title: Pinhole-Free and Surface-Nanostructured NiOx Film by Room-Temperature Solution Process for High-Performance Flexible Perovskite Solar Cells with Good Stability and Reproducibility.
abstract: Recently, researchers have focused on the design of highly efficient flexible perovskite solar cells (PVSCs), which enables the implementation of portable and roll-to-roll fabrication in large scale. While NiOx is a promising material for hole transport layer (HTL) candidate for fabricating efficient PVSCs on a rigid substrate, the reported NiOx HTLs are formed using different multistep treatments (such as 300-500 °C annealing, O2-plasma, UVO, etc.), which hinders the development of flexible PVSCs based on NiOx. Meanwhile, the features of nanostructured morphology and flawless film quality are very important for the film to function as highly effective HTL of PVSCs. However, it is difficult to have the two features coexist natively, particularly in a solution process that flawless film will usually come with smooth morphology. Here, we demonstrate the flawless and surface-nanostructured NiOx film from a simple and controllable room-temperature solution process for achieving high performance flexible PVSCs with good stability and reproducibility. The power conversion efficiency (PCE) can reaches a promising value of 14.53% with no obvious hysteresis (and a high PCE of 17.60% for PVSC on ITO glass). Furthermore, the NiOx-based PVSCs show markedly improved air stability. Regarding the performance improvement, the flawless and surface-nanostructured NiOx film can make the interfacial recombination and monomolecular Shockley-Read-Hall recombination of PVSC reduce. In addition, the formation of an intimate junction of large interfacial area at NiOx film/the perovskite layer improve the hole extraction and thus PVSC performances. This work contributes to the evolution of flexible PVSCs with simple fabrication process and high device performances.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pok Fu Lam, Hong Kong SAR, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pok Fu Lam, Hong Kong SAR, China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Materials Science & Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Francis
authors.initials: F
authors.lastname: Lin
authors.affiliation: Department of Physics, The Hong Kong University of Science & Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
authors.forename: Hexiang
authors.initials: H
authors.lastname: He
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pok Fu Lam, Hong Kong SAR, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Mao
authors.affiliation: Department of Physics, The Hong Kong University of Science & Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
authors.forename: Kam Sing
authors.initials: KS
authors.lastname: Wong
authors.affiliation: Department of Materials Science & Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Alex K-Y
authors.initials: AK
authors.lastname: Jen
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong , Pok Fu Lam, Hong Kong SAR, China.
authors.forename: Wallace C H
authors.initials: WC
authors.lastname: Choy
keywords: NiOx nanostructure; flexible solar cells; hole transport layer; perovskite solar cells; room temperature