Propriedades estruturais e eletrônicas de novos sistemas de perovskitas calcogênicas com potencial para aplicações fotovoltaicas/optoeletrônicas

Abstract

Chalcogenic perovskites are proposed materials for electronic and optical applications due to their electronic structure. The study of non-oxide perovskite systems was addressed in this work in order to explore structural, electronic and vibrational properties of these systems, with the aim of analyzing which material would be promising for future photovoltaic/optoelectronic applications. In addition to the oxygen-based system, systems with total substitutions in the O anion starting from the compound MgTiO3 (MTO), an oxide perovskite well known in the literature, were also studied. For this, other elements of the chalcogen family present in the periodic table were chosen; creating the MgTiS, MgTiSe, MgTiTe systems. The choice of these being derived from similar systems. The structural, electronic and vibrational properties of such systems were treated using quantum mechanical simulations based on the Density Functional Theory (DFT), combined with the PBE exchange and correlation functional. All investigated systems were computationally treated using the computational package Crystal17, using pseudopotential and all electron bases, in order to improve the accuracy of the data obtained. The results showed positive replacements with the creation of new systems that presented lower bandgap values, more conducive to applications involving solar energy conversion. In the case of MgTiS, the gap was reduced to 1.58eV, for MgTiSe the gap was reduced to 0.89eV and for MgTiTe the gap reached 0.09eV. Thus, the replacement of oxygen by sulfur is the most favorable for the desired application.