Electronic and optical behaviour of lanthanum doped CaTiO₃ perovskite

Abstract

To improve the efficiency of perovskite based solar cells, doping of heavier elements in Perovskite materials (ABX 3 ) can modulate its electronic and optical properties significantly. Thus it is important to understand the possible microscopic origin of the band gap modification and optical enhancement after heavier element doping using first-principles studies. Here we investigate the effect of La doping, while substituting the Ca atom, on the electronic and optical properties in CaTiO 3 perovskite material using generalized gradient approximation within density functional theory. We observe a decrease in lattice constants and bond lengths in La x Ca 1−x TiO 3 , mainly due to re-distribution of electronic charge density between La and Oxygen, as confirmed by charge density contour. We further notice a widening of electronic band gap and an upward shift of Fermi level into the conduction band, thus characterizing La x Ca 1−x TiO 3 as an n-type material. DOS diagram attributes this shift mainly due to the appearance of La p-DOS and d-DOS and their repulsion with N p-DOS, when La enters into the host lattice at Ca site. Investigation of optical properties upon La Doping in CaTiO 3 exhibits further shifting of polarization and refractive index to lower values as compared to its pure counterpart, due to dominating semiconducting behavior and hence one observes a blue shift in absorption and reflection spectrum accordingly. Energy loss function is found to be consistent with absorption and extinction coefficient measured in case of La x Ca 1−x TiO 3 . All these results are found to be consistent with the existing experimental and first-principles studies.

Oxynitride Perovskite: Computational Approach to Correlate Structural, Electronic, and Optical Properties of c-BiAlO3/N3

“…Since optical properties can be used to demonstrate light–matter interaction, we explore the subsequent optical properties such as the refractive index, dielectric function, energy loss function, absorption, and reflectivity of BiAlO 3 in comparison with different substitutions of N in the energy range 0–30 eV, as presented in Figure . The optical behavior of a material depends upon frequency, so if one determines the dielectric function of that material, it would give information about all other optical properties of that material via the Maxwell equation . There are two parts of a dielectric function, i.e., real ε 1 and complex ε 2 .…”

“…The optical behavior of a material depends upon frequency, so if one determines the dielectric function of that material, it would give information about all other optical properties of that material via the Maxwell equation. 64 There are two parts of a dielectric function, i.e., real ε 1 and complex ε 2 . The real part (ε 1 ) explains the polarization or the energy point where the electrons start exciting.…”

Structural and Optical Properties of Calcium Titanate Prepared from Gypsum

“…CaTiO 3 is a chemically stable n-type semiconductor with a broad bandgap of 3-3.5 eV [8]. Ca ions are located at the corners (1/2, 1/2, 1/2), Ti at the body center (0, 0, 0), and oxygen at the face center (1/2, 0, 0; 0, 12, 0; 0, 0, 1/2) [9]. CaTiO 3 is an alkaline earth metal titanate composed of earth-abundant nontoxic elements.…”

Neoteric advances in affordable photocatalytic energy conversion and storage with perovskites nanocrystals: A review

“…The basic structure of any perovskite is a composition of cations and anions arranged in a particular fashion. They have a general formula of ABX 3 , where A and B are cations usually alkali or alkaline earth metals, and X is an anion usually oxygen 12 . Whereas, in halogen perovskites, X is replaced by a group VII‐A element usually fluorine and iodine.…”