Synergetic enhancement of thermoelectric performances by localized carrier and phonon scattering in Cu 2 Se with incorporated fullerene nanoparticles.

C 60 /Cu 2 Se thermoelectric nanocomposites were synthesized with various amounts of fullerene (C 60 ; 0.03, 0.3, 0.5, 0.7 mol%) incorporated in Cu 2 Se. The thermoelectric figures of merits ( zT ) of the C 60 /Cu 2 Se nanocomposites were enhanced by 20-30% compared to that of pure Cu 2 Se, reaching a value of 1.4 at 773 K. The primary cause of zT enhancement is the synergetic effect of thermal conductivity reduction by phonon scattering and Seebeck coefficient increase by carrier localization that results from incorporation of C 60 nanoparticles. Theoretical calculations for Seebeck coefficient enhancement and lattice thermal conductivity reduction were performed. The Seebeck coefficients of C 60 /Cu 2 Se nanocomposites were around 43% higher than that of pure Cu 2 Se, whereas the reduction of lattice thermal conductivity with incorporation of C 60 was around 40-50%.