Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 8: Photovoltaics
HL 8.7: Talk
Monday, March 20, 2017, 11:15–11:30, POT 251
Investigating photocurrents on a micrometer scale: Ultra-broadband reflection microscopy and photo-current imaging of structured thin-film solar cells — •Moritz Gittinger1, Regina-Elisabeth Ravekes2, Ralf Vogelgesang1, Martin Vehse2, Carsten Agert2, Christoph Lienau1, and Martin Silies1 — 1AG Ultrafast Nano-Optics, Carl von Ossietzky Universität Oldenburg, Germany — 2Next Energy EWE Research Centre for Energy Technology, Oldenburg, Germany
Silicon thin-film solar cells are promising candidates in the quest for higher quantum efficiencies. Currently, though, they still suffer from an inefficient light coupling due to the thin, sub-µm thick absorber material. Light trapping using honeycomb-structured ZnO electrodes appear to be a low-cost and large-scale approach to significantly increase the external quantum efficiency (EQE) of the cell [1]. Here, we present a fast optical far-field technique to map simultaneously the locally-induced photocurrent in and the reflected light from these honeycomb-structured films with varying honeycomb dimensions with micrometer resolution and in a broad spectral range. We observe locally varying photocurrents and reflection signals that reflect the periodic variation of local optical density of states of the two-dimensional honeycomb pattern of the cell. The local fluctuations are quantitatively analyzed in terms of a one-parameter scaling theory for random light localization [2] and are correlated to the EQE of the cell. [1] R.-E. Nowak et al., IEEE Journal of Photovoltaics 5, 479 (2015) [2]Th. M. Nieuwenhuizen, M.C.W. van Rossum, PRL 74, 2674 (1995)