Investigating the effect of oxygen vacancy on electronic, optical, thermoelectric and thermodynamic properties of CeO2 (ceria) for energy and ReRAM applications: A first-principles quantum analysis

Abstract

CeO₂ thin film-based devices have become hot favorite candidates for researchers due to the outstanding characteristics of ceria such as memory storage materials, high oxygen storage capacity, excellent chemical and thermal stability, high transparency in visible region and highly tunable energy band structures. Developing suitable materials for industrial uses like optoelectronic and thermoelectric devices is the primary goal of researchers in the field of renewable energy. Herein, we have investigated the optical, thermoelectric and thermodynamic properties of CeO₂ and ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ as promising candidates for energy applications using first-principles calculations. We can observe significant absorption of incident photons by CeO₂ and ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ near UV region. The highest peaks of the ${\epsilon }_2(\omega )$ are present around 3.7$$eV in spin $\uparrow$ channel, however, in spin $\downarrow$ channel, the highest peaks of the ${\epsilon }_2(\omega )$ are present around 3.5$$eV. The most intense peaks that emerge are due to the transitions of O[${2p}^4$] to Ce [${4f}^1$]. The investigated values of $n(\omega )$ reveal that CeO₂ and ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ are active optical materials. CeO₂ and ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ reflect a negligible number of incident photons ($\sim 20$%) in the entire energy range. The positive value of the S shows that the CeO₂ under study is p-type semiconductor, while ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ is n-type semiconductor as its S value is negative. The S values for CeO₂ are close to the established standard. As a result, CeO₂ is a viable thermoelectric material for use in devices. The figure of merit (ZT) spectra reveals that CeO₂ ($\mathrm{\text{ZT}}=1.01$) is a more capable candidate for thermoelectric materials compared to ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ ($\mathrm{\text{ZT}}=0.14$). The investigated thermodynamic parameters reveal that CeO₂ and ${\mathrm{\text{CeO}}}_2+{\mathrm{\text{V}}}_{\mathrm{\text{O}}}$ are dynamically stable compounds.