Harnessing the Solar Spectrum using InN-Based Nanostructures

Magnolia Optical Technologies announced that it is collaborating with Dr. Roger Welser of the Kopin Corporation in developing indium nitride (InN)-based quantum dot solar cells for NASA and Defense applications.

“The goal of the current program is to develop high performance solar cells that are resistant to extreme conditions while achieving high solar electric power conversion efficiency,” said Dr. Welser, Kopin’s Director of New Business and Product Development. “The advanced solar cell structure incorporating InN-based nanostructures can harness a very large fraction of the solar spectrum while minimizing the effects of high temperatures and high-energy radiation. This technology will enable photovoltaic power systems of future NASA space exploration missions and can be applied to other defense applications.”

The solar electric conversion efficiency of traditional semiconductor solar cells is limited by a fundamental tradeoff between the current generated by photon absorption and the operating voltage of the device. Photons with energies below the band gap of the semiconductor pass right through the device and do not contribute to the photogenerated current. High energy photons can be absorbed, but the resulting electrons are collected and extracted at a lower voltage limited by the semiconductor band gap.

“Quantum effects in nanostructured materials enable new innovative device concepts that can radically enhance the operation of traditional semiconductor devices” said Dr. Ashok Sood, President of Magnolia. “For example, a larger fraction of the solar spectrum can be harnessed while maximizing the solar cell operating voltage by using quantum wells and quantum dots embedded in a higher band gap barrier material. Nanostructured devices thus provide a means to decouple the usual dependence of short circuit current on open circuit voltage that limits conventional solar cell design. Ultra-high conversion efficiencies are predicted for solar cells that collect both low and high energy photons from the solar spectrum while maintaining high voltage operation.”

Magnolia and Kopin have successfully collaborated on previous efforts utilizing GaN-based materials and look forward to future joint program pursuits.

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