KR101266674B1 - Inverted Organic Solar cells and Manufacturing Method Threreof using Solution processed oxide semiconductor - Google Patents

Abstract

The present invention is to improve the efficiency and life of the organic solar cell. In order to solve all the problems of shortening the lifespan of the transparent electrode due to the acidity of PEDOT: PSS, which is used as the hole transport layer, and the improvement of low energy conversion efficiency due to the low carrier mobility, which is the limit of organic electronic devices. In the present invention, the PEDOT: PSS is not used and the SnO ₂ thin film based on the solution process is used as the electron transport layer to increase the electron conductivity to increase the efficiency of the organic solar cell and to extend the device life due to the corrosion resistance of the SnO ₂ thin film. I was.
Solution process based manufacturing method is still advantageous in terms of production cost per power by lowering the manufacturing cost of the organic solar cell.

Description

Inverted Organic Solar cells and Manufacturing Method Threreof using Solution processed oxide semiconductor}

The present invention relates to a solar cell, and more particularly, to an electron transport layer forming technology for transferring electrons generated in an organic thin film that is an active layer of an organic solar cell.

Among the technologies for alternative energy, especially the expectation and research on solar cells are very active, and the demand for increasing the efficiency of solar cells and reducing the cost per power is more urgent. PEDOT: PSS, a conductive polymer thin film used in electronic devices including solar cells, is an organic material mainly used as an anode (anode) or a hole transport layer of various organic thin film electronic devices because of its transparency and excellent conductivity. However, the hole conductivity of PEDOT: PSS itself is relatively lower than that of the inorganic thin film, which causes a problem of efficiency limitation.

In addition, PEDOT: PSS thin film is very sensitive to oxygen or moisture and shows acidity when in solution, which can damage ITO (Indium tin oxide) thin film used as an electrode when implementing a device. There is a disadvantage. In order to overcome this problem, it is necessary to develop an organic solar cell that replaces PEDOT: PSS to improve the life of the device and reduce the sensitivity to oxygen and moisture to prolong the stability of the device. have.

The basic structure of the organic solar cell has a structure of “transparent conductive film / organic compound / metal electrode”, and ITO (Indium tin oxide) is used as the anode (anode) of the organic solar cell. Metal having a low work function such as aluminum (Al) is mainly used as a cathode (cathode). An organic semiconductor material is present between the two electrodes, so that the organic semiconductor material is present as an active layer which forms electron-hole pairs using the absorbed solar energy. The active layer is mainly deposited by spin coating a solution of a donor material and an acceptor material, and recently, such as an ink jet method or a spray coating method. It is laminated by the method. When light is incident on the organic solar cell, electron-hole pairs are formed in a donor material, and the electron-hole pairs thus formed are separated at the interface of the material, so that holes are separated toward the anode and electrons toward the cathode. Current is generated.

However, when the electron transport layer is inserted between the transparent conductive film and the organic compound, it is possible to fabricate the organic solar cell in the reverse direction by using the transparent conductive film as a cathode and Ag, Au, Pt, etc. as an anode. The electron transport layer may increase the stability of device characteristics by applying an inorganic thin film instead of an organic thin film. The inorganic thin film used as the electron transporting layer must have a transparent property and high electron conductivity in order to increase light transmission.

In addition, as mentioned above, a buffer layer such as an electron transport layer has a corrosion resistance against moisture and oxygen, and thus, it is necessary to solve the problem of deteriorating device characteristics in a short time by corroding the transparent electrode.

In addition, the demand for lowering the manufacturing cost per power of solar cells should be satisfied.

Therefore, an object of the present invention is to provide an electron transport layer of a new material that has a high electron conductivity and a corrosion resistance against oxygen and moisture in a buffer layer in contact with a transparent electrode of an organic solar cell, and thus does not deteriorate the transparent electrode. It is to provide a method of manufacturing an organic solar cell that can sufficiently reduce the manufacturing cost of.

Accordingly, the present invention adopts a SnO ₂ thin film manufactured by a solution-based process having a low manufacturing cost as an electron transporting layer to manufacture an organic solar cell having a reverse structure using the same, the efficiency of the organic solar cell through the high electron conductivity of the inorganic thin film In addition, the stability of the organic solar cell device may be improved through corrosion resistance of the inorganic thin film. SnO ₂ thin film manufactured by solution-based process shows high transmittance of more than 90%, further contributing to the efficiency of solar cell, and having proper work function value to transfer electrons to transparent conductive film sufficiently to achieve the object of the invention. .

That is, the present invention provides an electronic device having an anode / active layer / cathode, wherein the cathode and the active layer

A mixture of a precursor material including tin and an organic solvent is laminated on the cathode in a thin film, and the heat treatment is performed to form a SnO ₂ thin film as an electron transporting layer, and the precursor material used to obtain the SnO ₂ thin film is chloride. An electronic device comprising at least one of tin chloride, tin iodide, tin acetate, tin chloride dihydrate, and tin nitrate. It is possible to provide a method for producing.

