Ilaria Rosella Pagliaro An important study published in Nature Energy reveals an innovative method for producing perovskite solar cells, promising a breakthrough in the field of solar energy
©University of Colorado Boulder
The realm of solar energy is poised for a significant transformation with the development of an advanced type of solar cell. Crafted by an international team led by a researcher from the University of CU Boulder, these new cells promise to outperform the efficiency of current solar panels, which are traditionally silicon-based. This breakthrough, documented in the journal Nature Energy, introduces perovskite cells as the cutting-edge in solar technology.
Currently, the majority of solar panels on the market are made from silicon, boasting an energy conversion efficiency of 22%. This means that only a fraction of solar energy is transformed into electricity, largely due to silicon’s limited ability to absorb specific wavelengths of light. Beyond this limitation, silicon production is known for its high costs and substantial energy consumption.
In this context, perovskite, a synthetic semiconductor material, emerges with the potential to convert solar energy more efficiently and at reduced production costs compared to silicon. Michael McGehee, a professor in the Department of Chemical and Biological Engineering at CU Boulder, highlights the revolutionary importance of perovskites in the energy sector:
“We are still witnessing a rapid electrification, with more and more cars being powered by electricity. We hope to retire more coal plants and eventually get rid of natural gas plants. If we think of having a completely renewable future, then we have to consider that the markets for wind and solar energy need to expand at least five to ten times from where they are today.”
To achieve this, the industry must improve the efficiency of solar cells. But a significant challenge in producing them from perovskite on a commercial scale is the process of coating the semiconductor on glass plates that constitute the building blocks of the panels. Currently, the coating process must occur in a small box filled with inert gas, such as nitrogen, to prevent the perovskites from reacting with oxygen, reducing their performance.
Greater efficiency
The research explored the use of perovskite solar cells in combination with silicon cells to form tandem cells. This combination leverages the ability of each material to absorb different parts of the solar spectrum, potentially increasing panel efficiency beyond 50%. McGehee observes that the expansion of wind and solar energy markets is essential for a renewable future, and improving solar cell efficiency is crucial for this goal.
A key challenge in commercializing perovskite cells concerns the semiconductor coating process, which currently requires isolated environments to prevent oxidation. However, the discovery of the use of dimethylammonium formate (DMAFo) offers a solution by allowing coating in ambient conditions without compromising material performance.
Perovskite solar cells with DMAFo have demonstrated an efficiency of 25%, comparable to the current record of 26%. Moreover, this innovation has significantly improved the stability of the cells. While silicon panels maintain 80% of their performance for 25 years, perovskites tend to degrade more rapidly. However, cells treated with DMAFo have maintained 90% of their efficiency after 700 hours of exposure to artificial light, suggesting a step towards long-term stability, though McGehee remains cautious:
“This is fine for the research stage. But when you start coating large pieces of glass, it becomes increasingly difficult to do so in a nitrogen-filled box. It’s too early to say they are as stable as silicon panels, but we are on a good path. Although this is a very encouraging result, there are 8,000 hours in a year.”
McGehee’s team is actively developing tandem cells with a real efficiency of over 30% and a lifespan equal to that of silicon panels. This study represents a step forward towards the commercialization of perovskite cells. McGehee also leads an academic-industrial consortium that has received $9 million in funding for the development of stable and commercially viable perovskite tandem cells.
These innovations not only promise to increase efficiency and reduce costs but could also extend the use of solar energy to new applications, such as charging electric vehicles and powering drones and sailboats. After years of research, perovskites are reaching efficiency levels comparable to silicon cells, paving the way for a future where they could dominate the solar energy market.
