In this project we study the synthesis of various nanostructures including binary and ternary metal oxide nanowires and nanoparticles. These nanostructures such as ZTO and ZGO nanowires have important applications in nanoelectronic devices and dye or quantum dot sensitized solar cells.
In this project we fabricate quantum dot sensitized solar cells (QDSSCs) with photoanodes based on metal oxide nanowires or nanoparticles. We coat the QDs on the photoanodes using approaches such as the physical deposition-based Pulsed Laser Deposition (PLD) method or the chemical solution-based Successive Ionic Layer Adsorption and Reaction (SILAR) method. We also characterize QDSSC performance and study carrier transport and recombination processes in these devices using different measurement techniques including Intensity Modulated Photocurrent/Photovoltage Spectroscopy.
QDSSCs typically contain liquid electrolytes such as the popular polysulfide electrolyte. However, liquid electrolytes often cause issues such as QD corrosion and dissolution and harm the long-term cell stability. In this project we investigate polymer electrolytes, a type of solid-state electrolytes, for QDSSC applications. Compared with other types of solid-state electrolytes such as hole transporting materials, polymer electrolytes have certain advantages including easy penetration into the porous photoanode films and good wettability with nanostructure-based photoanodes.
In this project we study 1/f noise and random telegraph signals (RTS) in field effect transistors (FETs) based on nanowires. These noise characteristics contain important information on charge transport and fluctuations in materials and devices, and have been widely used as quality and reliability indicators for semiconductor devices. For FETs based on nanostructures, because of their large surface-to-volume ratio and not well-passivated surface states, RTS-related current fluctuations are more pronounced due to enhanced trapping/detrapping and scattering events caused by the surface or interface trap states. Therefore, for these nanowire-FETs 1/f noise and RTS measurements have become a unique electrical characterization method to study their defect states and related charge transport phenomena.