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 the area of 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 pure organic materials to yield low-cost thermoelectrics with mechanically flexible form-factors. These thermoelectrics may be used to convert waste heat into electricity, thereby providing the potential to 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.

Research efforts in the group revolve around a common theme of understanding and using 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. For example, we are working to better understand how the chemical structures of surface ligands influence interfacial energetics, charge transfer processes, and material and device stability. These investigations have direct applications to the development of improved electrode interfaces for perovskite solar cells and light emitting diodes, and to the development of organic-inorganic composite materials for thermoelectrics and transparent electrodes. To interrogate interfacial chemistry and energetics we rely on 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). Please visit our research pages and view our publications to learn more..