The solar energy world is on the brink of a revolution as scientists race to develop a new type of solar cell that promises to convert electricity more efficiently than today’s panels. In a recent paper published in the journal Nature Energy, a researcher from CU Boulder and his international collaborators unveiled an innovative method to manufacture these next-generation solar cells, known as perovskite cells, a critical step towards their commercialization.

Currently, nearly all solar panels are made from silicon, which has an efficiency of 22 percent, meaning they convert only about one-fifth of the sun’s energy into electricity. Additionally, producing silicon is both expensive and energy-intensive.

Enter perovskite, a synthetic semiconducting material that has the potential to convert substantially more solar power than silicon at a lower production cost. “Perovskites might be a game changer,” said Michael McGehee, a Professor in the Department of Chemical and Biological Engineering and a Fellow with CU Boulder’s Renewable & Sustainable Energy Institute.

Scientists have been experimenting with stacking perovskite solar cells on top of traditional silicon cells to create tandem cells. By layering the two materials, each absorbing different parts of the sun’s spectrum, these tandem cells can potentially increase efficiency by over 50 percent.

“We’re still seeing rapid electrification, with more cars running off electricity. We’re hoping to retire more coal plants and eventually get rid of natural gas plants,” said McGehee. “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 tenfold from where it is today.” Achieving this expansion requires improving the efficiency of solar cells.

A significant challenge in commercializing perovskite solar cells is the process of coating the semiconductor onto glass plates, which must currently occur in a small box filled with non-reactive gas, such as nitrogen, to prevent oxidation. McGehee and his collaborators sought to overcome this obstacle.

The research team discovered that adding dimethylammonium formate (DMAFo) to the perovskite solution before coating could prevent the material from oxidizing, allowing the coating process to occur in ambient air. Experiments showed that perovskite cells made with the DMAFo additive could achieve an efficiency of nearly 25 percent on their own, comparable to the current efficiency record for perovskite cells of 26 percent. The additive also improved the cells’ stability.

In an exclusive interview with Tech Briefs, McGehee discussed the technical challenges and the breakthrough solution:

Tech Briefs: What was the biggest technical challenge you faced while adding DMAFo?

McGehee: The challenge was making these solar cells in air. That’s the challenge that has existed for years, and dimethylammonium formate is the solution to that. Formate is a reducing agent, and it can keep the iodide from oxidizing. We also had to figure out that formate is an anion, so there has to be a cation to balance the charge without modifying the perovskite itself. Dimethylammonium was a good choice because it’s large enough not to enter the perovskite crystal structure. That was part of the thought process: first, we need a reducing agent, and formate is a good choice, then we need a large cation to pair with it.

As the solar industry continues to evolve, innovations like the perovskite cell and advancements in manufacturing techniques are paving the way for more efficient and cost-effective renewable energy solutions. The future of solar energy looks bright, with the potential for substantial improvements in both performance and accessibility.

By Impact Lab