The FET performance was significantly improved by Self-Assembled Monolayer (
n-Octyltrichlorosilane (OTS)[O0168]); the OTS-treated device demonstrated the highest performance with a hole carrier mobility of 1.52 cm
2/Vs and an on/off ratio of 1.5 ×10
7 (Figure 1).
In the bare device (without SAM), two weak peaks assignable to face-on orientation were observed (Figure 3b, black arrow), which would create the disadvantage of carrier passes parallel to the substrate (Figure 4a). On the other hand, such peaks were not observed in the pentacene film on the OTS-treated substrate (Figure 3b). It is one reason why the mobility was higher in the OTS-treated OFET device.
A part of X-ray diffraction (XRD: Smart Lab) was conducted at Advanced Characterization Nanotechnology Platform of the University of Tokyo, supported by "Nanotechnology Platform" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.