Novel butterfly-shaped organic semiconductor and single-walled carbon nanotube composites for high performance thermoelectric generators

Herein, a series of novel butterfly-shaped small-molecule organic semiconductors (OSCs) have been designed, synthesized and complexed with single-walled carbon nanotubes (SWCNTs) as p-type thermoelectric materials. The butterfly-shaped molecules exhibit curved molecular structures, which tune their frontier molecular orbitals and increase their interactions with SWCNTs. A systematic study shows that the composites based on butterfly-shaped OSCs exhibit significantly improved thermoelectric performances compared with that of the composite based on the analoguous planar OSC. The enhanced thermoelectric performances are attributable to the higher activation energy, improved doping level and charge transport process between the organic molecules and SWCNTs. The butterfly-shaped OSC and SWCNT composite opens up a new avenue for the design of thermoelectric materials and devices.