Impact of front-side point contactpassivation geometry on thin-film solar cell performance.pdfVIP

Solar Energy Materials Solar Cells 165 (2017) 94–102 Contents lists available at ScienceDirect Solar Energy Materials Solar Cells journal homepage: /locate/solmat Impact of front-side point contact/passivation geometry on thin-?lm solar cell performance Giovanna Sozzia,?, Simone Di Napolia, Roberto Menozzia, Benjamin Bissigb, Stephan Buechelerb, Ayodhya N. Tiwarib a Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181A, 43124 Parma, Italy b Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland MARK ARTICLE INFO Keywords: Thin ?lm CIGS solar cells Surface passivation Point contact Numerical simulations Bu?er layer Grain-Boundary ABSTRACT In this work, we perform an extensive campaign of three-dimensional numerical simulations of CIGS solar cell structures to investigate the e?ect of a surface-passivated CIGS with point contacts openings on the cell performance parameters (Jsc, Voc, FF and η). Detailed analysis of the combination of passivation thickness, point contact size and pitch is performed under the hypothesis of highly defective CIGS front surface and ideal chemical passivation: e?ciencies close to the case of ideal (i.e., defect-free) CdS/CIGS interface can be achieved by optimized nanometer-scale point contact arrays. To account for ?eld-e?ect passivation due to positive residual charge density, Qf, within the passivation layer, we vary Qf in the range 1010–1013 cm?2 under the two extreme scenarios of ideal or ine?ective chemical passivation. Several examples of CIGS cells with di?erent bu?er layers (CdS, ZnO, ZnMgO, In2S3, Zn(O, S)) are also analyzed. We ?nd that a positive Qf in the interval 1012– 5·1012 cm?2 can help completely recover the ideal cell e?ciency, irrespective of the chemical passivation e?ect and even in the presence of unfavorable conduction band alignment at the bu?er/CIGS heterojun