Patternable and flexible thermoelectric generators based on Bi2Te3/silk fibroin composites for temperature sensing and wearable applications

Abstract

Thermoelectric (TE) materials are functional materials that can directly convert heat energy into electrical energy, and have a positive effect on alleviating the energy crisis. Inorganic semiconductor materials have attracted extensive attention due to their excellent TE properties, among which Bi2Te3 is the best and most widely used inorganic TE material at room temperature. However, inorganic TE materials are still restricted by unfavorable factors such as scarcity of raw material resources, heavy metal pollution, high price, high rigidity, and complex processing technology, which greatly limit their development process. Therefore, it is urgent to develop flexible TE materials with high performance, non-polluting, non-toxic and low price. The combination of silk fibroin and inorganic TE materials not only retains the properties of TE materials, but also improves their flexibility. Here, the Bi2Te3/SF TE films are successfully fabricated by the evaporation-assisted self-assembly method with Seebeck coefficient of 199 μV⋅K−1 (p-type) and −240 μV⋅K−1 (n-type). In order to verify the feasibility of collecting and utilizing ambient heat energy in real life, the Bi2Te3/SF TE films are cut into various patterns (such as, flower, rabbit, tree, etc) to collect wasted ambient heat. Further, the Bi2Te3/SF thermoelectric generator (TEG) reaches a maximum power of 21 nW at a temperature difference of 43.5 K. A series of self-power temperature sensing demonstrations from single TE film, TEG, to TEG array are proposed to demonstrate their potential applications in the field of self-power sensors. Finally, by inserting Bi2Te3/SF TEG array into a bracelet, a self-powered smart bracelet can be successfully constructed, demonstrating the feasibility of the Bi2Te3/SF TE film in the development of self-powered wearable electronics.