EPFL and CSEM Achieve Remarkable 31.25% Efficiency in Perovskite-on-Silicon Tandem Solar Cells

© Quentin Jeangros (CSEM) & Chin Yu Xin (CSEM) - Electron microscopy image of the front side of the high-efficiency perovskite-on-silicon tandem solar cells

Scientists from EPFL’s Photovoltaics and Thin Film Electronics Laboratory (PV-Lab) and CSEM have made significant strides in the field of photovoltaics, particularly in perovskite-on-silicon tandem solar cells. Their latest breakthrough, reaching an impressive efficiency of 31.25%, showcases the immense potential of this emerging technology. The achievement, published in the renowned journal Science, represents a crucial advancement towards a greener and more sustainable energy future.


While silicon solar cells have been widely used in the industry for their reliability and affordability, they are nearing their maximum theoretical efficiency limit of 29%. In order to surpass this limitation and drive down the cost of solar electricity, scientists from EPFL and CSEM have been exploring innovative approaches, including tandem architectures that stack multiple solar cells.

Tandem solar cells optimize solar energy utilization by capturing different parts of the solar spectrum. EPFL and CSEM researchers collaborated to develop a tandem device that combines a perovskite top cell with a silicon bottom cell featuring micrometric pyramids. The textured surface of the silicon cell presents challenges for the deposition of perovskite, but the scientists successfully overcame this hurdle by developing techniques to coat nanometric layers on textured surfaces. As a result, they achieved certified power conversion efficiency of 31.25%, surpassing the 30% milestone for low-cost technologies. The breakthrough findings, originally announced in 2022, have now been detailed in the Science journal.

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Recombination losses at the perovskite interface with the electron selective contact have been a limitation for perovskite-on-silicon tandem cells. To address this issue, EPFL and CSEM scientists incorporated an additive in the perovskite processing sequence. This additive effectively regulated the perovskite crystallization process and passivated the perovskite top interface, particularly on textured surfaces.

The experimental validation of the efficiency potential of perovskite-on-silicon tandem solar cells in Science paves the way for further research efforts focused on scalability and reliability. EPFL and CSEM aim to bring this transformative technology closer to commercial viability, accelerating its adoption and contributing to the global energy transition.

The breakthrough achieved by EPFL’s PV-Lab and CSEM in perovskite-on-silicon tandem solar cells demonstrates remarkable progress in the field of photovoltaics. With their significant efficiency improvement and ongoing efforts to address scalability and reliability challenges, these institutions are driving the adoption of this promising technology and playing a pivotal role in shaping a more sustainable energy landscape.

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