Product Information
As dependence on fossil fuels, such as petroleum, coal, and natural gas, is being lowered, efforts are underway to realize a low-carbon society based on renewable energy sources such as sunlight and wind.
In Japan, solar power is regarded as the most promising source, and a high goal of installing solar panels on approximately 30% of all houses (14 million houses) in 2030 has been set. Silicon solar cells are used for almost all panels for domestic use. However, since the increase of the production of silicon solar cells is limited, the above-mentioned high goal cannot be attained even if the installation cost is further reduced.
Dye-sensitized solar cells are attracting attention as the next-generation solar cells in place of silicon solar cells because they can make drastic reduction of power generation cost a reality. The CO2 payback time of this type of cell is shorter than that of silicon solar cells, and the cells can be manufactured in processes with low environmental loads. The dye-sensitized solar cells are variable in material and have significant potential.
Solvents having high polarity are used in the electrolytes of dye-sensitized solar cells. Therefore, general-purpose sealants are swollen or dissolved by the electrolytes and cannot give sufficient durability.
Because of this, we have designed and combined electrolyte-resistant sealant component chemical structures to improve the electrolyte resistance. (Table 1)
"The pigments from which the name "dye-sensitized solar cell" comes absorb light energy in the photoelectrode and convert it into electrical energy. Since the pigments are sensitive to heat, it is desirable to use a sealant which can cure without heating. In consideration of productivity, we introduced a photopolymerizable functional group which can cure in a short time at room temperature into the sealant composition." <Yasunaga>
For dye-sensitized solar cells, a main sealing agent for laminating photoelectrode and opposite electrode and an end sealing agent for closing the electrolyte fill ports are used. (Fig. 1)
The main sealing agent will come into contact with the electrolyte after curing, but the end sealing agent will come into contact with the electrolyte in the uncured state. Therefore, the end sealing agent in the uncured liquid state must be insoluble in the electrolyte and must be able to cure quickly under light irradiation even if it comes into contact with the electrolyte.
"ThreeBond 3035B consisting of materials having low polarity repels electrolytes which have high polarity like oil and water. Therefore, it is insoluble in the electrolyte. In addition, we have selected various photoinitiators for starting the light-curing reaction to reduce curing inhibition caused by iodine contained in the electrolyte." <Yasunaga>
ThreeBond 3035B (Fig. 2) is a sealant for dye-sensitized solar cells excelling in solvent resistance and durability and can be used both for main sealing for laminating electrodes and for end sealing for sealing electrolyte fill ports.
Since the sealant cures quickly under light irradiation at room temperature, the pigments are not thermally damaged, and high productivity can be obtained.
It can be applied with dispensers and screen printing machines by controlling the fluidity.
"We intend to improve its thermal resistance and durability to apply it to a wider environment and contribute to the field of renewable energy." <Yasunaga>
Introduction of sealant, ThreeBond 3035B, for sealing electrolytes in next-generation dye-sensitized solar cells
The dye-sensitized solar cell consists of a photoelectrode, an opposite electrode, and an electrolyte between these electrodes. The cell continually generates electricity through the oxidation-reduction reaction cycles performed in the electrolyte to function as a battery.
Deterioration in the oxidation-reduction reaction directly affects the functionality of the cell. Because of this, preventing leakage, alteration, and deterioration of the electrolyte is a very important technique for the practical use of dye-sensitized solar cells.
Therefore, we have started the investigation of sealant for electrolyte sealing and developed and launched ThreeBond 3035B.
Commentator
Kana Yasunaga
Functional Material Development Section, Development Department, Research and Development Division