3D and Multimodal X‐Ray Microscopy Reveals the Impact of Voids in CIGS Solar Cells
Giovanni Fevola, Christina Ossig, Mariana Verezhak, Jan Garrevoet, Harvey Guthrey, Martin Seyrich, Dennis Brückner, J. Hagemann, Frank Seiboth, Andreas Schropp, Gerald Falkenberg, Peter Stanley Jørgensen, Azat Slyamov, Zoltan Imre Balogh, Christian Strelow, Tobias Kipp, Alf Mews, Christian G. Schroer, Shiro Nishiwaki, Romain Carron, Jens Wenzel Andreasen, Michael Stückelberger
Abstract
Abstract Small voids in the absorber layer of thin‐film solar cells are generally suspected to impair photovoltaic performance. They have been studied on Cu(In,Ga)Se 2 cells with conventional laboratory techniques, albeit limited to surface characterization and often affected by sample‐preparation artifacts. Here, synchrotron imaging is performed on a fully operational as‐deposited solar cell containing a few tens of voids. By measuring operando current and X‐ray excited optical luminescence, the local electrical and optical performance in the proximity of the voids are estimated, and via ptychographic tomography, the depth in the absorber of the voids is quantified. Besides, the complex network of material‐deficit structures between the absorber and the top electrode is highlighted. Despite certain local impairments, the massive presence of voids in the absorber suggests they only have a limited detrimental impact on performance.