KR100983414B1 - Organic solar cell manufacturing method by transparent electrode surface patterning - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic solar cell having improved light energy conversion efficiency. To this end, the present invention provides a method of improving the efficiency of an organic solar cell by patterning a surface of a transparent electrode. The organic solar cell according to the present invention comprises a transparent electrode having a pattern formed on a glass substrate; A photoactive layer comprising an electron donor and an electron acceptor formed on the electrode; A metal halogen layer formed on the photoactive layer; It is configured to include a cathode formed on the metal halogen layer. In the organic solar cell according to the present invention, the surface area of the device is increased and light trapping is improved, thereby improving the light energy conversion efficiency of the organic solar cell.

Organic solar cells, conductive polymers, light capture, soft lithography, plasma etching

Description

Method for fabricating organic solar cells by patterning transparent electrode surface {Method for fabricating of Organic Solar Cells by Patterning Nanoscale Transparent Conducting Oxide Electrode}

The present invention relates to an organic solar cell, and relates to a method for manufacturing an organic solar cell using a thin film having improved light conversion efficiency.

Photovoltaic cells are devices that convert light energy directly into electrical energy. Solar cells are largely divided into inorganic solar cells and organic solar cells. Compared with organic solar cells, inorganic solar cells, which are mainly silicon, have high conversion efficiency, but they are expensive in the manufacturing process and have limitations on weight and flexibility. Have Therefore, demand for organic solar cells is expected mainly in the market where inorganic solar cells cannot be used, and researches for increasing energy conversion efficiency, which are disadvantages of organic solar cells, are actively conducted.

Organic solar cells basically have a thin film structure. Indium tin oxide (ITO), which is a transparent electrode, is used as an anode, and a metal electrode such as aluminum having a low work function is used as a cathode. The photoactive layer is composed of an electron donor and an electron acceptor with a thickness of about 100 nm, and uses a two-layer structure or a composite thin film structure of an electron donor layer and an electron acceptor layer.

Representative prior art regarding organic solar cells is US Patent 5.331,183. Para-phenylene vinylene (PPV) series between a transparent electrode (anode) and an aluminum electrode (cathode) such as a substrate and a thin film of tin-doped indium oxide (ITO) formed thereon 6,6-phenyl-C61-butyl acid methyl ester (PCBM; [6,6] -phenyl C61 butyric acid methyl ester), a fullerene derivative mixed well with organics and fullerenes The solar cell was realized by mixing the layers. However, the organic solar cells manufactured as described above have disadvantages in industrial applications due to their low energy conversion efficiency.

As a method for increasing the low energy conversion efficiency as described above, various attempts have been made, and there is a method of effectively transferring electrons to the electrode. Korean Patent Laid-Open Publication No. 2005-87247 discloses a method of vertically arranging carbon nanotubes vertically arranged with a conductive polymer as a photoactive layer material to efficiently transfer electrons to an electrode to increase energy conversion efficiency.

In the present invention, in order to increase the efficiency of the organic solar cell, by developing a method of increasing the light energy conversion efficiency by causing light scattering and light trapping effect through the surface treatment on the transparent electrode, the present invention was completed.

An object of the present invention is to provide a method for increasing the light energy conversion efficiency of the organic solar cell.

Still another object of the present invention is to provide a simple and low cost process in manufacturing an organic solar cell having improved light energy conversion efficiency.

In order to achieve the above object, the present invention provides a method for manufacturing an organic solar cell having a patterned transparent electrode having high light conversion efficiency.

In one embodiment, (a) preparing a glass substrate coated with a transparent electrode; (b) patterning the transparent electrode surface; (c) forming a photoactive layer comprising an electron donor and an electron acceptor on the patterned transparent electrode; (d) providing an organic solar cell manufacturing method comprising forming a metal halogen layer and a metal electrode layer on the photoactive layer.

Indium tin oxide (ITO) may be used as the transparent electrode.

The patterning may use a first patterning process using capillary force lithography (CFL) and a second patterning process using plasma, in which a pattern is formed by a capillary phenomenon.

Capillary lithography for primary patterning may be performed by spin-coating a polystyrene solution on a transparent electrode-coated glass substrate, heating a polydimethylsiloxane (PDMS) mold in a periodic pattern.

The process of capillary lithography is preferably carried out at 130 ° C. for 20 minutes.

After the process of capillary lithography, an oxygen plasma process can be added to remove the polystyrene residue.

Plasma processes for secondary patterning may use argon plasma.

In the oxygen plasma process, 300W source power and -200V bias are preferably performed for 30 seconds at 10.3 mtorr.

In argon plasma process, 300W source power and -28V bias at 5.6mtorr is recommended for 2 minutes up to 3 minutes 30 seconds.

