Seebeck coefficient and thermal conductivity in doped C60

Abstract

Pressed bulk samples of C60 doped with P, Co, Al, and Bi have been investigated for their thermoelectric properties. These samples show extremely low thermal conductivity, typically in the range of 0.1–0.3W∕Km at room temperature. The Seebeck coefficients of Co, Al, and Bi doped C60 solids are in the tens of μV∕K; however, for P doped C60 samples, a very large Seebeck coefficient in the order of 103μV∕K was observed. The value of the Seebeck coefficient seems to depend sensitively on the P concentration and changes sign upon annealing at 100°C. Ab initio density functional theory calculations show that the calculated electronic structures and the activation energies strongly depend on the dopants in C60 solids. The high Seebeck coefficient in studied P doped C60 is due to the system’s unique dopant and concentration.