Abstract 

Self-assembled monolayers (SAMs) represent an effective strategy for the development of perovskite solar cells (PSCs). High-performance PSCs are typically fabricated in an inert atmosphere because ambient moisture disrupts phosphonic-acid SAMs on transparent conductive oxides, leading to surface inhomogeneity and direct exposure of the transparent conductive oxide. However, this dependence on glovebox fabrication constraints scalability and cost-effective manufacturing. Here we present a ternary self-assembled molecular contact comprising glycerol dimethacrylate and 1-acetylguanidine that serves as a process-tolerant hole-selective contact. Glycerol dimethacrylate acts as a cosolvent during SAM deposition to improve film uniformity and is subsequently transformed into a hydrophilic binary network upon mild thermal curing, firmly anchoring the SAM to the substrate, whereas 1-acetylguanidine is incorporated to further suppress interfacial defects. Wide-bandgap PSCs fabricated in ambient conditions achieve a power conversion efficiency of 21.20% (1.00 cm2), with an open-circuit voltage of 1.28 V. When implemented in monolithic perovskite/silicon tandems, cells achieve a power conversion efficiency of 31.72% (certified 31.36%) and 32.60% for fabrication in ambient and inert conditions, respectively. These findings demonstrate that our tailored hole-selective contact provides a robust and process-tolerant interfacial engineering approach for high-efficiency perovskite and tandem photovoltaics manufactured under ambient conditions.

UNIST, in collaboration with King Abdullah University of Science and Technology (KAUST), has developed a groundbreaking coating that unlocks large-scale, ambient-condition production of high-performance perovskite/silicon tandem solar cells.

Led by Distinguished Professor Sang Il Seok of the School of Energy and Chemical Engineering and Professor Kyoung Jin Choi of the Department of Materials Science and Engineering, the team engineered a three-component interface layer that ensures uniform coverage and reduces defects during fabrication. This innovation allows the production of tandem cells outside of costly, sealed environments—an essential step toward commercialization.

The resulting devices achieved a certified efficiency of 31.36%, with peak performance reaching 31.72%. Remarkably, they maintained over 92% of their initial efficiency after 600 hours in oxygen-rich, high-temperature conditions, and over 90% after 1,000 hours under continuous illumination—all without encapsulation.

This technology not only delivers record efficiencies but also simplifies manufacturing, drastically reducing costs and enabling large-area production in standard environments. It paves the way for affordable, high-efficiency solar solutions that can be deployed at scale.

The research team includes Gwisu Kim and Young Im Noh from UNIST, and Adi Prasetio from KAUST as first co-authors. The corresponding authors are Professors Sang Il Seok and Kyoung Jin Choi from UNIST, and Professor Stefaan De Wolf from KAUST. Contributions also came from researchers from the Chinese University of Hong Kong, Shenzhen (CUHKSZ) and Forschungszentrum Jülich GmbH (FZJ) in Germany. 

Professor Choi states, “Our findings align with the K-Moonshot Project, a national initiative focused on developing ultra-high-efficiency multi-junction solar cells, which brings us closer to realizing practical and affordable solar energy.” Professor Seok adds, “Demonstrating stability and high efficiency in open air indicates that the technology is ready for industrial-scale production.”

Published in Nature Photonics  on June 1, this breakthrough was supported by Hyundai Motor Company, the National Research Foundation of Korea (NRF), the Ministry of Science, and ICT (MSIT), the Korea Energy Technology Evaluation and Planning Agency (KETEP), and the Ministry of Trade, Industry and Energy (MOTIE).

Journal Reference

Gwisu Kim, Adi Prasetio, Young Im Noh,  et al.,  “Ternary self-assembled molecular contact for ambient-processed perovskite/silicon tandem solar cells,”  Nat. Photon. , (2026).