Solar cells painted onto exterior walls

Imagine a next-generation paint coating, the kind you spray on the outside of your house, that uses sunlight to generate electricity that can be used to power appliances and devices inside your home.

A team of researchers at the University of Notre Dame has made a major step toward making that vision a reality, creating an inexpensive " solar paint" that generates energy using semiconductor nanoparticles.

"We want to do something revolutionary beyond current silicon-based solar technology ," said Prashant Kamat, the John A. Zahm Professor of Chemistry and Biochemistry and a researcher at Notre Dame's Center for Nano Science and Technology (NDnano), who led the research.

"This requires incorporating electricity-generating nanoparticles, called quantum dots, into a spreadable compound. We have created a single-layer solar paint that can be applied to any conductive surface without the need for special equipment."

The new material developed by the team has been introduced in the American Chemical Society (ACS) Nano journal, titled "Sun-Believable Solar Paint. A Transformative One-Step Approach for Designing Nanocrystalline Solar Cells", published on December 6, 2011. The article said that cadmium sulfide or cadmium selenide is coated around titanium dioxide nanoparticles. These particles are suspended in a water-alcohol mixture to form a paste.

This paste is brushed onto a transparent conductive material and exposed to light to generate electricity.

"The best photovoltaic conversion efficiency we have achieved so far is 1%, which is far behind the typical 10 to 15% efficiency of commercial silicon solar cells," Kamat explained.

"But this coating is cheap to make and can be prepared in large quantities. If we can get some efficiency gains, we could really make a difference in meeting future energy needs."

“That’s why we named this new paint Sun-Believable,” he added.

Kamat and his team also plan to investigate ways to improve the stability of the new material.

The Notre Dame NanoScience Center is a leading nanotechnology center in the world. Its mission is to study and control the properties of materials and devices, and to interface with biological systems, at the nanoscale.