New Low Cost Solar Cell Assembles Itself

The price of solar panels has been sinking like a stone for the past few years, and that could be just the beginning of a low cost solar power future. When that happens, it will be partly due to the development of solar cells made of organic materials, which are less efficient but far cheaper than the current gold standard, the metalloid silicon. With that in mind let’s take a look at the latest news out of Rice University and Penn State, where researchers have developed a relatively efficient organic solar cell based on a compound polymer that assembles itself into tidy bands.

Block copolymer solar cell courtesy of Rice University.

Low Cost Solar Cells That Assemble Themselves

The Rice/Penn State team discovered a block copolymer, P3HT-b-PFTBT, which they created within a “sandwich” topped by a layer of glass/indium tin oxide, on an aluminum substrate.

When exposed to a relatively low heat of 165 degrees Celsius, the polymer self-assembled into distinct bands only 16 nanometers wide, conveniently aligned perpendicular to the glass top. Stretched between the glass and the aluminum, the bands create an ideal channel for electrons.

The team still doesn’t know why the copolymer lines up in bands, but for now they are satisfied with the achievement of a solar conversion efficiency of almost three percent.

Going by Rice’s own reference figure of up to 25 percent conversion efficiency for silicon solar cells, three percent sounds pretty pathetic. However, for an organic solar cell that’s pretty good. When you factor in numerous other advantages of organic solar cells, it’s clear that affordability and flexibility of application are just as important as conversion efficiency, in terms of getting new solar technology out of the lab and into the hands of consumers.

Low Cost Solar Cells: Follow The Money

When we look at these research projects, we always try to remember to check out who the funders are, because you never know when something interesting might pop up. For example, the Air Force and Army have teamed on a solar cell efficiency project with the University of Buffalo, and the Navy and Air Force are supporting a Princeton solar cell efficiency project.

In this case, we followed the money to the usual suspects, namely the Department of Energy and the National Science Foundation, but the Shell Center for Sustainability is also listed by Rice as a supporter of the research.

The Shell Center (yes, that Shell…and this Shell) launched at Rice University in 2002 under the following mission:

“…to foster an interdisciplinary program of research, outreach, and education to address actions that can be taken to ensure the sustainable development of communities’ living standards, interpreted broadly, to encompass all factors affecting the overall quality of life.”

The Shell Center originally encompassed sustainable development in Gulf of Mexico communities, namely Texas with a focus on the Houston/Galveston area. Its plan for 2015 includes extending its outer range from the Florida Keys to the Yucatan Peninsula. No word yet on whether it plans to go as far as Alaska, some day.

All snark aside, don’t hold your breath for Shell Oil to convert a major part of its revenue stream to selling block copolymer solar cells any time soon. The Rice/Penn State research is still in the beginning stages and aside from improving the cell’s conversion efficiency, the team still has to tackle some sticky durability factors.

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