Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 12: Quantum Optics II

Q 12.5: Talk

Monday, March 5, 2018, 15:00–15:15, K 0.016

Optimization of photovoltaic upconversion by tailoring the photonic density of states — •Fabian Spallek, Andreas Buchleitner, and Thomas Wellens — Physikalisches Institut, Albert-Ludwigs-Universität Freiburg

Upconversion materials, which convert two low-energy photons into one photon with higher energy, combined with photonic structures, open promising possibilities to improve the efficiency of silicon solar cells by utilizing the full range rather than only a fraction of the solar spectrum [1]. Quantum yield and the luminescence enhancement, which quantify the overall efficiency of the embedded upconverter material, are determined by the interplay of energy transfer processes, local irradiance and local density of (photonic) states - all of which can be influenced by photonic dielectric nanostructures. We derive the local density of states from macroscopic QED, for arbitrary finite multi-layered dielectric structures. This allows us to optimize the structure, such as to enhance desired, or to suppress unwanted spontaneous emission processes from distinct excited energy levels of the upconverter material. In combination with previous results on the optimization of the local irradiance in multi-layered structures [2], we compare our predictions for the achievable luminescence and upconversion quantum yield to thus far experimentally implemented [1] Bragg structures.

[1] C. L. M. Hofmann et al., Opt. Express 24, 14895 (2016)

[2] F. Spallek et al., J. Phys. B: At. Mol. Opt. Phys. 50, 214005 (2017)