First-principles study of electronic and optical properties of hybrid perovskites for use of solar cells

Abstract

Nowadays, hybrid perovskites are highly investigated materials for their optimal electronic and optical properties, making them semiconductors of the highest capacity for their use as solar energy harvesters in a photovoltaic device, so their study is very important. Finding their structure that defines these properties involves arduous effort and a lot of computational resources. In this thesis we studied the hybrid perovskites of lead methylammonium (MA) halides, MAPbX3 where (X=I, Cl, Br), for simulating their structural, optical, and electronic properties. Each perovskite presents three structural phases which are (in order of symmetry) the orthorhombic, tetragonal and cubic phase. For each of the phases of its respective perovskite, its structural parameters, and optical properties such as the real and imaginary part of the dielectric function, refractive index, reflectivity, and its absorbance spectrum were calculated. For the electronic properties, the band structure, density of states (DOS), and projected density of states (PDOS) are presented. The results for each perovskite are then compared with their own phases and between the other perovskites and their experimental reported results to show their optimal structure to obtain the best properties for each of the perovskites for use as a light-absorbing layer of a solar cell. Our computed results indicate that the cubic Iodine hybrid perovskite is the best candidate for its experimental application in photovoltaic devices, exhibiting the largest absorption peak in the visible region of the solar spectrum. The optical and electronic properties were close to the experimental ones, and the perovskite structure’s impact on its properties is demonstrated.