[Zurück]

C. Watzenböck:
"Modeling Impact Ionization in solar cells";
Vortrag: Computaional Material Science Seminar, Wien; 06.12.2018.

The efficiency in conventional solar cells is restricted by the Shockley-Queisser [1] limit to 34%. In a new class of materials (e.g. oxide-hetero-structures [2]) where the electron-electron scattering is dominating over the electron-phonon scattering this limit might be overcome. We model the time-dependence by means of a (small) Hubbard-cluster[3], where the electromagnetic field is take into account by means of the Peierls substitution [4]. Our results show that already small two-dimensional systems show impact ionization, which may be utilized to overcome the Shockley-Queisser limit. Moreover, we analyze the influence of phonons at the level of the Hubbard-Holstein model.

[1] Shockley, W. and Queisser, H. J. (March, 1961) Detailed Balance Limit
of Efficiency of p-n Junction Solar Cells. Journal of Applied Physics, 32,
510-519.
[2] Assmann, E., Blaha, P., Laskowski, R., Held, K., Okamoto, S., and Sangiovanni, G. (February, 2013) Oxide Heterostructures for Efficient Solar Cells.
Physical Review Letters, 110, 078701.
[3] (1963) Electron correlations in narrow energy bands. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 276(1365), 238-257.
[4] Peierls, R. (Nov, 1933) Zur Theorie des Diamagnetismus von Leitungselektronen. Zeitschrift für Physik, 80(11), 763-791.