TWI594472B - Dye-sensitized solar cell and method for manufacturing thereof - Google Patents

Description

Dye sensitized solar cell and method of manufacturing same

The present invention provides a dye-sensitized solar cell and a method of manufacturing the same, comprising a composite counter electrode having high conductivity, wherein a porous graphene layer is disposed on a platinum layer to increase pores for electron transfer.

Dye-sensitized solar cells have been widely used and are actively developed in the industry because of their environmental protection, low manufacturing cost, high temperature resistance, transparency, and the advantages of being a flexible battery.

The main structure of the dye-sensitized solar cell comprises a working electrode, an electrolyte and a counter electrode arranged in sequence between two transparent conductive substrates. Among them, a photosensitizer (or light dye) is adsorbed on the working electrode to absorb light energy and convert it into electric energy. How to effectively increase the photoelectric conversion efficiency and stability of the dye-sensitized solar cell, the material and structural characteristics of the substrate, the working electrode, the electrolyte and the counter electrode are decisive factors.

Basically, the working electrode is a semiconductor nanomaterial, such as titanium dioxide (TiO ₂ ), zinc oxide (ZnO), and tin oxide (SnO ₂ ). Since the photosensitizer is distributed in the semiconductor nanomaterial, if the surface area of the semiconductor nanomaterial is higher, the photosensitizer for adsorbing light is more; and if the transmittance of the transparent conductive substrate is higher, The more light that is incident, the higher the convertible power. In addition, common counter electrode materials include carbon black, platinum (Pt) and conductive polymers, such as PEDOT and other materials.

At present, graphene has been used in the technical field of solar cells. Since graphene is a two-dimensional carbon material, atoms are connected to each other to form a honeycomb-like structure, and are rich in electrons and have electronic characteristics, which allow electrons to migrate freely within the layer, and thus have good electrical conductivity. The use of graphene in dye-sensitized solar cells can effectively improve the photoelectric conversion efficiency.

The present inventors have found that although graphene has been used in the field of solar cells, graphene is usually applied directly between layers of a solar cell to form a thin film layer, and electron transport is performed by its own pores.

However, the inventors have found that if the graphene is further formed in an overlapping manner between the layers of the solar cell, it can not only provide a higher reaction surface area by the pores of the graphene itself, but also increase the photocurrent, and more by graphene. The contact points between the overlaps form a complete electronic path, which accelerates electron transport and thus effectively improves photoelectric conversion efficiency.

That is, the present invention provides a dye-sensitized solar cell comprising: a composite counter electrode comprising a platinum layer and a porous graphene layer disposed on the platinum layer; a working electrode, wherein the porous graphene layer is located Between the platinum layer and the working electrode; and an electrolyte between the working electrode and the composite counter electrode.

In a preferred embodiment, the adhesive is a mixture of polyvinylidene fluoride (PVDF), cellulose, or the like.

In a preferred embodiment, the pore size in the porous graphene layer is 25 to 500 nm.

In a preferred embodiment, the plurality of graphene holes have a hole size of a hole It is 1 nm to 10 μm.

In a preferred embodiment, the working electrode is TiO ₂ , SnO ₂ and ZnO.

In a preferred embodiment, the porous graphene layer has a thickness of 1 to 50 μm.

The invention provides a method for preparing a composite counter electrode for a dye-sensitized solar cell as described above, which comprises: (a) providing a platinum layer; (b) mixing a plurality of graphenes with an adhesive to obtain a graphene slurry; And (c) applying the graphene slurry to the platinum layer, drying the graphene slurry to obtain a porous graphene layer formed on the platinum layer to form the composite counter electrode.

In a preferred embodiment, the plurality of graphenes are mixed with the adhesive by ultrasonic waves.

In a preferred embodiment, the concentration of the plurality of graphene in the graphene slurry is 0.01 to 10 wt%.

The present invention provides a method of fabricating a dye-sensitized solar cell comprising: (a) preparing a composite counter electrode by the method of the present invention; (b) providing a working electrode, wherein the porous graphene layer is located in the platinum layer and Between the working electrodes; and (c) providing an electrolyte between the working electrode and the composite counter electrode.

1‧‧‧Composite counter electrode

3‧‧‧Porous graphene layer

5‧‧‧ Platinum layer

7‧‧‧ Graphene

9‧‧‧ pores

11‧‧‧Adhesive

13‧‧‧ Graphene slurry

15‧‧‧Electrical substrate

17‧‧‧Working electrode

19‧‧‧ Electrolytes

Figure 1 is a dye-sensitized solar cell of the present invention.

Figure 2 is a composite counter electrode of the present invention.

3 is a method of preparing a composite counter electrode for a dye-sensitized solar cell of the present invention.

