RESEARCHNEWS Game changing innovation
A RESEARCHER from the University of Missouri has developed a flexible solar PV sheet that he says captures more than 90% of the available energy from sunlight. He plans to make prototypes available to consumers within the next five years. Efficiency is a problem with today’s solar panels; they only collect about 20 percent of available light.
Patrick Pinhero, an associate professor in MU Chemical Engineering says energy generated using traditional methods of solar collection is inefficient. The device his team has developed can harvest the heat from industrial processes and convert it into usable electricity. Their ambition is to extend this concept to a direct solar facing nantenna device capable of collecting solar irradiation in the near infrared and optical regions of the solar spectrum.
Working with his former team at the Idaho National Laboratory and Garrett Moddel, an electrical engineering professor at the University of Colorado, Pinhero and his team have now developed a way to
accessible to everyone,” Pinhero said. “If successful, this product will put us orders of magnitude ahead of the current technologies we have available today.”
extract electricity from the collected heat and sunlight using special high-speed electrical circuitry.
This team also partners with Dennis Slafer of MicroContinuum to immediately enable transfer of laboratory bench-scale technologies into manufacturable devices that can be inexpensively mass-produced. “Our overall goal is to collect and utilize as much solar energy as is theoretically possible and bring it to the commercial market in an inexpensive package that is
As part of a rollout plan, the team is securing funding from the U.S. Department of Energy and private investors. The second phase features an energy-harvesting device for existing industrial infrastructure, including heat-process factories and solar farms. Within five years, the research team believes they will have a product that complements conventional PV solar panels.
Because it’s a flexible film, Pinhero believes it could be incorporated into roof shingle products, or be custom-made to power vehicles. Once the funding is secure, Pinhero envisions several commercial product spin-offs, including infrared (IR) detection. These include improved contraband-identifying products for airports and the military, optical computing, and infrared line-of-sight telecommunications.
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ORNL boosts PV to new heights
WITH the creation of a 3-D nanocone- based solar cell platform, a team led by Oak Ridge National Laboratory’s Jun Xu has boosted the light-to-power conversion efficiency of PV by nearly 80 percent. The technology substantially overcomes the problem of poor transport of charges generated by solar photons.
“To solve the entrapment problems that reduce solar cell efficiency, we created a nanocone-based solar cell, invented methods to synthesize these cells and demonstrated improved charge collection efficiency,” said Xu, a member of ORNL’s Chemical Sciences Division.
The new solar structure consists of n-type nanocones surrounded by a p-type semiconductor. The n-type nanoncones are made of zinc oxide and serve as the junction framework and the electron conductor. The p-type matrix is made of polycrystalline cadmium telluride and serves as the primary photon absorber medium and hole conductor.
With this approach at the laboratory scale, Xu and colleagues were able to obtain a light-to-power conversion efficiency of 3.2 percent compared to 1.8 percent efficiency of conventional planar structure of the same materials.
Key features of the material include its electric field distribution that achieves efficient charge transport; the synthesis of nanocones using inexpensive methods; and the minimization of defects and voids in semiconductors. Because of efficient charge transport, the new solar cell can tolerate defective materials and reduce cost in fabricating next-generation cells.
“The important concept behind our invention is that the nanocone shape generates a high electric field in the vicinity of the tip junction, effectively separating, injecting and collecting minority carriers, resulting in a higher efficiency than that of a conventional planar cell made with the same materials,” Xu said.
Research that forms the foundation of this technology was accepted by this year’s Institute of Electrical and Electronics Engineers photovoltaic specialist conference and will be published in the IEEE Proceedings. The papers are titled “Efficient Charge Transport in Nanocone Tip-Film Solar Cells” and “Nanojunction solar cells based on polycrystalline CdTe films grown on ZnO nanocones.”
Other contributors to this technology are Sang Hyun Lee, X-G Zhang, Chad Parish, Barton Smith, Yongning He, Chad Duty and Ho Nyung Lee.
www.solar-pv-management.com Issue V 2011
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