Organic transistors based on airbrushed small molecule-insulating polymer blends with mobilities exceeding 1 cm2 V−1 s−1†
Abstract
Spray-coating, has recently fueled scientific interest as a versatile solution-processing technique for the realization of organic electronic devices, such as organic field-effect transistors (OFETs). In the present work, air-brush method was used for the deposition of semiconducting blends of triisopropylsilylethynyl-pentacene (TIPS-PEN) and common insulating polymers of polystyrene or polymethylmethacrylate. The use of such blend systems not only resulted in an improved wet film formation but also enabled efficient control over the crystallization process. A systematic study on the effect of different composition ratio on the morphology and crystallinity of the sprayed films as well as their macroscopic uniformity, was carried out. Both blend systems revealed well-ordered TIPS-PEN crystalline domains on the top surface, indicative of the pronounced phase separation phenomena. The optimized airbrushed OFETs exhibited excellent electrical characteristics with a maximum hole mobility value of 1.3 cm2 V−1 s−1, negligible hysteresis, near-zero turn-on voltages and on/off current ratio greater than 105. Additionally, the transistors revealed good long-term environmental stability, with no significant degradation after a period of 13 months. These results represent an important step for present and future applications of spaying techniques toward the controlled growth of high performance and environmentally stable OFETs.