February 01, 2011

Carbon nanotubes for better solar cells

Angewandte Chemie International Edition - Flexible, Light-Weight, Ultrastrong, and Semiconductive Carbon Nanotube Fibers for a Highly Efficient Solar Cell

Tubes for sunlight: Solar cells with high short-circuit photocurrent, incident monochromatic photon-to-electron conversion efficiency, and power conversion efficiency have been made from flexible, light-weight, ultrastrong, and semiconductive nanotube fibers (see picture above). The alignment of the nanotubes in the fiber is crucial for the excellent charge separation and charge transport properties observed.

Chinese researchers fabricated fibers – with tunable uniform diameters ranging from micrometers to millimeters – that could be spun with lengths of tens of meters or even longer. High-resolution transmission electron microscopy indicates a multiwalled structure for the building nanotubes with diameter of approximately 8.5 nm in the fiber. Their nanotube fiber demonstrates much higher values in both specific strength and specific stiffness than current engineering fibers. The specific strength of a nanotube fiber is 2.9 times that of T1000, the strongest commercial fiber, and the specific stiffness is 3.9 times that of M70J, the stiffest commercial fiber.

9 pages of supplemental material

The novel solar cells based on the nanotube fibers. (a) The scheme
showing the device structure (yellow for electrolyte, red for dye, and gray cylinder for nanotubes). (b) and (c) Photographs of representative devices.

Prior research from 2009, Nature Nanotechnology - Electrochromatic carbon nanotube/polydiacetylene nanocomposite fibres

Chromatic materials such as polydiacetylene change colour in response to a wide variety of environmental stimuli, including changes in temperature, pH and chemical or mechanical stress, and have been extensively explored as sensing devices. Here, we report the facile synthesis of carbon nanotube/polydiacetylene nanocomposite fibres that rapidly and reversibly respond to electrical current, with the resulting colour change being readily observable with the naked eye. These composite fibres also chromatically respond to a broad spectrum of other stimulations. For example, they exhibit rapid and reversible stress-induced chromatism with negligible elongation. These electrochromatic nanocomposite fibres could have various applications in sensing.

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