German Researchers Achieve 27.1% Efficiency and 6800-Hour Stability with Solvent-Free Perovskite-Silicon Tandem Solar Cell

September 6, 2026

PV Magazine Germany

Overview

A team from the University of Freiburg and Fraunhofer ISE in Germany has developed a fully solvent-free perovskite-silicon tandem solar cell achieving a 27.1% power conversion efficiency. This innovative and scalable sequential evaporation method demonstrated remarkable stability, retaining 97.06% of its initial efficiency after 6800 hours of dark storage under nitrogen. This breakthrough significantly advances the potential for industrial-scale, high-throughput production of perovskite solar cells, addressing critical environmental and cost challenges.

In Depth

Key Findings

Researchers from the University of Freiburg and Fraunhofer Institute for Solar Energy Systems (ISE) in Germany have reported a significant advancement in perovskite-silicon tandem solar cell technology, achieving a power conversion efficiency of 27.1% using a completely solvent-free manufacturing process. This innovative approach also demonstrated exceptional long-term stability, maintaining 97.06% of its initial efficiency after 6800 hours of dark storage in a nitrogen atmosphere.

Technical Details

Conversion Efficiency: The tandem cell achieved a certified power conversion efficiency of 27.1%.
Manufacturing Process: The key innovation lies in the fully solvent-free sequential evaporation method. This technique eliminates the use of organic solvents during perovskite layer formation, which not only reduces environmental impact but also simplifies the manufacturing process and potentially lowers production costs.
Stability: A major challenge for perovskite solar cells has been their long-term stability. This study addresses that by demonstrating impressive stability, with the cell retaining over 97% of its original efficiency after prolonged dark storage. This level of stability is crucial for commercial viability.
Scalability: The research team emphasized that this solvent-free sequential evaporation approach is inherently scalable and suitable for high-throughput industrial production, marking a critical step toward mass manufacturing.

Background & Context

Perovskite solar cells are widely recognized as a promising next-generation photovoltaic technology due due to their high power conversion efficiency and low manufacturing costs. Tandem structures, combining perovskite with conventional silicon cells, offer the potential to surpass the theoretical efficiency limits of single-junction cells. However, issues related to perovskite material stability and scalability in large-scale production have been persistent barriers to commercialization. This German research tackles these fundamental hurdles directly.

Strategic Significance & Outlook

The development of a solvent-free manufacturing method coupled with enhanced stability is a game-changer for the industrialization of perovskite-silicon tandem solar cells. This eco-friendly and cost-effective production pathway is expected to significantly accelerate the adoption of solar power, playing a vital role in the global energy transition. Future work will focus on further increasing efficiency and validating the long-term performance under real-world outdoor conditions to pave the way for widespread deployment.

Source: https://www.pv-magazine.com/2026/08/28/solvent-free-perovskite-silicon-tandem-solar-cell-achieves-27-3-efficiency/

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