Janam Jhaveri and Jennifer Obligacion have been named the recipients of the Maeder Graduate Fellowship in Energy and the Environment for the academic year 2014-2015. Mr. Jhaveri and Ms. Obligacion are graduate students in the departments of electrical engineering and chemistry, respectively. The abstracts below summarize the research they will conduct during the year. Selection for the Maeder Fellowship is based on the potential of the research and researcher to help develop technical solutions to ensure our sustainable energy and environmental future.
Silicon/Organic and Silicon/Metal-Oxide Heterojunctions: A New Class of High-Efficiency Low-Cost PV
Solar photovoltaics (PV), the technology that converts sunlight into electricity, have immense potential to challenge fossil fuels as an electricity source. Nevertheless, the laws of economics dictate that to achieve large-scale adoption of solar PV, the cost needs to be reduced to the point where it can compete with fossil fuels (known as grid parity). For silicon solar cells, which form ~90% of the PV market, a significant and slowly declining component of the cost is due to the high-temperature (> 800°C) processing required to form p-n junctions. As such, this research project aims to replace p-n junctions in silicon and establish new low-temperature processes to convert silicon wafers to highly efficient solar cells. More specifically, by depositing certain organic or metal oxide semiconductors on silicon near room temperature, silicon-based heterojunctions for PV can be created.
For the year of the fellowship, this research will focus on exploring suitable materials for a “hole-blocking” silicon heterojunction for PV, such as amorphous titanium dioxide. A key focus will be the recombination of minority carriers via defect levels at the TiO2/Si interface, and chemical preparation techniques for optimizing the interface structure and stability. The hole blockers will be integrated into solar cells to demonstrate system performance and efficiency. Thus, this research aspires to develop a new class of silicon-based solar cells that are both low-cost and highly-efficient.
Development of Base Metal Catalysts for C-H Borylation
Nearly all organic compounds have carbon-hydrogen bonds. Direct and selective functionalization of these ubiquitous C-H linkages into more useful and versatile functional groups has application in the synthesis and discovery of new polymers, pharmaceuticals, and electronic materials. Transition metal-catalyzed C-H borylation, the formation of carbon-boron bonds directly from C-H bonds, has attracted much attention due to the versatility of the resulting organoboron products in organic synthesis. Current methods for C-H borylation rely on expensive, scarce, and toxic metals such as rhodium and iridium. Extracting and purifying these metals creates a considerable environmental and carbon dioxide footprint.
This research project aims to provide more inexpensive, less toxic, and earth-abundant base metal alternatives to the more widely and traditionally used precious metal catalysts in C-H borylation. The challenge in realizing this objective is enabling the two-electron redox changes typically associated with heavy metals to occur with first row transition elements that favor one-electron chemistry. For the duration of the fellowship, approaches to overcoming this challenge will be explored through rational ligand design. Specifically, focus will be on the synthesis of iron and cobalt catalysts that enable improved activity and potentially unique reactivity as compared to precious metal catalysts. Mechanistic studies will be conducted and the results will be used as guiding principles for subsequent catalyst development and optimization. The discovery of promising catalytic systems based on first row transition metals aims to highlight the fact that their unique electronic structures can potentially result in better catalysts that will ultimately allow us to exploit Earth’s abundant resources more efficiently.