RESEARCH I REVIEW
Stable and cost-cutting
perovskite solar cell Perovskite solar cells show tremendous promise in propelling solar power into the marketplace. The cells use a hole-transportation layer, which promotes the effi cient movement of electrical current after exposure to sunlight. However, manufacturing the hole-transportation organic materials is very costly and lack long term stability.
PUBLISHING IN SCIENCE, a team of scientists in China, led by Professor Hongwei Han in cooperation with Professor Michael Grätzel at EPFL, have developed a perovskite solar cell that does not use a hole- transporting layer, with 12.8% conversion effi ciency and over 1000 hours stability under full sunlight in ambient
temperature. The innovation can reduce the cost of perovskite cells, and fi rmly propel them into the marketplace.
Hybrid organic–inorganic methylammonium lead halide perovskites have attracted intense attention for thin-fi lm photovoltaics, due to their large absorption coeffi cient, 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.
A team of scientists at the Michael Grätzel Centre for Mesoscopic Cells of Huazhong University in China in cooperation with the Laboratory for Photonics and Interfaces at EPFL directed by Michael Grätzel have successfully manufactured a perovskite solar cell that does not need a hole-transportation layer. The solar cell shows comparative energy conversion effi ciency (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 fi lm. The solar cell’s scaffolding was made using a double layer of titanium dioxide and zirconium dioxide covered by a porous carbon fi lm 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 effi ciency than conventional hole conductor free perovskite cells. The use of
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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.
This work represents a collaboration between EPFL’s Laboratory of Photonics And Interfaces and the Michael Grätzel Centre for Mesoscopic Cells of Huazhong University of Science and Technology (China).
©2014 Permission required. Angel Business Communications Ltd.
Journal 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 Letters, 2014; 140728125936002 DOI: 10.1021/nl501962c.
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