fantastic plastic

A team of researchers at MIT, headed by Marc Baldo, have developed solar concentrators based on coatings of organic dyes on glass or plastic substrates. Sunlight absorbed by the dye molecules is re-emitted at different wavelengths and waveguided to the photovoltaic cells at the edge of the glass substrate. From the press release:

The dye-based organic solar concentrator functions without the use of tracking or cooling systems, greatly reducing the overall cost compared to other concentrator technologies. […] Some light passes through the concentrator and can be absorbed by lower voltage solar cells underneath. Alternatively, the partially transmissive concentrator can function as a window.

In the published work (Science) the dye layers were deposited from the vapor phase, but solution processing is in principle also possible.
Apparently very similar luminescent solar concentrators were first developed in the 1970’s, but suffered from absorption of the light before it reached the edges, as well as poor stability of the dyes.
While the stability of the current devices is also not good enough yet for products, the inventors believe the technology could be commercialized within three years.
Covalent Solar, a company being spun out of MIT by three of its inventors (Michael Currie, Jon Mapel, and Shalom Goffri) is working on achieving this goal.

Konarka, developers of organic photovoltaics,

today announced it has raised $45 million in private capital financing. The financing was led by Mackenzie Financial Corporation, a leading investment management firm with over $60 billion in assets under management, and was co-led by existing investor, Good Energies, a leading investor in the renewable energy industry. Lead investors from prior rounds also participated, including Draper Fisher Jurvetson (DFJ), Asenqua Ventures, New Enterprise Associates (NEA) and 3i. Other participating current investors include Vanguard Ventures, Chevron Ventures, Massachusetts Green Energy Fund, NGEN Partners and Angeleno Group. The financing was agented by Lehman Brothers.

Konarka (organic photovoltaics) and Toppan Forms (Data Print Services and information management services)

have signed a joint agreement to accelerate the development, manufacturing and commercialization of polymer-based organic photovoltaic (OPV) technologies for consumer and electronic applications. Under the agreement, the mutual goal is to bring Konarka’a organic photovoltaic material, Power Plastic®, to market.

“Konarka’s Power Plastic is flexible, thin, printable and low in cost, providing our organization with promising new business opportunities as we strive to become an integrated information management service company,” commented Masanori Akiyama, president and CEO of Toppan Forms. “With the full-fledged advent of the ubiquitous society under way, we need an ever-present power technology that can be integrated with pervasive networked devices for information collection and distribution. We are delighted to collaborate with Konarka, the world leader in OPV technologies, to accelerate the commercialization of this transformational power technology to the market place.” […]

“The partnership with Toppan Forms represents a key milestone for the commercialization of Power Plastic,” commented Rick Hess, president and CEO of Konarka. “This relationship enables each company to focus its expertise and resources on key product development processes, continuing our go-to-market strategy of partnering with leading global companies for a variety of applications.”

From the Press release: (pdf, html)

BASF and Bosch are to cooperate in the innovative field of organic photovoltaics (OPV) and are founding members of the technology initiative of Germany’s Federal Ministry of Education and Research (BMBF). [… ] Last year, photovoltaic modules had a global market volume of €8 billion. The segment is expected to grow by more than 20 percent annually until 2020. The BMBF will provide €60 million for research to develop this highly attractive market, while the initiative’s current industry partners – which include, alongside BASF and Bosch, Merck (Darmstadt) and Schott (Mainz) – plan to spend up to €300 million. […]

Stake in Heliatek

To further develop the new technology, BASF and Bosch are also cooperating on special research activities with the Dresden-based company Heliatek GmbH. BASF Venture Capital GmbH and Robert Bosch GmbH are each investing €1.6 million in the start-up company, which was founded in 2006. The other investors are Wellington Partners and the ‘High-Tech Gründerfonds’. Heliatek specializes in the manufacture of new-generation organic solar cells. The company is working on an ultra-efficient technology to build large-scale modules on cheap, flexible substrates using a roll-to-roll production process.

BASF is conducting research into semi-conductive organic materials with high thermal and photo-thermal stability. […] BASF contributes its broad-based expertise in the field of organic electronics and the design, synthesis and production of complex organic compounds to the project. […]

The researchers want to develop organic solar cells that convert at least ten percent of the incident light into energy and offer a service life of more than ten years. BASF’s “Joint Innovation Lab – Organic Electronics”, which was opened last year in Ludwigshafen, acts as a cooperation platform for the industry and university partners. Experts from a range of disciplines are also working on organic light emitting diodes (OLEDs) at the JIL, a technology also based, like organic photovoltaics, on organic semi-conductive materials.

Kyosemi Corporation is developing solar cells consisting of 1mm spheres on a flexible substrate.
More information on the Sphelar solar cells: production process, main features, overview (PDF):

In mid-2006, Kyosemi Corp. plans to begin full-scale mass production of its Sphelar spherical micro solar cell at its Eniwa Operation in Eniwa City, Hokkaido, Japan.
While existing planar solar cells can take light only from their elevation surface, the Sphelar cell allows light to reach its cells from all directions because it has a spherical surface, providing a high level of photoelectric conversion efficiency. […]
The company uses conditions of microgravity to form the Sphelar cells from molten silicon. Surface tension causes the silicon to take on a nearly perfect spherical shape. Due to segregation effects gained during the solidification process, single crystal silicon with a purity of 99.9999 percent can be obtained. The pn junctions are created using an n-plus diffusion process. Silver paste is used to attach electrodes. The product is finished with a coat of reflection film. […]
If a Sphelar cell is encapsulated in acrylic resin, it can be turned into Flexible Sphelar sheet, a thin solar cell module whose shape can flexibly be changed into, say, a crescent or a curved form.
A module made with a series of Sphelar cells connected in parallel on silicone resin achieves a photo electric conversion efficiency of 19 percent.

See also this earlier article (”Spherical Solar Cells Solve Issue of 3-D Sunlight Reception”, 2003).