solution is coated on the first electrode 20, and then the mixed substrate 10 having the first electrode 20 coated with the mixed solution is formed. Solvent assisted annealing may be included in a container containing a solvent of the solution. Thereafter, the method may further include thermal annealing the photoactive layer 30 that has undergone the solvent assisted annealing. In this case, since the crystallinity of the photoactive layer 30 may be further increased through the solvent assisted annealing and heat treatment, the photoelectric conversion efficiency of the organic solar cell may be improved.

The forming of the second electrode 40 may include thermal evaporation, e-beam evaporation, radio frequency (RF) sputtering, or magnetron sputtering of the photoactive layer 30. The method can be appropriately selected and performed.

In addition, the method may further include forming a hole transport layer between the forming of the first electrode 20 and the forming of the photoactive layer 30, and forming the photoactive layer 30. And forming an electron transport layer between the second electrode 40 and the step of forming the second electrode 40.

Hereinafter, preferred examples are provided to aid the understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited to the following experimental examples.

Synthesis Example 1: Synthesis of conjugated polymer (morphology controller) having a hydrophobic functional group at the terminal>

The conjugated polymer (morphology controller) which has a hydrophobic functional group at the terminal was synthesize | combined using Reaction Scheme 1 below.

Scheme 1

5 g (30 mmol) of Compound (1) was added to a 500 mL 2-neck flask, and 120 ml of a mixed solvent of acetic acid and chloroform (CHCl ₃ ) (1: 1) was added thereto. 60 mmol of NBS was dissolved in 80 ml of DMF at 0 ° C, and the solution was injected very slowly into the flask at low temperature using a dropping funnel. After injection, the mixture was reacted at 0 ° C. for 3 hours, quenched with water, extracted with methylene chloride (CH ₂ Cl ₂ ), and purified through silica column to obtain compound (2). (Yield 90%)

5 g (15.33 mmol) of Compound (2) was placed in a nitrogen-substituted 2-neck flask, and 30 ml of dried THF was added to dissolve and stir well, and 4.8 mmol of MeMgBr was slowly added thereto, followed by reflux for 1 hour. After the temperature was lowered to room temperature, 0.37 mmol of Ni (dppp) Cl ₂ catalyst was added thereto, followed by stirring at room temperature for 30 minutes to form compound (3). The Grignard reagent immediately introduced with trifluorovinyl ether (Grignard) was introduced. 4.8 mmol of phosphorus compound (4) was added thereto and reacted at room temperature for 2 hours. After the reaction, precipitated in methanol and filtered to synthesize Compound (5). (Yield 50%)

Comparative Example 1:

A glass substrate coated with ITO was used as the first electrode, and PEDOT: PSS was coated with a hole transport layer to a thickness of 20 nm on the first electrode. 50 mg (1: 1 weight ratio) of the mixture of P3HT and PCBM was dissolved in 1 ml of dichlorobenzene to prepare a mixed solution, followed by spin coating on the hole transport layer to form a photoactive layer having a thickness of 200 nm.

Experimental Example 1

A glass substrate coated with ITO was used as the first electrode, and PEDOT: PSS was coated with a hole transport layer to a thickness of 20 nm on the first electrode. P3HT and Compound (5) synthesized in Synthesis Example 1 were mixed in a weight ratio of 98: 2, and the mixture and PCBM were mixed in a weight ratio of 1: 1. 50 mg of the final mixture was dissolved in 1 ml of dichlorobenzene to prepare a mixed solution, and then spin-coated on the hole transport layer to form a photoactive layer having a thickness of 200 nm.

Experimental Example 2

A photoactive layer was formed by the same method as Experimental Example 2, except that P3HT and Compound (5) synthesized in Synthesis Example 1 were mixed at a weight ratio of 70:30.

3 is a X-ray diffraction (XRD) graph of the photoactive layer prepared according to Comparative Example 1, Experimental Example 1 and Experimental Example 2, respectively.

Referring to FIG. 3, the crystallinity of P3HT is affected even when the compound (5) synthesized in Synthesis Example 1 is not introduced into the photoactive layer (Comparative Example 1) or when it is introduced (Experimental Example 1 and Experimental Example 2). It can be seen that does not have.

4A to 4C are TEM (Transmission Electron Microscope) images of the photoactive layers prepared according to Comparative Example 1, Experimental Example 1, and Experimental Example 2, respectively. In each image, the white part represents P3HT and the black part represents PCBM.

4A to 4C, when the compound (5) synthesized in Synthesis Example 1 was not introduced into the photoactive layer (FIG. 4A and Comparative Example 1), the case was introduced (FIG. 4B, Experimental Example 1 and FIG. 4C). , Experimental Example 2) it can be seen that a distinct phase separation between P3HT and PCBM. Therefore, it can be seen that the nano phase fine phase separation between the electron donor material and the electron acceptor material is promoted by the introduction of the compound (5) synthesized in Synthesis Example 1.

