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Center for Nonlinear Studies |
Non-radiative decay limits the efficiency of semiconductor-based optoelectronic devices such as solar cells by converting useful electronic energy into heat. It has been known for more than half a century that such decay is facilitated by defects, but theoretical prediction of exactly which defects facility non-radiative decay has remained a challenge. In order to develop a predictive understand of the role such defects are playing in this process, we are developing nonadiabatic molecular dynamics and multireference electronic structure methods and applying them to cluster models of semiconductor defects. In doing so, we have shown that clusters designed to mimic specific defects on the surface of silicon exhibit efficient non-radiative decay via conical intersections at energies accessible by visible light. The presence and energies of such intersections elucidate some unusual features of the photoluminescence spectrum of nanostructured silicon which arise upon oxidation.
Host: Sergei Tretiak