TY - GEN A1 - Bär, Marcus A1 - Song, X. A1 - Caballero, R. A1 - Duarte, Roberto Felix A1 - Gerlach, Dominic A1 - Kaufmann, Christian A1 - Schock, Hans-Werner A1 - Wilks, Regan G. T1 - Na incorporation into Cu(In,Ga)Se2 thin-film solar cell absorbers deposited on polyimide: Impact on the chemical and electronic surface structure T2 - Journal of Applied Physics N2 - Na has deliberately been incorporated into Cu(In,Ga)Se2 (“CIGSe”) chalcopyrite thin-film solar cell absorbers deposited on Mo-coated polyimide flexible substrates by adding differently thick layers of NaF in-between CIGSe absorber and Mo back contact. The impact of Na on the chemical and electronic surface structure of CIGSe absorbers with various Cu-contents deposited at comparatively low temperature (420 °C) has been studied using x-ray photoelectron and x-ray excited Auger electron spectroscopy. We observe a higher Nasurface content for the Cu-richer CIGSe samples and can distinguish between two different chemical Na environments, best described as selenide-like and oxidized Na species, respectively. Furthermore, we find a Cu-poor surface composition of the CIGSe samples independent of Na content and — for very high Na contents — indications for the formation of a (Cu,Na)–(In,Ga)–Se like compound. With increasing Nasurface content, also a shift of the photoemission lines to lower binding energies could be identified, which we interpret as a reduction of the downward band bending toward the CIGSe surface explained by the Na-induced elimination of InCu defects. Y1 - 2012 SN - 1089-7550 VL - 111 IS - 3 SP - 034903 ER - TY - GEN A1 - Bär, Marcus A1 - Klaer, Joachim A1 - Duarte, Roberto Felix A1 - Barreau, Nicolas A1 - Weinhardt, Lothar A1 - Wilks, Regan G. A1 - Heske, Clemens A1 - Schock, Hans-Werner T1 - Surface Off-Stoichiometry of CuInS2 Thin-Film Solar Cell Absorbers T2 - IEEE Journal of Photovoltaics N2 - In this paper, X-ray photoelectron and X-ray-excited Auger electron spectroscopy was used to investigate the chemical surface structure of CuInS2 thin-film solar cell absorbers.We find that the [In]/[Cu] surface composition can vary between 1.6 (±0.4) and 3.7 (±0.7), depending on relatively minor variations in the absorber formation process and/or whether additional wet-chemical treatments are performed. These variations are primarily due to differences in the Cu surface concentration. The corresponding change of the modified In Auger parameter is interpreted as being indicative of a change in the chemical environment of In as a function of Cu off-stoichiometry. Y1 - 2013 UR - https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6380521 SN - 2156-3381 VL - 3 IS - 2 SP - 828 EP - 832 ER - TY - GEN A1 - Bär, Marcus A1 - Couziniè-Devy, François A1 - Duarte, Roberto Felix A1 - Klaer, Joachim A1 - Pookpanratana, Sujitra A1 - Blum, Monika A1 - Zhang, Yi A1 - Denlinger, Jonathan D. A1 - Yang, Wanli A1 - Wilks, Regan G. A1 - Weinhardt, Lothar A1 - Schock, Hans-Werner A1 - Southerland Kessler, Jude A1 - Heske, Clemens T1 - The Heavily Intermixed In2S3/Cu(In,Ga)Se2 Interface as Revealed by Photoelectron and Soft X-ray Emission Spectroscopy T2 - 2013 IEEE 39th Photovoltaic Specialists Conference, (PVSC 2013), Tampa, Florida, USA, 16 - 21 June 2013 Y1 - 2013 SN - 978-1-4799-3300-6 SN - 978-1-4799-3299-3 U6 - https://doi.org/10.1109/PVSC.2013.6744280 SP - 857 EP - 862 PB - IEEE CY - Piscataway, NJ ER -