title: High-performance hole-extraction layer of sol-gel-processed NiO nanocrystals for inverted planar perovskite solar cells.
abstract: Hybrid organic/inorganic perovskite solar cells have been rapidly evolving with spectacular successes in both nanostructured and thin-film versions. Herein, we report the use of a simple sol-gel-processed NiO nanocrystal (NC) layer as the hole-transport layer in an inverted perovskite solar cell. The thin NiO NC film with a faceted and corrugated surface enabled the formation of a continuous and compact layer of well-crystallized CH3 NH3 PbI3 in a two-step solution process. The hole-extraction and -transport capabilities of this film interfaced with the CH3 NH3 PbI3 film were higher than those of organic PEDOT:PSS layers. The cell with a NiO NC film with a thickness of 30-40 nm exhibited the best performance, as a thinner layer led to a higher leakage current, whereas a thicker layer resulted in a higher series resistance. With the NiO film, we observed a cell efficiency of 9.11 %, which is by far the highest reported for planar perovskite solar cells based on an inorganic hole-extracting layer.
authors.affiliation: Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Department of Chemistry, The Hong Kong University of Science and Technology.
authors.forename: Zonglong
authors.initials: Z
authors.lastname: Zhu
authors.forename: Yang
authors.initials: Y
authors.lastname: Bai
authors.forename: Teng
authors.initials: T
authors.lastname: Zhang
authors.forename: Zhike
authors.initials: Z
authors.lastname: Liu
authors.forename: Xia
authors.initials: X
authors.lastname: Long
authors.forename: Zhanhua
authors.initials: Z
authors.lastname: Wei
authors.forename: Zilong
authors.initials: Z
authors.lastname: Wang
authors.forename: Lixia
authors.initials: L
authors.lastname: Zhang
authors.forename: Jiannong
authors.initials: J
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Yan
authors.forename: Shihe
authors.initials: S
authors.lastname: Yang
keywords: NiO nanocrystals; energy conversion; inorganic hole-extraction layers; organic-inorganic hybrid composites; perovskite solar cells