X-Ray photoelectron spectroscopy characteristics of a novel organic semiconductor BTQBT and its derivatives

Abstract

X-Ray photoelectron spectra of bis[1,2,5]thiadiazole-p-quinobis(1,3-dithiole)(BTQBT) reveal that the sulfur and carbon atoms in the molecules show four- and two-peak profiles, respectively, and are in mixed-valence states. Substitution of the sulfur atoms linked to nitrogen atoms by selenium atoms removes the mixed valency of sulfur. In systems with asymmetrical molecular skeletons, such as TMBTQBT, TMTBTQBT and DBBTQBT, sulfur and carbon atoms are also in mixed-valence states. TMBTQBT shows the largest energy difference between the C 1s and S 2p peaks, indicating the largest charge distribution. Each of the S 2p and C 1s peaks is accompanied by shake-up satellites located to higher energy at ca. 2.7 eV from the corresponding photoelectron main peak.