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International Journal of Photoenergy
Volume 2015 (2015), Article ID 410549, 9 pages
http://dx.doi.org/10.1155/2015/410549
Research Article

Graded Carrier Concentration Absorber Profile for High Efficiency CIGS Solar Cells

DEIM, University of Palermo, Viale delle Scienze, Building 9, 90128 Palermo, Italy

Received 28 November 2014; Revised 9 April 2015; Accepted 19 April 2015

Academic Editor: Cheuk-Lam Ho

Copyright © 2015 Antonino Parisi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We demonstrate an innovative CIGS-based solar cells model with a graded doping concentration absorber profile, capable of achieving high efficiency values. In detail, we start with an in-depth discussion concerning the parametrical study of conventional CIGS solar cells structures. We have used the wxAMPS software in order to numerically simulate cell electrical behaviour. By means of simulations, we have studied the variation of relevant physical and chemical parameters—characteristic of such devices—with changing energy gap and doping density of the absorber layer. Our results show that, in uniform CIGS cell, the efficiency, the open circuit voltage, and short circuit current heavily depend on CIGS band gap. Our numerical analysis highlights that the band gap value of 1.40 eV is optimal, but both the presence of Molybdenum back contact and the high carrier recombination near the junction noticeably reduce the crucial electrical parameters. For the above-mentioned reasons, we have demonstrated that the efficiency obtained by conventional CIGS cells is lower if compared to the values reached by our proposed graded carrier concentration profile structures (up to 21%).