The present invention provides a dye-sensitized solar cell comprising: a composite counter electrode comprising a platinum layer and a porous graphene layer disposed on the platinum layer; a working electrode, wherein the porous graphene layer is located in the platinum layer And the working electrode; and an electrolyte between the working electrode and the composite counter electrode. As shown in FIG. 1 , a dye-sensitized solar cell of the present invention is provided between two conductive substrates 15 , which comprises a composite counter electrode 1 , an electrolyte 19 and a working electrode 17 ; wherein the composite counter electrode 1 comprises a graphene layer 3 and platinum Layer 5, and the graphene layer 3 has the property of being porous.

The above-mentioned porous graphene layer 3 is formed by adhering a plurality of graphenes to each other on the platinum layer 5 through an adhesive. As shown in FIG. 2, a plurality of graphenes 7 are adhered to each other on the platinum layer 5, and are fixed by an adhesive 11, and a plurality of graphenes 7 have pores 9 therebetween. The size of the pores 9 is 25 to 500 nm. For example, 25 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm; if the pore size is too small, the catalytic active center exposed by the graphene 7 is too small; The graphene 7 has a large pore size, which in turn causes low conductivity. Therefore, the pores of the graphene 7 should be in the above range to provide a large electrolyte adsorption area, increase the electron transfer efficiency, and effectively improve the photoelectric conversion efficiency.

The above adhesive is a mixture of polyvinylidene fluoride (PVDF), cellulose or the like. Since polyvinylidene fluoride (PVDF) and cellulose are materials for preparing a porous film, it is advantageous to form a porous material. In addition, it has been experimentally found by the inventors that the use of polyvinylidene fluoride (PVDF) and cellulose in combination with graphene can be prepared as defined above. A graphene layer of pore size to facilitate electron transport. Polyvinylidene fluoride (PVDF) and cellulose can be mixed and used in other solvents, such as water, N-methyl-2-pyrrolidone (NMP), dimethyl hydrazine, N,N-dimethyl acetamidine. Amine (DMAc), N,N-dimethylformamide (DMF), methyl ethyl ketone, acetone, tetrahydrofuran, tetramethylurea, trimethyl phosphate, hexane, pentane, benzene, toluene, methanol Aliphatic hydrocarbons such as ethanol, carbon tetrachloride, o-dichlorobenzene, trichloroethylene, low molecular weight polyethylene glycol, aromatic hydrocarbons, chlorinated hydrocarbons, or other chlorinated organic liquids.

The plurality of graphenes have a length and a width of 0.02 to 10 μm, a thickness of about 2 to 10 nm, a pore size of 1 nm to 10 μm, and a specific surface area of 10 m ² /g to 1000 m ² /g. The length and width of the graphene may be, for example, 0.02 μm, 1 μm, 3 μm, 5 μm, 7 μm, or 10 μm. The thickness of the graphene may be, for example, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. The pores on the graphene may be, for example, 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm. , 8μm, 9μm or 10 m; specific surface area may be, for example, ^{10m 2 / g, 20m 2 /} g, 50m 2 / g, 70m 2 / g, 100m 2 / g, 150m 2 / g, 200m 2 / g, 250m 2 / g 300m ² /g, 350m ² /g, 400m ² /g, 450m ² /g, 500m ² /g, 550m ² /g, 600m ² /g, 650m ² /g, 700m ² /g, 750m ² /g ^{, 800m 2 / g, 850m 2} / g, 900m 2 / g, 950m 2 / g or 1000m ² / g.

The above working electrode may be TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ , In ₂ O ₃ , CdS, ZnS, CdSe, GaP, CdTe, MoSe ₂ , WO ₃ , KTaO ₃ , ZrO ₂ , SrTiO ₃ , WSe ₂ , SiO ₂ , CdS or a combination thereof, and preferably TiO ₂ , SnO ₂ and ZnO. Further, the working electrode is added with a photosensitizer comprising an organometallic complex such as an organic ruthenium series or a purple series, or an oxime series, a coumarin series, a cyanine series or a rhodamine organic dye.

The above electrolyte may be a general-purpose electrolyte comprising a liquid electrolyte, a colloidal electrolyte or a solid electrolyte. The electrolyte is a redox electrolyte, for example, a combination of redox ions such as iodine, iron, tin, bromine, chromium, ruthenium, etc., Hodge, etc., preferably an iodine-based or bromine-based electrolyte, such as potassium iodide or dimethyl iodide. A mixture of propyl imidazolium, lithium iodide, or the like or iodine. The electrolyte of the present invention comprises a nitrile, a guanamine, an ether, a carbonate lactone, or a combination thereof, such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, benzonitrile, Diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, ethylene carbonate, propylene carbonate, γ- Butyrolactone, or γ-valerolactone. Further, the gel electrolyte is a gelled electrolyte by adding a gelling agent or a polymer to the electrolytic solution, and the solid electrolyte is a redox electrolyte solution and a polymer such as a polyethylene oxide derivative. .

