Copper phthalocyanine as an efficient dopant in development of solar cells

Organic semiconductors having conjugate bonds, such as phthalocyanines, are well known photoconductors. Phthalocyanines absorb light on either side of blue-green region in the visible spectrum. And polyaniline which has conjugate bonds is photosensitive. When polyaniline thin films are prepared with copper phthalocyanine powder the magnitude of absorption of the films not only increases but also broadens, indicating a wide absorption region between 1.7 and 2.3 eV and above 3.0 eV of the visible spectrum. Thus copper phthalocyanine is shown to increase the efficiency of solar cells made of conducting polymers such as polyaniline. The use of iodine along with copper phthalocyanine in preparation of thin films is shown to smooth the broadening effect in absorption of solar cells. Attempts are underway to increase the absorption on either end of the visible spectrum, viz., infrared as well as ultraviolet regions, using suitable dopants. This would ensure the overall efficiency of solar cells made of organic photoconductive materials to absorb solar energy from infrared to ultraviolet regions of the optical spectrum, thereby making them more efficient solar energy converters. Copyright (C) 1997 Elsevier Science Ltd.