Organic nanowires for smaller solar cells

Irish researchers have measured photoconductivity in a single polymer nanowire, a finding that could lead to inexpensive miniaturised solar cells and photo detectors.

Both devices work by converting light into electricity, and building smaller versions of the devices will rely on nanostructured materials with good photoconducting properties. The properties of inorganic photoconducting nanowires, such as ZnO or Si, have been measured, but relatively little is known about the properties of organic nanowires. Organic nanowires could be both chemically tunable and relatively inexpensive to integrate into electronic circuits.

Gareth Redmond’s group at the Tyndall National Institute in Cork, Ireland has succeeded in measuring photoconductivity in a single polymer nanowire. The researchers fabricated the 200nm wide, 15µm long polymer wires using a simple template wetting technique. Metal contacts were made on either end of a single wire to measure the photo-induced current over several on–off cycles of a near-ultraviolet laser.

The wires’ quantum efficiency, or the number of current-carrying electrons produced per photon hitting the wire, is about 0.1 per cent, which is comparable with several inorganic nanowires. As in many polymer-based electronic devices, the limiting factors may be the non-crystalline structure and poor electrical contact with the metal leads.