title: Graphene frameworks promoted electron transport in quantum dot-sensitized solar cells.
abstract: Graphene frameworks (GFs) were incorporated into TiO2 photoanode as electron transport medium to improve the photovoltaic performance of quantum dot-sensitized solar cells (QDSSCs) for their excellent conductivity and isotropic framework structure that could permit rapid charge transport. Intensity modulated photocurrent/photovoltage spectroscopy and electrochemical impedance spectroscopy results show that the electron transport time (τ(d)) of 1.5 wt % GFs/TiO2 electrode is one-fifth of that of the TiO2 electrode, and electron lifetime (τ(n)) and diffusion path length (Ln) are thrice those of the TiO2 electrode. Results also revealed that the GFs/TiO2 electrode has a shorter electron transport time (τ(d)), as well as longer electron lifetime (τ(n)) and diffusion path length (Ln), than conventional 2D graphene sheets/TiO2 electrode, thus indicating that GFs could promote rapid electron transfer in TiO2 photoanodes. Photocurrent-voltage curves demonstrated that when incorporating 1.5 wt % GFs into TiO2 photoanode, a maximum power conversion efficiency of 4.2% for QDSSCs could be achieved. This value was higher than that of TiO2 photoanode and 2D graphene sheets/TiO2 electrode. In addition, the reasons behind the sensitivity of photoelectric conversion efficiency to the graphene concentration in the TiO2 were also systematically investigated. Our results provide a basic understanding of how GFs can efficiently promote electron transport in TiO2-based solar cells.
authors: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences , Taoyuan South Road 27, Taiyuan, 030001 China.
authors: Yanyan
authors: Y
authors: Zhu
authors: Xin
authors: X
authors: Meng
authors: Huijuan
authors: H
authors: Cui
authors: Suping
authors: S
authors: Jia
authors: Jianhui
authors: J
authors: Dong
authors: Jianfeng
authors: J
authors: Zheng
authors: Jianghong
authors: J
authors: Zhao
authors: Zhijian
authors: Z
authors: Wang
authors: Li
authors: L
authors: Li
authors: Li
authors: L
authors: Zhang
authors: Zhenping
authors: Z
authors: Zhu