Breaking the Evaporation Barrier: Formamidinium Eutectics Propel Perovskite-Silicon Tandem Cells to 31.5% Efficiency, Paving Way for Large-Scale Production

August 9, 2026

ScienceDaily USA

Overview

Researchers have developed an innovative thermal evaporation technique using formamidinium iodide (FAI) eutectics, achieving a record 31.5% steady-state efficiency for 1 cm² perovskite-silicon tandem solar cells and an impressive 30.0% on large 200 cm² wafers. This breakthrough overcomes the long-standing challenge of FAI degradation during evaporation, enabling precise compositional control and high uniformity crucial for large-scale manufacturing and accelerating the commercialization of high-efficiency tandem photovoltaics.

In Depth

Background

Perovskite-silicon tandem solar cells are widely recognized as the most promising technology to surpass the theoretical efficiency limit of single-junction silicon solar cells, typically around 29%. However, their commercialization hinges on simultaneously addressing three critical challenges: achieving high efficiency, ensuring long-term stability, and enabling low-cost, large-scale manufacturing. While solution processing methods are inexpensive, they often struggle with achieving uniform film quality and controlling defects over large areas. Conversely, thermal evaporation offers excellent uniformity and reduced defect density, making it attractive for thin-film production, but the thermal decomposition of perovskite materials, especially formamidinium-based organic salts, has historically presented a significant barrier to forming high-efficiency perovskite layers.

Key Findings

A research team has successfully developed an innovative thermal evaporation method that leverages formamidinium iodide (FAI) eutectics, setting a new benchmark with a remarkable steady-state power conversion efficiency (PCE) of 31.5% for a 1 cm² perovskite-silicon tandem solar cell. Crucially, this advanced method also demonstrated an impressive 30.0% PCE on a large-area 200 cm² wafer, a critical step towards industrial application. This technology directly addresses and resolves the persistent challenge of FAI degradation during thermal evaporation, enabling the precise compositional control and exceptional uniformity essential for large-scale production. This breakthrough significantly accelerates the potential for commercial mass production of high-efficiency tandem solar cells.

Technical Details

Thermal evaporation is a highly desirable manufacturing technique for thin films due to its inherent advantages in achieving superior uniformity and significantly reduced defect density compared to conventional solution processing methods, making it ideally suited for large-area applications. The primary hurdle for perovskite materials, particularly formamidinium-based organic salts, has been their susceptibility to decomposition when heated for evaporation. To overcome this, the researchers developed a novel precursor material that forms low-melting-point eutectics by carefully combining FAI with specific additives. This innovative approach facilitates stable evaporation while effectively suppressing thermal decomposition, allowing for precise control over film thickness and promoting uniform crystal growth. The result is the formation of high-quality perovskite layers over expansive areas. The dual achievement of 31.5% efficiency on a small 1 cm² cell and maintaining a robust 30% efficiency on a practical 200 cm² wafer powerfully underscores the commercial viability and scalability of this manufacturing approach.

Strategic Significance & Outlook

This novel thermal evaporation technology is strategically positioned to play a pivotal role in the large-scale manufacturing of high-efficiency perovskite-silicon tandem solar cells. The demonstration of 30% efficiency on a 200 cm² scale directly paves the way for the industrial production of solar modules. Future research and development efforts will concentrate on further optimizing the cost-effectiveness of this technology, conducting rigorous long-term durability testing, and facilitating the seamless transition to complete module products. This monumental progress is anticipated to dramatically enhance the cost-performance ratio of solar power, making it an indispensable factor in accelerating the global transition towards renewable energy sources.

Source: https://www.sciencedaily.com/releases/2026/08/260805123456.htm

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