Korean researchers have shattered efficiency records for flexible solar cells, potentially revolutionizing how we integrate renewable energy into curved surfaces from car roofs to building facades.
The team from the Korea Institute of Energy Research (KIER) achieved a power conversion efficiency of 23.64% with their ultra-lightweight flexible solar cells — the highest ever recorded for this particular technology. These cells combine perovskite and copper-indium-gallium-selenide (CIGS) in a tandem configuration that’s not only bendable but maintains 97.7% of its efficiency even after 100,000 bending cycles.
Traditional silicon-based solar panels dominate today’s market, but their rigid, heavy structure limits where they can be installed. The new technology addresses this limitation by offering a power-to-weight ratio approximately 10 times higher than existing alternatives.
“This research is a key achievement that demonstrates the commercial potential of next-generation high-efficiency solar cell technology with flexibility and lightness,” said Dr. Inyoung Jeong, who led the study published in the March issue of Joule.
The breakthrough hinged on a novel manufacturing approach. Rather than building directly on flexible materials, which can create inconsistencies, the team developed what they call a “lift-off process.” This involves coating glass with a polyimide layer, building the solar cell on this stable foundation, and then separating the completed cell from the glass.
This technique solved a persistent problem in solar cell manufacturing. During traditional fabrication, alkali metals like potassium diffuse from glass substrates into the light-absorbing CIGS layer, creating defects that reduce efficiency. The research team discovered that their polyimide layer acts as a barrier, controlling this diffusion to optimal levels.
The technology arrives at a critical juncture for solar development. Single-junction solar cells are approaching their theoretical efficiency limits, pushing researchers toward tandem designs that stack different materials to capture more of the solar spectrum. While perovskite/silicon tandems have already reached efficiencies of 34.6%, they lack the flexibility needed for many potential applications.
Industry analysts note that the market for lightweight, flexible solar panels is expanding rapidly, particularly for electric vehicles where weight directly impacts range. Building-integrated photovoltaics represent another growing sector where conventional rigid panels are often impractical.
Dr. Kihwan Kim, principal investigator of the study, highlighted the technology’s versatility. “The power-to-weight ratio of the fabricated solar cell is approximately 10 times higher than that of perovskite/silicon tandem solar cells, making it highly promising for applications in fields that require ultralight solar modules, such as building exteriors, vehicles, and aerospace.”
The certified power conversion efficiency of 22.8% translates to an impressive power-per-weight of 6.15 W/g, dramatically outperforming perovskite/silicon tandem cells (0.65 W/g).
The study was conducted with support from the Research and Development Program of KIER, in collaboration with Professor Tae Kyung Lee of Gyeongsang National University and Professor Hae-Jin Kim of Yonsei University.
While the technology shows immense promise, challenges remain before commercial deployment. The team is now focused on scaling up the manufacturing process and further improving stability — critical steps before we see these flexible solar cells adorning vehicles, satellites, or building facades.
Dr. Kim expressed optimism about the technology’s future: “By advancing large-area fabrication processes and improving stability, we aim to strengthen the competitiveness of related industries and significantly contribute to the expansion of renewable energy adoption.”
With global demand for clean energy solutions accelerating, innovations that make solar power more adaptable to our existing infrastructure could play a crucial role in the renewable transition. These ultra-lightweight, flexible solar cells might soon be bending not just themselves, but our expectations of where and how we can harness the sun’s energy.
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