HALL-EFFECT OBSERVATION IN THE NEW ORGANIC SEMICONDUCTOR BIS(1,2,5-THIADIAZOLO)-P-QUINOBIS(1,3-DITHIOLE) (BTQBT)

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 x 10(3)-OMEGA cm and 2.7 x 10(5)-OMEGA 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 (rho(perpendicular-to)/rho(parallel-to) almost-equal-to 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.