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Benzo[1,2-b:6,5-b′]dithiophene(dithiazole)-4,5-dione derivatives: Synthesis, electronic properties, crystal packing and charge transport
Y.A. Getmanenko, M. Fonari, C. Risko, B. Sandhu, E. Galán, L. Zhu, P. Tongwa, D.K. Hwang, S. Singh, H. WangShow More
Published in Royal Society of Chemistry
Volume: 1
Issue: 7
Pages: 1467 - 1481
A series of dihalo- and bis-aroyl-substituted benzo[1,2-b:6,5-b′] dithiophene-4,5-diones were synthesized, and their electronic, electrochemical, and electrical properties investigated. Synthetic strategies to increase (i) the conjugation length of the base molecular structure-through introduction of thiophene units bearing electronically neutral substituents (hydrogen or alkyl groups) or strong electron-withdrawing pentafluorobenzoyl group(s)-and (ii) the electron affinity-by moving to a benzo[1,2-d:4,3-d′]bis(thiazole)-4,5- dione structure-were developed. Molecular packing in the single crystal was studied by single-crystal X-ray structural analysis, and this information was subsequently used in the determination of the electronic band structures, densities of states (DOS), effective transfer integrals, and effective charge-carrier masses via density functional theory (DFT) methods. The charge-carrier transport properties of the benzo[1,2-b:6,5-b′]dithiophene- 4,5-dione and benzo[1,2-d:4,3-d′]bis(thiazole)-4,5-dione derivatives were investigated through the fabrication and characterization of organic field-effect transistors (OFETs) via both solution-processed and vacuum-deposited films. 2,7-Bis-pentafluorobenzoyl-benzo[1,2-b:6,5-b′] dithiophene-4,5-dione (10a) exhibited field-effect behavior with an average electron mobility μe = 4.4 (±1.7) × 10-4 cm2 V-1 s-1 when the active layer was vacuum-deposited, and a larger μe= 6.9 × 10-3 cm2 V-1 s-1 when the active layer was solution-processed. These results are in stark contrast with the DFT-determined electronic band structure and effective mass, which indicate that the material possesses good intrinsic charge-carrier transport characteristics. The combined results reveal the importance of thin-film processing and that further processing refinements could lead to improved device performance. Only one material with benzo[1,2-d:4,3-d′]bis(thiazole)-4,5-dione core, 2,7-bis-(4-n-hexyl-thiophene-2-yl)-benzo[1,2-d:4,3-d′]bis(thiazole)-4, 5-dione (19d), showed average μe = 8.2 × 10-5 cm2 V-1 s-1 in OFET with solution-processed active layer. Unexpectedly, measurable hole transport was observed for 2,7-bis-(5-n-nonyl-thiophen-2-yl)-benzo[1,2-b:6,5-b′]dithiophene-4, 5-dione (19b) (μh = 8.5 × 10-5 cm2 V-1 s-1) and 2,6-bis-(thiophen-2-yl)-3,5-di-n-hexyl-4H- cyclopenta[1,2-b:5,4-b′]dithiophen-4-one (30a) (μh = 3.7 × 10-4 cm2 V-1 s-1). © The Royal Society of Chemistry 2013.
About the journal
JournalData powered by TypesetJournal of Materials Chemistry C
PublisherData powered by TypesetRoyal Society of Chemistry