Improved Device Performance of Solution-Processed Single-Wall Carbon Nanotube Transistors by a Patterning Technique Using a Selective Surface Treatment.

During the fabrication processes for single-wall carbon nanotube thin-film transistors (SWCNT-TFTs), the impurities of organic residues such as photoresist and developer can be induced, which affects the charge transport. As a result, solution-processed SWCNT-TFTs exhibit poor and non-uniform device performance regardless of the intrinsic electrical characteristics. Here, we demonstrate a patterning technique using a selective surface treatment with solution-processed hydrophobic fluorocarbon copolymer in SWCNT-TFTs. By using the difference of wettability in a selective area, a channel region in SWCNT-TFTs can be patterned without the conventional photolithography and etching process. Furthermore, the optimized surface treatment results in denser random networks of SWCNTs in the channel patterned by such technique, compared to the dropcasted SWCNT. The statistical results of the key device metrics such as mobility and threshold voltage extracted from 30 SWCNT-TFTs conclusively prove the improved device performance of SWCNT-TFTs fabricated by such pattering technique. We believe that this work can provide a promising route to stimulate the process innovation of fabrication for high performance solution-processed electronics based on SWCNT random networks.