KR20090019596A - Organic solar cell and fabrication method thereof - Google Patents

Abstract

An organic solar cell and fabrication method thereof is provided to allow separation of the electron-hole pair easily by using a nano-pattern formed between an electron accepting layer and a hole accepting layer and increasing contact of them. In an organic solar cell and fabrication method thereof, a hole-transport layer(330) and hole accepting layer(340) are formed on a transparent substrate(310) having the first electrode(320). The nano pattern is formed on the hole accepting layer, and the electron acceptation layer is formed on the hole accepting layer nano pattern is formed. The second electrode is formed on the electron acceptation layer. The nano pattern is formed between the hole accepting layer and electron accepting layer.

Description

Organic solar cell and its manufacturing method {ORGANIC SOLAR CELL AND FABRICATION METHOD THEREOF}

The present invention relates to an organic solar cell and a manufacturing method thereof, and more particularly, to an organic solar cell in which a transparent substrate coated with a first electrode layer, a hole transporting layer, a hole receiving layer, an electron receiving layer, and a second electrode layer are deposited sequentially. The present invention relates to an organic solar cell and a method of manufacturing the same, which increase the efficiency of a solar cell by forming a nanopattern between the hole receiving layer and the electron receiving layer to facilitate charge separation of the electron-hole pair.

Recent rising oil prices, global environmental problems, depletion of fossil energy, waste disposal of nuclear power generation, and the selection of locations due to the construction of new power plants are raising interest in new and renewable energy. Research and development on batteries is being actively conducted.

A solar cell is a device that converts light energy into electrical energy by using a photovoltaic effect. The solar cell is classified into a silicon solar cell, a thin film solar cell, a dye-sensitized solar cell, and an organic polymer solar cell. . These solar cells are used independently as main power sources such as electronic clocks, radios, unmanned light towers, satellites, rockets, etc., and are also used as auxiliary power sources in connection with commercial AC power systems. Increasingly, interest in solar cells is increasing.

In such solar cells, it is very important to increase the conversion efficiency related to the ratio of converting incident sunlight into electrical energy. Various studies have been conducted to increase the conversion efficiency, and the development of a technology for increasing the conversion efficiency by actively incorporating a thin film having a high light absorption coefficient into the solar cell has been actively conducted.

1 shows a structure of a conventional p-n junction solar cell. As shown in FIG. 1, the conventional pn junction solar cell 100 includes an organic substrate 110, a transparent electrode layer 120, a p-type semiconductor layer 130, an n-type semiconductor layer 140, and an Ag electrode layer ( 150).

In a p-n junction solar cell, an internal electric field is generated near the p-n junction between the p-type semiconductor layer 130 and the n-type semiconductor layer 140, and charge separation occurs. That is, the exciton, which is an electron-hole pair, is charge separated in the vicinity of the p-n junction, so that the electrons move to the Ag electrode layer 150, and the positive curve moves toward the name electrode layer 120.

However, in the p-n junction solar cell, the distance that the separated electrons can move without recombination is typically within 10 nm. Therefore, there is a problem that only electron-hole pairs generated in the region of about 10 nm from the p-n junction portion are charge-separated and contribute to the collection of electrons and holes.

On the other hand, Figure 2 shows the structure of a conventional bulk heterojunction solar cell.

As shown in FIG. 2, the conventional bulk heterojunction solar cell 200 includes a glass substrate 210, a transparent electrode layer 220, a hole transport layer 260, a photoelectric conversion layer 290, and an Al electrode layer 250. do.

The photoelectric conversion layer 290 includes a hole acceptor 270 and a florene (C ₆₀ ) derivative 280 as an electron acceptor formed therein. Thus, since the hole acceptor 270 and the florene derivative 280 serving as the electron acceptor are uniformly dispersed, the same effect as that of the pn junction is dispersed throughout the photoelectric conversion layer 290. Therefore, even if the movable distance of the electron-hole pair in the hole acceptor 270 is short, since the pn junction is distributed over a wide range, the recombination of the electron-hole pair can be prevented to some extent.

However, in order to effectively prevent recombination of the electron-hole pairs, the thickness of the photoelectric conversion layer 290 in which the hole acceptor 270 and the florene derivative 280 are dispersed must be increased. There is a problem in that the electron acceptor, Floren (C ₆₀ ) is also an ideal electron acceptor that accepts the separated electrons well, but is not a suitable material for transferring electrons to the electrode, so the electron acceptor There is a problem that the efficiency is lowered because the electrons are not sufficiently transferred to the cathode electrode.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and in the organic solar cell in which the transparent substrate coated with the first electrode layer, the hole transport layer, the hole accepting layer, the electron accepting layer, and the second electrode layer are deposited sequentially, the hole accepting layer It is an object of the present invention to provide an organic solar cell that increases the efficiency of a solar cell by forming a nanopattern between the electron accepting layer and an electron-hole pair to facilitate charge separation and transfer of charge to an electrode.

