Highly integrated fiber-shaped thermoelectric generators with radially heterogeneous interlayers

The construction of high-density thermoelectric (TE) pairs on small TE devices to improve the utilization of thermal energy has garnered extensive attention. The fabrication of high-density TE pairs in fiber-shaped TE devices with curved surfaces remains challenging. Herein, we report a flexible scrolled TE module with interlayers of radial heterojunction that possesses high-density p-n junctions, accomplished by rolling a patterned carbon nanotube film (active material layer) and a cellulose acetate nanofiber membrane (insulation). This module achieves high integration of ~3.32 mm3 per TE pair and a high output voltage density of ~65.4 mV/cm2 at a temperature difference of 41 K when the length of the scrolled module is 2 cm. Furthermore, a fiber-shaped TE device is designed by interconnecting the scrolled modules. The design of p-n junctions in the axial and radial directions of the fiber-shaped device is realized, and an open-circuit voltage (Voc) density of 0.176 mV/(cm·K) is achieved. In addition, the fiber-shaped TE device can be woven with commercial yarns to construct TE fabric for harvesting the thermal energy of the human body through alternating scrolled modules. This indicates its potential application for the harvesting of wearable energy.