Year: 2026
Type: preprint
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.
Source: arXiv (Cornell University)
Authors: Chen, Lijun, Zhao, Sitong, Nigmetova, Gaukhar, Romero, David Garcia, Pitaro, Matteo, Lerda, Sofia, Mosconi, Edoardo, Aidi, Michael, van Netten, Douwe, Kraft, Julia, Li, Jiaxiong, Pinna, Jacopo, Serafimova, Asya, Grubišić-Čabo, Antonija, Protesescu, Loredana, Portale, Giuseppe, Rudolf, Petra, De Angelis, Filippo, Loi, Maria Antonietta
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223901543