Interfacial Doping and Band Bending Boosting Thermoelectric Power Factor in 1T′-MoTe2/Bi2Te3 Quantum-Dot Films

Superlattice films are promising candidates for obtaining excellent thermoelectric performance because the hetero-interface can effectively regulate both carrier and phonon transport. However, the atomic and electronic structures at the hetero-interface remain largely unexplored, limiting the deep understanding of interfacial effects. Here, 1T'-MoTe2/Bi2Te3 quantum-dot films were fabricated for investigating the 1T'-MoTe2/Bi2Te3 hetero-interface and its effect on electrical transport. Atomic-scale characterizations indicate apparent Mo doping at the hetero-interface, while band structure calculations and transport measurements reveal that Mo doping can reconstruct the conduction band and enhance band degeneracy, leading to a large carrier effective mass of ∼1.6 m0. Meanwhile, spectroscopy measurements verify donor-like states and local band bending at the hetero-interface, which introduce modulation doping and thereby enable synergistically optimized electron density and carrier mobility. As a result, the best (1T'-MoTe2)0.8(Bi2Te3)12 film achieves a peak power factor of ∼3.74 mW m-1 K-2 at 325 K. These findings provide new insights of interfacial effects on synergistically optimizing carrier transport and electrical properties of thermoelectric superlattice or quantum-dot films.