A team of researchers, led by the University of Sydney, have used a new approach that could be the key to producing low cost and environmentally friendly perovskite solar cells, while achieving a new efficiency milestone for these cells.
The researchers said they had made crucial improvements to the process of ‘gas quenching’ to fabricate perovskite thin films. The research team successfully demonstrated a steady-state conversion efficiency of 23.6%, which they claim is the highest efficiency achieved for perovskite solar cells produced using the ‘gas quenching’ technique.
“This is significant for low solvent (therefore, lower cost and reduced toxicity) and scalable manufacturing of efficient [perovskite solar cells],” the research paper says.
Current manufacturing techniques rely on the use of “anti-solvent” in the production of perovskite solar cells. These anti-solvents can both increase the cost of solar cell manufacturing perovskite solar cells, as well as ultimately being toxic to the environment.
By eliminating the use of the anti-solvents, while maintaining similar levels of performance, the is the potential to produce lower cost and environmentally friendly next-generation solar cells.
“Many high-performance perovskite solar cells are fabricated using ‘anti-solvents’, to assist in the formation of good-quality multi-crystalline perovskite film. However, many of these solvents are toxic,” University of Sydney PhD student and lead author Shi Tang said.
“We use gas quenching of the perovskite surface to achieve the same outcome. This reduces the amount of solvent used. Also, unlike anti-solvent treatment, gas quenching is compatible with other methods that are critical for large-scale manufacturing. In our work, we have developed methods that are compatible with gas-quenched-deposition for passifying defects at the surface of the film and within the bulk of the perovskite layer. This allows us to achieve a very high energy conversion efficiency” Tang added.
The researchers said that they had made improvements to the production processes that use the ‘gas quenching’ technique, setting a new milestone for the conversion efficiency the cells can demonstrate over an extended period, and using a method that can be applied in other production processes to achieve similar performance improvements.
Key to this, the paper says, was the use of potassium iodide in precursor materials, which improved the quality of thin films and their performance in the solar cells. Potassium iodide is commonly used as a dietary supplement, found in iodize salt to prevent iodine deficiency.
“Our next step is to apply these discoveries for large area cells, for perovskite-tandems. Cells of this kind are also used for testing new techniques being developed in our lab to improve cells’ durability, following on our work from last year that was published in Science,” corresponding-author and research team leader professor Anita Ho-Baillie said