Solution-processed random carbon nanotube networks used in a thin-film transistor

The single-walled carbon nanotube (CNT) was discovered in 1993 [1], with a rolled graphene character [2]. Individual CNTs have a low density, high stiffness, and high axial strength [3]. CNT thin films exhibit superior visible and infrared optical transmittance comparable with the commercial indium tin oxide layer [4]. Depending on the chirality, single-walled CNTs can be either metallic or semiconducting [5]. As-grown CNTs contain both semiconducting and metallic species [6,7]. The metallic content can be eliminated by electrical breakdown [8] or by using density gradient sorting [9]. Semiconducting CNTs used in field-effect transistors exhibit near ballistic transport and high mobility [10,11]. The superior mechanical, optical, and electronic properties of CNTs make them attractive as emerging research material. In recent years, random CNT networks have been applied in high-frequency technique [12-14], chemical and biosensing [15-17], and in flexible and stretchable logic circuits [18-22].