@article{296ce2cf407a43048ba7a6d2b12a0d5a,
title = "A Cytop Insulating Tunneling Layer for Efficient Perovskite Solar Cells",
abstract = "Improvement of the interface between the perovskite layer and the electron-transport layer (ETL) is critical toward the advancement of planar perovskite solar cells (PSCs). It is important to obtain a uniform and pinhole-free ETL that can minimize film defects and thus undesirable electron–hole recombination between the perovskite layer and cathode. However, this is extremely difficult because the rough perovskite surface causes charge–carrier recombination, facilitates large leakage currents, and inevitably deteriorates the electron-extraction efficiency. Here, fluorine-containing insulating polymers, poly(perfluorobutenylvinylether) (Cytop), are used as the tunneling layer in planar PSCs for the first time, resulting in a significant improvement in the power conversion efficiency (PCE) from 11.9% to over 14.5%. It is found that the Cytop layer not only fills the pinholes of the perovskite surface to decrease the trap concentration, but can also provide a strong electron-extraction ability to facilitate charge-transfer process and restrict charge recombination. In addition, improved water resistance is demonstrated using Cytop, which significantly extends the PSC lifetime (78% of initial PCE vs 22% for control after 1500 h) and increases the practical applicability.",
keywords = "Cytop, electron extraction, insulating polymers, perovskites, tunneling layers",
author = "Yifan Zheng and Wei Shi and Jaemin Kong and Di Huang and Katz, {Howard E.} and Junsheng Yu and Taylor, {Andr{\'e} D.}",
note = "Funding Information: This research was funded by the National Natural Science Foundation of China (NSFC) (Grant No. 61675041) and the Foundation for Innovation Research Groups of the NSFC (Grant No. 61421002). The authors gratefully acknowledge the National Science Foundation NSF‐PECASE award (CBET‐0954985) and the China Scholarship Council (No. 201506070069) for partial support of this work. The Yale Institute for Nanoscience and Quantum Engineering (YINQE), Yale West Campus Materials Characterization Core, and NSF MRSECDMR 1119826 (CRISP) provided facility support. The authors also thank the assistance of Dr. Min Li (Yale West Campus Materials Characterization Core) for the XPS and UPS measurement. Mechanistic analysis by Katz of the Cytop activity in promoting charge separation was supported by the Department of Energy, Office of Basic Energy Sciences (Grant No. DE‐FG02‐07ER46465). Funding Information: This research was funded by the National Natural Science Foundation of China (NSFC) (Grant No. 61675041) and the Foundation for Innovation Research Groups of the NSFC (Grant No. 61421002). The authors gratefully acknowledge the National Science Foundation NSF-PECASE award (CBET-0954985) and the China Scholarship Council (No. 201506070069) for partial support of this work. The Yale Institute for Nanoscience and Quantum Engineering (YINQE), Yale West Campus Materials Characterization Core, and NSF MRSECDMR 1119826 (CRISP) provided facility support. The authors also thank the assistance of Dr. Min Li (Yale West Campus Materials Characterization Core) for the XPS and UPS measurement. Mechanistic analysis by Katz of the Cytop activity in promoting charge separation was supported by the Department of Energy, Office of Basic Energy Sciences (Grant No. DE-FG02-07ER46465). Publisher Copyright: {\textcopyright} 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim",
year = "2017",
month = oct,
day = "16",
doi = "10.1002/smtd.201700244",
language = "English (US)",
volume = "1",
journal = "Small Methods",
issn = "2366-9608",
publisher = "John Wiley and Sons Ltd",
number = "10",
}