In addition, the present invention, in the electronic device manufacturing method, the organic solvent is distilled water (DI water), methanol (methanol), ethanol (ethanol), isopropanol (isopropanol), 2-methoxyethanol (2-methoxyethanol) It can provide a method for producing an electronic device, characterized in that it comprises at least one of dimethylformamide.

In addition, the present invention provides a method for manufacturing an electronic device, characterized in that the molar concentration of the precursor material in the preparation of the solution for the electron transport layer manufacturing method is 0.005 ~ 0.3 M with respect to the material to be used as a solvent. can do.

In addition, the present invention, in the electronic device manufacturing method, in order to uniformly disperse the precursor material containing tin in the organic solvent, a solution in which the precursor material containing tin and the organic solvent is mixed at a temperature of 30 ~ 70 ℃ 1 ~ 5 It is possible to provide a method for manufacturing an electronic device, characterized in that the stirring process for a time.

In addition, the present invention can provide a method of manufacturing an electronic device, characterized in that the heat treatment temperature of the thin film is 300 to 600 ℃ in the electronic device manufacturing method.

Further, according to the present invention,

On the cathode made of a transparent electrode, a SnO ₂ thin film is formed as an electron transporting layer using the above-described method of manufacturing an electronic device,

On the SnO ₂ thin film, a chlorobenzene solution mixed with P3HT: PCBM was laminated and heat treated at a temperature of 100 to 120 ° C. to form an active layer as a thin film.

Gold (Au), silver (Ag), platinum (Pt) of any one of the organic thin film solar cell characterized in that it can be provided by depositing an anode.

According to the present invention, in order to overcome the shortcomings of the PEDOT: PSS thin film having a short life due to corrosion to the transparent electrode, the use of the PEDOT: PSS made of an organic thin film element is eliminated, and instead SnO ₂ thin film is adopted as the electron transport layer, By fabricating an organic solar cell having a reverse structure having an ITO transparent electrode as a cathode and a metal electrode as an anode, stability characteristics with time can be improved.

In addition, the method of manufacturing an electron transporting layer according to the present invention and an organic solar cell using the same provide an inexpensive manufacturing cost while still increasing the electron conductivity by using an inorganic thin film as an electron transporting layer in a solution process and compared to a conventional organic thin film. It can also contribute to the improvement of battery efficiency.

FIG. 1 shows an energy band diagram according to a material of an organic solar cell using the SnO ₂ thin film according to the present embodiment as an electron transporting layer.
2 shows a method of manufacturing an organic solar cell using the SnO ₂ thin film according to the present embodiment as an electron transporting layer.
3 is a block diagram of an organic solar cell manufactured according to FIG. 2.
4 illustrates a voltage-current density graph (JV) of an organic solar cell using the SnO ₂ thin film according to the present embodiment as an electron transporting layer.
FIG. 5 is a graph showing the results of measuring the SnO ₂ thin film according to the present embodiment to determine whether the SnO ₂ thin film was grown as a result of TG-DTA (weight change analysis with increasing temperature).

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

As shown in FIG. 2, an organic solar cell as shown in FIG. 3 is manufactured by performing steps 1 to 7 below.

Stage 1

In order to fabricate an organic solar cell according to FIG. 2, a transparent electrode / glass substrate (ITO / Glass) having a transparent electrode formed on a glass substrate is subjected to a photolithography operation in a HCl: HNO ₃ : DI water (distilled water) solution. Wet etching is performed for 1 hour. The ratio of HCl: HNO ₃ : DI water (distilled water) is preferably 45 to 49: 1 to 5:50 in volume ratio. Through wet etching, a rectangular ITO patterning with a line width of about 2-4 mm is formed.

Step 2

A solution for forming a buffer layer (also called an electron transporting layer) adjacent to the organic solar cell active layer on the transparent electrode / glass substrate is prepared. In other words, a precursor material including tin and an organic solvent mixture are prepared to form a buffer layer. The solution is prepared using tin chloride as the solute and 2-methoxyethanol as the solvent. At this time, the concentration of the solution is preferably set to 0.005 ~ 0.3 M in molar concentration. The solution thus prepared is stirred at room temperature to 70 ° C., preferably at 50 ° C., at 100 to 500 rpm, preferably at about 300 rpm.

The solute may be tin iodide, tin acetate, tin chloride dihydrate, tin nitrate, or the like in addition to tin chloride. In addition, as a solvent for dissolving the tin chloride, di water, (methanol), ethanol (ethanol), isopropanol, 2-methoxyethanol, 2-dimethylethanol, dimethylformamide One or more of dimethylformamid may be used.

Step 3

The mixture of tin chloride and 2-methoxyethanol prepared in step 2 is again 1 to 5 hours at room temperature to 100 ° C., preferably at 30 to 70 ° C. for 30 minutes to 2 hours. More preferably, the solution is prepared by stirring at 50 ° C. for 1 hour at a speed of about 100 to 500 rpm, preferably about 300 rpm.

