A team of researchers at six Fraunhofer institutes has made significant progress in developing advanced tandem solar cells that combine high efficiency with sustainability.

Over five years, the team worked on creating solar cells made from perovskite and silicon, aiming to improve their performance and durability while using eco-friendly methods.

These new tandem solar cells are expected to play a key role in the next leap forward for solar energy technology.

Tandem solar cells stack two types of materials—silicon and perovskite—to capture more sunlight and generate more energy compared to traditional solar cells.

In their “MaNiTU” project, researchers created new perovskite materials and tested them against existing ones.

They achieved impressive results, including a tandem solar cell with an efficiency of 31.6% on a 1-square-centimeter cell, one of the highest efficiencies achieved using scalable production processes.

However, the team discovered that only perovskites containing lead could reach these high efficiencies.

To address environmental concerns, they developed recycling methods to safely handle and reuse lead-containing materials, ensuring sustainability throughout the product lifecycle.

The researchers focused on creating manufacturing processes that could be easily scaled up for industrial use.

They combined vapor deposition and wet-chemical techniques to produce high-quality perovskite films on textured silicon solar cells. This “hybrid route” method ensures that the technology can be applied to large-scale production.

While lead-containing perovskites achieved the best performance, the team also investigated lead-free alternatives.

Using advanced techniques like spray drying, they tested many materials. Unfortunately, none of the lead-free options matched the efficiency of lead-based perovskites.

Despite this, the researchers gained valuable insights into the stability and properties of these alternative materials, which could guide future development.

To minimize the environmental impact of tandem solar cells, the team developed advanced recycling processes. These methods allow for the recovery and reuse of valuable materials, including lead, ensuring a circular economy for solar panels. According to Professor Peter Dold of Fraunhofer IWKS, this approach ensures long-term sustainability while maintaining high energy efficiency.

The next step involves transferring this technology from the lab to real-world applications. Researchers worked with industrial partners to develop high-performance system components, such as advanced contact materials, for large-scale production.

They also addressed challenges like temperature sensitivity in perovskite cells by creating innovative coating processes.

The researchers performed detailed analyses of the tandem cells, identifying an upper efficiency limit of 39.5%.

They also developed computational models to predict the performance of absorber materials and their interfaces, which could improve not only solar cells but also technologies like hydrogen energy.

The “MaNiTU” project has put Europe at the forefront of photovoltaic innovation, paving the way for a new era of efficient, sustainable solar energy.

With continued industrial collaboration, these tandem solar cells could soon become a cornerstone of clean energy solutions worldwide.