Optimized barrier layer enables high-performance bismuth telluride-based thermoelectric devices

Abstract

Conventional metals or Ni-based barrier layers (BLs) often suffer from interdiffusion, Cracking, phase segregation, and poor adhesion, limiting device reliability. To overcome this issue, we systematically develop a strategy to design an optimal alloy BL. Fifteen elemental metal-based analogues are fabricated using high-throughput methods and screened against four key failure modes: cracking, segregation, activation, and diffusion. The optimized BL composition is then designed based on four theoretical principles: (i) thermal expansion coefficient matching, (ii) negative interfacial reaction energy, (iii) maximized migration barrier energy, and (iv) work functions alignment. Consequently, a Ti2.7Al2.3 alloy BL is identified, exhibiting superior performance across all criteria. An optimized TED incorporating this BL delivers a large output power density of 0.52 W/cm2 and a high conversion efficiency of 6.02% at a hot-side temperature of 525 K, with no observable performance degradation over 30 days of continuous operation. This work offers a generalizable pathway for developing advanced bismuth telluride (Bi2Te2.7Se0.3)-based BL.