title: Ultrafast ion migration in hybrid perovskite polycrystalline thin films under light and suppression in single crystals.
abstract: Understanding the influence of light on ion migration in organic-inorganic halide perovskite (OIHP) materials is important to understand the photostability of perovskite solar cells. We reveal that light could greatly reduce the ion migration energy barrier in both polycrystalline and single crystalline OIHP. The activation energies derived from conductivity measurement under 0.25 Sun decrease to less than one half of the values in the dark. A typical ion drift velocity in CH3NH3PbI3polycrystalline films is 1.2 μm s-1under 1 Sun, compared with 0.016 μm s-1under 0.02 Sun. Ion migration across the photoactive layers in most OIHP devices thus takes only subseconds under 1 Sun illumination, which is much shorter than what it was thought to take. Most important of all, ion migration through a single crystal surface is still too slow to be observed even after illumination for two days due to the large ion diffusion activation energy, >0.38 eV.
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu and School of Science, China University of Geosciences, Beijing, 100083, P. R. China.
authors: Jie
authors: J
authors: Xing
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu.
authors: Qi
authors: Q
authors: Wang
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu.
authors: Qingfeng
authors: Q
authors: Dong
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu and Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083, P. R. China.
authors: Yongbo
authors: Y
authors: Yuan
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu.
authors: Yanjun
authors: Y
authors: Fang
authors: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, 68588, NE, USA. jhuang2@unl.edu.
authors: Jinsong
authors: J
authors: Huang