Ilan Gur

Searching for a Better Thermal Battery

Improved materials for storing heat could save energy in applications such as heating and cooling and could enhance generation from solar thermal plants. Energy storage has mainly focused on electrochemical systems (1). However, more than 90% of the worlds primary energy generation is consumed or wasted thermally. Thermal energy storage has a broad and critical role to play in making energy use more sustainable for heating and cooling, solar energy harvesting, and other applications. Thermal storage technologies are still based on solutions developed decades ago, such as molten salt, ice, and paraffin phase-change systems, whose performance and cost do not merit widerscale adoption. Progress in materials science, chemistry, and engineering may lead to dramatic breakthroughs in thermal energy storage that could improve the efficiency with which we produce, distribute, and consume energy.

Nanocrystal Solar Cells

This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.