<p>This study investigates the impact of ceramic substrate materials on the performance of thermoelectric generators (TEGs), focusing on four key ceramics: alumina (Al₂O₃), aluminum nitride (AlN), magnesium oxide (MgO), and silicon carbide (SiC). By employing a validated unicouple model, the effects of substrate thermal conductivity, thickness, and leg length on power output and efficiency were analyzed. Findings reveal that material properties, particularly thermal conductivity and electrical insulation, play a critical role in optimizing TEG performance. Among the materials, aluminum nitride emerged as the most effective, achieving near-optimal performance with shorter leg lengths and thinner substrates. The study provides novel insights into the interplay of material selection and geometric optimization, demonstrating that innovative configurations, such as shorter leg lengths paired with high-performance ceramics, can significantly enhance efficiency and reduce production costs, offering a transformative approach to thermoelectric energy conversion.</p>