The global climate crisis demands a shift to renewable energy sources. Solar photovoltaics (PVs) are widely considered the most feasible renewable technology to meet global energy demands, and solar photo-electrocatalysis is a promising approach to decarbonize industrial chemical production. However, scaling solar energy harvesting technologies to meet energy demands must be done economically and sustainably, minimizing materials consumption, toxicity, energy intensity of the processing, and cost per watt.

My research aims to leverage the strong light-matter interaction of van der Waals (vdW) chalcogenides for solar energy harvesting with drastically reduced materials consumption while also developing low-cost solution processing of elemental vdW chalcogenides for PVs. In this defense, I present work to (i) engineer vdW metal dichalcogenide nanophotonic structures to achieve broadband near unity solar absorption in extremely thin (18 nm) layers; (ii) apply hybrid light-matter states sustained by thin films of vdW metal dichalcogenides to PVs; and (iii) develop a precursor and process to fabricate thin film elemental chalcogenide PVs with widely tunable bandgaps from solution phase for low cost, low temperature manufacturing without extremely hazardous solvents. Overall, these contributions offer potential paths for materials processing and optical design to make future solar energy technologies more sustainable.