Effects of oxygen variation on the improved structural stability, electronic and optical properties of ZnTeO compounds

Abstract

Crystalline ZnTeO thin films are promising materials for next generation photovoltaics. However, their structural stability and optical nonlinearity potential in bulk form have not been reported. Here, structural, electronic and optical properties of ZnTeO composites have been thoroughly studied using genetic algorithm and density functional theory (DFT). Energetically, mechanically and dynamically stable O-rich phases, namely Zn 2 Te 2 O 6 and ZnTeO 4 , were obtained. Ground-state properties such as lattice constants and simulated XRD were analyzed and compared to the experimental literature wherever possible. With a G 0 W 0 corrected band gap, these semiconducting phases display several desirable features, namely, Jahn-Teller distorted cations, hardness and shear anisotropy-induced optical nonlinearity that increase monotonically as O concentration elevates. Such trends appear to be consistent with that seen in the experimental study of ZnTeO thin film. It is observed that Zn-d, Te-p and O-p states have immense influence towards the electronic properties of these structures. Both phases exhibit steep elevation of absorption throughout the ultraviolet (UV) range, hitting peak value of ~5.0 × 10 5 cm −1 . Of particular interest, the non-centrosymmetric ZnTeO 4 has second harmonic generation coefficients (9.84 pm V −1 and 2.33 pm V −1 at static limit) greater than borates crystal and large birefringence that exceeds 0.08 in deep UV region, thus highlighting its potential pedigree as new optical materials in UV range.

Boosting the solar conversion efficiency of MoSe2/PtX2 (X = O, S) vdW heterostructure by strain and electric field engineering

“…The optical performance was investigated by analyzing the complex dielectric function ε(ω), which comprises the real ε 1 (ω) and imaginary ε 2 (ω) parts while ω denotes the frequency. The real and imaginary components were computed using the Kramers-Kronig formulation [46] and momentum matrix between the occupied and the unoccupied states. The light absorption of the substance (see figure 6) is signified by the imaginary part of the dielectric constant ε 2 (ω).…”

Constructing trifunctional MoTe2/As van der Waals heterostructures for versatile energy applications

“…The component of ε 2 ( ω ) was evaluated by the sum of matrix elements between the occupied and unoccupied bands while ε 1 ( ω ) was elicited from ε 2 ( ω ) via the Kramer–Kronig formula. 47–49 To reduce the disparity in qualitative accuracy between DFT results and experiments, an appreciable empty conduction band states and frequency grid points of 240 and 10 001, respectively, were assigned. The absorption coefficient α ( ω ) and refractive index n ( ω ) were then calculated to ascertain the absorption capacity and optical behavior of the heterostructure towards the solar spectrum via the following equation:…”

Prediction of stable silver selenide-based energy materials sustained by rubidium selenide alloying

“…6. The real part ε 1 ( ω ) was determined by application of the Kramers–Kronig dispersion relationship 63–66 on the imaginary part ε 2 ( ω ). Important optical properties such as refractive index n ( ω ) and α ( ω ) absorption coefficient were then calculated using the knowledge of the imaginary part ε 2 ( ω ) and the real part ε 1 ( ω ) of the dielectric function, as follows:…”