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

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 CeO2 + V-O as promising candidates for energy applications using first-principles calculations. We can observe significant absorption of incident photons by CeO2 and CeO2 + V-O near UV region. The highest peaks of the epsilon(2)(omega) are present around 3.7 eV in spin up arrow channel, however, in spin down arrow 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 CeO2 + V-O are active optical materials. CeO2 and CeO2 + V-O reflect a negligible number of incident photons (similar to 20%) in the entire energy range. The positive value of the S shows that the CeO2 under study is p-type semiconductor, while CeO2 + V-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 (ZT = 1.01) is a more capable candidate for thermoelectric materials compared to CeO2 + V-O (ZT = 0.14). The investigated thermodynamic parameters reveal that CeO2 and CeO2 + V-O are dynamically stable compounds.