“From computer chips to catalysts: Precise materials synthesis for sustainable energy applications”
With the growing demand for energy at the global scale coupled with a need to mitigate its environmental impact, there is strong interest in developing new and more efficient energy technologies. Efforts in the development of such sustainable energy technologies can be broadly classified into three categories: energy capture, especially from the sun due to the abundance of solar energy; energy storage, typically in the form of chemical bonds; and efficient energy consumption. The requirements to achieve these energy conversion processes with high efficiency has in turn motivated the need to design and construct materials at the nanoscale. Among the many synthetic strategies that are being applied to create these nanoscale components, atomic layer deposition (ALD), a technique widely used for making computer chips, has now emerged as one of the most exciting tools for the study, design, and fabrication of energy materials with improved properties and performance. This talk will describe our research applying ALD to the study of energy conversion devices, with focus on using the layer-by-layer synthesis permitted by ALD to generate the nanoscale materials with a high level of control over composition, structure, and thickness. I will present our work on photovoltaics, in which nanometer-scale interfacial layers are explored for both single junction and tandem perovskite solar cells. Different metal oxide layers such as vanadium oxide and tin oxide are shown to provide beneficial charge transfer, passivation, or operational stability in metal halide perovskite devices. A second example is the development of efficient catalysts that can drive the chemical conversion of renewable resources into useful products. One promising pathway is the catalytic conversion of synthesis gas (syngas, CO + H2) into oxygenates such as ethanol. I will describe how atomically-precise ALD titration of additive components onto supported metal catalysts allows for the tuning of activity and selectivity and provides new insights into structure-property relationships in these systems. The outlook for atomic scale surface modification using ALD to synthesize and study these important classes of energy conversion materials will be discussed.