Cleaner solarcells: a new way to make renewable energy more sustainable
Solar energy is one of the most important technologies for reducinggreenhouse gas emissions. Among the newest solar technologies, perovskitesolar cells have attracted worldwide attention because they can be highlyefficient, lightweight, and potentially cheaper to manufacture thanconventional silicon solar panels. However, there is an important challenge:many of the chemicals currently used to make perovskite solar cells are toxicand harmful to both people and the environment.
A recent study supported by the HEPAFLEX project presents a promisingsolution. Researchers developed an innovative method for producing perovskitesolar cells using water and alcohol-based inks, replacing many of thehazardous solvents traditionally used in manufacturing.
The work was carried out as a collaboration between the group of Prof.Eva Unger at the Helmholtz-Zentrum Berlin (HZB), Dr. Senol Öz (part ofthe HEPAFLEX project), and the group of Prof. Sanjay Mathur at the Universityof Cologne, together with international partners.
Why Does ThisMatter?
Most perovskite solar cells are produced using solvents such asdimethylformamide (DMF) and dimethyl sulfoxide (DMSO). While effective, thesechemicals can pose health and environmental risks during large-scaleproduction. As the technology moves closer to commercialization, finding saferalternatives becomes increasingly important.
The new research demonstrates that it is possible to create a perovskiteink using mostly water, isopropyl alcohol (a common alcohol used in cleaningproducts), and a special organic ionic liquid called methylammonium propionate(MAP). This combination allows the solar-cell materials to dissolve andform high-quality thin films without relying on highly toxic solvents.
How Are These SolarCells Made?
The researchers used a manufacturing technique called slot-diecoating. This process works similarly to industrial printing, where liquidink is spread evenly over a surface to create a thin layer. Because it can bescaled up for continuous production, slot-die coating is considered one of themost promising methods for manufacturing next-generation solar panels.
A major achievement of this work is that the new green ink can beapplied in a single coating step, simplifying production and reducingwaste. Previous water-based approaches often required several separateprocessing steps, making large-scale manufacturing more complicated.
What Did theResearchers Achieve?
Using their environmentally friendly ink, the team successfully producedworking perovskite solar cells with power conversion efficiencies of over 10%.While this is lower than the best laboratory perovskite cells available today,it demonstrates that safer and more sustainable manufacturing routes arepossible and can already deliver meaningful performance.
The researchers also found that the new ink remains stable duringstorage and can be processed under normal room conditions, reducing the needfor specialized manufacturing environments.
Benefits for Peopleand the Environment
To understand the wider impact of their innovation, the team carried outan environmental assessment comparing the new ink with conventionalformulations. The results showed
- Lower human toxicity risks.
- Reduced impacts associated with carcinogenic and non-carcinogenic chemicals.
- Lower formation of air pollutants that can affect human health.
- Reduced overall environmental burden in most categories examined.
These improvements suggest that future perovskite solar panels could beproduced more safely for workers while reducing environmental impactsthroughout the manufacturing process.
Looking Ahead
Perovskite solar cells have the potential to play a major role in theglobal transition to clean energy. This study shows that improving solartechnology is not only about increasing efficiency—it is also about makingmanufacturing safer, cleaner, and more sustainable. By replacing hazardoussolvents with water- and alcohol-based alternatives, researchers are helping toensure that the renewable energy technologies of the future are environmentallyresponsible from production to deployment.
As research continues, the next challenge will be scaling up thisapproach to larger solar modules and improving long-term durability. Ifsuccessful, these greener manufacturing methods could help accelerate theadoption of affordable and sustainable solar energy worldwide.
Source: Ünlü et al., Toward GreenProcessing of Perovskite Solar Cells: Protic Ionic Liquids Enable Water- andAlcohol-Based MAPbI3 Precursors Inks for Slot-Die Coating, AdvancedEnergy Materials (2025). Check the full article: https://doi.org/10.1002/aenm.202403626
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