EPFL and CSEM Achieve Landmark Photovoltaic Efficiency Milestone

In a significant step towards more efficient and cost-effective solar power generation, scientists from EPFL’s School of Engineering and the CSEM have unveiled the underlying science behind high-performance perovskite/silicon tandem solar cells. With a certified power conversion efficiency of 31.25%, this groundbreaking research, published in the journal Science, showcases the first instance where the 30% efficiency milestone has been surpassed using low-cost technology.

One limitation is that silicon solar cells are approaching the theoretical efficiency maximum of 29% allowed by the material. Increasing power conversion efficiencies beyond this mark is important to lower the cost of solar electricity further, promote its deployment and conquer new markets. To surpass this limitation scientists have been exploring innovative device architectures that involve stacking two or more solar cells in a tandem architecture. This enables a better use of solar energy as each cell is optimized to capture different parts of the solar spectrum.

By combining a perovskite top cell with a textured silicon bottom cell, the research teams at EPFL’s PV-Laband CSEM have optimized solar energy capture across a broader spectrum. Using a coating of nanometric layers on textured surfaces, the scientists enhanced the solar cell architecture by incorporating an additive that not only regulated the crystallization process but also passivated the perovskite top interface. This breakthrough paves the way for the future scalability and reliability of perovskite/silicon tandem solar cells, which hold tremendous potential for transforming the solar energy industry, fostering sustainability, and propelling us closer to a greener and cleaner energy future.