Hall-effect observation in the new organic semiconductor bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole)(BTQBT)

Abstract

Single crystals of bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole)(BTQBT) were grown either by recrystallization from a nitrobenzene solution or by sublimation in nitrogen atmosphere The electrical resistivities were 1.2 × 10³Ω cm and 2.7 × 10⁵Ω cm at room temperature for a crystal grown by recrystallization and that obtained by sublimation, respectively. These values are remarkably low for a single-component organic crystal. In addition, the BTQBT crystals have a small anisotropy in resistivity (ρ_⊥/ρ∥, ≈ 2), which is ascribed to strong intermolecular interactions inherent in the crystal structure. They show a Hall effect which is an unusual observation in organic semiconductors. The sign of carriers was determined to be positive and the Hall mobility was found to be ca. 4 cm² s^–1 V^–1 at room temperature.