After Gutenberg

In 2004 CNET staff writer Michael Kanellos perceived that “alternative energies are looking good again”. One of the companies that prompted the observation was Konarka, founded in 2003 by among others, Nobel Prize winner Alan Heeger. The company began to demonstrate that it could mass produce Power Plastic — solar cells made of thin layers of plastic.

Fast forward four years (My! How time flies when you are going in the red for foreign oil) and, In March of this year, as part of Solar America Initiative, Konarka was one of 13 companies to receive funding from the U.S. Department of Energy. DOE directed the biggest chunk of this rather modest funding at companies developing thin-film technologies. Other than Konarka, recipients included thin-film manufacturers BP Solar, Miasole, Nanosolar, and United Solar Ovonic; each received funding of about $20 million.

A challenge remains. PVL (Photo Voltaic Laminates) are cheaper to produce, in part because of R2R (Roll 2 Roll) manufacture, and in part because of less costly, for now, materials. Nevertheless, thin film solar cells are less efficient at converting light to electricity than solar cells made with crystalline silicon. To achieve similar power output requires more area, which adds to the total system cost

Developers also have observed that TFPV Thin Film Photo Voltaic) solar panels gain some advantage in less than ideal light exposure. Whereas considerable design has focused upon concentrating solar power upon the expensive single silicon crystal, photo electronic engineers have begun to achieve high conversion rates with VMJ (Vertical Multi Junction) solar cells.

As early as 1995 researchers reported to the National Renewable Energy Laboratory their nanotechnology findings from experiments fabricating multilayer solar cells of silicon or germanium.

Vertical contacts eliminate the need for conventional top and bottom ohmic contacts that obstruct light or impede reflection of lower than bandgap energy photons. These features and the inherent high-voltage and low-series resistance characteristics of the VMJ cell assures efficient operation at high power densities.

EERE (the office of Energy Efficiency and Renewable Energy) suggest solar farms as the best, immediate application, i.e. “bulk electric power generation for large-scale (>100-kW) central power stations in sunny, semi-arid regions of the world.” While VMJ cells are more complex than the current crop of thin film photo voltaic laminates, they still lend themselves to similar manufacturing processes. They promise manufacturing costs lower than crystalline silicon, plus robust reliability and “record-breaking performance” (Most recently, a DARPA funded consortium, led by the University of Delaware, used multiple innovations to achieve 42.8% from sunlight at standard terrestrial conditions with a crystalline silicon solar cell platform.)

“They is who?”

Well, one of the largest solar energy manufacturers, Sharp, claims that stacked triple junction thin film solar cells “can be fabricated on the same equipment as conventional tandem (two-layer) cells. Consequently, the shift to multiple active layers enables increases in conversion efficiencies and thus a lower price per watt, some claim competitive performance at 25% of the typical cost for commercially available solar cells.

And, then, there are the makers of semiconductors… Excuse me, makers of organic opto-electronic devices that are fast taking development into a whole new sphere.