KR101143477B1 - Organic solar cell and method of fabricating the same - Google Patents

Abstract

PURPOSE: An organic solar cell and a manufacturing method thereof are provided to improve solar cell efficiency by increasing an interfacial area of an electron donor layer and an electron accepting layer by adding a regular pattern to PN junction. CONSTITUTION: An anode(120) is formed on a transparent substrate(110). A regular pattern(123) is formed on an upper side of the anode. An electron accepting layer(130) is formed on the anode. A regular pattern(133) is formed on an upper side of the electron accepting layer. An electron donor layer(140) is formed on the electron accepting layer. A cathode(150) is formed on the electron donor layer.

Description

Organic solar cell and method of manufacturing the same {Organic solar cell and method of fabricating the same}

The present invention relates to an organic solar cell and a method for manufacturing the same, and more particularly, to an organic solar cell and a method for manufacturing the same by forming a patterned pn junction to improve efficiency.

Solar cells are photoelectric conversion elements that directly convert solar energy into electricity. The solar cells may be classified into silicon solar cells and organic solar cells according to materials used. While silicon solar cells are expensive and have limited reserves, they are limited to full-scale photovoltaic energy applications, while organic solar cells have low manufacturing costs due to low manufacturing costs and ease of manufacturing processes that do not require special vacuum equipment. This is very good. In addition, due to the low temperature process, the glass substrate or the flexible (flexible) substrate can be used, and accordingly, attention has recently been focused on the advantages such as the possibility of manufacturing a bendable device.

1 is a cross-sectional view of a general organic solar cell.

Referring to FIG. 1, in the conventional organic solar cell 1, a transparent electrode, which is an anode 20, is formed on a transparent substrate 10, and an electron receiving layer 30 and an electron donor layer 40 are formed on the anode 20. ) Are formed sequentially. The metal electrode serving as the cathode 50 is formed on the electron donor layer 40.

In order to absorb light in the electron-accepting layer 30 of the organic solar cell 1, the organic solar cell 1 should have a thickness of 100 nm or more, and the diffusion distance of excitons (electron-hole pairs) generated in the electron-accepting layer 30. Is about 10 nm. Therefore, the separation rate of the electron-holes (separation rate) is reduced, there is a problem that the efficiency is reduced.

In addition, even in a bulk-hetero junction having a bilayer structure, the electron accepting layer and the electron donor layer are isolated, and the interface area is small, resulting in low efficiency.

The technical problem to be solved by the present invention is to provide an organic solar cell having a high energy conversion efficiency by increasing the interface area between the electron receiving layer and the electron donor layer and a manufacturing method thereof.

In order to solve the above technical problem, the organic solar cell according to the present invention includes a positive electrode formed with a regular pattern on the upper surface; An electron receiving layer formed on the anode and having a regular pattern formed on an upper surface thereof according to the pattern shape of the anode; An electron donor layer formed on the electron accepting layer; And a cathode formed on the electron donor layer. As a result, the organic solar cell according to the present invention includes a patterned pn junction, thereby increasing the interface area between the electron receiving layer and the electron donor layer.

In such an organic solar cell, a regular pattern may be formed on an upper surface of the electron donor layer along a pattern shape of the electron receiving layer. The pattern of the anode and the electron receiving layer may include a plurality of pillars having two stages. At this time, the pillar has a height of b, the top length is 3a and the top and the top length is a top and the distance between adjacent pillars is a, where a is 10-100 nm, b is 20-200 nm. Can be.

In the method of manufacturing an organic solar cell according to the present invention, an anode having a regular pattern formed on an upper surface thereof is formed on a transparent substrate. An electron accepting layer having a regular pattern formed on an upper surface thereof is formed along the pattern shape of the anode on the anode. An electron donor layer and a cathode are sequentially formed on the electron accepting layer.

Forming an anode having a regular pattern on the top surface on a transparent substrate may include forming a cathode by applying a transparent electrode material on the transparent substrate and forming a regular pattern on the top surface by photolithography or nanoimprint. It may include a step.

According to the present invention, the solar cell efficiency can be improved by adding a regular pattern to the electron donor layer and the electron accepting layer interface, that is, the pn junction, to increase the interface area of the electron accepting layer and the electron donor layer.

The pattern formed between the electron donor layer and the electron accepting layer interface is a pattern of 100 nm or less three-dimensional structure formed by a three-dimensional pattern formed on the upper surface of the anode, and these patterns are regularly arranged in a one-dimensional or two-dimensional array of electrons The efficiency of the organic solar cell is improved by increasing the surface area of the donor layer and the electron accepting layer interface, facilitating the diffusion of excitons (electron-hole pairs) and increasing the separation, thereby reducing the recombination of the excitons.

Therefore, the present invention not only can provide a high efficiency organic solar cell, but also provides a solar cell having a high efficiency at a low cost and a simple manufacturing method, which can utilize an environmentally friendly and renewable energy source. It can be applied to manufacture.

