09 December 2011
Yale University researchers have developed a new way of guiding and channeling electrons within hybrid organic-inorganic photovoltaic devices. Better control of the structure and alignment of the materials in the photovoltaics could help improve efficiency by maximizing the amount of light that is successfully converted into electricity.
The team has developed a new way of channeling electrons within hybrid organic-inorganic PV devices that maximizes the amount of light successfully converted into electricity.Hybrid organic-inorganic solar cells hold promise as next generation low-cost, high efficiency photovoltaics but currently they can only a small fraction of light into energy. The problem is largely due to the poorly ordered structure of the active materials, which produces a convoluted path for the flow of electrons.
The researchers devised ways of more efficiently channeling the electrons through the system by aligning arrays of polymer-coated nanowires that can act as the active material for a solar cell.
“The key here is controlling the structure of the system on multiple levels, or length scales, and doing it in a manner that is conducive to fabrication of devices over large areas,” said Chinedum O. Osuji, a Yale engineering professor.
The entirely bottom-up approach involves preparing polythiophene-grafted ZnO core/shell nanocomposites. These nanocomposites are formed suspension and aligned in thin films with mechanical shear and magnetic fields. Side-functionalized polythiophenes attached to the single-crystal ZnO nanowires produce hybrid core/shell nanostructures in which the otherwise amorphous polymer forms a uniform crystalline layer and the chain backbones extend along the nanowire long axis.
The ability to magnetically align the core/shell constructs makes them scalable for large-area processing. The researchers are currently working on building and systematically testing actual solar cells using these highly ordered materials, Osuji said.
Support for the research was provided by the National Science Foundation.
Research Paper: Directed Self-Assembly of Hybrid Oxide/Polymer Core/Shell Nanowires with Transport Optimized Morphology for Photovoltaics, DOI: 10.1002/adma.201103708
Written by Nancy Lamontagne, Contributing Editor - US