The latest episode in the American Chemical Society's (ACS) award-winning "Global Challenges/Chemistry Solutions" podcast series features a new solar cell with high efficiency in converting sunlight into electricity and the durability to last and last.

In the podcast, Michael Graetzel, Ph.D., describes research that aimed to develop an improved version of a highly promising solar cell that is less expensive than conventional solar cells made from the semi-conductor material, silicon. These so-called dye-sensitized solar cells (DSCs), or Graetzel cells (named for the discoverer, Michael Graetzel), have other advantages.

They can be manufactured in light-weight flexible sheets, for instance, that are more durable and suitable for roll-up applications such as window shades. Hindering commercial use of DSCs has been their lack of stability, with the electricity output tending to decline over time. Graetzel is with the Ecole Polytechnique Federale de Lausanne in Switzerland.

The study reports development and successful lab tests of a new electrolyte composition suitable for the DSC, constructed with different material that is both stable and has a relatively high efficiency of 10 percent.

It has an improved electrolyte system, the substance that conducts electricity inside the solar cell. The new device retained at least 95 percent of that sun-converting ability for 1,000 hours of testing.

Global Challenges/Chemistry Solutions is a series of podcasts describing some of the 21st Century's most daunting problems, and how cutting-edge research in chemistry matters in the quest for solutions.

Global Challenges is the centerpiece in an alliance on sustainability between ACS and the Royal Society of Chemistry. Global Challenges is a sweeping panorama of global challenges that includes dilemmas such as providing a hungry, thirsty world with ample supplies of safe food and clean water; developing alternatives to petroleum to fuel society; preserving the environment and assuring a sustainable future for our children and improving human health.

During the 2011 global celebration of the International Year of Chemistry (IYC), Global Challenges/Chemistry Solutions also is focusing on the main themes of IYC - health, environment, energy and materials.