Performance evaluation of flexible thermoelectric generator with Bi2Te3 thin-film

In the information society, carrying devices such as smartphones and tablets is crucial, and ensuring their power supply is essential. Furthermore, from the perspective of energy security, being able to secure their power supply from low-quality energy sources could reduce dependence on fossil fuels. In this study, we fabricated a flexible thermoelectric generator capable of harvesting energy from a low-temperature difference between a low-temperature heat source and room or outdoor temperature and evaluated its performance. The device was fabricated by depositing an n-type Bismuth telluride (Bi2Te3) film onto a polyimide film substrate using radio frequency (RF) magnetron sputtering. A 3D printer was used to fabricate flexible fins for attaching and bonding the films. Owing to their adaptability, these flexible models can be installed on heat sources of different shapes. The experimental conditions for this study were as follows: the temperature in the test chamber was maintained at 25 ± 1 °C and that of the heat source ranged from 35 to 75 °C; further, thermoelectric elements in numbers varying from 1 to 6 were installed. The maximum open-circuit output voltage |E| and power generation (Pmax) were determined to be 11.4 mV and 69 nW, respectively. The fins with the Bi2Te3 thin film maintained a temperature of approximately 25 to 30 °C at the tip of the fin, even when exposed to the highest temperature (75 °C) of the heat source during the experiment. As a result, the thermoelectric device developed in this study has demonstrated the potential to power sensors operating in the tens of nW range.