Another object of the present invention, in the organic solar cell, a method of manufacturing an organic solar cell to form a nano-pattern between the hole receiving layer and the electron receiving layer to facilitate the charge separation of the electron-hole pair and the movement of the charge to the electrode. To provide.

According to an embodiment of the present invention for achieving the above object, preparing a transparent substrate coated with a first electrode, forming a hole transport layer and a hole receiving layer on the transparent substrate coated with the first electrode, A method of manufacturing an organic solar cell includes forming a nanopattern on the hole receiving layer, forming an electron accepting layer on the hole receiving layer on which the nanopattern is formed, and forming a second electrode on the electron receiving layer. do.

The forming of the nanopattern may include preparing a mold on which the nanopattern is formed, and transferring the nanopattern of the mold onto the hole receiving layer using a nanoimprinting method. .

The preparing of the mold in which the nanopattern is formed is preferably performed by laser interference lithography, electron beam lithography, or optical lithography.

On the other hand, according to another embodiment of the present invention for achieving the above object, an organic solar cell in which a transparent substrate, a hole transport layer, a hole receiving layer, an electron receiving layer, and a second electrode layer coated with the first electrode layer is deposited sequentially In example embodiments, an organic solar cell having a nanopattern formed between the hole receiving layer and the electron receiving layer is provided.

The nanopattern is preferably formed by imprinting a mold having a nanopattern formed on the hole receiving layer.

According to the present invention, the boundary contact surface between the hole receiving layer and the electron receiving layer is increased by the nano-pattern formed between the hole receiving layer and the electron receiving layer in the organic solar cell, thereby facilitating charge separation of the electron-hole pair and leaving the electrons. Is well collected without loss into the second electrode layer, thereby increasing the efficiency of the solar cell.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

As shown in FIG. 3, the organic solar cell 300 of the present invention includes a transparent substrate 310, a first electrode layer 320, a hole transporting layer 330, a hole receiving layer 340, an electron receiving layer 350, and The second electrode layer 360 is included.

As the transparent substrate 310, an organic substrate or a substrate having high light transmittance such as a transparent resin substrate such as polycarbonate, poly methyl methacrylate, polyimide, or the like is used.

The first electrode layer 320 is an electrode having high light transmittance, and may be formed on the transparent substrate 310 by being coated by a sputtering method or the like. As the first electrode layer 320, a conductive material such as indium tin oxide (ITO) or the like may be used.

The hole transport layer 330 is a material having electrical conductivity, and may be made of a material such as poly-3,4-ethylene dioxythiophene (PEDOT; Poly-3,4-Ethylenedioxythiophene).

The hole receiving layer 340 is a conductive conjugated polymer (Conjugated Polymer), and after the hole transport layer 330 is formed is deposited by a spin coating method in a global box to prevent oxidation. As the conjugated polymer, a material such as polythione pen derivative (P3HT), MEH-PPV, poly fluorene, or the like may be used.

The electron receiving layer 350 may be formed of a carbon cluster such as florene (C ₆₀ ).

Complex nanostructures are formed between the hole receiving layer 340 and the electron receiving layer 350. This is formed by imprinting (Imprinting) a stamp in which a fine nanostructure is formed after the hole receiving layer 340 is formed.

Due to the nanostructure, the boundary contact surface between the hole receiving layer 340 and the electron receiving layer 350 increases, and thus, the electrons are easily separated and the separated electrons are well collected without loss into the second electrode layer 360. The efficiency of the battery can be improved.

Stamps with an even pattern may be fabricated using various lithography techniques such as laser interference lithography, electron beam lithography, optical lithography, and the like. As the boundary contact surface between the hole accommodating layer 340 and the electron accommodating layer 350 is wider, the efficiency of the solar cell becomes higher. Therefore, the stamp is preferably produced by performing laser interference exposure or the like two or more times.

The second electrode layer 360 is a layer for efficiently collecting electrons. The second electrode layer 360 may be formed of a metal, an alloy, an electrically conductive compound, or a mixture of these materials having a small work function. Specifically, compounds such as alkali metals and oxides of alkali metals may be exemplified, and preferably, a metal such as aluminum (Al) may be used. The second electrode layer 360 may be formed by vacuum deposition, ion plating, or sputtering.

4 illustrates a manufacturing process of the organic solar cell 300 according to an embodiment of the present invention. Since detailed descriptions, such as materials of each component, have been described above, a description thereof will be omitted. Meanwhile, in all manufacturing processes of the organic solar cell 300 described with reference to FIG. 4, it is preferable to maintain a vacuum state to prevent oxidation.

