Eiji Fukuzaki

High performance solution-crystallized thin-film transistors based on V-shaped thieno[3,2-f:4,5-f′]bis[1]benzothiophene semiconductors

A new class of solution-processable thieno[3,2-f:4,5-f′]bis[1]benzothiophene (TBBT-V) semiconductors are investigated. Semiconductors with decyl substituents and two kinds of π-extended decylthienyl substituents are facially derivatized from functionalized dibromo-substituted TBBT-Vvia either a Negishi or a Stille cross coupling procedure. The solubilities of TBBT-V semiconductors are somewhat higher than those of their previously developed dinaphtho[2,3-b:2′,3′-d]thiophene (DNT-V) counterparts. Single crystal analysis together with a calculation study on the transfer integral and the band structure in decyl-substituted TBBT-V (C10-TBBT-V) clarifies that these semiconductors form two-dimensionally ordered herringbone packing structures and the effective mass in the columnar direction rivals that of the previously developed decyl-substituted DNT-V. The carrier mobilities of TBBT-V derivatives in solution grown into single-crystalline films are remarkable (up to 6.2 cm2 V−1 s−1). Furthermore, their operation voltages are apparently lower than those of previously developed DNT-V derivatives due to the optimized ionization potential of the TBBT-V core and further π-extension by substitution of the thienyl groups.