Effect of Barrier Material Accumulation on the Performance of Bi₂Te₃-Based Thermoelectric Generators

The barrier material placed between thermoelectric (TE) materials and electrodes plays a dominant role in the performance of a thermoelectric generator (TEG). Nickel (Ni) is widely used as a barrier material in Bi₂Te₃-based TEGs. Since the electroplating of Ni is an efficient technique in the coating of barrier materials, we observe that the barrier material accumulation on the surface of TE materials greatly restricts the output power and conversion efficiency of TEGs. Specifically, for an interface with accumulated barrier material, the output power can be reduced by more than 30%, while the interfacial strength can be reduced by around 18%. By optimizing the electroplating process, we realize a maximum output power of 0.62 W and a maximum conversion efficiency of 5.1% in a Bi₂Te₃-based TEG, which is much higher than that of commercial TEGs. Simultaneously, the bonding strength of the uniform interface reaches 49.36 N, which is 22.6% higher than that of the interface with barrier material accumulation. These results guide the design and fabrication of high-performance TEGs.