Chemistry and Biochemistry
Exciton dynamics and charge transport in organic molecular assemblies: At present, molecular-organic photovoltaics are much less efficient than the traditional inorganic solar cells. Our group aims to answer the followinq question: Can the unique properties of conjugated organic molecules/dyes be utilized to harvest a larger percentage of the solar energy, relative to traditional inorganic semiconductors? We will explore answers on a fundamental level, with particular attention to exciton dynamics and charge carrier mobilities. We employ a variety of laser-based spectroscopies (including ultrafast) to answer these questions. 2) Spectroscopy of the electrode/electrolyte interface of supercapacitors: The most remarkable features of electrochemical double-layer capacitors (or supercapacitors) are their high power densities and ability to be charged/discharged in seconds. These are significant advantages over batteries and fuel cells, which rely on much slower Faradaic chemistry. Furthermore, supercapacitors can be recharged 10^5-10^6 times without degradation, and have much less environmental impact in comparison with batteries. Despite these advantages for many applications, supercapacitors currently have a major shortcoming, namely low total energy density. Through the combined use of dielectric spectroscopy, Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy, my group aims for an in-depth understanding of the electrochemical double layer of confined systems that are at the heart of supercapacitors. The insights from these studies will help lead to a 10-fold improvement in energy density that is expected from theoretical considerations.