Cation and anion immobilization through chemical bonding enhancement with fluorides for stable halide perovskite solar cells

TitleCation and anion immobilization through chemical bonding enhancement with fluorides for stable halide perovskite solar cells
Publication TypeJournal Article
Year of Publication2019
AuthorsN.X Li, S.X Tao, Y. Chen, X.X Niu, C.K Onwudinanti, C. Hu, Z.W Qiu, Z. Xu, G. Zheng, L.G Wang, Y. Zhang, L. Li, H. Liu, Y.Z Lun, J.W Hong, X.Y Wang, Y.Q Liu, H.P Xie, Y.L Gao, Y. Bai, S.H Yang, G. Brocks, Q. Chen, H.P Zhou
JournalNature Energy
Volume4
Issue5
Pagination408-415
Date Published5/2019
Abstract

Defects play an important role in the degradation processes of hybrid halide perovskite absorbers, impeding their application for solar cells. Among all defects, halide anion and organic cation vacancies are ubiquitous, promoting ion diffusion and leading to thin-film decomposition at surfaces and grain boundaries. Here, we employ fluoride to simultaneously passivate both anion and cation vacancies, by taking advantage of the extremely high electronegativity of fluoride. We obtain a power conversion efficiency of 21.46% (and a certified 21.3%-efficient cell) in a device based on the caesium, methylammonium (MA) and formamidinium (FA) triple-cation perovskite (Cs0.05FA0.54MA0.41)Pb(I0.98Br0.02)3 treated with sodium fluoride. The device retains 90% of its original power conversion efficiency after 1,000?h of operation at the maximum power point. With the help of first-principles density functional theory calculations, we argue that the fluoride ions suppress the formation of halide anion and organic cation vacancies, through a unique strengthening of the chemical bonds with the surrounding lead and organic cations.

DOI10.1038/s41560-019-0382-6
Division

PSI

Department

PMI

PID

50d6fa95cf3a96c0d0b5553f8cbeb6f4

Alternate TitleNat. Energy

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