Perovskite/Silicon Tandem Solar Cells Achieved Via Thermal Evaporation

Researchers have developed a novel method for fabricating perovskite/silicon tandem solar cells by employing thermal evaporation, a technique that allows for precise control over material deposition and potentially lower manufacturing costs compared to solution-based methods. This advancement, detailed in a study published online on August 5, 2026, in the journal Nature, addresses key challenges in the large-scale production of highly efficient solar energy conversion devices. The team utilized a formamidinium-based perovskite composition, which has shown promise for its stability and optoelectronic properties. By integrating this perovskite layer with a silicon solar cell, the researchers aimed to create a tandem device capable of absorbing a broader spectrum of sunlight, thereby increasing overall power conversion efficiency.

The thermal evaporation process involves heating precursor materials to their vaporization point and then condensing them onto a substrate in a controlled vacuum environment. This method offers advantages such as excellent film uniformity, reduced defects, and the ability to deposit complex multi-layer structures without the need for solvents, which can sometimes degrade sensitive materials or leave residues. For perovskite solar cells, achieving stable and efficient interfaces between layers is critical, and thermal evaporation provides a pathway to engineer these interfaces with high precision. The formamidinium eutectic composition was specifically chosen for its favorable thermal properties and its compatibility with the evaporation process, aiming to overcome the degradation issues often associated with perovskite materials when exposed to heat and moisture.

This development is significant because perovskite/silicon tandem solar cells represent a promising next-generation photovoltaic technology. Silicon solar cells, which currently dominate the market, are highly efficient at converting near-infrared light, but their performance diminishes for higher-energy photons in the visible spectrum. Perovskites, on the other hand, excel at absorbing visible light. By stacking a perovskite layer on top of a silicon cell, the tandem structure can capture more of the solar spectrum, leading to theoretical efficiencies that surpass those of single-junction silicon cells. Previous attempts to create such tandem cells often relied on solution-based processing, which can be difficult to scale up and may introduce variability in performance. The thermal evaporation approach offers a more scalable and potentially more cost-effective manufacturing route.

The study published in Nature highlights the successful fabrication of these tandem cells, demonstrating their potential for high power conversion efficiency and improved operational stability. While specific efficiency figures and stability metrics are detailed within the full research paper, the advancement signifies a crucial step towards realizing the commercial viability of perovskite/silicon tandem solar technology. The ability to deposit perovskite layers uniformly and defect-free using thermal evaporation is a key enabler for achieving reproducible and high-performance devices. This research contributes to the ongoing global effort to develop more efficient and affordable renewable energy solutions, aiming to reduce reliance on fossil fuels and mitigate climate change.