Abstract
Solution-processed indacenodithiophene (IDT)-based small molecules with 1,3-indanedione (ID) as terminal acceptor units and 3,3 '-hexyl-terthiophene (IDT-3Th-ID(I)) or 4,4 '-hexyl-terthiophene (IDT-3Th-ID(II)) as pi-bridges, have been designed and synthesized for the application in organic field-effect transistors (OFETs) and organic solar cells (OSCs). These molecules exhibited excellent solubility in common organic solvents, good film-forming ability, reasonable thermal stability, and low HOMO energy levels. For the OFETs devices, high hole motilities of 0.52 cm(2)V (1) s (1) for IDT-3Th-ID(I) and 0.61 cm(2) V (1) s (1) for IDT-3Th-ID(II) were achieved, with corresponding high I-ON/I-OFF of ca. 10(7) and similar to 10(9) respectively. The OSCs based on IDT-3Th-ID(I)/PC70BM (2:1, w/w) and IDT-3Th-ID( II)/PC70BM (2: 1, w/w) without using any treatment of solvent additive or thermal annealing, showed power conversion efficiencies (PCEs) of 3.07% for IDT-3Th-ID(I) and 2.83% for IDT-3Th-ID(II), under the illumination of AM 1.5G, 100 mW/cm(2). The results demonstrate that the small molecules constructed with the highly pi-conjugated IDT as donor unit, 3Th as pi-bridges and ID as acceptor units, could be promising organic semiconductors for high-performance OFETs and OSCs applications. (C) 2014 Elsevier B. V. All rights reserved.