title: A supercell approach to the doping effect on the thermoelectric properties of SnSe.
abstract: We study the thermoelectric properties of tin selenide (SnSe) by using first-principles calculations coupled with the Boltzmann transport theory. A recent experimental study showed that SnSe gives an unprecedented thermoelectric figure of merit ZT of 2.6 ± 0.3 in the high-temperature (>750 K) phase, while ZT in the low-temperature phase (<750 K) is much smaller than that of the high-temperature phase. Here we explore the possibility of increasing ZT in the low-temperature regime by carrier doping. For this purpose, we adopt a supercell approach to model the doped systems. We first examine the validity of the conventional rigid-band approximation (RBA), and then investigate the thermoelectric properties of Ag or Bi doped SnSe as p- or n-type doped materials using our supercell method. We found that both types of doping improve ZT and/or the power factor of the low-temperature phase SnSe, but only after the adjustment of the appropriate doping level is achieved.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan. hs-nakamura@aist.go.jp.
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hisao
authors.initials: H
authors.lastname: Nakamura