Studying the impact of biaxial strain on the electronic and optical properties of $\textrm{Ba}_{2}\textrm{YBiO}_{6}$ and $\textrm{Ba}_{2}\textrm{ScBiO}_{6}$ double perovskites for optoelectronic applications: ab initio calculations

Abstract

We report the electronic, vibrational, and optical properties of specific double perovskites, i.e., $\textrm{Ba}_{2}\textrm{YBiO}_{6}$ (BYBO) and $\textrm{Ba}_{2}\textrm{ScBiO}_{6}$ (BSBO) using first-principle calculations based on density functional theory. The stability of both the compounds has been confirmed by their elastic and thermodynamic properties. The effects of strain on the electronic and optical properties of BYBO and BSBO; with an external range of $-5$ to $+5\%$. Electronic properties show semiconducting behavior with bandgap ($E_{\textrm{g}}$) values of; $E_{\textrm{g}} = 1.68 \,\hbox {eV}$ and $E_{\textrm{g}} = 1.35 \,\hbox {eV}$, for BYBO and BSBO, respectively with indirect bandgap alignment. On application on external tensile strain $\ge +3\%$, the bandgap of BYBO and BSBO undergoes a transition from indirect alignment to direct alignment, whereas the electronic bandgap alignment does not change with compressive strain. Interestingly, the magnitude of the bandgap shows contrasting behavior, i.e., the bandgap increases (up to 0.9–1 eV) with compressive strain and decreases (up to 0.7–0.8 eV) with tensile strain. The wavelength values calculated in the absorption spectra of the pristine samples are 373 nm for BYBO and 434 nm for BSBO; suggesting their potential suitability as alternatives for “solar cell” applications, photodetectors, superlenses, photovoltaic devices, etc.