Semiconducting
[(Bi<sub>4</sub>Te<sub>4</sub>Br<sub>2</sub>)(Al<sub>2</sub>Cl<sub>6–<i>x</i></sub>Br<sub><i>x</i></sub>)]Cl<sub>2</sub> and [Bi<sub>2</sub>Se<sub>2</sub>Br](AlCl<sub>4</sub>): Cationic
Chalcogenide Frameworks from Lewis Acidic Ionic Liquids
- Publication date
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Abstract
Lewis
acidic organic ionic liquids provide a novel synthetic medium to prepare
new semiconducting chalcogenides, [(Bi<sub>4</sub>Te<sub>4</sub>Br<sub>2</sub>)(Al<sub>2</sub>Cl<sub>5.46</sub>Br<sub>0.54</sub>)]Cl<sub>2</sub> (<b>1</b>) and [Bi<sub>2</sub>Se<sub>2</sub>Br](AlCl<sub>4</sub>) (<b>2</b>). Compound <b>1</b> features a cationic
[(Bi<sub>4</sub>Te<sub>4</sub>Br<sub>2</sub>)(Al<sub>2</sub>Cl<sub>5.46</sub>Br<sub>0.54</sub>)]<sup>2+</sup> three-dimensional framework,
while compound <b>2</b> consists of cationic layers of [Bi<sub>2</sub>Se<sub>2</sub>Br]<sup>2+</sup>. Spectroscopically measured
band gaps of <b>1</b> and <b>2</b> are ∼0.6 and
∼1.2 eV, respectively. Thermoelectric power measurements of
single crystals of <b>1</b> indicate an n-type semiconductor
