Issue 8, 2024

Defect-less formamidinium Sn–Pb perovskite grown on a fluorinated substrate with top-down crystallization control for efficient and stable photovoltaics

Abstract

Ideal bandgap formamidinium tin–lead perovskites (FASn0.5Pb0.5I3) are appealing for fabricating thermally stable single-junction and tandem perovskite photovoltaics. However, attempts to obtain high device efficiency are limited to the preparation of defect-less perovskite films. Herein, we propose a trifluoroacetamide (TFOA)-modified NiOx hole-transport layer (HTL) as a substrate for growing the FASn0.5Pb0.5I3 film, where TFOA molecules interact with both NiOx and perovskite layers, resulting in a less stressed, more intimate, and energetically favorable bottom contact. Besides, the thermo-driven iodide migration in the perovskite film is also suppressed. Furthermore, dual-function formylhydrazide vapor (FHV) treatment was applied during the annealing process, which not only offers a reducing atmosphere to prevent Sn2+ oxidation but also helps to achieve top-down crystallization control in the presence Lewis basic formamide groups, leading to the formation of a homogeneous perovskite film with closely packed large grains and reduced defects. Ultimately, an optimal efficiency of 21.12% with a nearly 80% fill factor (FF) was achieved for the TFOA-FHV co-treated device, which is currently the highest one for FA-based tin–lead perovskite solar cells (PSCs) in NiOx HTL systems. Moreover, the stability of unencapsulated devices also showed significant improvements under various test scenarios.

Graphical abstract: Defect-less formamidinium Sn–Pb perovskite grown on a fluorinated substrate with top-down crystallization control for efficient and stable photovoltaics

Supplementary files

Article information

Article type
Paper
Submitted
14 Dec 2023
Accepted
12 Mar 2024
First published
12 Mar 2024

Energy Environ. Sci., 2024,17, 2845-2855

Defect-less formamidinium Sn–Pb perovskite grown on a fluorinated substrate with top-down crystallization control for efficient and stable photovoltaics

Y. Zhou, T. Guo, J. Jin, Z. Zhu, Y. Li, S. Wang, S. Zhou, Q. Lin, J. Li, W. Ke, G. Fang, X. Zhang and Q. Tai, Energy Environ. Sci., 2024, 17, 2845 DOI: 10.1039/D3EE04343F

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