Perovskite solar cells: A game-changer in renewable energy

Tandem cells: Boosting solar panel efficiency by over 50 percent


Researchers have made strides in the development of next-generation solar cells using perovskite semiconductors, paving the way for more cost-effective and efficient systems to power homes, cars, boats, and drones.

The solar energy landscape is on the cusp of a revolution, with researchers racing to create a new breed of solar cells that can convert electricity more efficiently than the current standard. Published in the journal Nature Energy on February 26, a new paper detailed an innovative method to manufacture these new solar cells, known as perovskite cells, marking a crucial milestone in the commercialization of what many consider the next generation of solar technology.

Conventionally, the majority of solar panels are constructed from silicon, boasting an efficiency of 22%. However, these panels can only convert approximately one-fifth of the sun's energy into electricity, as silicon absorbs only a limited proportion of sunlight's wavelengths, making the production process expensive and energy-intensive.

Perovskite, a synthetic semiconducting material, presents an alternative with the potential to substantially increase solar power conversion while reducing production costs. Michael McGehee, a professor in the Department of Chemical and Biological Engineering and fellow with CU Boulder's Renewable & Sustainable Energy Institute, expressed optimism about perovskite's potential, stating, "Perovskites might be a game changer."

The developments in perovskite solar cells represent a significant leap forward in the quest for more efficient and cost-effective solar technology, with the potential to revolutionize the renewable energy landscape and drive the transition towards a sustainable future.

One of the promising approaches in harnessing the potential of perovskite solar cells is by stacking them on top of traditional silicon cells to create tandem cells. This innovative method of layering the two materials, each absorbing a different part of the sun's spectrum, has the potential to increase the panels' efficiency by over 50%.

McGehee emphasized the urgency for improved solar cell efficiency, especially in light of the increasing electrification trend and the push for a fully renewable future. He noted, "If you believe that we're going to have a fully renewable future, then you're planning for the wind and solar markets to expand by at least five to ten-fold from where it is today."

However, a major challenge in commercializing perovskite solar cells lies in the process of coating the semiconductor onto the glass plates, the fundamental components of panels. Currently, the coating process necessitates a small box filled with non-reactive gas, such as nitrogen, to prevent the perovskites from reacting with oxygen, which diminishes their performance. McGehee highlighted the limitations of this approach, particularly as the scale of production increases.

In a significant breakthrough, McGehee and his collaborators discovered that adding dimethylammonium formate (DMAFo) to the perovskite solution before coating could prevent the materials from oxidizing, enabling the coating to take place outside the confined environment of a nitrogen-filled box, in ambient air. Experiments revealed that perovskite cells made with the DMAFo additive could achieve an efficiency of nearly 25% on their own, comparable to the current efficiency record for perovskite cells of 26%. Furthermore, the additive improved the cells' stability, a critical factor for long-term performance.

While these findings are indeed promising, McGehee cautioned that longer tests are essential to assess the cells' durability over time. He underscored the need for extended testing to determine if perovskite cells can match the stability of silicon panels, which typically maintain at least 80% of their performance after 25 years.

The study represents a significant step forward in the commercialization of perovskite solar cells, with McGehee's team concurrently working on developing tandem cells with a real-world efficiency of over 30% that can match the operational lifetime of silicon panels. Through the Tandems for Efficient and Advanced Modules using Ultrastable Perovskites (TEAMUP) initiative, a U.S. academic-industry partnership led by McGehee, researchers are striving to create stable tandem perovskites that are commercially viable and can potentially surpass the efficiency of conventional silicon panels while maintaining long-term stability.

With higher efficiency and potentially lower price tags, these tandem cells could find broader applications than existing silicon panels, including potential installation on the roofs of electric vehicles, thereby extending their range by 15 to 25 miles per day under sunlight exposure. The implications also extend to the potential use of such panels in powering drones and sailboats, presenting a significant advancement in sustainable energy solutions.

After a decade of research in perovskites, McGehee expressed confidence in the potential of perovskite cells, stating, "We are taking perovskites to the finish line. If tandems work out well, they certainly have the potential to dominate the market and become the next generation of solar cells."

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