Abstract The structural stability, elastic, optoelectronic, and thermoelectric characteristics of anti‐perovskites Na 3 XO (X = Cu, Ag) have been studied using density functional theory (DFT). The computed formation energy suggests these materials' potential synthesis and thermal stability. The structural and elastic properties of Na 3 CuO and Na 3 AgO anti‐perovskite compounds were analyzed using the Perdew–Burke–Ernzerhof (GGA‐PBE) generalized gradient potential approximation. The electronic and thermoelectric properties are calculated using the TB‐mBJ approximation. The materials are identified as direct narrow band gap semiconductors with band gaps of 0.65 and 0.43 eV. The analysis of two‐dimensional charge density contours indicates that Na 3 CuO and Na 3 AgO have a mixed bonding character, as validated by the investigation of electron charge density. We analyzed the optical properties of Na 3 CuO and Na 3 AgO, including dielectric function, refractive index, absorbance, optical reflectivity, and energy loss, using photon energy up to 6 eV. The investigated thermoelectric characteristics demonstrate figure of merit (ZT) values of 0.58 and 0.56 at room temperature. Consequently, the analyzed anti‐perovskites might address waste heat management requirements and sustainable energy solutions.
