Abstract
Possible superconductivity in the recently discovered (Tl,K)FexSe2 compounds is studied from the viewpoint of doped Mott insulator. The Mott insulating phase is examined to be preferred in the parent compound at x=1.5 due to the presence of Fe-vacancies. Partial filling of vacancies at the Fe-sites introduces electron carriers and leads to electron-doped superconductivity. By using a two-orbital Hubbard model in the strong-coupling limit, we find that the s-wave pairing is more favorable at small Hund's coupling, and dx2−y2-wave pairing is more favorable at large Hund's coupling.