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For the last few years technical improvements of compositions and preparation procedures for perovskite-based solar cells have remarkably enhanced their energy conversion efficiency. Crystal and electronic structures together with ion diffusion in partially substituted cubic methylammonium (MA) perovskite based on lead halide MA0.5X0.5PbI3, where X is the cation, are theoretically investigated using density functional theory and molecular dynamics methods. The electronic structure of partially substituted perovskites studied is similar to the MAPbI3 structure, however, the band gap changes compared to their structures. Partial MA substitution distorts the lattice, which prevents MA or X diffusion between A sites in the perovskite crystal. The partial cation substitution affects the electronic structure and distorts the crystal lattice of perovskite, which makes it possible to control the optical properties of the material in different spectral regions and to influence the electronic composition of defects. [ABSTRACT FROM AUTHOR]

Composites based on carbon black/high-density polyethylene composites and, as well as linear low-density polyethylene containing graft copolymers of low molecular weight polyethylene and acrylic acid, have been produced. The introduction of graft copolymers into the polyethylene matrix helps to reduce the average size of carbon black particles in the composition, reduce the melt viscosity and improve the thermal stability of carbon black-filled compositions, which is important for the production of pipe products based on polyethylene. [ABSTRACT FROM AUTHOR]

The compositions of graft low molecular weight polyethylene and acrylic acid copolymer with starch were synthesized. The carboxyl groups of the copolymer and the hydroxyl groups of starch enter into chemical reaction with the formation of an ester bond, as was proved by the FTIR spectroscopy. The X-ray diffraction analysis of the graft copolymer mixture with starch revealed a decrease in the degree of crystallinity. Graft copolymers were used as compatibilizers in polymeric compositions of low-density polyethylene with starch. The presence of a graft copolymer in the composition is favorable to obtain smaller starch particles in the polyethylene matrix and improve the physical and mechanical properties of the composition. [ABSTRACT FROM AUTHOR]