High mobility n-channel organic field-effect transistors based on soluble C60 and C70 fullerene derivatives

We report on n-channel organic field-effect transistors (OFETs) based on the solution processable methanofullerenes [6,6]-phenyl-C61-butyric acid ester ([60]PCBM) and [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM). Despite the fact that both derivatives form glassy films when processed from solution, their electron mobilities are high and on the order of 0.21 cm2/V s and 0.1 cm2/V s, for [60]PCBM and [70]PCBM, respectively. Although the derived mobility of [60]PCBM is comparable to the best values reported in the literature, the electron mobility of [70]PCBM is the highest value reported to date for any C70 based molecule. We note that this is the only report in which C60 and C70 methanofullerenes exhibit comparable electron mobilities. The present findings could have significant implications in the area of large-area organic electronics and organic photovoltaics where C60 derivatives have so far been the most widely used electron acceptor materials.

Fluorine containing C60 derivatives for high-performance electron transporting field-effect transistors and integrated circuits

We report on electron transporting organic transistors and integrated ring oscillators based on four different solution processible fluorine containing C60 derivatives. Electron mobilities up to 0.15 cm2/V s are obtained from as-prepared bottom-gate, bottom-contact transistors utilizing gold source-drain electrodes. Despite the high mobility, no long-range structural order could be identified with the semiconductor films exhibiting amorphouslike characteristics. The good electron transport is attributed to the structural symmetry of the fullerene derivatives and the enhanced π-π interactions between C60 units even in the case of amorphouslike films. These advantageous characteristics make fluorine containing C60 derivatives attractive for application in high-performance, large-area organic electronics.

Solution processed self-assembled monolayer gate dielectrics for low-voltage organic transistors.:Section Title: Electric Phenomena

Low-voltage org. transistors are sought for implementation in high vol. low-power portable electronics of the future. Here we assess the suitability of three phosphonic acid based self-assembling mols. for use as ultra-thin gate dielecs. in low-voltage soln. processable org. field-effect transistors. In particular, monolayers of phosphonohexadecanoic acid in metal-monolayer-metal type sandwich devices are shown to exhibit low leakage currents and high geometrical capacitance comparable to previously demonstrated self-assembled monolayer (SAM) type dielecs. [1, 2] but with a higher surface energy. The improved surface energy characteristics enable processing of a wider range of org. semiconductors from soln. Transistors based on a no. of soln.-processed org. semiconductors with operating voltages below 2 V are also demonstrated. [on SciFinder(R)