Researchers at Hebei University of Technology, Jiaxing Daze Photoenergy Co., Jiaxing Nanhu University, Taizhou University, Chimie ParisTech (CNRS, PSL Research University, France), Tianjin University, Harbin Institute of Technology (Shenzhen), Nankai University, and the National University of Defense Technology, have developed a molecular additive strategy that boosts inverted perovskite solar cells to a certified stabilized efficiency of 27.10% (peak 27.39%) while enabling large-area bifacial modules that exceed 22% efficiency on both sides and retain 99.6% of their output after 5,000 hours of continuous illumination.
Perovskite solar cells are now efficient enough that remaining performance losses are governed less by light harvesting and more by small defects that form during rapid film crystallization and concentrate at surfaces, grain boundaries, and buried interfaces. Molecular additives are a common way to passivate these defects, but the field has run into a persistent trade-off: molecules that bind strongly to defects can also pack too densely or create insulating interfacial layers that block charge transport, while additives designed for easy charge transport often bind too weakly to be effective passivators.
The team's approach, which they call steric-gated dual-site chelation, is built around a molecule named 2,2′-(adamantane-1,3-diyl)diacetic acid (ADA-DA), which combines two carboxymethyl binding groups with a rigid three-dimensional adamantane scaffold. The two binding sites allow ADA-DA to chelate strongly to undercoordinated lead defects, while the bulky adamantane cage regulates how densely the molecules pack at the interface, preventing the transport-blocking layers that can result from simpler, single-site or flat aromatic additives. Compared with a monocarboxylate analog (ADA-MA) and a planar aromatic diacid (PH-DA) tested alongside it, ADA-DA showed the strongest binding to undercoordinated lead centers in the researchers' modeling and interfacial analysis, consistent with more effective defect saturation through bidentate chelation.
Incorporated directly into the perovskite precursor and processed via vacuum-flash crystallization, ADA-DA produced films with more compact microstructure and reduced defect signatures, homogenized surface potential, suppressed non-radiative recombination, and a higher barrier against ion migration relative to devices made without it. The researchers translated the film-level improvements directly into device and module performance: small-area inverted solar cells reached the certified 27.10% stabilized efficiency, and the same molecular strategy scaled successfully to large-area bifacial modules, which exceeded 22% efficiency from both sides while showing minimal degradation, retaining 99.6% of their initial power output over 5,000 hours of continuous operation under maximum power point tracking.
The authors position steric-gated dual-site chelation as a generalizable molecular design principle, one that treats binding multiplicity and steric bulk as parameters to be engineered together rather than optimized separately, offering a route to simultaneously improve efficiency, device-to-device reproducibility, and long-term operational stability in scalable perovskite photovoltaics, including bifacial architectures relevant to building-integrated applications.
