Abstract:
Intermediate band photovoltaics hold the promise of being highly efficient and cost effective photovoltaic cells. Intermediate states in the band gap, however, are known to facilitate nonradiative recombination. Much effort has been dedicated to producing metallic intermediate bands in hopes of producing lifetime recovery -- an increase in carrier lifetime as doping levels increase. We show that lifetime recovery induced by the insulator-to-metal transition will not occur, because the metallic extended states will be localized by phonons during the recombination process. Only trivial forms of lifetime recovery, e.g., from an overall shift in intermediate levels, are possible. Future work in intermediate band photovoltaics must focus on optimizing subgap optical absorption and minimizing recombination, but not via lifetime recovery.

Biosketch:
Jacob Krich is a theoretical condensed matter physicist interested in the quantum mechanical properties of materials at the nanoscale, and especially on applications of these properties to clean energy science. Jacob is completing his Ph.D. in Physics at Harvard University, where he has explored the physics of devices being considered for use in advanced classical computers or quantum computers. He received his MMath from Oxford University, where he studied as a Rhodes Scholar, and his B.A. in Physics from Swarthmore College. His Ph.D. work has focused on the interplay of quantum mechanics and assorted types of disorder and randomness in the functioning of semiconductor devices.