Thermoelectric materials play a crucial role in converting heat into electricity, offering significant potential for applications in waste heat recovery and cooling. Herein, an innovative approach that combines an organic–inorganic hybrid superlattice structure with nanocrystal‐amorphous composite nanolayers is introduced. The nanocrystal‐amorphous composite enhances the Seebeck coefficient resulting in a notable twofold improvement in the power factor. The superlattice, alternating self‐assembled organic monolayers and inorganic nanolayers, effectively reduces lattice thermal conductivity by creating multiple interfaces that scatter phonons effectively. The integration of the nanocrystal‐amorphous composite nanolayers into the superlattice provides a dual advantage, simultaneously boosting the power factor and suppressing thermal conductivity. This synergistic effect leads to exceptional thermoelectric performance in the 4‐mercaptophenol/Sb₂Te₃ superlattice, with achieved figure of merit (ZT) values of 3.48 at 300 K and reaching a peak ZT value exceeding 4.0 at 400 K while surpassing 2.5 over the temperature range from 300 to 500 K. These results suggest that this innovative approach paves the way for the development of highly efficient thermoelectric materials, propelling efforts toward more energy‐efficient and environmentally friendly solutions.

Semiconducting metal oxides are gaining attention in thermoelectric applications, where performance is evaluated by the figure of merit (ZT), which depends on the power factor (S²σ) and thermal conductivity (κ). However, achieving high ZT values in these materials remains challenging. This study introduces a distinct strategy to enhance thermoelectric performance by infiltrating aluminum-doped zinc oxide (AZO) into poly(methyl methacrylate) (PMMA) films using the vapor-phase infiltration (VPI) technique. The resulting AZO/PMMA hybrid films exhibit a unique composite structure with AZO nanocrystals embedded within an amorphous PMMA matrix. This structure facilitates energy-dependent carrier scattering (the energy filtering effect) at the AZO/PMMA interfaces, thereby enhancing the Seebeck coefficient, while phonon scattering at the interfaces reduces thermal conductivity. By precisely controlling VPI parameters, we achieved a uniform dispersion of AZO nanocrystals within the PMMA matrix. The optimized AZO/PMMA hybrid film demonstrated a power factor of 1306 μW m⁻¹ K⁻² and a thermal conductivity of 1.02 W m⁻¹ K⁻¹, resulting in a ZT value of approximately 0.384 at 300 K, which is one of the highest reported for metal oxide thermoelectric materials near room temperature. The successful integration of AZO into the PMMA matrix via VPI opens new pathways for developing high-performance, flexible thermoelectric materials.