Heterostructured semiconductor single-walled carbon nanotube films for solution-processed high-performance field-effect transistors

In this paper, we report a simple and effective method to simultaneously achieve a high chargecarrier mobility and low off current in conjugated polymer-wrapped semiconducting singlewalled carbon nanotube (s-SWNT) transistors by applying a SWNT bilayer. To achieve the high mobility and low off current, highly purified and less purified s-SWNTs are successively coated to form the semiconducting layer consisting of poly (3-dodecylthiophene-2,5-diyl) (P3DDT)-wrapped high-pressure carbon mono oxide (HiPCO) SWNT (P3DDT-HiPCO) and poly (9, 9-din-dodecylfluorene) (PFDD)-wrapped plasma discharge (PD) SWNT (PFDD-PD). The SWNT transistors with bilayer SWNT networked film showed highly improved hole field-effect mobility (6.18. +/-. 0.85 cm(2)V(-1)s(-1) average), on/off current ratio (107), and off current (similar to 1 pA). Thus, the combination of less purified PFDD-PD (98%-99%) charge-injection layer and highly purified s-P3DDT-HiPCO (> 99%) charge-transport layer as the bi-layered semiconducting film achieved high mobility and low off current simultaneously.