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| The vanadyl phthalocyanine thin film transistors were fabricated on the various organosilane self-assembled monolayer (SAM) modified substrates, and how the performance of these transistors affected by the surface properties was studied. The morphologies and X-ray diffraction (XRD) spectrums of vanadyl phthalocyanine films on different SAM-modified surfaces were studied. The study of atomic force microscopy (AFM) and XRD reveals that the vanadyl phthalocyanine film on octadecyltrichlorosilane (OTS) modified substrate has much larger crystal size and better crystalline than those on phenyltrichlorosilane (PTS), 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS) as well as non-modified substrates, and which contributes that the mobility of corresponding device is several and several dozen times relative to other ones. In addition, by means of static contact angle measurements, the wettabilities of water on silicon dioxide substrates modified with various organosilane SAMs were studied. The results of static contact angle measurements, XRD and AFM reveal that not only the surface hydrophobicity but also the length and type of organic capping group in organosilane SAMs affect the growth of VOPc films and device performance. The highest mobility for the transistor on OTS treated substrates may be due to that the attractive force between VOPc and OTS modified surface is smallest. The crystalline and crystal grain size of VOPc film on PTS is somewhere in between that on OTS treated and non-modified substrate may be the existence of attractive force between VOPc and SiO2 for the length of phenyl group in PTS is much shorter than alkyl chain group in OTS. The VOPc films' performance and crystalline on FDTS treated are worse than that on PTS, which may be the existents of attractive force between -CF3 and VOPc. |
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| Keywords:Organosilane self-assembled monolayer; Surface properties; Organic thin film transistors |
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