title: Ambipolar-transporting coaxial nanotubes with a tailored molecular graphene-fullerene heterojunction.
abstract: Despite a large steric bulk of C(60), a molecular graphene with a covalently linked C(60) pendant [hexabenzocoronene (HBC)-C(60); 1] self-assembles into a coaxial nanotube whose wall consists of a graphite-like pi-stacked HBC array, whereas the nanotube surface is fully covered by a molecular layer of clustering C(60). Because of this explicit coaxial configuration, the nanotube exhibits an ambipolar character in the field-effect transistor output [hole mobility (micro(h)) = 9.7 x 10(-7) cm(2) V(-1) s(-1); electron mobility (micro(e)) = 1.1 x 10(-5) cm(2) V(-1) s(-1)] and displays a photovoltaic response upon light illumination. Successful coassembly of 1 and an HBC derivative without C(60) (2) allows for tailoring the p/n heterojunction in the nanotube, so that its ambipolar carrier transport property can be optimized for enhancing the open-circuit voltage in the photovoltaic output. As evaluated by an electrodeless method called flash-photolysis time-resolved microwave conductivity technique, the intratubular hole mobility (2.0 cm(2) V(-1) s(-1)) of a coassembled nanotube containing 10 mol % of HBC-C(60) (1) is as large as the intersheet mobility in graphite. The homotropic nanotube of 2 blended with a soluble C(60) derivative [(6,6)-phenyl C(61) butyric acid methyl ester] displayed a photovoltaic response with a much different composition dependency, where the largest open-circuit voltage attained was obviously lower than that realized by the coassembly of 1 and 2.
authors: Nanospace Project, Exploratory Research for Advanced Technology-Solution Oriented Research for Science and Technology, Japan Science and Technology Agency, National Museum of Emerging Science and Innovation, Tokyo 135-0064, Japan.
authors: Yohei
authors: Y
authors: Yamamoto
authors: Guanxin
authors: G
authors: Zhang
authors: Wusong
authors: W
authors: Jin
authors: Takanori
authors: T
authors: Fukushima
authors: Noriyuki
authors: N
authors: Ishii
authors: Akinori
authors: A
authors: Saeki
authors: Shu
authors: S
authors: Seki
authors: Seiichi
authors: S
authors: Tagawa
authors: Takeo
authors: T
authors: Minari
authors: Kazuhito
authors: K
authors: Tsukagoshi
authors: Takuzo
authors: T
authors: Aida