5 is a selected-area electron diffraction (SAED) pattern of the photoactive layer prepared according to Comparative Example 1, Experimental Example 1 and Experimental Example 2, respectively.

Referring to FIG. 5, the crystallinity of PCBM is increased when the compound (5) synthesized in Synthesis Example 1 is not introduced into the photoactive layer (Comparative Example 1) than when introduced (Experimental Example 1 and Experimental Example 2). It can be seen.

Therefore, when the results shown in FIGS. 3, 4A to 4C, and 5 are comprehensively analyzed, a conjugated polymer (morphology controller) having a hydrophobic functional group at the terminal is introduced into the photoactive layer, thereby maintaining the crystallinity of the electron donor material. It can be seen that the crystallinity of the electron acceptor material can be increased to increase the contact area of the electron donor material and the electron acceptor material. Furthermore, since the exciton separation is promoted by the increased D-A interface, it can be expected that the photoelectric conversion efficiency of the organic solar cell can be improved.

Comparative Example 2

A glass substrate coated with ITO was used as the first electrode, and PEDOT: PSS was coated with a hole transport layer to a thickness of 20 nm on the first electrode. 50 mg (1: 1 weight ratio) of the mixture of P3HT and PCBM was dissolved in 1 ml of dichlorobenzene to prepare a mixed solution, followed by spin coating on the hole transport layer to form a photoactive layer having a thickness of 200 nm. Next, the substrate on which the photoactive layer was formed was put in a chalet containing a small amount of dichlorobenzene for 2 hours to gradually form a film. Thereafter, Ca and Al were sequentially vacuum deposited on the photoactive layer to a thickness of 25 nm and 100 nm to form a second electrode, thereby manufacturing an organic solar cell.

<Manufacture example 1>

The same method as in Comparative Example 2, except that P3HT and Compound (5) synthesized in Synthesis Example 1 were mixed in a weight ratio of 98: 2, and the mixture and PCBM were mixed in a weight ratio of 1: 1. To perform an organic solar cell was prepared.

6A and 6B are current-voltage curves showing efficiency characteristics of organic solar cells manufactured according to Comparative Example 2 and Preparation Example 1, respectively.

6A and 6B, when the compound (5) synthesized in Synthesis Example 1 was not introduced (Comparative Example 2) into the photoactive layer (Comparative Example 2), the photoelectric conversion efficiency of the organic solar cell was increased. It can be seen that the improvement.

Comparative Example 3

A glass substrate coated with ITO was used as the first electrode, and PEDOT: PSS was coated with a hole transport layer to a thickness of 20 nm on the first electrode. 50 mg (1: 1 weight ratio) of the mixture of P3HT and PCBM was dissolved in 1 ml of dichlorobenzene to prepare a mixed solution, followed by spin coating on the hole transport layer to form a photoactive layer having a thickness of 200 nm. Next, the substrate on which the photoactive layer was formed was put in a chalet containing a small amount of dichlorobenzene for 2 hours to gradually form a film, and then heat-treated at 110 ° C. for 10 minutes. Thereafter, Ca and Al were sequentially vacuum deposited on the photoactive layer to a thickness of 25 nm and 100 nm to form a second electrode, thereby manufacturing an organic solar cell.

<Manufacture example 2>

The same method as in Comparative Example 3, except that P3HT and Compound (5) synthesized in Synthesis Example 1 were mixed in a weight ratio of 98: 2, and the mixture and PCBM were mixed in a weight ratio of 1: 1. To perform an organic solar cell was prepared.

7A and 7B are current-voltage curves showing efficiency characteristics of organic solar cells manufactured according to Comparative Example 3 and Preparation Example 2, respectively.

Referring to FIGS. 7A and 7B, when the compound (5) synthesized in Synthesis Example 1 was not introduced (Comparative Example 3) into the photoactive layer (Comparative Example 3), the photoelectric conversion efficiency of the organic solar cell was increased. It can be seen that the improvement.

6A and 7A, and 6B and 7B, respectively, it can be seen that when the heat treatment is performed after the photoactive layer is formed, the photoelectric conversion efficiency of the organic solar cell can be further improved.

8A and 8B are current-voltage curves measured in a dark state of organic solar cells manufactured according to Comparative Example 2, Preparation Example 1, Comparative Example 3, and Preparation Example 2, respectively.

Referring to FIGS. 8A and 8B, an organic embodiment is obtained when the compound (5) synthesized in Synthesis Example 1 is not introduced (Comparative Example 2 and Comparative Example 3) than when introduced (Preparation Example 1 and Preparation Example 2). It can be seen that the series resistance of the battery decreases (FIG. 8A) and the rectification rate increases (FIG. 8B). This suggests that the crystallinity of the photoactive layer is improved by introducing a conjugated polymer having a hydrophobic functional group at the terminal as described above, and ultimately suggests that the photoelectric conversion efficiency of the battery can be improved.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes by those skilled in the art within the spirit and scope of the present invention. You can change it.