The above porous graphene layer has a thickness of 1 to 50 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm. When the thickness of the porous graphene layer is less than 10 nm, pores cannot be effectively produced and electron transport cannot be assisted. Above 200 nm, since the graphene layer is too thick, electron transport is reduced, and both of them lower the conversion efficiency.

The method for preparing the composite counter electrode for a dye-sensitized solar cell of the present invention comprises: (a) providing a platinum layer; (b) mixing a plurality of graphenes with an adhesive to obtain a graphene slurry; c) after coating the graphene slurry onto the platinum layer, drying the graphene slurry to obtain a porous graphene layer formed on the platinum layer to form the composite counter electrode. As shown in FIG. 3, a plurality of graphenes 7 are placed in the adhesive 11 to form a graphene slurry 13, which is applied to the platinum layer 5 and dried to form a graphene layer 3.

In the above step (b), the method of mixing the graphene slurry can use ultrasonic waves. Mixing or blending, ultrasonic mixing is preferred.

In the above step (c), the coating method of the graphene slurry comprises a spin coating method, a rod coating method or a knife coating method, and the spin coating method is preferred. And drying the graphene slurry at a temperature of 100 to 500 ° C and a time of 10 to 60 minutes, such as 100 ° C, 150 ° C, 200 ° C, 250 ° C, 300 ° C, 350 ° C, 400 ° C, 450 ° C, 500 ° C; Points, 20 points, 30 points, 40 points, 50 points or 60 points.

In the above graphene slurry, the concentration of the plurality of graphene is 0.01 to 10 wt%, for example, 0.01 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%. %, or 10wt%. When the graphene concentration is less than 0.01% by weight in the graphene slurry, the density of the graphene is too low due to the lack of graphene, so that it is difficult to cause overlap, and thus it is difficult to generate pores; and when it is higher than 10% by weight, the graphene overlaps each other. Too high a density may cause stacking of graphene and difficulty in generating pores, both of which reduce the conversion efficiency of dye-sensitized solar cells.

A method for manufacturing a dye-sensitized solar cell, comprising: (a) preparing a composite counter electrode by the above preparation method; (b) providing a working electrode, wherein the porous graphene layer is located at the platinum layer and the working electrode And (c) providing an electrolyte between the working electrode and the composite counter electrode. Among them, the working electrode and the electrolyte in the manufacturing method are the same as the working electrode and the electrolyte described above.

Since the dye-sensitized solar cell of the present invention has a composite counter electrode of porous graphene, it can accelerate electron transfer and improve photoelectric conversion efficiency.

[Specific embodiment]

In the following, the disclosure of the invention will be specifically described using specific embodiments. However, the disclosure of the present invention is not limited to the following examples.

Example 1 - Preparation of Composite Counter Electrode 1

A plurality of graphenes (length and width of about 5 μm; thickness of about 2 to 10 nm; specific surface area of 20 to 40 m ² /g) are placed in polyvinylidene fluoride (PVDF) to form a graphene slurry, so that the concentration of graphene is 0.05 wt%. After uniformly mixing for 60 minutes by ultrasonic vibration, the graphene slurry was applied onto a platinum layer having a thickness of about 100 μm by a spin coater to form a graphene layer having a thickness of about 10 μm, and dried at a temperature of 100 ° C for 60 minutes to form a graphene layer. Composite counter electrode 1.

Example 2 - Preparation of composite counter electrode 2

The composite counter electrode 2 was prepared in the same manner as in Example 1 except that the concentration of graphene in the graphene slurry was 1.00 wt%.

Example 3 - Preparation of composite counter electrode 3

The composite counter electrode 3 was prepared in the same manner as in Example 1 except that the concentration of graphene in the graphene slurry was 5.00 wt%.

Example 4 - Preparation of composite counter electrode 4

The composite counter electrode 4 was prepared in the same manner as in Example 1, except that the concentration of graphene in the graphene slurry disposed was 7.00 wt%.

Example 5 - Preparation of Composite Counter Electrode 5

The composite counter electrode 5 was prepared in the same manner as in Example 1 except that the concentration of graphene in the graphene slurry disposed was 10.00% by weight.

Comparative Preparation Example 1 - Preparation of Composite Counter Electrode 6

The composite counter electrode 6 is prepared in the same manner as in the first embodiment, and the difference lies in the configuration. In the graphene slurry, the concentration of graphene was 0.005 wt%.

