Using a flexographic printer for organic field effect transistors

Field effect transistors (FETs) are key elements in printed electronic applications. Electronics are expanding into new fields where cost of manufacture is critical, which has lead to the development of new methods for preparing devices. Such application areas are for example simple devices used in packages and other "throw away" products where embedded electronics may give additional value. In this work flexible organic FETs are studied, where the flexographic (flexo) printing method is used for manufacture of polymer elements in the device. The main component geometry used in this study is the thin film transistor and the flexographic printing method is used primarily for manufacture of semiconductor and dielectric layers using solutions of regioregular poly(3hexylthiophene) and polyhydroxystyrene, respectively. The use of flexographic printing methods for doublelayer polymer structures are investigated and the devices are characterized in various stages of manufacture. The electrode layers are initially made from metal thin films using standard methods, or by using a flexo printed etching mask, as the resolution and printing quality of high conductivity polymers using the flexo printing method is not as such ideal for the desired transistor channel dimensions/geometry. The gate electrode is made using inkjet or flexo for conducting polymer electrodes or by metal evaporation. The flexographic printing method is chosen as it allows for lowcost fabrication using organic material in solution and the process is easily scaled for high volumes.