Novel Fluorinated Dithienothiophene-Based Self-Assembled Monolayers as Hole-Selective Contacts for Mixed Tin–Lead Perovskite Solar Cells

Min Hsuan Tsai^a

^aDepartment of Chemical Engineering, National Chung Hsing University, Taichung, Taiwan

NIPHO26
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO26)

Pavia, Italy, 2026 June 8th - 9th

Organizers: Giulia Grancini, Feng Gao and Robert Hoye

Poster, Min Hsuan Tsai, 031
Publication date: 22nd April 2026

Mixed Tin-lead (Sn–Pb) perovskite are strong candidates for the narrow-bandgap sub-cell in all-perovskite tandems, but Sn²⁺ oxidation and poor buried-interface quality remain major obstacles.¹ Conventional SAMs such as 2PACz and MeO-2PACz were not designed for the mixed Sn²⁺/Pb²⁺ surface, leaving a mismatch in both energy alignment and passivation.² Here we introduce dithienothiophene (DTT)-based SAMs ’’ CHL-2, CHL-2-oF, and CHL-2-mF ’’carrying a fused DTT core, methoxytriphenylamine donors, and dual carboxylic acid anchors.³ DFT calculations show that fluorine at the meta-position makes the molecule a better match for the Sn²⁺/Pb²⁺ sites on the perovskite surface, and MD simulations confirm that CHL-2-mF binds more strongly to both the Sn–Pb perovskite and ITO than the other two SAMs.⁴ Films grown on fluorinated SAMs show larger crystalline domains and more uniform PL quenching across the active area.⁵ CHL-2-mF devices outperform both reference SAMs in V_OC, fill factor, and PCE, with consistent results. These findings show that tuning the fluorine position on a DTT scaffold is an effective route to better buried interfaces in narrow-bandgap perovskite solar cells.

References:

[1] F. M. Rombach, A. Dasgupta, M. Kober-Czerny, H. Jin, J. M. Ball, J. A. Smith, M. D. Farrar and H. J. Snaith, Nature Communications 2025 16:1, 2025, 16, 5450-.

[2] Z. Zhang, R. Zhu, Y. Tang, Z. Su, S. Hu, X. Zhang, J. Zhang, J. Zhao, Y. Xue, X. Gao, G. Li, J. Pascual, A. Abate and M. Li, Advanced Materials, 2024, 36, 2312264.

[3] A. Al-Ashouri, E. Köhnen, B. Li, A. Magomedov, H. Hempel, P. Caprioglio, J. A. Márquez, A. B. M. Vilches, E. Kasparavicius, J. A. Smith, N. Phung, D. Menzel, M. Grischek, L. Kegelmann, D. Skroblin, C. Gollwitzer, T. Malinauskas, M. Jošt, G. Matič, B. Rech, R. Schlatmann, M. Topič, L. Korte, A. Abate, B. Stannowski, D. Neher, M. Stolterfoht, T. Unold, V. Getautis and S. Albrecht, Science (1979)., 2020, 370, 1300–1309.

[4] H. Tang, Z. Shen, Y. Shen, G. Yan, Y. Wang, Q. Han and L. Han, Science (1979)., 2024, 383, 1236–1240.

[5] D. Li, Q. Lian, T. Du, R. Ma, H. Liu, Q. Liang, Y. Han, G. Mi, O. Peng, G. Zhang, W. Peng, B. Xu, X. Lu, K. Liu, J. Yin, Z. Ren, G. Li and C. Cheng, Nature Communications 2024 15:1, 2024, 15, 7605-.

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.