Comparative Preparation Example 2 - Preparation of Composite Counter Electrode 7

The composite counter electrode 7 was prepared in the same manner as in Example 1 except that the concentration of graphene in the graphene slurry disposed was 20% by weight.

Comparative Preparation Example 3 - Preparation of Composite Counter Electrode 8

A plurality of graphenes (length and width of about 5 μm; thickness of about 2 to 10 nm; specific surface area of 20 to 40 m ² /g) were placed in isopropyl alcohol to form a graphene slurry having a graphene concentration of 0.05% by weight. After uniformly mixing for 60 minutes by ultrasonic vibration, the graphene slurry was applied onto a platinum layer having a thickness of about 100 μm by a spin coater to form a graphene layer having a thickness of about 25 μm, and dried at a temperature of 100 ° C for 60 minutes to form a composite. Counter electrode 6.

Comparative Preparation Example 4 - Preparation of Composite Counter Electrode 9

The composite counter electrode 9 was prepared in the same manner as in Comparative Preparation Example 1, except that the concentration of graphene in the graphene slurry disposed was 5% by weight.

Examples 6 to 10 - Preparation of dye-sensitized solar cells 1 to 5

An encapsulation film is disposed between the counter electrode of Examples 6 to 10 and the working electrode (Tripod tech), and after hot pressing, the electrolyte (Yongguang Chemical, colloidal electrolyte EL-300) is injected to form a dye. The sensitized solar cells 1 to 5, and their performance test results are shown in Table 1, respectively.

Comparative Examples 1 to 5 - Preparation of Dye-Sensitized Solar Cells 6 to 10

An encapsulation film is provided between the counter electrode of the preparation examples 1 to 4, the platinum layer and a working electrode (Tripod tech), and after hot-press encapsulation, the electrolyte (Yongguang Chemical, colloidal electrolyte EL-300) Injection, forming dye-sensitized solar cells 6 to 10, etc. The test results are shown in Table 1.

As shown in Table 1, Comparative Examples 1 and 2 were compared with Examples 1 to 5 to show that the conversion efficiency of the dye-sensitized solar cell was better when the graphene concentration was between 0.05 and 10% by weight. Comparing Comparative Examples 3 and 4 with Examples 1 to 5, it can be seen that when isopropyl alcohol is used as the adhesive, the pores of the graphene layer cannot reach between 10 and 500 nm, resulting in conversion efficiency of the dye-sensitized solar cell. Not good. Comparing Comparative Example 10 with Examples 1 to 5, it can be seen that when the platinum layer does not have a graphene layer, the conversion efficiency of the dye-sensitized solar cell is low.

1‧‧‧Composite counter electrode

3‧‧‧Porous graphene layer

5‧‧‧ Platinum layer

7‧‧‧ Graphene

9‧‧‧ pores

11‧‧‧Adhesive

Claims (10)

A dye-sensitized solar cell comprising: a composite counter electrode comprising a platinum layer and a porous graphene layer disposed on the platinum layer; a working electrode, wherein the porous graphene layer is located in the platinum layer and the work Between the electrodes; and an electrolyte between the working electrode and the composite counter electrode. A dye-sensitized solar cell according to claim 2, wherein the adhesive is a mixture of polyvinylidene fluoride (PVDF), cellulose or the like. The dye-sensitized solar cell of claim 1, wherein the porous graphene layer is formed by overlapping a plurality of graphenes and has a pore size of 25 to 500 nm. The dye-sensitized solar cell of claim 3, wherein the plurality of graphenes have a hollow pore size of 1 nm to 10 μm. The dye-sensitized solar cell of claim 1, wherein the working electrode is TiO ₂ , SnO ₂ and ZnO. The dye-sensitized solar cell of claim 1, wherein the porous graphene layer has a thickness of 1 to 50 μm. A method for preparing a composite counter electrode for a dye-sensitized solar cell according to claim 1, comprising: (a) providing a platinum layer; (b) mixing a plurality of graphenes with an adhesive to obtain a graphene slurry; (c) After the graphene slurry is applied onto the platinum layer, the graphene slurry is dried to obtain a porous graphene layer formed on the platinum layer to form the composite counter electrode. The method of claim 7, wherein the plurality of graphenes are mixed with the adhesive by ultrasonic waves. The method of claim 7, wherein the concentration of the plurality of graphene in the graphene slurry is 0.01 to 10% by weight. A method for manufacturing a dye-sensitized solar cell, comprising: (a) preparing a composite counter electrode by the method of claim 7; (b) providing a working electrode, wherein the porous graphene layer is located at the platinum layer and the working electrode And (c) providing an electrolyte between the working electrode and the composite counter electrode.