Abstract: Alexi Arango

Analysts predict that within two to four years electricity generated from photovoltaics will cost less than grid electricity, making it the cleanest, cheapest, and most abundant form of energy generation.  The rise of solar energy, however, could fail to materialize if current photovoltaic technologies cannot meet the staggering manufacturing volumes needed to satisfy demand.  Next-generation photovoltaics fabricated from unconventional semiconductors—such as organic molecular solids, conjugated polymers and inorganic semiconducting nanocrystals—promise to solve existing manufacturing bottlenecks due to their superior processing advantages, low cost and earth-abundance.  Unfortunately, power conversion efficiencies are currently too low for terrestrial energy applications.  How can the efficiency be increased beyond the present limits?  The most uncompromising hurdle is the open-circuit voltage, often well below the theoretical limit for even the best device architectures.  We are exploring new device architectures employing cascade energy alignment, a new thin-film deposition technique employing low-damage sputtering, and a new measurement technique employing electromodulation spectroscopy to build an understanding of the limits to open-circuit voltage and, ultimately, break this important barrier to higher efficiency.