Evaluation of the intrinsic charge carrier transporting properties of linear- and bent-shaped π-extended benzo-fused thieno[3,2-b]thiophenes†
* Corresponding authors
a
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
E-mail:
t-sakurai@chem.eng.osaka-u.ac.jp, seki@chem.eng.osaka-u.ac.jp, miura@chem.eng.osaka-u.ac.jp
Fax: +81-6-6879-4586
b RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
Abstract
The intrinsic charge carrier transporting properties of two isomeric linear- and bent-shaped 7-ring benzo-fused thieno[3,2-b] thiophenes and their octyl-substituted analogues were newly investigated using flash-photolysis (FP-) and field-induced (FI-) time-resolved microwave conductivity (TRMC) techniques. FP-TRMC study in the solid state revealed that octyl-substitution potentially improved the photoconductivity due to the enhanced crystalline lamellar packing. After this screening process, local-scale hole mobilities at the thienoacene–poly(methylmethacrylate) insulator interfaces were precisely recorded using FI-TRMC, reaching up to 4.5 cm2 V−1 s−1 for the linear-shaped non-alkylated thienoacene. The combination of FP- and FI-TRMC measurements provides a rapid and quantitative evaluation scheme even for a variety of compounds with some issues in the processing conditions, leading to the optimized structure of the compounds used as active (interfacial) layers in practical electronic devices.