Jinzhi Li

Morphology and structure of mono- and few-layer graphene produced by jet cavitation

We prepared mono- and few-layer graphene with micrometer-sized dimensions in aqueous solution by a jet cavitation method starting from common crystal graphite, which is totally green, facile, low-cost, and laborsaving. The graphene yield by our method is estimated as ∼4 wt. % by statistical analysis. Diverse microscopy is used to characterize the morphology, microstructure, and near-edge fine structure of the prepared nanosheets. It is found that partial folding allows realization of rotational stacking fault in otherwise perfect samples. The folded graphene with Morie patterns could be ideal specimens for experimentally probing band structure and electronic properties of graphene with different stacking styles.

Parallel molecular stacks of organic thin film with electrical bistability

A thin film of 1,1-dicyano-2,2-(4-dimethylaminophenyl) ethylene (DDME) has been grown by a modified vacuum deposition. The films were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning tunneling microscopy (STM). Highly ordered parallel molecular stacks were repeatedly observed with STM under ambient conditions. The dc current–voltage (I–V) characteristics of device Au/DDME/Au were measured, and the film was found to possess good electrical bistability and electrochromic properties. Nanometer-scale recording was realized on the film by applying pulse voltage between the STM tip and substrate. The possible switching mechanism is discussed.

Growth and characterization of polyaniline 7,7,8,8-tetracyanoquino-dimethane (TCNQ) complex films grown by vacuum evaporation

Abstract High quality polycrystalline polyaniline/7,7,8,8-tetracyanoquino-dimethane (PANI–TCNQ) complex thin films have been grown by vacuum evaporation. A scanning tunneling microscope, transmission electron microscopy and high resolution scanning electron microscopy characterized the films. The films showed totally different optical and electrical properties from both of PANI and TCNQ films. Unusual two-dimensional aggregates were observed in the films. A charge transfer phenomenon, from the PANI chains to the TCNQ molecules, was observed from the Fourier transfer infrared spectrum. Compared with that of PANI and TCNQ thin films, the structural and electrical properties of the PANI–TCNQ thin films are discussed.