Researchers have developed a new method for producing tandem solar cells, in which two solar cells working together to use a wider range of the solar spectrum.

The physical properties of the semiconductor materials in each cell allow one to absorb light at longer wavelengths and the other to absorb light at shorter wavelengths. Researchers have made tandem solar cells before, but the vapor-deposition methods used to produce the multilayer structure have made the cells relatively expensive.

Jin Young Kim and colleagues now describe a cheaper method for making a tandem semiconducting polymer cell, in which all of the layers, including the electrode connecting the two units, are processed from solution. They used bulk heterojunction materials made from semiconducting polymers and fullerene derivatives.

The cell’s efficiency exceeds 6 percent at illumination of 200 milliwatts per cm2, which is quite good for cells produced via an all-solution method.

Reference: “Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing,” by J.Y. Kim et al.
DOI: 10.1126/science.1141711

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