Bulk Bi₂Te₃-based bendable thermoelectric device with highly elastic Cu-Be alloy foils

The binary Cu-Be alloy features high elasticity and yield strength. Hence, it can be used as an electrode material for bulk Bi₂Te₃-based thermoelectric (TE) devices to create bendability. First, TE materials and Cu-based electrodes were both coated with Ni/Au multilayers, which acted as diffusion barriers. Subsequently, the TE legs were connected to the Cu alloy electrode via soldering. Diffusion barriers enhanced the bonding strength and decreased the internal resistance of the TE generator. Furthermore, the internal resistance remained stable after a cyclic bending test, indicating the high flexibility of the device. The cooling performance was estimated by measuring the temperature on one side of the device while various current intensities were applied. The output power was measured using different temperature gradients and compared to the output power generated by a thermoelectric device for heat treatment.