We have investigated the effect of organic solvents that are used for spin coating 2,7-didodecylbenzothieno[3,2-b]benzothiophene (C12-BTBT) on the electrical characteristics of organic field-effect transistors (OFETs) having a top-gate/bottom-contact configuration to develop high-performance OFETs with simplified solution processes. It is found that spin coating C12-BTBT using binary solvent mixtures comprising toluene and high-boiling point solvents such as p-xylene and mesitylene allows the production of large polycrystalline domains having well-ordered edge-on oriented structures. The solution-processed C12-BTBT OFET devices processed using the binary solvent mixtures exhibit high average field-effect mobilities of greater than 7 cm2 V−1 s−1, low average threshold voltages (Vth) of less than −1 V, and high maximum mobilities of approximately 10 cm2 V−1 s−1. Further, the devices exhibit good operational stabilities, and small Vth shifts of less than 0.5 V are observed after applying a gate bias stress of approximately −1 MV cm−1 for 104 s.
- Binary solvent mixture
- Organic field-effect transistors
- Spin coating
- Top-gate configuration