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Flexible perovskite/CIGS tandem solar cells developed using the antisolvent-seeding approach. Credit: NIMTE
A breakthrough by Chinese scientists has pushed flexible solar technology forward by solving a major design challenge: bonding smooth perovskite layers to rougher CIGS substrates.
Their new technique uses smart solvent manipulation and a seeded layer to improve adhesion, efficiency, and durability. The result is a flexible tandem solar cell that rivals rigid models in power output, and it can bend thousands of times without losing much performance. This could be the turning point in making ultra-efficient, lightweight solar cells ready for real-world use.
Boosting Solar Cell Efficiency with Better Adhesion
Chinese researchers have developed a method to make flexible tandem solar cells more efficient and durable by improving the way the top and bottom layers stick together.
At the core of this design is copper indium gallium selenide (CIGS), a widely used semiconductor known for its tunable bandgap, strong light absorption, low sensitivity to temperature changes, and excellent long-term stability. These properties make CIGS an ideal material for the bottom layer of next-generation tandem solar cells.
In flexible tandem solar cells, a top layer of perovskite, an efficient light-absorbing material, is paired with a CIGS bottom layer. This combination offers great potential for lightweight, high-performance solar panels. However, the rough texture of the CIGS layer makes it difficult to deposit high-quality perovskite films on top, creating a key obstacle to commercial development.
A Clever Strategy to Improve Layer Bonding
In a study published today (April 18) in Nature Energy, a research group led by Prof. Jichun Ye from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences has developed an innovative antisolvent-seeding strategy to enhance the performance of perovskite top cells on rough surfaces.
Scientists separated the processes of self-assembled monolayer (SAM) adsorption and dissolution while simultaneously integrating perovskite seeding. They utilized a high-polarity solvent to prevent SAM clustering during dissolution, while a low-polarity solvent acted as an antisolvent to promote the formation of a dense SAM during adsorption. Additionally, a pre-mixed seed layer improved the wettability and crystallinity of the perovskite, ensuring strong adhesion to the substrate.
Breaking Records in Flexible Solar Cell Efficiency
With these innovations, the team fabricated a 1.09 cm² flexible monolithic perovskite/CIGS tandem solar cell. Competing with top rigid counterparts, the device achieved an impressive stabilized efficiency of 24.6% (certified at 23.8%), one of the highest reported values for flexible thin-film solar cells to date.
After 320 hours of operation and 3,000 bending cycles at a radius of 1 cm, the device retained over 90% of its initial efficiency, demonstrating exceptional mechanical durability and long-term stability.
A Leap Toward Commercial Solar Breakthroughs
This achievement paves the way for developing cost-effective, high-performance flexible tandem solar cells, advancing the commercial application of tandem solar cell technology.
Reference: 18 April 2025, Nature Energy.
DOI: 10.1038/s41560-025-01760-6
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