Abstract
We studied the thickness variation of equally doped ZnO:Al films used as conductive window layer in Cu(In,Ga)(Se,S)2 (CIGSSe) thin film solar cells. The IV-characteristics of solar cells with window layer thickness of d1=200nm exhibit a strong enhancement of the short-circuit current density JSC (ΔJSC = 3mA/cm2) as compared to samples with module-like ZnO:Al-film thickness (d2=1200nm). Accordingly, the quantum efficiency reveals the spectral regimes where the JSC-gain occurs. Moreover, current-voltage measurements reveal that the cells with thicker ZnO:Al exhibit slightly decreased open circuit voltage VOC. This finding can be assigned to a decreased net-doping density NA, which appears to be introduced by additional heat flux during the longer process time required for deposition of thicker ZnO:Al films. However, the improved efficiency of solar cells with thinner window layer comes along with an increase of the series resistance (RS) by almost a factor of 2, which will have consequences for the series connection of elements in a module. XRD-diffractograms and SEM cross-section imaging suggest that the enhanced RS in cells with thin ZnO:Al is not exclusively related to the thickness but is also due to a reduced (002)-texture and an elongated lateral charge carrier pathway.
Similar content being viewed by others
References
M. A. Green, K. Emery, Y. Hishikawa, and W. Warta, Progress in Photovoltaics: Research and Applications (2010).
N. G. Dhere, Solar Energy Materials and Solar Cells 95, pp. 277–280 (2010).
D. Kieven, J. Chen, R. Klenk, T. Rissom, Y. Tang, and M. C. Lux-steiner, Progress in Photovoltaics: Research and Applications 18, pp. 209–213 (2010).
O. Kluth, B. Rech, L. Houben, S. Wiedera, G. Schöpe, C. Benekinga, H. Wagner, A. Löffl, H.W. Schock, Thin Solid Films 351, pp. 247–253 (1999).
Y. Hagiwara, T. Nakada, A. Kunioka, Sol. Energy Mater. Sol. Cells 67, pp. 267–271 (2001).
S. S. Hegedus and W. N. Shafarman, Progress in Photovoltaics: Research and Applications 12, pp. 155–176 (2004).
R. Heller and J. McGannon, J. Appl. Phys. 21, p. 1283 (1950)
N. P. Dasgupta, S. Neubert, W. Lee, O. Trejo, J.-R. Lee, and F. B. Prinz, Chemistry of Materials, pp. 4769–4775 (2010).
J.-H. Lee and B.-O. Park, Thin Solid Films 24, pp. 94–99 (2003).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Keller, J., Knipper, M., Parisi, J. et al. Impact of thickness variation of the ZnO:Al window layer on optoelectronic properties of CIGSSe solar cells. MRS Online Proceedings Library 1324, 1803 (2011). https://doi.org/10.1557/opl.2011.1058
Published:
DOI: https://doi.org/10.1557/opl.2011.1058