Enhanced Grain Size and Crystallinity in CH 3 NH 3 PbI 3 Perovskite Films by Metal Additives to the Single-Step Solution Fabrication Process

Methods of obtaining large grain size and high crystallinity in absorber materials play an important role in fabrication of high-performance methylammonium lead iodide (MAPbI 3 ) perovskite solar cells. Here we study the effect of adding small concentrations of Cd 2+ , Zn 2+ , and Fe 2+ salts to the perovskite precursor solution used in the single-step solution fabrication process. Enhanced grain size and crystallinity in MAPbI 3 films were obtained by using 0.1% of Cd 2+ or Zn 2+ in the precursor solution. Consequently, solar cells constructed with Cd- and Zn-doped perovskite films show a significant improvement in device performance. These results suggest that the process may be an effective and facile method to fabricate high-efficiency perovskite photovoltaic devices.