Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 6: Photovoltaics I
HL 6.13: Talk
Monday, March 12, 2018, 12:45–13:00, EW 203
Inhomogeneities in wide-gap Cu(In,Ga)Se2 solar cells — •Aleksandra Nikolaeva1, Maximilian Krause1, Jose Marquez1, Charles Hages1, Sergej Levcenko1, Thomas Unold1, Wolfram Witte2, Dimitrios Hariskos2, and Daniel Abou-Ras1 — 1Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563 Stuttgart, Germany
Inhomogeneities in Cu(In,Ga)Se2 solar cells related to the different net doping densities NA in neighboring grains can limit the open-circuit voltage. The present work gives insight into local electrical and optoelectronic properties of wide-gap Cu(In,Ga)Se2 solar cells ([Ga]/([In]+[Ga])=0.66) with different buffer layers by using electron-beam-induced current (EBIC) and cathodoluminescence measurements. Combining these techniques on the same identical position of cross-sectional specimens makes it possible to investigate the spatial distribution of inhomogeneities in the corresponding solar cells. From the EBIC profiles perpendicular to the substrate, values for the widths of the space-charge region wSCR, which are proportional to NA-0.5, as well as for the diffusion lengths LD of the charge carriers (related to the lifetime of the minority charge carriers) were extracted. It is shown that wSCR and therefore NA exhibits fluctuations depending on the buffer layer applied. The average values of wSCR and LD were confirmed by capacitance-voltage and quantum efficiency analysis of the solar cells.