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Polarity and Air-Stability Transitions in Field-Effect Transistors Based on Fullerenes with Different Solubilizing Groups

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journal contribution
posted on 12.06.2013, 00:00 by Hojeong Yu, Han-Hee Cho, Chul-Hee Cho, Ki-Hyun Kim, Dong Yeong Kim, Bumjoon J. Kim, Joon Hak Oh
A series of o-xylene and indene fullerene derivatives with varying frontier molecular orbital energy levels were utilized for assessing the impact of the number of solubilizing groups on the electrical performance of fullerene-based organic-field-effect transistors (OFETs). The charge-carrier polarity was found to be strongly dependent upon the energy levels of fullerene derivatives. The o-xylene C60 monoadduct (OXCMA) and indene C60 monoadduct (ICMA) exhibited unipolar n-channel behaviors with high electron mobilities, whereas the bis- and trisadducts of indene and o-xylene C60 derivatives showed ambipolar charge transport. The OXCMA OFETs fabricated by solution shearing and molecular n-type doping showed an electron mobility of up to 2.28 cm2 V–1 s–1, which is one of the highest electron mobilities obtained from solution-processed fullerene thin-film devices. Our findings systematically demonstrate the relationship between the energy level and charge-carrier polarity and provide insight into molecular design and processing strategies toward high-performance fullerene-based OFETs.