Perhaps nothing showcases technology’s ability to innovate and change lives better than the science behind 
renewable power. Solar power’s high cost is well-established, but scientists at CalTech are developing cells with such hyper–
efficiency they could potentially eclipse the question of price.


A team of researchers, led by professor Harry Atwater, is studying concepts that will enable solar cells to capture more of the sunlight spectrum. Contemporary solar cells only catch a small band of the spectrum. Most of the sunlight is wasted. As a result, their efficiency falls below 20 percent.


The Atwater team is determined to do much better. In fact, it is looking at cells with an efficiency of greater than 50 percent.


Exercising “light management” through the use of nanotechnology, the technology is designed to split and capture the different colors of light in the spectrum. Each wavelength of light would then be directed to a unique cell specifically designed to absorb and convert that light into electricity. The result is better efficiency.


In an interview in the April issue of MIT’s Technology Review, Atwater said ultrahigh efficiency in solar cells is “the best lever we have” for reducing the cost of solar power because the cost of solar panels have dropped dramatically. Increasing efficiency and decreasing the number of cells needed are the next steps in the process of reducing the overall costs of solar. 


“Within a few years, there won’t be any point to working on technology that has efficiency that’s less than 20 percent,” Atwater said.


The scientific community has recognized the importance of the work. Last summer, Atwater and Albert Polman of the Dutch Research Institute received the prestigious ENI Renewable and Non-conventional Energy Prize for their collaborative research.