Nanophotonics for the terawatt solar age: New concepts for generation of electricity and fuels from sunlight

The recent rapid drop of solar module prices and global growth of photovoltaics has moved frontiers for solar energy research towards new challenges and opportunities, including new nanophotonics-based tandem photovoltaic structures that have potential to leverage the enormous existing manufg. base for Si photovoltaics. I will describe new approaches for nanophotonic design of high efficiency photovoltaics and photoelectrochem. generation of solar fuels. First, I describe a tandem-on-Si luminescent solar concentrator concept that uses quantum dot luminophores and nanoantennas to enable 30-100x concn. of diffuse sunlight onto small III-V compd. semiconductor cells, with potential for beyond-Si module efficiencies. Another direction towards achieving cost-effective III-V tandem-on-Si structures employs nanowire top cells prepd. via epitaxy-free and vacuumfree processing methods. Finally, emerging two-dimensional semiconductor materials such as transition metal dichalcogenides (TMDCs) and layered perovskites with high luminescence yields and favorable bandgaps are interesting candidates for tandem photovoltaics. I will also discuss approaches to use of tandem nanophotonic structures for photoelectrodes and light management in high efficiency, stable photoelectrochem. devices for water-splitting and carbon dioxide redn