Step 4

P3HT and PCBM organic materials for preparing the active layer of the organic solar cell were prepared and dissolved in a chlorobenzene solvent at a concentration of about 15 mg / ml and 12 mg / ml, respectively, and then stirred at 100 rpm for about 3 hours. stirring) (In the above P3HT is

regioregular poly (3-hexylthiophene) and PCBM is an abbreviation for phenyl-C61-butyric acid methyl ester.)

Step 5

Prepare the tin chloride and 2-methoxyethanol mixed solution prepared in step 3 as the buffer layer (electron transport layer) on the transparent electrode / glass substrate (ITO / Glass) on which ITO patterning prepared in step 1 is formed. 10 to 50 seconds at a speed of about 1000 to 5000 rpm, preferably about 3500 rpm, preferably about 30 seconds by spin casting to deposit a thin film having a thickness of about 30 nm, and then about 300 to 600 ° C. The heat treatment is carried out at a temperature of 60 to 200 minutes, preferably about 120 minutes.

The method of laminating the electron transport layer may use dip coating, spray coating, inkjet, roll-to-roll printing coating, etc. in addition to spin casting.

6 steps

After moving the ITO substrate on which the SnO ₂ thin film was laminated to a glove box of a moisture-free and oxygen-free atmosphere, the chlorobenzene solution mixed with P3HT: PCBM prepared in step 4 was laminated for about 30 seconds at around 1500 rpm using a spin casting method. And heat treatment at a temperature of about 60 to 200 ° C, preferably about 120 ° C.

7 steps

Samples deposited up to the active layer of the organic solar cell are moved into a thermal evaporator for cathode deposition, and gold (Au), silver (Ag), platinum (Pt), and the like are deposited to the cathode. In this case, the thickness of the electrode is one of gold, silver, and platinum, and the thin film is deposited within 150 nm, and after electrode deposition is completed, it is again 5 minutes to 30 minutes at 60 to 200 ° C. in a moisture-free, oxygen-free glove box. Preferably, the heat treatment is performed after about 10 minutes at 120 ℃.

While lowering the manufacturing cost as described above, the electron transport rate is significantly increased, and the electron-hole pair generated in the active layer is reduced by the recombination to reduce the organic solar cell can be produced with high efficiency.

4 shows a current-voltage characteristic curve of the organic solar cell manufactured according to the present embodiment. 4 shows that the current-voltage characteristics of the organic solar cell were measured by 1 to 5 times the number of times the SnO ₂ thin film was repeatedly formed by the above method.

5 is a result of measuring the SnO ₂ thin film by TG-DTA (weight change analysis with increasing temperature) to determine whether the SnO ₂ thin film is grown. In particular, the heat treatment temperature of the electron transport layer is 500 ° C. According to this case, it can be seen that the SnO ₂ thin film was grown.

It is to be understood that the invention is not limited to the disclosed embodiment, but is capable of many modifications and variations within the scope of the appended claims. It is self-evident.

No reference

Claims (7)

In the electronic device having an anode / active layer / cathode, between the cathode and the active layer,
A mixture of a precursor material including tin and an organic solvent is laminated on the cathode in a thin film, and the heat treatment is performed to form a SnO ₂ thin film as an electron transporting layer, and the precursor material used to obtain the SnO ₂ thin film is chloride. An electronic device comprising at least one of tin chloride, tin iodide, tin acetate, tin chloride dihydrate, and tin nitrate. Method of preparation.
delete The method of claim 1, wherein the organic solvent is distilled water (DI water), methanol (methanol), ethanol (ethanol), isopropanol (isopropanol), 2-methoxyethanol (2-methoxyethanol), dimethylformamide (dimethylformamide) Method of manufacturing an electronic device comprising at least one. The method of claim 1, wherein the molar concentration of the precursor material is 0.005 to 0.3 M with respect to the material to be used as a solvent. The method of claim 4, wherein the solution containing the precursor material containing tin and the organic solvent is stirred at a temperature of 30 to 70 ° C. for 1 to 5 hours to uniformly disperse the precursor material including tin in an organic solvent. A method of manufacturing an electronic assistant, characterized in that. The method of manufacturing an electronic device according to claim 1, wherein the heat treatment temperature of the thin film is 300 to 600 ° C. 7. On the cathode made of a transparent electrode, a SnO ₂ thin film is formed as an electron transporting layer using the electronic device manufacturing method of claim 6,
On the SnO ₂ thin film, a chlorobenzene solution mixed with P3HT: PCBM was laminated and heat treated at a temperature of 100 to 120 ° C. to form an active layer as a thin film.
An organic thin film solar cell, which is produced by depositing any one of gold (Au), silver (Ag), and platinum (Pt) with an anode.

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