A computational study of ZnFeX2 (X = S, Se, Te) Nano-clusters having photovoltaic applications

Abstract

Iron pyrites, FeS2, is one of the most interesting photovoltaic materials because of its excellent absorption coefficient, environmentally friendly, and inexpensive nature however, it has low energy gap than the optimal range. Incorporating Zn in FeS2 results in the enhancement of electronic and optical properties. This article examines the geometry, electronic, optical, and thermochemical properties of nano-cluster FeX2 doped with Zn (X = S, Se, Te) using the Conceptual Density Functional Theory (CDFT) approach. The HOMO-LUMO energy gap of ZnFeX2 lies between 1.509 eV and 2.830 eV, making these clusters suitable for photovoltaic applications. A significant improvement has been observed in the energy gap after doping Zn in the FeX2 nano-cluster. The electronic distribution of frontier orbitals (HOMO and LUMO) and the density of states for ZnFeX2 are reported in this work. The result specifies that ionization potential, energy gap, molecular hardness, dipole moment, optical electronegativities, vibrational frequencies, and IR spectra decrease from ZnFeS2 to ZnFeSe2 to ZnFeTe2. However, the reverse trend is observed for softness, heat capacity, and entropy. The refractive index and dielectric constant of ZnFeX2 are also computed. The calculated bond length of ZnFeX2 corresponds to the reported values. Our computed result establishes the significant photovoltaic applications of ZnFeS2.