An integral p-n connected all-graphene fiber boosting wearable thermoelectric energy harvesting

Fiber-based thermoelectric (TE) generators have arose significant attention in recent years for portable energy supply devices. However, it is still a great challenge to fabricate integral p-n type connected graphene fibers (GFs) at present. Herein, we prepared p-type GFs by a simple process of chemical reduction. An integral p-n connected all-graphene fiber without additional adhesive was obtained with discontinuous doping with electron-donating polyethyleneimine ethoxylated (PEIE). The integral p-n connected GFs displayed a steady electrical conductivity, excellent flexibility and acceptable tensile properties. Furthermore, a flexible wearable TE generator was fabricated through integrating as-prepared integral p-n connected GFs into flexible polydimethylsiloxane (PDMS) substrate, exhibiting a stable output power at the temperature difference between human body and air temperature, which may provide a good reference for fiber-based wearable TE energy supply.