New coating strategy may lead to improved solar cells

Washington, Feb 24 : A team of Northwestern University researchers has developed a new anode coating strategy that significantly enhances the efficiency of solar energy power conversion, which may lead to improved solar cell performance.

The research was led by Tobin J. Marks, the Vladimir N. Ipatieff Research Professor in Chemistry in the Weinberg College of Arts and Sciences and Robert Chang, professor of materials science and engineering in the McCormick School of Engineering and Applied Science.

This breakthrough in solar energy conversion promises to bring researchers and developers worldwide closer to the goal of producing cheaper, more manufacturable and more easily implemented solar cells.

Such technology would also greatly reduce the dependence on burning fossil fuels for electricity production as well as reduce the combustion product: carbon dioxide, a global warming greenhouse gas.

For developing the strategy, the Northwestern researchers employed a laser deposition technique that coats the anode with a very thin (5 to 10 nanometers thick) and smooth layer of nickel oxide.

This material is an excellent conductor for extracting holes from the irradiated cell but, equally important, is an efficient "blocker" which prevents misdirected electrons from straying to the "wrong" electrode (the anode), which would compromise the cell energy conversion efficiency.

In contrast to earlier approaches for anode coating, the Northwestern nickel oxide coating is cheap, electrically homogeneous and non-corrosive.

In the case of model bulk-heterojunction cells, the Northwestern team has increased the cell voltage by approximately 40 percent and the power conversion efficiency from approximately 3 to 4 percent to 5.2 to 5.6 percent.

The researchers currently are working on further tuning the anode coating technique for increased hole extraction and electron blocking efficiency and moving to production-scaling experiments on flexible substrates.

ANI