In the photoactive layer, the electron acceptor may use a fullerene or a fullerene derivative, and the electron donor may use a para-phenylene vinylene (PPV) -based polymer or a polythiophene-based derivative. have.

It is preferable that the thickness of the said photoactive layer is 80-100 nm.

It is preferable that the thickness of the said metal halogen layer is 0.5-1 nm.

The thickness of the metal electrode layer is preferably 80 ~ 100nm.

Through the patterning of the transparent electrode, deformation of the three-dimensional structure of the photoactive layer positioned on the transparent electrode, the metal halogen layer formed on the photoactive layer, and the cathode formed on the metal halogen layer is applied.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a view showing a three-dimensional structure of the organic solar cell according to the present invention, Figure 2 is a view showing a cross-sectional structure of the organic solar cell patterned periodically the surface of the transparent electrode. The cross-sectional structure of the organic solar cell after coating the photoactive layer 3 on the patterned transparent electrode 2 periodically and depositing aluminum as the metal halide layer 4 and lithium as the metal electrode layer 5 is shown. Fig. 3 is a process chart showing a process of patterning a transparent electrode, wherein (a) to (e) represent capillary lithography processes, and (f) to (h) are oxygen plasma and argon plasma. A diagram illustrating a process of going through.

Organic solar cell manufacturing method employing a transparent electrode formed with a periodic pattern according to the present invention can increase the light energy conversion efficiency of the organic solar cell by causing an increase in the surface area of the device and the light trapping effect. Further, in the patterning process of the transparent electrode, a simple and low-cost patterning is possible by using a capillary lithography process and a plasma etching process.

An object of the present invention is to provide a method for improving the light energy conversion efficiency of an organic solar cell. The composition of the present invention (a) preparing a glass substrate coated with a transparent electrode; (b) patterning the transparent electrode surface; (c) forming a photoactive layer comprising an electron donor and an electron acceptor on the patterned transparent electrode; (d) providing a method of manufacturing an organic solar cell, including forming a metal halogen layer and a metal electrode layer on the photoactive layer.

Hereinafter, the components and technical features of the present invention will be described in more detail with reference to the following non-limiting examples. However, the following embodiments are only intended to describe the present invention in detail, and are not intended to limit the technical scope of the components of the present invention to those illustrated in the embodiments. The documents cited in the present invention are incorporated herein by reference.

Example

Example 1-4 Preparation of Patterned Indium Tin Oxide (ITO) Coated Glass Substrate

Spin coating 5% by weight of polystyrene solution on an indium tin oxide (ITO) coated glass substrate (6), and then placing a polydimethylsiloxane (PDMS) mold having a periodic pattern, Heated for a minute to form a primary pattern by capillary lithography. To remove the polystyrene residue, the oxygen plasma process was performed for 30 seconds with a source power of 300 W and a bias of -200 V at 10.3 mtorr. For the second patterning, the argon plasma process was performed with a source power of 300W and a bias of -28V at 6 mtorr for 2 minutes up to 3 minutes 30 seconds (Examples 1-4).

TABLE 1

Example 1 After the first patterning, argon plasma process for 2 minutes Example 2 After the first patterning, the argon plasma process proceeds for 2 minutes and 30 seconds with the second patterning Example 3 After the first patterning process, proceed to the argon plasma process for 3 minutes by the second patterning Example 4 After the first patterning, the argon plasma process proceeds for 3 minutes and 30 seconds with the second patterning

Example 5-8 Fabrication of Organic Solar Cell Employing Patterned Indium Tin Oxide (ITO)

Electron-accepting chain 6,6-phenyl-C61-butyl acid methyl ester (PCBM; [6,6] -phenyl C61 butyric acid methyl ester), an electron donor, as a photoactive layer on a patterned substrate prepared in Examples 1 to 4 An indium poly-3-hexylthiophene (P3HT; poly (3-hexyl-thiophene)) was coated and a lithium fluoride layer and an aluminum layer were deposited to prepare an organic solar cell.

Comparative Example 1: Fabrication of Organic Solar Cell Adopting General Indium Tin Oxide (ITO)

6,6-phenyl-C61-butyl acid methyl ester (PCBM; [6,6] -phenyl C61 butyric acid methyl ester) which is an electron acceptor as a photoactive layer on a substrate coated with a general ITO having no pattern formed on its surface An organic solar cell was manufactured by coating a donor poly-3-hexylthiophene (P3HT; poly (3-hexyl-thiophene)) and depositing a lithium fluoride layer and an aluminum layer.

Experimental Example 1: Roughness and step measurement of the substrate surface by atomic force microscope (AFM)

The roughness and step height of the surface of the substrates prepared in Examples 1 to 4 were measured by an atomic force microscope (AFM, THERMOMICROSCOPES), and the results are shown in FIG. 4. As shown in Figure 4, it can be seen that as the argon plasma process time increases, the height and roughness of the ITO surface pattern increases.

