DFT Investigation of Optoelectronic Properties for CaAO3 (A = Ti, Zr, and Hf)

Abstract

In recent times, the synthesis and simulation of perovskite materials have gained significant interest in renewable energy. The diverse metal-halide perovskites are very useful in optoelectronic devices. However, lead-based perovskites are toxic, unstable, and vulnerable to degradation when exposed to high temperatures, and their instability is the major restriction for their commercial use. This research paper centered on the first-principles calculations of structural and optoelectronic features of CaAO3 (A= Ti, Zr, and Hf) by employing the Generalized Gradient Approximation (GGA) Perdew-Burke-Ernzerhof (PBE), and DFT+ TB-mBJ exchange-correlation functional. The calculations of the electronic properties revealed that the CaAO3 (A= Ti, Zr, Hf) has indirect and direct band gaps. To treat the electron-electron interactions, we utilized the PBE exchangecorrelation functional, which revealed non-phonon-assisted energy gaps of 2.5 eV, 3.51 eV, and 3.70 eV, and phonon-assisted energy gaps of 1.88 eV, 3.21 eV, and 3.64 eV for CaAO3 (A= Ti, Zr, and Hf), respectively. These values are consistent with the reported theoretical literature. By employing the DFT+ mBJ exchange correlation functional, the direct band gaps (non-phonon-assisted) of 3.21 eV, 4.70 eV, and 5.21 eV and indirect band gaps (phonon-assisted) of 2.73 eV, 4.24 eV, and 5.03 eV were obtained, which are in excellent agreement with the limited experimental values reported, though with slight underestimation. Moreover, the optical absorption spectra, dielectric constants, and refractive index calculations testify to their applications in optoelectronic devices.