Investigation regarding the role of chloride in organic-inorganic halide perovskites obtained from chloride containing precursors.

As the photovoltaic performance of a device is strongly influenced by the morphology of perovskite, achieving precise control over the crystal formation of organic-inorganic halide perovskites synthesized in the ambience of chloride ions has garnered much attention. Although the resulting morphology dictates the performance of the device considerably, the understanding of the role of chloride ions has been scant. To unravel this mystery, we investigated three different organic-inorganic halide perovskite materials grown from the chloride-containing precursors under different but optimized conditions. Despite the presence of chloride ions in the reaction mixture, scanning transmission electron microscopy- energy dispersive spectroscopy (STEM-EDS) reveals that the CH3NH3PbI3 perovskites formed are chloride-free. Moreover bright field transmission electron microscopy indicates that chloride ions effect the growth of the CH3NH3PbI3.