Interface and Process Engineering of Scalable FIRA-Processed Perovskite Solar Cells via Cascade Self-Assembled Monolayers

Byung Gi Kim^a^,^b, Sandy Sanchez Alonso^a, Michael Graetzel^b

^aLaboratory of Photonics and Interfaces (LPI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

^bOrganic Nanomaterials Laboratory (ONML), School of Integrative Engineering, Chung-Ang University, Seoul 06974, Republic of Korea

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

A1 Beyond Efficiency: Perovskite Optoelectronics for Scalable and Stable Devices

Palma, Spain, 2026 October 26th - 30th

Organizers: Guixiang Li and Silver-Hamill Turren-Cruz

Oral, Byung Gi Kim, presentation 332
Publication date: 22nd July 2026

Inverted p-i-n perovskite solar cells (PSCs) have emerged as highly promising architectures since their inception [1]. However, obtaining highly reproducible and uniform perovskite films over hydrophobic self-assembled monolayers (SAMs) remains a critical bottleneck [2]. While molecular design strategies like amorphous self-assembled multilayers have been proposed to mitigate interfacial degradation [3], scalable alternatives to conventional anti-solvent quenching are urgently required. This work introduces an optimized Flexible Infrared-Assisted (FIRA) crystallization methodology combined with a sol-gel derived NiOx / Cascade SAM hole transport layer (HTL) [4]. To address the severe dewetting of the perovskite solution, we utilize a sequential hybrid SAM configuration (MeO-2PACz/V-1779) in conjunction with 1,6-hexylenediphosphonic acid (6dPA) to achieve dual-site interfacial passivation and enhanced surface wettability [5, 6]. Our investigations reveal that the duration of the vacuum pre-step is a key parameter regulating crystallization kinetics [7]. Precise tuning of the sol-gel chemistry and metal oxide interfaces [8, 9] enables the optimization of carrier transport. Specifically, increasing the vacuum pre-step from 40 to 60 seconds dramatically suppresses the photoinactive yellow delta-phase network at the grain boundaries from 7.3% to 2.5%, as quantified by Optical Microscopy (OM) morphology analysis. This suppression eliminates shunt pathways and reduces the dark leakage current, which is critical for both photovoltaic and photodetector performances [10]. Consequently, the optimized FIRA-PSC achieved a champion power conversion efficiency (PCE) of 17.1% (Voc = 1.07 V, FF = 67%) on a diluted NiOx stack, showcasing a viable pathway for high-throughput, solvent-green manufacture of highly stable perovskite optoelectronics.

References:

[1] Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050–6051.

[2] Marčinskas, M.; Kasparavičius, E.; Al-Ashouri, A.; KTU; HZB. Wettability Improvement of a Carbazole-Based Hole-Selective Monolayer for Reproducible Perovskite Solar Cells. ACS Energy Lett. 2023, 8, 1060–1061.

[3] Feng, Q.; Liu, K.-K.; Wang, D.; Yuan, S.; Su, Z.; Lou, Z.; Lou, Z.; Ziwei, L.; Kalasariya, N.; Jiang, W.; Wu, X.; Jen, A. K.-Y. Amorphous self-assembled multilayers for perovskite solar cells with improved reverse bias stability. Nature Energy 2026, 11, 412–424.

[4] Chae, G. Y.; Kim, B. G.; Lim, J.; Kim, J. Y.; Jeong, J. H.; Ha, D. H.; Wang, D. H. Synergistic Dual Engineering of NiOx via Ethylenediamine Chelation and Gamma-Ray Irradiation for Enhanced Interfacial Transport in Perovskite Solar Cells. Small Methods 2026, 10, e70628.

[5] Ha, D. H.; Kim, B. G.; Jeong, J. H.; Chae, G. Y.; Jang, W.; Wang, D. H. Multi-Bridged Lewis-Functionalized Self-Assembled Monolayers for Enhanced Interfacial Affinity in Perovskite Photoelectric Sensors. ChemSusChem 2025, 18, e202500061.

[6] Kim, B. G.; Goda, E. S.; Kim, J. Y.; Ha, D. H.; Chae, G. Y.; Wang, D. H. Preferential crystallographic orientation via alpha-CN stereo-directional effect for superior perovskite indoor photodetectors. J. Mater. Chem. C 2025, 13, 12000–12009.

[7] Ha, D. H.; Lim, J. H.; Kim, J. Y.; Chae, G. Y.; Lee, Y. M.; Kim, M. S.; Kim, B. G.; Wang, D. H. Sequential Hybrid Self-Assembled Monolayers Enabling Uniform Coverage and Efficient Hole Extraction in Perovskite Photoelectronics. SSRN Preprint 2026.

[8] Kim, B. G.; Jang, W.; Park, Y. J.; Kang, J. H.; Seo, J. H.; Wang, D. H. Chelating Agent Mediated Sol-Gel Synthesis for Efficient Hole Extracted Perovskite Photovoltaics. J. Phys. Chem. C 2020, 124, 25184–25195.

[9] Kim, B. G.; Jang, W.; Wang, D. H. Facile NiOx Sol-Gel Synthesis Depending on Chain Length of Various Solvents without Catalyst for Efficient Hole Charge Transfer in Perovskite Solar Cells. Polymers 2018, 10, 1227.

[10] Yang, Z.; Kim, B. G.; Lim, J.; Wang, D. H. Long-term noninvasive cardiac monitoring via Neutralized interfacial design for noise-suppressed near-infrared organic photodetectors. Appl. Surf. Sci. 2025, 682, 161488.

Acknowledgements:

Byung Gi Kim gratefully acknowledges the financial support from the Swiss Government Excellence Scholarships for the postdoctoral research fellowship at EPFL. This work was also supported by the HEFAFLEX Project funding.

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