Abstract:
Calcium Oxide is a potential candidate for thermal energy storage at high temperatures in
the range of 450-600 °C. the reversible solid gas reaction of Ca(OH)2/CaO system offers high
energy density, long storage period and cost effectiveness. Our aim in this work is to explore it as
a potential thermoelectric and optoelectronic material by tuning its band gap by different metal
doping and creation of oxygen vacancies. Density functional theory technique is used to model the
electronic, optical, and thermoelectric properties of modified and unmodified materials. Calcium
oxide is a wide band gap material having an indirect band gap of 6.0 eV while a direct band gap
of 7.1 eV has been determined experimentally. Therefore, to tune its band gap, it was doped with
cadmium and zinc (25% each), while 25% and 3.12% oxygen vacancies were created in pure CaO.
it was found that the indirect band gap was reduced to 4.47 eV and 4.25 eV for Zn and Cd doping
respectively, while 25% and 3.12% oxygen vacancy reduced the band gap to 1.51 eV and 3.19 eV
respectively. CaO with 3.12% Oxygen vacancy was found to have the highest figure of merit which
makes it potential thermoelectric material. In the visible region, 25% Oxygen doped was found to
have the highest absorption compared to all systems which makes it potential material for solar
cell fabrication
