Ga-grading and Solar Cell Capacitance Simulation of an industrial Cu(In,Ga)Se2 solar cell produced by an in-line vacuum, all-sputtering process

• Published in: Thin solid films Vol. 636; pp. 367 - 374
• Main Authors: Bras, Patrice, Frisk, Christopher, Tempez, Agnès, Niemi, Esko, Platzer-Björkman, Charlotte
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.08.2017
• Subjects: Cadmium-free; Copper indium gallium selenide; Engineering Science with specialization in Electronics; Gallium-grading; In-line vacuum; SCAPS; Sputtering; Teknisk fysik med inriktning mot elektronik; Copper indium gallium selenide; Gallium-grading; SCAPS; In-line vacuum; Sputtering; Cadmium-free
• ISSN: 0040-6090; 1879-2731; 1879-2731
• DOI: 10.1016/j.tsf.2017.06.031

Cadmium-free Cu(In,Ga)Se2 (CIGS) solar cells are fabricated on stainless steel substrate using an industrial, in-line vacuum, all sputtering process. The absorber layer is deposited from compound CIGS targets and crystallized simultaneously by high temperature processing. In-depth compositional and structural characterization of the chalcopyrite material is conducted and a Solar Cell Capacitance Simulator (SCAPS) model for the complete device is set-up. Ga-grading of the absorber through the successive use of different CIGS target compositions and resulting in solar cell performance enhancement is shown. At the research and development scale, efficiency values of 15.1% and 13.2% are reported for 1cm2 and 225cm2 total area solar cells, respectively. Successful transfer to production is also demonstrated. A series of a hundred 225cm2 solar cells produced following an optimized process including the Ga grading studied in the present contribution average at 14.8% total area efficiency. •Cd-free Cu(In,Ga)Se2 solar cells are fabricated on stainless steel substrates.•All the layers in the solar cell are sputtered in-line vacuum.•A SCAPS model for the complete device is set-up.•Bandgap grading through sputtering from compound CIGS targets is shown.•Power conversion efficiencies above 14% on 225cm2 are reported.