Modelling and measurement of the metastable defect distribution in chalcopyrite-based thin film solar cells

Metastable behaviour in chalcopyrite-based solar cells is often related to the presence of intrinsic defects in the absorber layer which can change configuration through thermally activated transitions. The facilities to model these defects have recently been introduced in the software SCAPS (a one-dimensional solar cell simulator developed at the University of Gent and freely available to the research community). The presence of these defects leads to strongly non-uniform defect densities which can explain admittance spectroscopy measurement results under different bias conditions. In particular the appearance of a peak with a characteristic energy of about 0.13 eV which only appears when the spectrum is measured under forward bias conditions can be related to the presence of the IIICu-defect.

► The presence of metastable defects in CIGS leads to non-uniform defect densities.
► This leads to voltage dependent admittance spectroscopy results.
► We discuss such a measurement which is related to the presence of an IIICu-defect.
► The measurement is simulated with SCAPS, which can model metastabilities.