Experimental Example 2: Measurement of Light Absorption of Photoactive Layer

The light absorption of the photoactive layer of the organic solar cell prepared in Comparative Example 1 and Examples 5 to 8 was measured using a UV-VIS absorber (Mecasys, Optizen2120uvpuls), and the results are shown in FIG. 5. As shown in FIG. 5, it can be seen that the light absorption increases as the argon process time increases, thereby causing a light trapping effect.

Experimental Example 3: Evaluation Experiment of Current-Voltage Characteristics (hereinafter, I-V Characteristics)

IV characteristics of the organic solar cells prepared in Comparative Examples 1 and 5 to 7 using a solar simulator (Luzchem, LZC-SSR, Keithley 2400 sourcemeter) under standard conditions (air mass 1.5, 100 mW / cm ² , 25 ° C) ) And the results are shown in FIG. 6. As shown in Figure 6, it can be seen that as the process time of the argon plasma increases, the efficiency of the device shows an efficiency improvement of up to 38% compared to the comparison device of 0.97% to a maximum of 1.27%. In addition, Table 2 summarizes the increased device efficiency.

TABLE 2

Argon Plasma Process Time Charge rate (%) Device efficiency (%) Increased efficiency (%) Comparative Example 1 0.28 0.96 - Example 5 0.35 1.06 10.0% Example 6 0.35 1.13 16.8% Example 7 0.31 1.27 30.9%

As described above, the method of manufacturing an organic solar cell according to the present invention forms a pattern on a transparent electrode, thereby causing an increase in the surface area of the device and a light trapping effect, thereby increasing the light energy conversion efficiency of the organic solar cell. In addition, the method for patterning the transparent electrode of the present invention can obtain a fine pattern in a simple and inexpensive process, the industrial value of the technology is high.

1 is a view showing a three-dimensional structure of an organic solar cell patterned transparent electrode surface according to the present invention.

2 is a cross-sectional view of an organic solar cell patterned with a transparent electrode surface according to the present invention.

3 is a process chart showing a manufacturing process of an organic solar cell patterned transparent electrode surface according to the present invention.

4 is a graph of roughness and step height of the substrate surface measured using an atomic force microscope (AFM).

5 is a graph showing the results of measuring light absorption of the photoactive layer of the organic solar cell of the present invention.

6 is a graph showing the results of measuring electrical characteristics of the organic solar cell of the present invention.

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

1: glass substrate 2: patterned transparent electrode layer

3: photoactive layer 4: metal halogen layer

5: metal electrode layer 6: glass substrate coated with transparent electrode

7: polystyrene layering 8: polydimethylsiloxane (PDMS) mold

Claims (14)

(a) preparing a glass substrate coated with indium tin oxide (ITO) as a transparent electrode; (b) patterning the transparent electrode surface using a first patterning process using capillary force lithography (CFL) and a second patterning process using argon plasma; (c) forming a photoactive layer comprising an electron donor and an electron acceptor on the patterned transparent electrode; (d) forming a metal halogen layer and a metal electrode layer on the photoactive layer. delete delete The method of claim 1, wherein the electron acceptor of the photoactive layer of step (c) is a fullerene or fullerene derivative, the electron donor is a poly-para-phenylene vinylene (PPV) -based polymer or polythiophene An organic solar cell manufacturing method characterized by using a (PT; polythiophene) derivative. The method of claim 1, wherein the metal halide layer of step (d) is lithium fluoride. The method of claim 1, wherein the metal electrode layer of step (d) is aluminum. The method of claim 1 or 4, wherein the electron acceptor of step (c) is 6,6-phenyl-C61-butyl acid methyl ester (PCBM; [6,6] -phenyl C61 butyric acid methyl ester ), And the electron donor is poly-3-hexylthiophene (P3HT; poly (3-hexyl-thiophene)). The method of claim 1, wherein the capillary force lithography (CFL) process is performed by heating a polydimethylsiloxane (PDMS) mold at 20 ° C. for 20 minutes. The method of claim 1, wherein after the first patterning, an oxygen plasma process for removing the residues is added. The method of claim 1, wherein the argon plasma manufacturing process is performed at a source power of 300 W and a bias of −28 V at 5.6 mtorr. The method of claim 9, wherein the oxygen plasma manufacturing process is performed at a source power of 300 W and a bias of −200 V at 10.3 mtorr. An organic solar cell prepared by the method of any one of claims 1 to 4. An organic solar cell prepared by the method of claim 7. An organic solar cell prepared by the method of any one of claims 8 to 11.

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