Unified contact layers design for highly efficient segmented PbTe/Bi2Te3 thermoelectric devices

Abstract

The development of segmented thermoelectric devices is often constrained by complex fabrication processes and the lack of interfacial materials compatible across different segments. Here, we demonstrate a unified contact layer design using TiTe2 for p-type PbTe/(Bi, Sb)2Te3 (BST) segmented thermoelectric devices guided by thermodynamic phase diagram analysis and validated through experimental investigations. The TiTe2 exhibits matched thermal expansion, exceptional chemical inertness, and low contact resistivity with both PbTe and BST. This enables a one-step spark plasma sintering (SPS) process that replaces conventional multi-step soldering, reducing interfacial parasitic resistance to below 5% of total device resistance. The optimized p-type segmented single leg achieved a record energy conversion efficiency of 15.3% at a temperature difference (ΔT) of 450 K, while a two-pair module achieved an efficiency of 13.5% at a ΔT of 500 K, outperforming conventional PbTe-based devices. The proposed interface design and simplified fabrication protocol provide a robust framework for advancing next-generation thermoelectric module development.