NUS researchers have developed a groundbreaking vapour-deposition method that dramatically improves the long-term and high-temperature stability of perovskite-silicon (Si) tandem solar cells. This is the first time vapour deposition has been successfully applied to industrial micrometre-textured silicon wafers, the actual wafer structure used in commercial solar cells manufacturing, marking a major milestone for translating laboratory-scale tandem solar cells into real-world products.
The new method enables conformal, high-quality perovskite growth on industrial micrometre-scale textured silicon wafers, a critical requirement for mass production, and delivers more than 30 per cent power-conversion efficiency with operational stability far exceeding 2,000 hours, including T₉₀ lifetimes - the time taken for performance to drop to 90 per cent of initial output - of over 1,400 hours at 85 deg C under 1-sun illumination, a standard benchmark in solar energy representing a light intensity of 1000 watts per square metre. These results represent one of the most durable perovskite-Si tandem solar cells ever reported, validating a viable pathway toward commercial photovoltaic modules.
This work was led by Assistant Professor Hou Yi, who is a Presidential Young Professor in the Department of Chemical and Biomolecular Engineering under the College of Design and Engineering at NUS, and Head of the Perovskite-based Multijunction Solar Cells Group at the Solar Energy Research Institute of Singapore (SERIS) at NUS.
The findings were published in Science on 19 December 2025.
Long-lasting solar cells for real world applications
For tandem solar cells to be deployed on rooftops, solar farms, and industrial facilities, they must endure years of high temperatures, humidity, and intense sunlight. Achieving such long-term durability on industrial textured silicon wafers, rather than on specialised laboratory surfaces, is essential for real-world manufacturing. Although vapour deposition has long been viewed as a scalable and industry-friendly approach, it had never successfully produced stable, high-quality perovskite layers on true industrial silicon with large textures. By accomplishing this for the first time, the NUS team has overcome a major manufacturing barrier and demonstrated the level of high-temperature stability needed for future commercial deployment.
"Achieving both high efficiency and long-term durability on industrial textured silicon is essential for tandems to become commercially viable," said Asst Prof Hou.
A new molecular strategy for balanced vapour adsorption
During vapour deposition, organic perovskite precursor molecules struggle to adsorb uniformly onto the steep pyramid textures that define industrial silicon wafers. This imbalance leads to poor film formation and rapid degradation under heat. To resolve this, the researchers designed a specialised molecule that binds to the silicon surface and enhances the adsorption of organic molecules during vapour deposition, allowing the perovskite film to grow smoothly with the correct chemical balance.
As a result, the vapour-deposited tandem devices displayed exceptional thermal endurance. They sustained stable operation for well over 1,000 hours under continuous illumination and maintained strong performance during extended exposure at 85 deg C, which is one of the most demanding ageing tests in the solar industry. Achieving such high-temperature stability in perovskite-based tandems is rare and even more significant given that it was realised on industrial textured wafers using a scalable manufacturing method.
"With vapour-deposited perovskites, we are addressing two fundamental challenges at one go: compatibility with real industrial silicon wafers and stable operation under heat," said Asst Prof Hou. "This is the first evidence of vapour-grown perovskite tandem cells achieving the required durability for commercial deployment, bringing us closer to practical and reliable tandem solar modules."
Next step
The NUS team will now work on scaling the vapour-deposition method from small solar cells to large-area modules and integrating the process into pilot manufacturing lines. "Our next phase is to demonstrate full-size, durable tandem modules under real operating conditions," said Asst Prof Hou. "This will bring us a step closer to commercial deployment."
