Effect of non-stoichiometry of initial reagents on morphological and structural properties of perovskites CH3NH3PbI3

Anatolii Belous; Sofiia Kobylianska; Oleg V'yunov; Pavlo Torchyniuk; Volodymyr Yukhymchuk; Oleksandr Hreshchuk

doi:10.1186/s11671-018-2841-6

Effect of non-stoichiometry of initial reagents on morphological and structural properties of perovskites CH₃NH₃PbI₃

Nanoscale Res Lett. 2019 Jan 5;14(1):4. doi: 10.1186/s11671-018-2841-6.

Authors

Anatolii Belous¹, Sofiia Kobylianska¹, Oleg V'yunov², Pavlo Torchyniuk¹, Volodymyr Yukhymchuk³, Oleksandr Hreshchuk³

Affiliations

¹ V.I. Vernadskii Institute of General and Inorganic Chemistry of the NAS of Ukraine, Kyiv, Ukraine.
² V.I. Vernadskii Institute of General and Inorganic Chemistry of the NAS of Ukraine, Kyiv, Ukraine. vyunov@ionc.kiev.ua.
³ V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine.

Abstract

The properties of films of organic-inorganic perovskites CH₃NH₃PbI_2.98Cl_0.02 depending on the ratio of starting reagents in solutions (PbI₂:{CH₃NH₃I + CH₃NH₃Cl}) has been investigated. It was found that the formation of the perovskite structure with the ratio of the initial reagents PbI₂: CH₃NH₃I = 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 PbI₂: CH₃NH₃I = 1:2, the formation of the perovskite structure occurs through the intermediate compound (CH₃NH₃)₂PbI₄, and when the ratio is 1:3-(CH₃NH₃)₃PbI₅ and (CH₃NH₃)₂PbI₄. Independent on the ratio of the initial components (CH₃NH₃I:PbI₂), 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.

Keywords: Chemical reaction; Film; Metal halide perovskite; Microstructure; Raman spectroscopy.