Simultaneous adsorption of dye molecules and coadsorbates is important for the fabrication of high-efficiency dyesensitized
solar cells, but its mechanism is not well understood. Herein, we use a quartz crystal microbalance with
dissipation technique (QCM-D) to study dynamically and quantitatively the sensitization of TiO2in situ. We investigate
dye loading for a ruthenium(II) polypyridyl complex (Z907), of a triphenylamine-based D-π-A dye (Y123), and of a
ullazine sensitizer (JD21), as well as the simultaneous adsorption of the latter two with the coadsorbate
chenodeoxycholic acid. By combining the QCM-D technique with fluorescence measurements, we quantify molar ratios
between the dye and coadsorbate. Furthermore, we will present first studies using liquid-phase AFM on the adsorbed dye
monolayer, thus obtaining complementary microscopic information that may lead to understanding of the adsorption
mechanism on the molecular scale.
We discuss our recently developed method to selectively functionalize mixed ligand gold nanoparticles at two specific
defect points in the ligand shell and to join the nanoparticles together into chains by placing reactive molecules at those
two points. Here we use infrared spectroscopy to confirm that the process of functionalizing those defect points rapidly
reaches equilibrium. In addition, we demonstrate the quantitative reproducibility of the chaining reaction, and we discuss
the case in which we perform the same functionalization procedure on homoligand nanoparticles.
Ligand-coated metallic nanoparticles are powerful new materials for nano-electronic and photonics applications. They can be readily synthesized and their stability and solubility allows them to be cast in complex composite materials or self-assembled into quasi-ordered films. We demonstrate that, in the presence of reducing dyes with a large two-photon cross-section and metal salts, it is possible to induce the growth of metal nanoparticles in composite films under optical excitation or irradiation with electrons. We demonstrate further that continuous metal structures can be obtained via laser irradiation of the composites and that, with two-photon excitation, 3D structures can be fabricated. Silver, copper, and gold microstructures have been fabricated via two-photon excitation. The composition of our polymeric precursor is described in detail. In order to achieve highly-homogenous solid-state solutions of nanoparticles dissolved in polyvinylcarbazole (PVK), we have synthesized tailor-made nanoparticles on which we have introduced a mixture of carbazoyl-terminated octylthiol and simple octylthiols.. Preliminary experiments on e-beam lithography show that thin films of nanoparticles doped with suitable dyes and metal salts are efficient precursors form metal structures.
Conference Committee Involvement (1)
Nanomaterials and Their Optical Applications
5 August 2003 | San Diego, California, United States