title: Solution-Processible Crystalline NiO Nanoparticles for High-Performance Planar Perovskite Photovoltaic Cells.
abstract: In this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite photovoltaic (PV) cells, in which precrystallized NiO nanoparticles (NPs) without post-treatment are used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent perovskite photoactive layer. Compared to the conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (
  
  
  
  PSS) HTL, the NiO HTL had excellent energy-level alignment with that of CH3NH3PbI3 and improved electron-blocking capability, as analyzed by photoelectron spectroscopy and diode modeling, resulting in Voc ~0.13 V higher than conventional
  
  
  
  PSS-based devices. Consequently, a power conversion efficiency (PCE) of 15.4% with a high fill factor (FF, 0.74), short-circuit current density (Jsc, 20.2 mA·cm(-2)), and open circuit voltage (Voc, 1.04 V) having negligible hysteresis and superior air stability has been achieved.
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Uisik
authors.initials: U
authors.lastname: Kwon
authors.affiliation: Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Korea.
authors.forename: Bong-Gi
authors.initials: BG
authors.lastname: Kim
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Duc Cuong
authors.initials: DC
authors.lastname: Nguyen
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Jong-Hyeon
authors.initials: JH
authors.lastname: Park
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Na Young
authors.initials: NY
authors.lastname: Ha
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Seung-Joo
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Korea.
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Ko
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.
authors.forename: Soonil
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Gachon University, Seongnam 13120, Korea.
authors.forename: Daeho
authors.initials: D
authors.lastname: Lee
authors.affiliation: Division of Energy Systems Research, Ajou University, Suwon 16499, Korea.|Department of Electrical and Computer Engineering, Ajou University, Suwon 16499, Korea.
authors.forename: Hui Joon
authors.initials: HJ
authors.lastname: Park