Thermally dried ink-jet process for 6,13-bis(triisopropylsilylethynyl)-pentacene for high mobility and high uniformity on a large area substrate

In this study we developed a simple ink-jet process for 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene), which is known as a high-mobility soluble organic semiconductor, to achieve relatively high-mobility and high-uniformity performance for large-area applications. We analyzed the behavior of fluorescent particles in droplets and applied the results to determining a method of controlling the behavior of TIPS-pentacene molecules. The grain morphology of TIPS-pentacene varied depending on the temperature applied to the droplets during drying. We were able to obtain large and uniform grains at 46 °C without any "coffee stain". The process was applied to a large-size organic thin-film transistor (OTFT) backplane for an electrophoretic display panel containing 192×150 pixels on a 6-in.-sized substrate. The average of mobilities of 36 OTFTs, which were taken from different locations of the backplane, was 0.44±0.08 cm2V-1s-1, with a small deviation of 20%, over a 6-in.-size area comprising 28,800 OTFTs. This process providing high mobility and high uniformity can be achieved by simply maintaining the whole area of the substrate at a specific temperature (46 °C in this case) during drying of the droplets.