<p> Converting waste heat into usable electrical energy stands as a vital step toward sustainable energy solutions. This investigation examines how incorporating distinct side groups, amino (NH₂), hydroxyl (OH), and thiol (SH) into the central ring of an anthracene molecule influences its thermoelectric behavior. Using a computational approach grounded in density functional theory DFT and the quantum transport theory framework, we assessed how each substitution affects. We have predicted the impact of different substitutions on the transport behavior. The NH₂ group notably boosted both the Seebeck coefficient and electrical conductance, resulting in a peak figure of merit ZT near 5.3 at the Fermi energy. In contrast, the incorporation of the SH group led to a reduction in the ZT value, indicating a negative impact compared to pure anthracene. While the OH substitution resulted in performance gains, these findings suggest that carefully chosen functionalization strategies can significantly enhance the thermoelectric performance of organic molecular systems.</p>