Incomplete P1 scribing lines between neighboring Mo back electrodes in Copper indium gallium selenide: Cu(In,Ga)Se-2 (CIGS) thin-film modules have been repaired by removing the Mo remnants in the P1 laser line. The repair is achieved by melting and evaporating the Moremnant with an electrical current. We develop a repair process that is robust to different lengths of the P1 line interruption, to arbitrary defect positions and defect numbers both within one scribing line and the complete module. Furthermore, the repair method provides a reliable feedback about a successful defect repair, whereby affected P1 scribing lines can be located and defects can be counted.

Intentionally implemented scribing failures in Cu(In,Ga)Se-2 modules are studied using electroluminescence (EL) and dark lock-in thermography (DLIT). While the EL images do not allow a non-ambiguous defect distinction, the DLIT images reveal characteristic defect patterns for each defect type. In order to explain the DLIT defect appearance, we model and simulate the scribing defects in a network simulation model. The simulations yield characteristic current flow patterns for each scribing defect type and thus aid in the understanding and interpretation of the measurements. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The influence of the i-ZnO/CdS buffer layer combination on intentionally produced defects in Cu(In,Ga)Se2 (CIGS) minimodules is investigated by electroluminescence (EL) imaging in the work by Misic et al. (pp. 541–546). Shunts with diameters of about 100 μm were produced by mechanically removing locally one or several layers during the module production process. The cover image schematically illustrates a defect-free CIGS solar cell next to three intentionally implemented defective layer sequences together with their corresponding EL images. The authors find that the i-ZnO/CdS buffer combination mitigates shunts effectively, despite a hole in the CIGS absorber and Mo electrode. However, the high-ohmic i-ZnO layer alone without the CdS buffer layer is less effective. Misic et al. demonstrate that the covering coating by the chemical bath deposited CdS fills cavities and covers rough edges at the damaged Mo and CIGS, and thus provides a smoothened surface where the sputtered i-ZnO can form an intact high-ohmic layer between the front and back electrode. In this work it is argued that the i-ZnO/CdS buffer layer has a strong shunt mitigating effect. This may be an important aspect to consider in the development of Cd-free buffer combinations or buffer layers for kesterite-based solar cells.

We study the appearance of both scribing failures and Cu-rich debris, formed during Cu(In,Ga)Se 2 (CIGS) coevaporation, in electroluminescence (EL) and dark lock-in thermography (DLIT) images. We observe that for most of the defect types, there is a characteristic appearance of EL and DLIT that allows reliable diagnostics. We also point to defect scenarios where different defects appear similar. With regard to scribing defects, we find that the reliability of defect identification increases with the length of the line interruption, while for Cu-rich debris, we find that the geometrical size and position within the cell significantly determine its defect appearance and, therefore, the ability to diagnose it.

The influence of the i-ZnO/CdS buffer layer on intentionally produced defects in Cu(In, Ga)Se-2 (CIGS) mini-modules is investigated by electroluminescence (EL) imaging. Macroscopic shunts of the dimension of 100 mu m in length and several mm in width were produced by mechanically removing locally one or several of the layers during the module production process. After creating the defects the modules were finished in the usual way. It is found that heavy shunts were produced whenever the doped ZnO: Al came into contact with the Mo back contact. The decline of photovoltaic performance is seen by a decrease of the EL intensity of the damaged cell. In contrast, considerable shunt mitigation was observed whenever the i-ZnO/CdS buffer combination was present. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim