Perovskite Solar Cells Made Stable

By sidestepping the hole-transportation layer, scientists have developed a cheaper and more stable perovskite-based solar cell.

AsianScientist (Jul 22, 2014) – Scientists have developed a perovskite solar cell that is stable over 1,000 hours under full sunlight. The innovation can reduce the cost of perovskite cells, and firmly propel them into the marketplace. These results have been published in the journal Science.

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 long diffusion length. However, these cells are also costly because of the hole-transportation layer, which demands high purity materials and complicated fabrication procedures. Furthermore, applications for perovskite solar cells are presently limited by their lack of long term stability.

A team of scientists at the Michael Grätzel Center for Mesoscopic Cells of Huazhong University in China in cooperation with the Laboratory for Photonics and Interfaces at Ecole Polytechnique Fédérale de Lausanne 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 percent) and was shown to be stable for over 1,000 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 and amino acid templating agent was used to promote the pervoskite nucleation and crystal growth within the pores.

The resulting perovskite crystals showed much higher electrical charge generation and collection efficiency than conventional hole conductor free perovskite cells. The use of organic-hole conductor free triple layer also resulted in strikingly 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.

The article can be found at: Mei et al. (2014) A hole-conductor–free, fully printable mesoscopic perovskite solar cell with high stability.

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Source: Ecole Polytechnique Fédérale de Lausanne; Photo: Scott Robinson/Flickr/CC.
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