Bakehe, S.; Klenk, R.; Lux-Steiner, M.Ch.: Widegap Cu(InGa)S_2 thin film solar cells on transparent substrates. In: Hoffmann, W. [Ed.] : Nineteenth European Photovoltaic Solar Energy Conference : proceedings of the international conference held in Paris, France, 7 - 11 June 2004Munich, Florence: WIP, ETA, 2004, p. 1714-1717
Abstract:
ABSTRACT: We have previously demonstrated the potential of Cu(In,Ga)S2 (CIGS) for realizing high efficiency wide-gap chalcopyrite-based solar cells. CIGS absorber films were prepared by multi-source evaporation using a Cu-poor/Cu-rich deposition sequence onto soda-lime glass substrates coated with different transparent conductive oxides (TCOs). The Ga/In-ratio was adjusted for a band gap of more than 1.6 eV. The properties of films and cells are compared to those deposited onto standard glass/Mo substrates. Films with reasonable morphology and good adhesion to the substrate were obtained on most of the investigated TCOs. Also, electrical and optical properties of the TCO typically did not deteriorate strongly during absorber preparation. Our best result so far is a cell with an efficiency of about 8% on indium-tin-oxide (ITO). At an absorber band gap of 1.64 eV this cell exhibited an open circuit voltage of 775 mV, a fill factor of 55% and a short circuit current density of 18.6 mA/cm2. To our knowledge, this is currently the best wide-gap chalcopyrite-based cell on a glass/TCO substrate. The cell was slightly shunted but there were no indications for a non-ohmic behavior of the ITO/CIGS contact Keywords: CuInS2 , Thin Film , TCO Transparent Conducting Oxides