We aim to facilitate the development of solar cells and thermoelectrics through understanding and manipulating interfacial chemistries and energetics. These interfaces are key to determining the performance and stability of a photovoltaic device or thermoelectric composite material, yet they are also one of the least understood areas. In photovoltaics we are currently focused on organometal halide perovskites, which are inexpensive materials that can be solution processed to yield photovoltaic efficiencies that are on par with silicon. These perovskites have tremendous potential to help meet the world's continuously growing energy need, but first a number of challenges must be addressed. In thermoelectrics, we are focusing on organic-inorganic composites and polymers to yield low-cost thermoelectrics with mechanically flexible form-factors. These thermoelectrics may be utilized to convert wasted heat into electricity, which may allow them to one day power wearable electronic devices (e.g., a smart watch) or improve the efficiency of automobiles and power plants. We also have a fundamental effort on doping of organic semiconductors, including how dopant and polymer structure impact material energetics and charge transport properties. Please visit our research pages to learn more.
Research efforts in the group revolve around a common theme of understanding and utilizing interfacial chemistry and energetics to control charge transfer processes, interfacial electronic structure, film morphologies, and material stability. Although many of our research efforts are fundamental in nature, most of the more fundamental phenomena have direct relevance to energy conversion and energy storage devices. We aim to understand fundamental material and interface properties and connect these properties with device processes and device performance. For example, we are working to better understand how the chemical structures of surface modifiers correlate with interfacial energetics and charge transfer processes, with results of this work having direct applications to the development of improved electrode interfaces for perovskite solar cells or light emitting diodes and the development of organic-inorganic composite materials for thermoelectrics or transparent electrodes. To interrogate interfacial chemistry and energetics we utilize a powerful analytical tool set. Heavily utilized, and largely customized, analytical tools include ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), inverse photoelectron spectroscopy (IPES), optical spectroscopies (UV-Vis, fluorescence), and sensitive external quantum efficiency (EQE) measurements. We also use a suite of morphological characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). To learn more about our specific research projects please visit our research page.