title: Semiconducting [(Bi4Te4Br2)(Al2Cl(6-x)Br(x))]Cl2 and [Bi2Se2Br](AlCl4): cationic chalcogenide frameworks from Lewis acidic ionic liquids.
abstract: Lewis acidic organic ionic liquids provide a novel synthetic medium to prepare new semiconducting chalcogenides, [(Bi4Te4Br2)(Al2Cl5.46Br0.54)]Cl2 (1) and [Bi2Se2Br](AlCl4) (2). Compound 1 features a cationic [(Bi4Te4Br2)(Al2Cl5.46Br0.54)](2+) three-dimensional framework, while compound 2 consists of cationic layers of [Bi2Se2Br](2+). Spectroscopically measured band gaps of 1 and 2 are ∼0.6 and ∼1.2 eV, respectively. Thermoelectric power measurements of single crystals of 1 indicate an n-type semiconductor.
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Kanishka
authors.initials: K
authors.lastname: Biswas
authors.forename: In
authors.initials: I
authors.lastname: Chung
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Song
authors.forename: Christos D
authors.initials: CD
authors.lastname: Malliakas
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Freeman
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis