New Additives to Perovskite Tandem Solar Cells Boost Efficiency, Stability

Researchers were able to fabricate this perovskite solar cell that overcomes problems with stability.

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The National Renewable Energy Laboratory (NREL), U.S. Department of Energy, has demonstrated a tin-lead perovskite cell which overcomes stability issues and increases efficiency. The tandem cell with two layers of perovskites measured 25.5% efficiency.


Perovskites are a high-efficiency material for solar cells. However, research continues to improve the technology.

After 1,500 hours continuous operation, or for more than 62 days, the new NREL cell maintained 80% of its maximum efficiency.

Kai Zhu (a senior scientist at NREL) said that this is an accelerated aging experiment in the laboratory and was co-author of a paper detailing the findings. “At this tandem efficiency level the best reported stability is usually several hundred hours.”

Perovskite is a crystalline structure, not a particular element like silicon. The solar cells are made of a chemical solution that has been attached to a substrate. Kai Zhu, Jinhui Tong and Jinhui Tong were the authors of this article. They said that a tandem perovskite cells, which have two layers joined together to capture slightly different parts of the sun’s spectrum, is more efficient than 30%.

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Qi Jiang, Andrew Ferguson, Ji Hao and Axel Palmstrom are the other co-authors of NREL. Amy Louks, Steven Harvey and Steven Harvey , Haipeng Lu. Ryan France, Fei Zang, Mengjin Yang, John Geisz. Matthew Beard, Darius Kuciauskas and Joseph Berry are also co-authors. The University of Colorado-Boulder, University of Toledo are also contributing.

In a paper published in Science in 2019, many of these scientists demonstrated a tin-lead tandem, perovskite cell that achieved an efficiency of 23.1%. The researchers remediated any tin-related problems by adding the chemical compound Guanidinium Thiocyanate to the cell, which led to significant improvements in its structural and optoelectronic properties. When sunlight triggers electron movement, solar cells produce electricity. The cell’s efficiency is enhanced by a longer carrier life associated with electron movement. Guanidinium thiocyanate was added to increase the carrier lifespan from 200 nanoseconds to 1 microsecond.

The scientists improved upon the earlier experiment by adding phenethylammonium Iodide and guanidinium Thiocyanate. The carrier life of the improved tin-lead perovskite increased to approximately 9 microseconds. The combination additives reduced the defect density due to tin oxidation to levels that were unprecedented in tin-lead and comparable to those for lead-only Perovskites.

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At 2.1142 volts, the new cell demonstrated an increase in voltage. The best-certified tandem device recorded 2.048 volts.

This research was funded by the U.S. Department of Energy’s Solar Energy Technologies Office.

NREL is the primary U.S. Department of Energy national laboratory for energy efficiency and renewable energy research and development. The Alliance for Sustainable Energy, LLC manages NREL for the Energy Department.

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