Dr. David Mitzi, IBM Research Develops High-Efficiency Solar Cell

February 15, 2010

IBM has built a solar cell -- where the key layer that absorbs most of the light for conversion into electricity, is made entirely of readily-available elements -- that set a new world record for efficiency and holds potential for enabling solar cell technology to produce more energy at a lower cost. Comprised of copper (Cu), tin (Sn), zinc (Zn), sulfur (S), and/or selenium (Se), the cell's power conversion demonstrates an efficiency of 9.6 percent -- 40 percent higher than the value previously attained for this set of materials. In order to achieve progress in solar cell research, IBM is leveraging its world-class expertise in microprocessor technology, materials and manufacturing.

"In a given hour, more energy from sunlight strikes the earth than the entire planet consumes in a year, but solar cells currently contribute less than 0.1 percent of electricity supply -- primarily as a result of cost," said Dr. David Mitzi, who leads the team at IBM Research that developed the solar cell. "The quest to develop a solar technology that can compare on a cost per watt basis with the conventional electricity generation, and also offer the ability to deploy at the terawatt level, has become a major challenge that our research is moving us closer to overcoming."

Magnified view of the kesterite cross section.

The IBM researchers describe their achievement of the thin-film photovoltaic technology in a paper published in Advanced Materials this week, highlighting the solar cell's potential to accomplish the goal of producing low-cost energy that can be used widely and commercially.

The solar cell development also sets itself apart from its predecessors as it was created using a combination of solution and nanoparticle-based approaches, rather than the popular, but expensive vacuum-based technique. The production change is expected to enable much lower fabrication costs, as it is consistent with high-throughput and high materials utilization based deposition techniques including printing, dip and spray coating and slit casting.

Currently available thin film solar cell modules based upon compound semiconductors operate at 9 to 11 percent efficiency levels, and are primarily made from two costly compounds -- copper indium gallium selenide or cadmium telluride. Attempts to create affordable, earth abundant solar cells from related compounds that are free of indium, gallium or cadmium have not exceeded 6.7 percent, compared to IBM's new 9.6 efficiency rating.

Over the past several years, IBM researchers have pioneered several breakthroughs related to creating inexpensive, efficient solar cells. IBM does not plan to manufacture solar technologies, but is open to partnering with solar cell manufacturers to demonstrate the technology.