Extremely Low Contact Resistivity of Bi₂Te₃-Based Modules Enabled by NiP-Based Alloy Barrier

Electrode diffusion barrier plays an important role in thermoelectric cooling devices. Compared with p-type Bi_0.5Sb_1.5Te₃, the compatibility between commercial Ni barrier and n-type Bi₂Te_2.7Se_0.3 is a key bottleneck to enhance the performance of Bi₂Te₃-based cooling devices. This paper proposed a NiP alloy barrier to improve the compatibility with n-type Bi₂Te_2.7Se_0.3, and systemically investigated the contact and interfacial dynamics properties. Due to the low diffusion rate of NiP alloy, the initial interfacial contact resistivity of Bi₂Te_2.7Se_0.3/NiP is as low as 0.90 μΩ cm², and it further can be depressed below 1.98 μΩ cm² even after aging at 423 K for 35 days, indicating the superior thermal stability of the NiP barrier layer compared to the commercial Ni barrier layer. Based on the NiP barrier, a 15-pair bismuth telluride device is prepared and a high cooling temperature difference of 71.5 K at a hot-side temperature of 304 K is achieved, which proves the practical applications potential of NiP barrier for Bi₂Te₃-based modules.