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A new stable and cost-cutting type of perovskite solar cell

© 2014 EPFL

© 2014 EPFL

Scientists at the Michael Grätzel Center for Mesoscopic Cells have made a perovskite solar cell that does not require a hole-conducting layer. The novel solar cell achieved energy conversion efficiency of 12.8% and was stable for over 1000 hours under full sunlight. The innovation is expected to significantly reduce the cost of these promising solar cells.

Perovskite solar cells show tremendous promise in propelling solar power into the marketplace. The cells use a hole-transportation layer, which promotes the efficient movement of electrical current after exposure to sunlight. However, manufacturing the hole-transportation organic materials is prohibitively costly. Publishing in Science, a team of scientists in China, led by Michael Grätzel at EPFL, have developed a perovskite solar cell that does not use a hole-transporting layer, with 12.8% conversion efficiency and over 1000 hours stability under full sunlight in ambient temperature. The innovation can reduce the cost of perovskite cells, and firmly propel them into the marketplace.

Hybrid organic–inorganic methylammonium lead halide perovskites have attracted intense attention for thin-film photovoltaics, due to their large absorption coefficient, high charge carrier mobility and diffusion length. However, these cells are also costly because of the hole-transportation layer, which demands high purity materials and complicated fabrication procedures.

A team of scientists at the Michael Grätzel Center for Mesoscopic Cells of Huazhong University in China have successfully manufactured a perovskite solar cell that does not need a hole-transportation layer. The solar cell shows comparative energy conversion efficiency (12.8%) and was shown to be stable for over 1000 hours in direct sun exposure.

The scientists fabricated the new solar cell by drop-casting a solution of lead iodide, methylammonium iodide, and 5-ammoniumvaleric acid iodide through a porous carbon film. The solar cell’s scaffolding was made using a double layer of titanium dioxide and zirconium dioxide covered by a porous carbon film. The resulting mixed-cation perovskite crystals showed higher electrical charge efficiency than conventional perovskite cells. The triple layer also resulted in better surface contact, leading to considerably high stability.

Perovskite solar cells are ideally placed to meet the increasing demands for renewable energy in the future. This breakthrough innovation addresses one of their major limiting factors, and paves the way for a new, cost-effective branch of development in this type of solar cell.

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This work represents a collaboration between EPFL’s Laboratory Of Photonics And Interfaces and the Michael Grätzel Center for Mesoscopic Cells of Huazhong University (China).

Reference

Mei A, Li X, Liu L, Ku Z, Liu K, Rong Y, Xu M, Hu M, Chen J, Yang Y, Grätzel M, Han H. A hole-conductor–free, fully printable mesoscopic perovskite solar cell with high stability. Science 345:6194 DOI: 10.1126/science.1254763


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