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arXiv · 2610.34293

Controlling Surface Chemistry in Tin-Lead Perovskites for High-Efficiency Solar Cells

Lijun Chen·Sitong Zhao·Gaukhar Nigmetova·David Garcia Romero·Matteo Pitaro·Sofia Lerda·Edoardo Mosconi·Michael Aidi·Douwe van Netten·Julia Kraft·Jiaxiong Li·Jacopo Pinna·Asya Serafimova·Antonija Grubišić-Čabo·Loredana Protesescu·Giuseppe Portale·Petra Rudolf·Filippo De Angelis·Maria Antonietta Loi
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Abstract

Interfacial nonradiative recombination limits tin-lead perovskite photovoltaics. Here we show that neutral ethylenediamine chelates undercoordinated metals at tin-rich surfaces, weakens metal-iodide bonds, and removes excess tin, reconstructing the surface towards a stoichiometric tin-to-lead ratio. In contrast, protonated ethylenediammonium iodide initially passivates undercoordinated metal sites before undergoing defect-assisted deprotonation. Atomistic simulations reveal that subsurface iodide vacancies promote iodide migration and lower the energetic cost of deprotonation. Ethylenediamine-induced reconstruction produces stronger n-type surface character, facilitates electron extraction into C60, and suppresses interfacial nonradiative recombination, enabling methylammonium-free solar cells with a power conversion efficiency of 25.86%. Together, these distinct surface reaction pathways and the defect-assisted evolution of the passivating species underscore the importance of understanding perovskite surface chemistry for the rational design of molecular passivation strategies.

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Lijun Chen, Sitong Zhao, Gaukhar Nigmetova, David Garcia Romero, Matteo Pitaro, Sofia Lerda, Edoardo Mosconi, Michael Aidi, Douwe van Netten, Julia Kraft, Jiaxiong Li, Jacopo Pinna, Asya Serafimova, Antonija Grubišić-Čabo, Loredana Protesescu, Giuseppe Portale, Petra Rudolf, Filippo De Angelis, Maria Antonietta Loi. 2026-10-25. Controlling Surface Chemistry in Tin-Lead Perovskites for High-Efficiency Solar Cells. https://arxiv.org/abs/2610.34293

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