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O: Fachverband Oberflächenphysik
O 84: Photovoltaics (jointly with CPP, DS and HL)
O 84.3: Vortrag
Freitag, 15. März 2013, 09:45–10:00, H2
Investigations of chemical gradients in Cu(In,Ga)Se2 thin film solar cells grown on polyimide substrate by high spatially resolved cathodoluminescence microscopy — •Stefan Ribbe1,2, Andreas Rahm1, Frank Bertram2, and Jürgen Christen2 — 1Solarion AG, Ostende 5, 04288 Leipzig, Germany — 2Institute for Experimental Physics, Otto-von-Guericke-Universität Magdeburg, Germany
Optical properties of Cu(In,Ga)S2(CIGS)-absorber layers for thin film solar cells have been studied by high spatially resolved cathodoluminescence (CL) at low temperature (T = 5K) to investigate lateral und vertical changes of the composition within the quaternary absorber. CIGS layers were grown on flexible polyimide foil by using an ion-beam assisted roll-to-roll process. To ensure high efficiency sodium fluoride was evaporated by an additional source during the process. The substrate temperature was varied above the standard value enabled by using an advanced polyimide substrate resisting higher temperatures. Cross sections of the thin film solar cells were prepared to investigate the vertical distribution of composition and its changes influenced by the substrate temperature. IV measurements showed an increase of the efficiency with higher substrate temperature suggesting less fluctuation of the composition and a smoother vertical gallium gradient. Furthermore a variation of the sodium content was made by variation of the evaporation temperature. Integral luminescence properties were investigated which showed a red shift and a broadening of the main peak with increased sodium content.