1 is a cross-sectional view of a general organic solar cell.
2 is a cross-sectional view of an organic solar cell according to the present invention.
3 is an enlarged view of a portion A of FIG. 2.
4 is a process-specific diagram for explaining the organic solar cell manufacturing method according to the present invention.

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 disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. The shape and the like of the elements in the drawings are exaggerated in order to emphasize a more clear description, elements denoted by the same reference numerals in the drawings means the same elements.

2 is a cross-sectional view of an organic solar cell according to the present invention, and FIG. 3 is an enlarged view of a portion A of FIG. 2.

2, the organic solar cell 100 according to the present invention includes an anode 120, an electron receiving layer 130, an electron donor layer 140, and a cathode 150 on a transparent substrate 110.

The transparent substrate 110 may be a glass substrate or a bendable polymer substrate. The bendable polymer substrate is characterized by high chemical stability, mechanical strength and transparency, preferably polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyether ether ketone (PEEK) , Polyethersulfone (PES) and polyetherimide (PEI).

A regular pattern 123 is formed on the upper surface of the anode 120 formed on the transparent substrate 110. The pattern 123 may be formed by a photolithography or a nano imprint method and will be described in detail in the manufacturing method described below. The anode 120 material includes a transparent oxide such as indium tin oxide (ITO), a conductive polymer, a carbon nanotube thin film, a graphene thin film, a graphene oxide thin film, and a metal with carbon It is formed by applying a transparent electrode material selected from the group consisting of a nanotube thin film and a mixture thereof on the transparent substrate (110).

The electron accepting layer 130 formed on the anode 120 also has a regular pattern 133 formed on the upper surface of the electron accepting layer 130 along the shape of the pattern 123 of the anode 120. The electron accepting layer 130 material is (6,6) -phenyl-C61-butyric acid methyl ester [(6,6) -phenyl-C61-butyric acid methyl ester, PCBM], (6,6) -phenyl-C71 Butyric acid methyl ester [(6,6) -phenyl-C71-butyric acid methyl ester, C70-PCBM], fullerene (C60), (6,6) -thienyl-C61-butyric acid methyl ester [(6,6) -thienyl-C61-butyric acid methyl ester; ThCBM], carbon nanotubes, and mixtures thereof. Such a material has a characteristic of being conformally coated on the anode 120, so that the pattern 133 is naturally formed along the shape of the pattern 123 of the anode 120 without the pattern 133 being deliberately formed. do.

Since the regular pattern 133 is formed on the upper surface of the electron receiving layer 130, the interface between the electron receiving layer 130 and the electron donor layer 140 formed thereon becomes a curved shape rather than a conventional flat shape. As a result, the organic solar cell 100 according to the present invention includes a patterned pn junction. As illustrated, the electron donor layer 140 may have a regular pattern 143 formed on an upper surface of the electron accepting layer 130 along the shape of the pattern 133, or may have a flat upper surface without the pattern 143.

The electron donor layer 140 material may be poly-3-hexylthiophene (P3HT), poly-3-poly-3-octylthiophene (poly-3-octylthiophene, P3OT), or polyparaphenylene. Vinylene [poly-p-phenylenevinylene, PPV], poly (dioctylfluorene) [poly (9,9'-dioctylfluorene)], poly (2-methoxy, 5- (2-ethyl-hexyloxy)- 1,4-phenylenevinylene) [poly (2-methoxy, 5- (2-ethyle-hexyloxy) -1,4-phenylenevinylene, MEH-PPV], poly (2-methyl, 5- (3 ', 7 '-Dimethyloctyloxy))-1,4-phenylenevinylene [poly (2-methyl, 5- (3', 7'-dimethyloctyloxy))-1,4-phenylene vinylene, MDMO-PPV] and their It may be selected from the group consisting of a mixture.

The cathode 150 material formed on the electron donor layer 140 may be selected from a metal.

Referring to FIG. 3, the patterns 123 and 133 of the anode 120 and the electron receiving layer 130 include a plurality of pillars each consisting of two ends 121, 122, 131, and 132. The pillar may have a cross section of square, circular, rectangular, or any other shape. For example, FIGS. 2 and 3 show a cross-sectional view of a square having a square, wherein the pillars have a height b and a top length 3a of the bottoms 121 and 131 and a top and 122 length and a top length a 122. , 132) and the distance between adjacent pillars is a, where a may be 10-100 nm and b may be 20-200 nm.

Accordingly, the pattern 133 formed between the electron donor layer 140 and the electron accepting layer 130 interface is a pattern of three-dimensional structure of 100 nm or less, and the electron donors are regularly arranged in a one-dimensional or two-dimensional array. By increasing the surface area of the interface between the layer 140 and the electron receiving layer 130, facilitating the diffusion of excitons (electron-hole pairs), and increasing the separation, the recombination of the excitons can be reduced, thereby increasing the efficiency of the organic solar cell. (120) It is characteristic from the pattern 123 formed in the upper surface.

