Effect of non-stoichiometry of initial reagents on morphological and structural properties of perovskites CHNHPbI.

The properties of films of organic-inorganic perovskites CHNHPbICl depending on the ratio of starting reagents in solutions (PbI:{CHNHI + CHNHCl}) has been investigated. It was found that the formation of the perovskite structure with the ratio of the initial reagents PbI: CHNHI = 1:1 occurs at 70-80 °C, and with the increase of the temperature of thermal treatment to 120 °C, the thermal destruction of the perovskite begins. When the ratio of the starting reagents PbI: CHNHI = 1:2, the formation of the perovskite structure occurs through the intermediate compound (CHNH)PbI, and when the ratio is 1:3-(CHNH)PbI and (CHNH)PbI. Independent on the ratio of the initial components (CHNHI:PbI), the ratio between the content of lead and iodine in the films remains unchanged, that is why a significant difference in the film properties could be explained by the anisotropy of the particle shape, which is consistent with the data of electron microscopy and X-ray diffractometry.