Published on Web 08/23/2008
Structure and Properties of Small Molecule-Polymer Blend Semiconductors for Organic Thin Film Transistors Jihoon Kang,† Nayool Shin,† Do Young Jang,† Vivek M. Prabhu,*,‡ and Do Y. Yoon*,† Department of Chemistry, Seoul National UniVersity, Seoul, 151-747, Korea, and Polymers DiVision, National Institute of Standards & Technology, Gaithersburg, Maryland 20899 Received June 4, 2008; E-mail:
[email protected];
[email protected] Organic semiconductors are generally regarded to be the most critical element of the new generation of optoelectronic devices such as printable flexible electronics and photovoltaic devices.1,2 Therefore, organic small molecule and polymer semiconductors3-5 have been actively investigated to obtain the desired electrical properties. However, their field-effect mobility, solution processability and long-term performance stability must still be substantially improved6 in order to match conventional amorphous silicon semiconductors whose field-effect mobilities reach as high as ca. 1 cm2/Vs. Recently, small molecule organic semiconductors have achieved field-effect mobilities over 1 cm2/Vs due to the intelligent design and synthesis of organic molecules with novel molecular packing structure and high crystallinity.4,7-9 However, the solution processing of small molecules, necessary for printable electronic devices, encounters serious issues including the nonuniform film thickness and coating problems such as dewetting. In comparison, polymer semiconductors are well suited for the solution-processing because of their excellent film-forming characteristics. But semiconducting polymer films generally show a limited charge carrier mobility (
