Promoting Room-Temperature n-type Bismuth Telluride Thermoelectrics via High-Potential Barrier Heterointerfaces

The donor effect of polycrystalline n-type bismuth telluride (Bi2Te3) during sample preparation usually results in the peak thermoelectric figure of merit (ZT) at temperatures above 400 K, severely restricting its application in the room-temperature (RT) range. A leap in RT performance requires innovative strategies that replace conventional methods of regulating point defects with limited effectiveness. We demonstrate excellent thermoelectric performance with an RT figure of merit, ZT = 1.2, and a maximum ZT = 1.3 at 325 K, by regulating the high-potential barrier heterointerfaces composed of La2O3 nanoparticles (NPs) and Bi2Te2.7Se0.3 (BTS). The created energy barriers at grain boundaries scatter and localize carriers through O–Bi ionic bonding and O–Te hybridization, enhancing the density of states in adjacent regions and leading to a rapid rise in the RT Seebeck coefficient (from 148.67 μV K–1 to 222.84 μV K–1 at 300 K). Another aspect of La2O3 NPs, as the second term of nano-oxide, introduces multiscale defect-scattering phonons, thereby enhancing thermal performance. Finally, at temperature difference ΔT = 10 K, a maximum output voltage and power, Vmax = 239.73 mV and Pmax= 10.50 mW, can be achieved with the fabricated TE module. Our findings underscore the full potential for promoting the performance of thermoelectric materials in the lower temperature region via high-energy barrier interface engineering.