1 is a cross-sectional view showing an organic solar cell according to an embodiment of the present invention.

2A and 2B are schematic diagrams showing the structure of the photoactive layer before and after the conjugated polymer having a hydrophobic functional group at its end is introduced into the photoactive layer, respectively.

3 is an X-ray diffraction (XRD) graph of the photoactive layers prepared according to Comparative Example 1, Experimental Example 1, and Experimental Example 2, respectively.

4A to 4C are TEM (Transmission Electron Microscope) images of the photoactive layers prepared according to Comparative Example 1, Experimental Example 1, and Experimental Example 2, respectively.

5 is a selected-area electron diffraction (SAED) pattern of the photoactive layer prepared according to Comparative Example 1, Experimental Example 1 and Experimental Example 2, respectively.

6A and 6B are current-voltage curves showing efficiency characteristics of organic solar cells manufactured according to Comparative Example 2 and Preparation Example 1, respectively.

7A and 7B are current-voltage curves showing efficiency characteristics of organic solar cells manufactured according to Comparative Example 3 and Preparation Example 2, respectively.

8A and 8B are current-voltage curves measured in a dark state of organic solar cells manufactured according to Comparative Example 2, Preparation Example 1, Comparative Example 3, and Preparation Example 2, respectively.

Claims (13)

First and second electrodes disposed to face each other; And A photoactive layer disposed between the first electrode and the second electrode and having an electron donor material and an electron acceptor material mixed therein; The electron donor material contains a conjugated polymer having a hydrophobic functional group at its end, The hydrophobic functional group is an aliphatic or aromatic compound containing fluorine, and the conjugated polymer is polythiophene, polycarbazole, polyfluorene, polysilole, polysilole, polyphenylene ( polyphenylene) and at least one selected from the group consisting of organic solar cells. delete delete The method of claim 1, The derivative is P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1-b; 3,4-b ' ] dithiophene) -alt-4,7- (2,1,3-benzothiadiazole)]), PCDTBT (poly [N-9 ″ -hepta-decanyl-2,7-carbazole-alt-5,5- (4 ') , 7'-di-2-thienyl-2 ', 1', 3'-benzothiadiazole)]), PFDTBT (poly (2,7- (9- (2'-ethylhexyl) -9-hexyl-fluorene) -alt -5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole))), MEH-PPV (poly- [2-methoxy-5- (2'-ethyl -hexyloxy) -1,4-phenylene vinylene]) or MDMO-PPV (poly [2-methoxy-5- (3,7-dimethyloctyloxy) -1,4-phenylene vinylene]). The method of claim 1, The conjugated polymer having a hydrophobic functional group at the terminal is an organic solar cell which is a compound represented by the following formula (1): <Formula 1>

Wherein n is an integer from 1 to 10,000,000. The method of claim 1, An organic solar cell containing from 0.5 to 95 parts by weight of a conjugated polymer having a hydrophobic functional group at the end with respect to 100 parts by weight of the total electron donor material constituting the photoactive layer. The method of claim 1, An organic solar cell containing 1 to 10 parts by weight of a conjugated polymer having a hydrophobic functional group at the terminal with respect to 100 parts by weight of the total electron donor material constituting the photoactive layer. The method of claim 1, And at least one of a hole transport layer interposed between the first electrode and the photoactive layer and positioned on the first electrode, and an electron transport layer interposed between the second electrode and the photoactive layer and positioned on the photoactive layer. Organic solar cells. Forming a first electrode on the substrate; Forming a photoactive layer in which an electron donor material containing an conjugated polymer having a hydrophobic functional group at its end and an electron acceptor material are mixed on the first electrode; And Forming a second electrode on the photoactive layer; The hydrophobic functional group is an aliphatic or aromatic compound containing fluorine, and the conjugated polymer is polythiophene, polycarbazole, polyfluorene, polysilole, polysilole, polyphenylene ( polyphenylene) and at least any one selected from the group consisting of derivatives thereof. 10. The method of claim 9, A conjugated polymer having a hydrophobic functional group at the terminal is an organic solar cell manufacturing method is a compound represented by the following formula (1): <Formula 1>

Wherein n is an integer from 1 to 10,000,000. The method of claim 9, wherein the forming of the photoactive layer, Applying a mixed solution of an electron donor material and an electron acceptor material containing a conjugated polymer having a hydrophobic functional group at its terminal on the first electrode; And a solvent assisted annealing step of putting the substrate on which the first electrode coated with the mixed solution is formed into a container containing the solvent of the mixed solution. The method of claim 11, wherein applying the mixed solution, Spin coating, dip coating, ink-jet printing, spray coating, screen printing, drop casting or doctor blade The organic solar cell manufacturing method to be carried out by the method of The method of claim 11, further comprising thermal annealing after performing the solvent assisted annealing.

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