Multiple exciton generation (MEG), the creation of more than one electron for each absorbed high energy photon, has only been observed and previously investigated in bulk and nanocrystal semiconductors. Ideally, MEG can provide increased efficiency limits in solar cells. Since nanocrystal (0D) based solar cells with MEG have yet to be developed, theoretical efficiency limits and a prototype of a 1D nanostructured solar cell are necessary.

Efficiency limits found by simulations of MEG with the inclusion of empirical non-idealities are described. These simulations give a solar cell efficiency limit of 33% with the inclusion of non-ideal MEG based on 1D nanostructures. Importantly, this result suggests that even a solar cell with MEG from this least efficient nanostructure can exceed the well-accepted Shockley-Queisser limit. Additionally, a novel procedure to fabricate a nanotip Si surface solar cell with proposed low reflectivity and a potential for MEG is detailed. An integration of fabrication techniques has been developed for the creation of densely packed nanotip surfaces that yield high performance broadband anti-reflection properties comparable to optimized quarter-wavelength coatings.

The developed nanotip surface is proposed to yield 1D limited MEG efficiency enhancements in addition to observable antireflection properties thus doubly improving on efficient photon conversion and solar cell efficiency. Optimizing the nanotip solar cell will set the framework for further investigation and characterization of the potential for MEG in Si nanotips.