Nanostructured surfaces

Synthesis and degradation of organic-inorganic compounds 

Torchyniuk P.V.1, V’yunov O.I.1, Yukhymchuk V.O.2, 
Hreshchuk O.M.2, Belous A.G.1

1 Solid State Chemistry Department, V.I. Vernadsky Institute of General and Inorganic Chemistry, NAS of Ukraine, Palladina ave., 32/34, Kyiv-03142, Ukraine.
Corresponding author e-mail: pasha.torchyniuk@gmail.com

2 V. E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Prospect Nauky, 45, Kyiv-03028, Ukraine.

Organic-inorganic halide perovskites are important for the development of elements for solar energy conversion. These materials are characterized by high productivity and low cost of manufacturing, their power conversion energy exceeds 22% [1]. Solar cells based on them would take leading positions in photovoltaic technologies due to increasing their stability over time. Humidity, temperature, oxygen and ultraviolet radiation cause degradation of perovskite materials [2].
The aim of this work was to synthesize and study the influence of humidity, radiation and time of exposure on the degradation of organic-inorganic perovskite films CH3NH3PbI3.
Solutions with different ratios of the initial reagents, PbI2 and CH3NH3I (1:1, 1:2, 1:3) in DMF were used for the synthesis of organic-inorganic compounds. The degradation of organic-inorganic perovskite films CH3NH3PbI3 was estimated using a complex of methods: XRD, Raman spectroscopy, etc. Films degradation was evaluated by the change in the content of the additional phase PbI2 with time from synthesis to 55 days. The film with the highest ratio of PbI2:CH3NH3I=1:3 decomposes the least, the film with an intermediate ratio of PbI2:CH3NH3I=1:2 is degraded most. This is also confirmed by the results of Raman spectroscopy. It has been shown that degradation of perovskite film results in transformation of the initial spectrum corresponding to the vibrational modes of CH3NH3PbI3 into a spectrum of PbI2. It was established that the degradation of perovskite film (which was estimated at radiation with a wavelength of 532 nm) was accelerated with increasing power density and radiation time.
The authors would like to thank the Ukrainian National Academy of Sciences for providing the research grant (34/19-Н) to support this work.

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