Enhanced thermoelectric properties of Bi2Te2.7Se0.3/hexagonal BN composites and optimized modules for power generation

Bismuth telluride-based materials are well known for their excellent thermoelectric (TE) properties within the near-room temperature range. However, the poor thermoelectric performance of their n-type counterparts has posed a major hindrance to the application of bismuth telluride-based thermoelectric generator (TEG). In this study, a dual optimization approach was implemented. Specifically, 2D ceramic nano-sized hexagonal boron nitride (h-BN) was introduced into n-type Bi 2 Te 2.7 Se 0.3 (BTS) to enhance its performance, aligning it with p-type materials. It is indicated that ceramic h-BN decoration leads to the emergence of a high density of dislocations, which boosts the phonon scattering and reduces lattice thermal conductivity significantly. Meanwhile, a high carrier mobility is maintained to ensure an improved power factor. With the addition of moderate ceramic h-BN, the composite material achieved a ZT value of 1.1 at 400 K. The geometric configuration of TEG was optimized using finite element methods to strike the optimal balance between output power ( P o u t ) and efficiency ( η ). Based on the structure optimization results, the predicted P o u t and η increased by 48 % and 36 %, respectively. The fabricated TEG demonstrated to achieve an efficiency of 6.4 %. This work allows the evolution from bismuth telluride-based prototype to a functional TEG advanced in room-temperature heat recovery.