When Molecules and Materials Clash: Pathways to high efficiency solution processed solar cells

Molecules figure prominently in the electronic properties of emerging materials ranging from organic photovoltaics (OPVs) to colloidal quantum dots (CQDs) and organo-halide perovskites used in solution processed photovoltaics and photodetectors. The Asbury group has pioneered the development of ultrafast infrared spectroscopy techniques to examine electronic processes in materials with particular focus on the influence that underlying molecular structures have on those processes. This talk will focus on two applications of infrared spectroscopy to examine electronic processes in

Photo-induced force microscopy: nanoscale imaging with chemical recognition

The advances in nanotechnology have intensified the need for tools that can characterize newly synthesized nano materials. A powerful approach to address this need is the combination of scanned probe techniques with optical illumination, which combines the nanoscopic resolution provided by a sharp tip with the chemical recognition provided by optical spectroscopy. A new and powerful technique in this direction is photo-induced force microscopy (PiFM), which enables spectroscopic probing of materials with a spatial resolution under 10 nm.

Probing structure and dynamics of hydration clusters at atomic scale: a combined STM and NC-AFM study

Ion hydration is of relevance for a wide range of systems, including electrochemistry, biological environments and atmospheric aerosols. In spite of massive experimental and theoretical efforts, the effect of ions on the structure and dynamics of water has been under persistent debate. Based on the ability to probe interfacial water at atomic scale [1-3], we further explore the interaction between water molecules and ionic species on a salt surface.

Optical and Scanning Probe of Single Organic Nanofibers

With all advantages and desirable characteristics of organic polymers as potential candidate for the next generation of electronics, optimizing the performance of plastic electronics still remains a great challenge. This is primarily because optoelectronic properties of polymer aggregates are a complex function of their molecular packing structure.

Intermolecular bonding

Bonding within a molecule has been fairly well understood, though it continues to attract attention nearly a century after Lewis/Langmuir defined a covalent bond. Could there be a 'bond' between molecules? [1,2] Hydrogen 'bonding' was proposed as an intermolecular bond by Latimer and Rodebush in 1920, within a few years after the covalent bond was defined.

Absorption Spectroscopy and Imaging from the Visible through Mid-IR with 20 nm Resolution Using AFM Probes

Correlated nanoscale composition and optical property maps are important to engineer nanomaterials in applications ranging from photovoltaics to sensing and therapeutics. Light absorption in the visible and near-IR probes electronic transitions, providing information on the band gap and defects. Light absorption in mid-IR probes vibrational transitions and provides information on chemical composition.

Single molecule dynamics at soft interfaces: from basic science to a $100,000,000,000 problem

Practical goals in materials engineering include minimal cost, maximum efficiency, and optimized longevity. As our experimental and theoretical methods to study nature’s molecular-scale design principles have improved, we have begun to understand that one reason nature can be so successful is that her engineering strategy often differs from ours.

Unconventional vibrational fingerprints at the scanning tunneling microscope junction: A personal look at tip-enhanced Raman spectroscopy

Scanning tunneling microscopy (STM) is an attractive tool to be complemented by optical spectroscopy because the molecule under optical interrogation can be directly visualized with the otherwise unattainable angstrom resolution. The simplest ensuing technique from that combination is tip-enhanced Raman spectroscopy (TERS). TERS utilizes a localized surface plasmon (LSP) at the tip apex to enhance the Raman signal. It is the gap-mode LSP that is sensitive to the gap distance, thereby provides the spatial resolution better than the diffraction limit.

Designing Absorption with Nanophotonics: from Photovoltaics to Chiral Metamaterials

Subwavelength nanostructures enable the manipulation and molding of light in nanoscale dimensions. This talk will first discuss the opportunities for enhancing photovoltaic performance using nanophotonic design, with a focus on recent work addressing luminescent solar concentrators. The combination of narrow band light emitting nanocrystals with wavelength-selective photonic materials enables high concentration ratios while capturing diffuse, rather than direct, sunlight and thereby improves photovoltaic performance.

On-Chip Integrated Nanowire Device with Controlled Nanogap for Electrical Characterization at Nanoscale Junctions

Electric field assisted precise positioning of Au and Ag segmented nanowires from dispersion onto a patterned chip surface has shown to be a facile, reliable and economical approach to create nanometer separated electrodes. The talk covers steps of fabrication of nanogap electrodes from the electrofluidically aligned nanowires and the performance of these devices in electrical measurement of different molecular biorecognition. The main theme of the talk will be on creation of on-chip integrated nanowire device with controllable nanogap.

UCI Department of Chemistry

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