Enhancement of thermoelectric performance in slightly charge-compensated CeyCo4Sb12 skutterudites

Minute amounts of Fe/Mn are selected to be doped into CeyCo4Sb12 filled skutterudites to slightly compensate for electrons donated by the fillers. As a direct result, the Ce filling fractions are enhanced from 0.11 to 0.16. The carrier concentrations are improved by a factor of more than two times to approach the optimal values, leading to greatly improved power factors. Meanwhile, the lattice thermal conductivity is expectedly suppressed by the increased Ce fillers in the voids of skutterudites. Consequently, a maximum ZT of 1.3 at 850 K is obtained, which is comparable to that in the best single-filled skutterudites.