First, as shown in FIG. 4A, the transparent substrate 310 coated with the first electrode layer 320 is prepared. The first electrode layer 320 may be coated on the transparent substrate 310 by sputtering or the like.

Thereafter, as shown in FIG. 4B, the hole transport layer 330 and the hole receiving layer 340 are formed on the transparent substrate 310 coated with the first electrode layer 320. The hole receiving layer 340 may be deposited by a spin coating method in a global box after the hole transport layer 330 is formed. After the hole receiving layer 340 is formed, curing is performed at an appropriate temperature.

Next, as shown in FIG. 4C, nano-imprinting is performed on the hole receiving layer 340 to form a nano pattern on the hole receiving layer 340. Nanoimprinting is performed by a nanoimprint lithography method using a stamp 410 in which a structure is also formed. The stamp 410 may be a mold made of a material such as silicon (Si), and the more complicated and finer the shape of the nanostructure is, the better.

The stamp 410 having the stripe pattern may be fabricated using various lithography techniques such as laser interference lithography, electron beam lithography, or optical lithography. As the boundary contact surface between the hole receiving layer 340 and the electron receiving layer 350 is wider, the efficiency of the solar cell becomes higher. Therefore, the nanostructure formed on the stamp is more finely and complicated by performing laser interference exposure or the like two or more times. desirable.

Due to the nanostructure, the boundary contact surface between the hole receiving layer 340 and the electron receiving layer 350 increases, thereby facilitating charge separation between the electron-hole pairs, and the lost electrons are lost to the second electrode layer 360. It can be collected well without increasing the efficiency of the solar cell.

Next, as shown in FIGS. 4D and 4E, the stamp 410 is demolded and the electron accepting layer 350 is deposited on the hole receiving layer 340 on which the nanopattern is formed. The deposition of the electron accepting layer 350 may be performed by chemical vapor deposition (CVD), or the like. In this process, it is preferable that there is no gap between the hole accommodating layer 340 and the electron accommodating layer 350.

Thereafter, as shown in FIG. 4F, the second electrode layer 360 is deposited by vacuum deposition, ion plating, sputtering, or the like.

5 illustrates the operation principle of the organic solar cell 300 according to the present invention.

When sunlight is incident on the organic solar cell 300, an exciton, an electron-hole pair, is generated in the hole receiving layer 340. When the electron-hole pair diffuses and reaches the interface between the hole receiving layer 340 and the electron receiving layer 350, charge separation occurs. Thereafter, the electrons 510 move toward the electron receiving layer 350 to reach the second electrode layer 360. On the other hand, the hole 520 is moved toward the first electrode layer 320 by the internal electric field of the hole acceptor 340.

In the present invention, by increasing the boundary surface area of the hole receiving layer 340 and the electron receiving layer 350 in which charge separation of the electron-hole pairs occurs, charge separation can easily occur to increase the efficiency of the solar cell.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and such changes or modifications are within the scope of the present invention. In addition, each component described herein may be replaced with a variety of configurations substantially the same. Those skilled in the art can also omit some of the components described herein without adding performance degradation or add components to improve performance. In addition, those skilled in the art may change the order of the method steps described herein according to the process environment or equipment. Therefore, the scope of the present invention should be determined not by the embodiments described, but by the claims and their equivalents.

1 is a cross-sectional view of a conventional p-n junction solar cell.

2 is a cross-sectional view of a conventional bulk heterojunction solar cell.

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

4A to 4F are process charts showing a manufacturing process of an organic solar cell according to an embodiment of the present invention.

5 illustrates an operation principle of an organic solar cell according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

310: transparent substrate 320: first electrode layer

330: hole transport layer 340: hole receiving layer

350: electron accepting layer 360: second electrode layer

410: stamp

Claims (5)

Forming a hole transporting layer and a hole receiving layer on the transparent substrate coated with the first electrode; Forming a nano pattern on the hole receiving layer; Forming an electron receiving layer on the hole receiving layer in which the nanopattern is formed; And Forming a second electrode on the electron accepting layer. The method of claim 1, Forming the nano pattern, Preparing a mold in which a nano pattern is formed; And transferring the nano-pattern of the mold onto the hole receiving layer using a nanoimprinting method. The method of claim 2, The method of preparing a mold in which the nanopattern is formed is performed by laser interference lithography, electron beam lithography, or optical lithography. In an organic solar cell in which a transparent substrate coated with a first electrode layer, a hole transport layer, a hole receiving layer, an electron receiving layer, and a second electrode layer are sequentially deposited, The organic solar cell, characterized in that the nano-pattern is formed between the hole receiving layer and the electron receiving layer. The method of claim 4, wherein The nano-pattern is an organic solar cell, characterized in that formed by imprinting a mold having a nano-pattern formed on the hole receiving layer.

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