Decoupling Electron and Phonon Transport in 3D-Printed Bismuth Telluride via Synergistic Compositional Co-Enrichment

Decoupling electronic and phononic transport requires nanoscale control over scattering landscapes. Here, we show that direct ink writing generates a hierarchical nanoarchitecture in Bi 2 Te 3 , which comprises nanopores (10-150 nm), amorphous-crystalline nanointerfaces, and dense grain boundary networks that suppress lattice thermal conductivity by around 50% from ∼0.6 W m −1 K −1 to ∼0.3 W m −1 K −1 , as quantitatively confirmed by Debye-Callaway modeling. Sb/Te/Se co-enrichment (Sb/Te co-enrichment was applied to the p -type BST system, while Te/Se co-enrichment was applied to the n -type BTS system) refines this nanopore distribution while driving atomic-scale intercalation of Sb/Te enrichment between quintuple layers, as directly visualized by atomic-resolution STEM-EDS, bridging van der Waals gaps to selectively restore electrical conductivity without compromising phonon scattering. The optimized p -type and n -type materials achieve peak ZT values of 0.87 (303 K) and 0.89 (423 K), respectively, which exceed commercial Bi 2 Te 3 performance. Single-leg generators deliver conversion efficiencies of 3.51% and 2.53%, ranking among the highest for additively manufactured thermoelectrics. This work demonstrates that process-generated nanoarchitectures, combined with atomic-scale compositional engineering, enable effective phonon–electron decoupling in printed thermoelectric materials.