Flexible layer-structured Bi2Te3 thermoelectric on a carbon nanotube scaffold

Inorganic chalcogenides are traditional high-performance thermoelectric materials. However, they suffer from intrinsic brittleness and it is very difficult to obtain materials with both high thermoelectric ability and good flexibility. Here, we report a flexible thermoelectric material comprising highly ordered Bi2Te3 nanocrystals anchored on a single-walled carbon nanotube (SWCNT) network, where a crystallographic relationship exists between the Bi2Te3 <<(1)over bar>2 (1) over bar0> orientation and SWCNT bundle axis. This material has a power factor of similar to 1,600 mu Wm(-1)K(-2) at room temperature, decreasing to 1,100 mu Wm(-1) K-2 at 473 K. With a low in-plane lattice thermal conductivity of 0.26 +/- 0.03 Wm(-1) K-1, a maximum thermoelectric figure of merit (ZT) of 0.89 at room temperature is achieved, originating from a strong phonon scattering effect. The origin of the excellent flexibility and thermoelectric performance of the Bi2Te3-SWCNT material is attributed, by experimental and computational evidence, to its crystal orientation, interface and nanopore structure. Our results provide insight into the design and fabrication of high-performance flexible thermoelectric materials.