Inkjet Printed Organic Thin Film Transistors: Achievements and Challenges

Abstract

Inkjet printing of organic thin film transistors is an enabling technology for many applications requiring low cost electronics such as RFID tags, sensors, e-paper, and displays. This review summarizes the achievements and remaining challendges in the field. An all inkjet printed organic thin film transistor is feasible, but manufacturability needs to be improved. Often, a hybrid process in which only some layers are inkjet printed is used. Development of devices requires optimization of (1) ink chemistry, (2) inkjet process, (3) substrate ink interaction, and (4) new device structures. Several conducting, dielectric and semiconducting materials have been used to formulate ink. It appears that metal nanoparticle based conducting ink and PEDOT:PSS are widely used materials to fabricate source, drain and gate electrodes. PVPh is the most popular dielectric material for inkjet printing. To print semiconducting layer, both polymers and oligomers/small molecules are used. Many high performance organic semiconductors are p-type, but few n-type organic semiconductors show excellent performance. In addition to improved materials, challenges inherent in the inkjet process also need solutions. These are registration, alignment of the source,and drain with gate, resolution, reducing off-state current, and roll-to-roll processing.