Interfacial Doping and Band Bending Boosting Thermoelectric Power Factor in 1T′-MoTe2/Bi2Te3 Quantum-Dot Films
Haoran Ge, Wei Liu, Zijun Wang, Yichen Wu, Xiangkun Hong, Junjie Li, Ziwei Li, Tingting Su, Tingting Luo, Zhengfei Wei, Anjiang Wang, Fan Yan, Qiwei Tong, Xianda Li, Xin Xie, Hao Sang, Yong Liu, Min Hong, Xinfeng TangAbstract
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.