Cocrystals in the form of crystalline nanosheets comprised of C and (metallo)porphyrins were prepared by using the liquid-liquid interfacial precipitation (LLIP) method where full control over the morphologies in the C/(metallo)porphyrins nanosheets has been accomplished by changing the solvent and the relative molar ratio of fullerene to (metallo)porphyrin. Importantly, the synergy of integrating C and (metallo)porphyrins as electron acceptors and donors, respectively, into nanosheets is substantiated in the form of a near-infrared charge-transfer absorption. The presence of the latter, as reflection of ground-state electron donor-acceptor interactions in the nanosheets, in which a sizable redistribution of charge density from the electron-donating (metallo)porphyrins to the electron-accepting C occurs, leads to a quantitative quenching of the localized (metallo)porphyrin fluorescence. Going beyond the ground-state characterization, excited-state electron donor-acceptor interactions are the preclusion to a full charge transfer featuring formation of a radical ion pair state, that is, the one-electron reduced fullerene and the one-electron oxidized (metallo)porphyrin.

Fullerene has been expected to realize next generation nanoelectronics as a key element. However, although single-fullerene switch operation using scanning tunneling microscope (STM) has been developed, the structural architecture with electrodes is still needed to make progress as devices. Because the fullerenes are smaller than 1.0 nm, which is suitable for the STM approach, the subnanometer size is still too small, even with the latest device electrode fabrication techniques. Here we present the principle experiment on a self-assembling fullerene nanowire to drive single-fullerene switch. A fullerene C60-nanowire (C60NW), which was synthesized at a liquid–liquid interface, exhibited negative differential resistance (NDR) and two-state resistance switching generated by local polymerization and depolymerization among the C60 molecules. A C60NW was electrically characterized after a preset treatment to induce C60NW conductivity by electron-beam (EB) irradiation to form an initial conduction path. A current though the C60NW increased more than 100-fold after the preset treatment, whereas an as-grown C60NW exhibited a nanoampere-level current under a 20 V bias voltage. The current–voltage characteristics showed a nonlinear current increase and NDR, leading to reproducible two-state resistance switching under bias-voltage modulation. The nonlinear current increase, the NDR, and the resistance switching are explained by local energy control of the current-induced connection and disconnection of C60 molecules, leading to tunneling current modulation toward a single element of C60 in a nanomaterial switching function.

n-Heptanol bearing a long hydrocarbon chain is for the first time attempted as poor solvent for reprecipitation of fullerene C60 crystals, which unprecedentedly prompts the selective synthesis of well-faceted parallelepiped, hexagonal plate, cuboctahedron, octahedron C60 crystals, as well as their derivatives with varying degrees of edge- and corner-truncation. Our comprehensive investigations support that morphology evolution is systematically modulated by the solvent proportion of n-heptanol, where increasing the proportion of n-heptanol gradually tunes C60 growth behavior from thermodynamic to kinetic regime, and thus induces a general shape evolution from parallelepiped or truncated parallelepiped, to an intermediate shape like hexagonal plate or truncated octahedron or cuboctahedron, eventually into octahedron. We also prove the existence of n-heptanol molecules as high as 10 wt % inside the final C60 polyhedral crystals, which results in the extraordinarily PL enhancement as well as an obvious blue-shift of PL peaks when compared to that of the solvent-free crystal. Our study provides a fundamental understanding toward the solvent-mediated shape-control process for organic polyhedral crystals, enlightening on solvent-intercalate-induced unique properties.

We discovered that solvents play a critical role in determining the morphology, formation process and intrinsic properties of several C70 one-dimensional microstructures, which show superior photoelectrochemical properties.