Thermoelectric generators for heat harvesting: From material synthesis to device fabrication

This work reports high performance thermoelectric materials based on an electrochemical deposition method. Ultra-thick (2 mm-thick) and dense electrodeposited thermoelectric films have been successfully synthesized. It is found that at 0.7 at% concentration of nickel doped bismuth telluride, the power factor increases to 2050 µV/m K2 which is approximately 3 times higher than that of an electrodeposited pure bismuth telluride film. Meanwhile, the measurement on a thermal conductivity of the nickel doped bismuth telluride shows an improvement, which is nearly 2 times reduction as compared to the pure bismuth telluride film. As a result, a higher ZT value (0.78) of the nickel doped bismuth telluride is more than 5 times better than that of the electrodeposited pure bismuth telluride under similar evaluation conditions. In addition, a highly scalable synthesis process on a 4-inch wafer size of the thermoelectric material-based electrodeposition technique has been demonstrated. It proves that this electrodeposition could open up a chance to develop mass production for the low cost and high performance thermoelectric materials synthesis. Moreover, four kinds of thermoelectric generators (TEGs) including TEGs #1, #2, #3 and #4 with different parameters have been fabricated, evaluated and compared. The metal doped thermoelectric material devices are able to harvest more power than that of the pure thermoelectric material device. The fabricated device is successfully integrated with a DC-DC booster of which output can reach 3 V when a temperature difference of 4 °C is applied across the TEG. The generated power can be used to light up an LED from this small temperature difference.