Carbon nanotube solar cells.
We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.
Department of Physics and Astronomy, California State University Northridge, Northridge, California, United States of America.
Colin
C
Klinger
Yogeshwari
Y
Patel
Henk W Ch
HW
Postma
D011211:Electric Power Supplies; D004566:Electrodes; D004867:Equipment Design; D006108:Graphite / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D012666:Semiconductors; D012993:Solar Energy
D037742:Nanotubes, Carbon; D006108:Graphite