title: Mesoporous SnO₂ single crystals as an effective electron collector for perovskite solar cells.
abstract: Mesoporous single crystals are prized for their fast electron transport and high surface area. Here we report the first synthesis of mesoporous SnO2 single crystals (SnO2 MSCs) by a simple silica-templated hydrothermal method, and its application in solution-processed perovskite solar cells (PSCs). A relatively low efficiency (3.76%) was obtained due to the strong charge recombination at the SnO2/perovskite interface. However, by coating a thin TiO2 barrier layer on SnO2via TiCl4 treatment, we were able to achieve an 8.54% power conversion efficiency (PCE). A dynamics study using impedance spectroscopy revealed a much lower transport resistance for the SnO2 MSC-based solar cells than for the TiO2 nanocrystal PSCs, but a stronger recombination. Significantly, the thin TiO2 coating layer on SnO2 considerably reduced the recombination while largely maintaining the superior electron-transport properties.
authors.affiliation: Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. chsyang@ust.hk.
authors.forename: Zonglong
authors.initials: Z
authors.lastname: Zhu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zheng
authors.forename: Yang
authors.initials: Y
authors.lastname: Bai
authors.forename: Teng
authors.initials: T
authors.lastname: Zhang
authors.forename: Zilong
authors.initials: Z
authors.lastname: Wang
authors.forename: Shuang
authors.initials: S
authors.lastname: Xiao
authors.forename: Shihe
authors.initials: S
authors.lastname: Yang