Efficient Near Room Temperature Thermoelectric Cooling and Power Generation with CuAgSe

ABSTRACT CuAgSe‐based materials are attractive for low‐temperature thermoelectric (TE) applications but are limited by bipolar conduction and relatively high thermal conductivity. Herein, we report a ligand‐free aqueous synthesis of Te‐doped CuAgSe (CuAgSe 1‐x Te x ), where structural and electronic modulation improve carrier transport and suppress phonon propagation. Ex‐situ time‐resolved X‐ray diffraction reveals a spontaneous growth mechanism, while density functional theory calculations show that Te‐5s and 5p orbitals hybridization generates localized states and an asymmetric density of states, thereby enhancing the Seebeck coefficient. Electron microscopy and strain analyses confirm that Te‐doping introduces a high density of lattice dislocations and grain boundaries, leading to a reduced lattice thermal conductivity of 0.11 W m −1 K −1 at 443 K. These synergistic effects translate into device‐level performance—the first integrated CuAgSe thermoelectric modules, exhibit a maximum cooling temperature difference of 27.3 K, and power density of 0.34 W cm −2 with a conversion efficiency of 3.6% at a modest temperature gradient of 136 K. These results demonstrate that CuAgSe 1‐x Te x enables efficient energy harvesting and localized cooling under small temperature gradient, underscoring the importance of structural and electronic design beyond conventional zT benchmarks.