Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: Photovoltaics (Joint session of HL and DF, organized by HL)

HL 12.3: Vortrag

Montag, 7. März 2016, 15:30–15:45, H2

Improved light harvesting and carrier collection using transparent nano-textured back contacts in sub-micron chalcopyrite absorber solar cells — •Wiebke Ohm^1,2, Wiebke Riedel^1,2, Ümit Aksünger², Martha Ch. Lux-Steiner^1,2, and Sophie Gledhill^1,2 — ¹Fachbereich Physik, Freie Universität Berlin, Berlin, Germany — ²Institut für Heterogene Materialsysteme, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany

We investigate bifacial Cu(In,Ga)Se₂ (CIGS) solar cells on glass/F:SnO₂ substrates with ZnO nanorods (NR) at the back contact and a reduced absorber thickness (<1 µ m). Optical simulations of reflection and depth resolved absorption were used to show the potential of ZnO NR in bifacial sub-micron CIGS solar cells to increase the short-circuit current J_SC. Next to anti-reflection properties a shift of the absorption closer to the pn-junction was identified for back side illumination enhancing charge carrier collection resulting in an overall J_SC increase by up to 30 %. The anti-reflection effect of ZnO NR at the solar cell back contact was observed using optical measurements and the anti-reflection enhancement was estimated resulting in a maximum photo current increase of 2 %. An overall 5 % increase in J_SC with NR was achieved, identified in I-V measurements for back side illumination. The external quantum efficiency, however, show that parasitic absorption in the NR-based back contact limits the photo current enhancement, whereas in a wide wavelength range 20 % J_SC increase is demonstrated.