Interfacial State Modulation toward High-Performance n-Type Bi₂Te2.7Se0.3 Thermoelectric Material

Advancements in optimizing n-type Bi2Te2.7Se0.3 (BTS) thermoelectrics prioritize integrating 2D nanoarchitectures, driven by their demonstrated capacity to inhibit lattice thermal conductivity while enhancing charge carrier mobility. Herein, interfacial engineering of van der Waals-integrated MoS2 nanosheets is proposed to achieve dual phonon-charge regulation. Through epitaxial growth at BTS grain boundaries and c-axis alignment, these 2D layers establish periodic heterojunctions that selectively scatter broad-frequency phonons, while their intrinsic high carrier mobility preserves electrical conductivity. Density functional theory reveals that Fermi level alignment creates asymmetric energy barriers, intensifying the energy filtering effect for an enhanced Seebeck coefficient. Simultaneously, the thermal transport measurements confirm suppressed bipolar conduction via interfacial charge redistribution. Through equilibrating this carrier mean free path competition, we achieve a ∼1.5 times enhancement in carrier mobility, dramatically boosting electrical conductivity and thereby synergistically enhancing the power factor. Through interface state modulation engineering, these heterostructures exhibit a remarkable figure of merit (ZT) of 1.32 at 425 K, with the average ZT (ZTave) = 1.23 maintained over the 300–500 K range. Notably, assembled modules yield Pmax = 0.74 W and η = 6% under ΔT = 150 K operational windows. This interfacial engineering-centric roadmap establishes 2D nanoarchitectonics as a paradigm for decoupling electron–phonon interdependence, unlocking transformative TE performance regimes.