DFT study of strain-induced optical shift in graphone, a 2D wide-bandgap semiconductor: Perspectives for photovoltaic and optoelectronic applications

Abstract

This study uses density functional theory (DFT) to examine the effect of strain on the optical properties of graphone. Based on previous studies linking the band gap to the dielectric function (Zheng et al., 2017; Onishi and Fu, 2024), we propose that mechanical strain can be used to tune electronic and optical properties. The undeformed structure exhibits a indirect gap of $4.21\text{eV}$ with an absorption onset near $4.21\text{eV}$. Tensile strain ($+30\text{\%}$) reduces the gap to $0.96\text{eV}$ and shifts the main absorption peak from $13.05\text{eV}$ to $2.33\text{eV}$, eventually closing the gap and inducing a semiconductor-to-semimetal transition. Conversely, compressive strain ($-30\text{\%}$) widens the gap to $5.58\text{eV}$, pushing absorption into the ultraviolet. Strain also modifies the dielectric function: ${\varepsilon }_1\left(\omega \right)$ increases by $\sim 18\text{\%}$ at low energies, while ${\varepsilon }_2\left(\omega \right)$ exhibits a redshift. The absorption coefficient increases from $4.5\times 10^5{\text{cm}}^{-1}$ to $5.9\times 10^5{\text{cm}}^{-1}$, accompanied by a $\sim 12\text{\%}$ decrease in transmission. These findings highlight strain engineering as an effective strategy for tailoring graphone’s optical performance.