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Abstract Faux‐hawk fullerenes are promising candidates for high‐performance organic field‐effect transistors (OFETs). They show dense molecular packing and high thermal stability. Furthermore, in contrast to most other C60derivates, functionalization of the fullerene core by the fluorinated group C6F4CF2does not increase their lowest unoccupied orbital position, which allows the use of air‐stable molecular n‐dopants to optimize their performance. The influence of n‐doping on the performance of OFETs based on the faux‐hawk fullerene 1,9‐C60(cyclo‐CF2(2‐C6F4)) (C60FHF) is studied. An analytic model for n‐doped transistors is presented and used to clarify the origin of the increase in the subthreshold swing usually observed in doped OFETs. It is shown that the increase in subthreshold swing can be minimized by using a bulk dopant layer at the gate dielectric/C60FHF layer instead of a mixed host:dopant layer. Following an optimization of the OFETs, an average electron mobility of 0.34 cm2 V−1 s−1, a subthreshold swing below 400 mV dec−1for doped transistors, and a contact resistance of 10 kΩ cm is obtained, which is among the best performance for fullerene based n‐type semiconductors.
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The first successful example of vacuum‐deposited organic photovoltaic (OPV) cells based on a fullerene derivative and a small‐molecule donor is reported. A series of thermally robust fluorous fullerene acceptors with experimental gas‐phase electron affinities ranging from 2.8 to 3.3 eV are paired with a new dicyanovinyl thiophene‐based molecular donor to enable direct comparison of their performance in planar and bulk heterojunction architectures in the cells fabricated by vacuum deposition. Unprecedented insights into the role of the acceptor intrinsic molecular and electronic structures are obtained, which are not obscured by solvent and additive effects as in the typical solution‐processed fullerene‐based OPV cells.
