Jianmei Chen

Enabling Light Work in Helical Self-Assembly for Dynamic Amplification of Chirality with Photoreversibility

Light-driven transcription and replication are always subordinate to a delicate chirality transfer. Enabling light work in construction of the helical self-assembly with reversible chiral transformation becomes attractive. Herein we demonstrate that a helical hydrogen-bonded self-assembly is reversibly photoswitched between photochromic open and closed forms upon irradiation with alternative UV and visible light, in which molecular chirality is amplified with the formation of helixes at supramolecular level. The characteristics in these superhelixes such as left-handed or right-handed twist and helical length, height, and pitch are revealed by SEM and AFM. The helical photoswitchable nanostructure provides an easily accessible route to an unprecedented photoreversible modulation in morphology, fluorescence, and helicity, with precise assembly/disassembly architectures similar to biological systems such as protein and DNA.

Scalable Fabrication of Multiplexed Plasmonic Nanoparticle Structures Based on AFM Lithography

A controllable and scalable strategy is developed to fabricate multiplexed plasmonic nanoparticle structures by mechanical scratching with AFM lithography, which exhibit multiplex plasmonic properties and surface-enhanced Raman scattering responses. It offers an intuitive way to explore the plasmonic effects on the performance of an organic light-emitting diode device integrating with multiplexed plasmonic nanostructures.

Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

Plamon-enhanced optoelectronic devices based on metal nanostructures

Optoelectronic devices can harvest, control and detect light and they are highly important in developing solar cells, sensors and lasers. Recently, the emergence of plasmonics has raised interest to examine the optical nanoantenna properties based on plasmonic metal nanostructures, which shows various promising applications including plasmonic chips, light generation, biosensing, and subwavelength and nonlinear optics. Currently plasmonic nanostructures has reached the stage of development where the subject of most investigations is not individual nanostructures but rather systems of much greater complexity. The multiplex nanomaterial system is expected to result in qualitative and quantitative improvements of their functional properties. Therefore developing optoelectronic device based on nanoantenna effect of multiplex plasmonic nanostructures would have a deep impact on microelectronic technologies, and it is particularly relevant to the demand for high performance antenna to be applied to the applications, e.g., electromagnetics, electro-optics. To achieve this goal, we have developed several new approaches to fabricate multiplex plasmonic nanostructures to assemble nanoparticles of different size with designated inter-particle distance and explore advanced optoelectronic devices based on the plasmonic effect of mutiplex plasmonic nanostructures.