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International Journal of Photoenergy
Volume 2009, Article ID 581068, 7 pages
Research Article

Squaraine Planar-Heterojunction Solar Cells

Swiss Federal Laboratories for Materials Testing and Research, EMPA, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland

Received 10 April 2009; Accepted 2 June 2009

Academic Editor: Mohamed Sabry Abdel-Mottaleb

Copyright © 2009 Bin Fan 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.


The photovoltaic performance of squaraine-based organic solar cells is investigated. Two squaraine derivatives with extraordinarily high extinction coefficients are used as electron donors in bilayer heterojunctions with fullerene as electron acceptor. Due to the very strong squaraine absorption band in the red spectral domain, antibatic behavior due to light filtering is observed in the photocurrent spectrum for film thicknesses of 35 nm to 40 nm. At reduced film thicknesses of 20 nm, this filtering effect at maximum absorption can be alleviated and power conversion efficiencies under simulated AM 1.5 full sun irradiation of 0.59% and 1.01% are obtained for the two squaraine derivatives, respectively. The photovoltaic properties of these cells are investigated with respect to electrode materials and chemical doping.