4 is a process-specific diagram for explaining the organic solar cell manufacturing method according to the present invention. It does not require vacuum deposition, and can be manufactured by a solution process such as spin coating, dip-coating, doctor blading, etc., which has great advantages in terms of manufacturing cost and ease of processing.

Referring to FIG. 4, the anode 120 is formed by applying the transparent electrode material as described above on the transparent substrate 110 with reference to (a). Then, referring to (b) to form a regular pattern 123 on the upper surface of the anode 120 by photolithography or nanoimprint. The shape of the pattern 123 is as described with reference to FIG. 3.

As is well known, the photolithography method is a method of forming a pattern 123 by forming an appropriate mask on the anode 120, and then etching a portion not covered by the mask with an etching gas and removing the mask. Photolithography or electron beam lithography of appropriate wavelengths can be used to form three-dimensional structures below 100 nm.

The nanoimprint method is a method of transferring a pattern 123 by preparing a mold made of a metal, a metal oxide, a ceramic, a semiconductor, etc., and making contact with the anode 120. The anode 120 is flowed by applying heat to the lower portion of the transparent substrate 110, and a mold having a pattern structure is positioned on the anode 120, and then a pressure is applied to the top of the mold to form a pattern 123 on the top surface of the anode 120. ) Or form a pattern 123 on the upper surface of the anode 120 by using a capillary phenomenon by placing a mold having a pattern structure on the anode 120 before the material of the anode 120 is solidified.

Next, referring to (c), the electron accepting layer 130 is formed on the anode 120. The material of the electron accepting layer 130 described above has the property of conformally applied on the anode 120, so that the pattern 133 naturally forms on the upper surface of the electron receiving layer 130 along the shape of the pattern 123 of the anode 120. Is formed.

The method may further include forming a hole transport layer between the anode 120 and the electron receiving layer 130. The hole transport layer is poly (3,4-ethylenedioxythiophene) -polystyrenesulfonate [poly (3,4-ethylenedioxythiophene) -polystyrenesulfonate], polyaniline, copper phthalocyanine (CuPC), polythiophenyl Be selected from the group consisting of polyhiophenylenevinylene, polyvinylcarbazole, poly-p-phenylenevinylene, poly (methyl phenyl silane), and mixtures thereof It can be formed by applying a hole transport material.

Subsequently, the electron donor layer 140 is formed with reference to (d), and the cathode 150 is formed with reference to (e). The electron donor layer 140 may have a pattern 143 but may have a flat top surface. This may be accomplished by methods including, but not limited to, spin-on techniques, contact planarization, and the like. And methods such as blanket etching, chemical mechanical polishing / planarization, and the like may also be used.

The method may further include forming an electron transport layer between the electron donor layer 140 and the cathode 150. The electron transport layer is formed by applying an electron transport material selected from the group consisting of lithium flouride (LiF), calcium, lithium, titanium oxide and mixtures thereof. .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the embodiment in which said invention is directed. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

Claims (9)

An anode having a regular pattern formed on an upper surface thereof;
An electron receiving layer formed on the anode and having a regular pattern formed on an upper surface thereof according to the pattern shape of the anode;
An electron donor layer formed on the electron accepting layer; And
An organic solar cell comprising a cathode formed on the electron donor layer. The organic solar cell of claim 1, wherein the electron donor layer has a regular pattern formed on an upper surface of the electron donor layer along a pattern shape of the electron accepting layer. The organic solar cell of claim 1, wherein the pattern of the anode and the electron receiving layer includes a plurality of pillars having two stages. 4. The pillar of claim 3, wherein the pillar has a height of b and a top length of 3a and a top of height and top length of a and the distance between adjacent pillars is a, wherein a is 10-100 nm, b is 20 An organic solar cell, characterized in that ~ ~ 200nm. (a) forming an anode having a regular pattern on the upper surface thereof on a transparent substrate;
(b) forming an electron receiving layer having a regular pattern formed on an upper surface thereof according to the pattern shape of the anode on the anode;
(c) forming an electron donor layer on the electron receiving layer; And
(d) forming an anode on the electron donor layer. The method of claim 5, wherein the electron donor layer is formed such that a regular pattern is formed on an upper surface of the electron donor layer along a pattern shape of the electron receiving layer. The method of claim 5, wherein the pattern of the anode and the electron accepting layer comprises a plurality of pillars having two stages. 8. The pillar of claim 7, wherein the pillar has a height of b and a top length of 3a and a top of height and top length of a and the distance between adjacent pillars is a, wherein a is 10-100 nm, b is 20 An organic solar cell manufacturing method, characterized in that ~ ~ 200nm. The method of claim 5, wherein step (a)
Forming a positive electrode by applying a transparent electrode material on the transparent substrate; And
Forming a regular pattern by photolithography or nano imprint on the upper surface of the anode.

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