Asymmetric Molecular Templating for Tailoring Interfacial Order in Scalable Inverted Perovskite Solar Cells

Taeyoon Ki^a^,^b, Jong-Guk Ahn^c, Sangcho Kim^b, Sangjin Kim^d, Min-ho Lee^e, In-wook Hwang^f, Jinju Jeong^g, Soobin Shim^h, Jaeboong Ahn^d, Jun Hong Park^h, Seungjin Lee^g, Jung-Yong Lee^e, Yousoo Kim^d, Ju-Hyeon Kim^j, Hongkyu Kang^b, Sukwon Hong^d, Kwanghee Lee^a^,^b

^aHeeger Center for Advanced Materials (HCAM), Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea

^bResearch Institute of Solar and Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea

^cCenter for Quantum Conversion Research (QCR), Institute for Basic Science (IBS), Gwangju 61005, Republic of Korea

^dDepartment of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea

^eSchool of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 34141 Daejeon, Republic of Korea

^fAdvanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.

^gDepartment of Energy Engineering, KI for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH)

^hDepartment of Materials Engineering and Convergence Technology, Gyeongsang National University (GNU), Republic of Korea

ⁱSurface and Interface Science Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

^jDepartment of Chemistry, The University of Tokyo, Tokyo 118-8656, Japan

^kDepartment of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Oral, Taeyoon Ki, presentation 021
Publication date: 11th March 2026

Interfacial disorder at the perovskite/C₆₀ contact represents a critical bottleneck for the scalability and operational stability of inverted perovskite solar cells because it induces spatially nonuniform electron extraction over large areas. While two-dimensional (2D) capping layers are widely employed for passivation, conventional symmetric spacer cations (e.g., Phenethylammonium cation) often fail to provide sufficient orientational control, resulting in poorly aligned layers that impede vertical charge transport. This work introduces a coherent molecular templating strategy utilizing an asymmetric spacer cation, which effectively suppresses unfavorable herringbone-type packing and promotes a preferential lamellar orientation at the perovskite surface. High-resolution transmission electron microscopy confirms that this interfacial order propagates through the perovskite/2D/C₆₀ organic heterojunction, guiding C₆₀ crystallization into a continuous network and enabling uniform electron extraction. Consequently, devices incorporating the asymmetric cation deliver certified power conversion efficiencies of 26.94% for small-area cells and 24.23% for 25-cm² modules (certified 23.21%), demonstrating significantly reduced cell-to-module losses. Furthermore, the templated interface enhances durability, maintaining over 93% of initial efficiency after 1,000 hours at 85 °C and achieving an operational T₈₀ exceeding 2,500 hours under continuous 1-sun illumination. These findings establish coherent molecular templating as a robust principle to integrate interfacial passivation with oriented charge-transport pathways for scalable optoelectronics.

Acknowledgements:

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT of the Republic of Korea (MSIT) (No. RS-2025-00514103). This work was also supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. RS-2024-00457537).

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