Energy transfer in nanostructured systems

Abstract

This dissertation contains a number of projects involving the experimental and theoretical investigation of energy transfer within nanostructured systems. Chapter 1 begins with an overview of pump-probe spectroscopy - the primary tool used for these investigations. We then look at the two classes of materials considered in the later chapters: dye sensitized solar cells and plasmonic nanoparticles. This covers the motivation for examining these systems and their photophysics. Chapters 2 and 3 focus on exploring squaraine-based dye sensitized solar cells. The former deals with how the anchor and bridge groups within these molecules affect the energy loss and transfer processes which determine cell efficiency. We see how dye structure relates to aggregation and how this hinders effective charge transfer. The latter considers sensitizers which include an additional porphyrin chromophore. Although this improves the amount of light absorbed, it also changes the charge transfer kinetics. Chapters 4 and 5 explore plasmonic nanoparticle systems which could be used as optical sensors. Chapter 4 looks at the mechanical properties of gold and silver nanorods and how it relates to the crystalline structure and temperature. Chapter 5 is a theoretical investigation of how gold and silver nanocubes couple to each other – a pump-probe experiment is proposed to further study the interaction. Chapter 6 looks at hybrid metal oxide-gold nanoparticles for use in catalysis. The chapter focuses on the synthetic control of nanoparticle shape. It describes the future work of how pump-probe spectroscopy could be used to investigate catalytic enhancement mechanisms.