Investigation of charge interaction between fullerene derivatives and single‐walled carbon nanotubes

Abstract The charge interaction and corresponding doping effect between single‐walled carbon nanotubes (SWNTs) and various fullerene derivatives, namely, C60, phenyl‐C61‐butyric acid methyl ester (PC61BM), methano‐indenefullerene (MIF), 1′,1″,4′,4″‐tetrahydrodi[1,4]methanonaphthaleno[5,6]fullerene (ICBA), 1,4‐bis(dimethylphenylsilylmethyl)[60]fullerene (SIMEF‐1), and dimethyl(orthoanisyl) silylmethyl(dimethylphenylsilylmethyl)[60]fullerene (SIMEF‐2), are investigated. A variety of analytical techniques, including field‐effect transistors (FETs) made of horizontally aligned arrays of SWNTs, is used as a means of investigation. Data from different measurements have to be used to obtain a concrete evaluation for the fullerene‐applied SWNTs. The data collectively points toward the conclusion that fullerenes with high molecular orbital energy levels, namely, MIF, SIMEF‐1, SIMEF‐2, and PC61BM, induce p‐type doping, while fullerenes with low molecular orbital energy levels, namely, ICBA and C60, induce n‐type doping on the carbon nanotubes. Nevertheless, the SWNTs retained p‐type characteristics because n‐doping induced by the fullerenes are weak compared to the p‐doping of the water and oxygen on carbon nanotubes. This means that fullerene derivatives have the ability to fine‐tune the energy levels of carbon nanotubes, which can play a crucial role in carbon nanotube‐based electronics, such as solar cells, light‐emitting devices, and FETs.