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Silicon Clathrates Executive Summary

Silicon Clathrates Executive Summary

Name: Silicon Clathrates
Elevator Pitch: InGaN nanowire materials for solar energy conversion
Department: Physics Department, Colorado School of Mines

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Our goal is to explore InGaN nanowire arrays as a low cost, high efficiency approach to solar energy conversion. The primary challenge facing InGaN solar cells today is the ability to grow material with an optimized band gap for the solar spectrum while maintaining sufficient electronic properties. Reaching high indium compositions has been a challenge because of the change in lattice constant with composition. The faculty is developing a promising route to effective indium incorporation: growth of core-shell structures where a GaN nanowire core is coated with a thin InGaN shell. Because of the low SRV of InGaN, nanowire solar cells may approach efficiencies obtained in bulk cells, and the small amount of material used allows for higher Voc and lower cost.

Transformative approaches to photovoltaics require high efficiencies (>20%) and low costs (<$1/W). Traditional single crystalline materials such as Si have a high enough efficiency, but are too expensive and use large amounts of material. Newer thin film approaches are low cost, but do not enable high enough efficiencies, especially in commercial modules.

There are two keys to achieving high efficiency: using high quantum efficiency material with almost no nonradiative recombination and using a thin layer in conjunction with a back reflector for improved voltage. Materials such as GaAs and InGaN have very high internal quantum efficiencies and low nonradiative losses as long as strain-induced defects are minimized, and they have strong absorption properties, allowing for thin layers. These materials are typically expensive single crystals that require lattice-matched substrates; however, there is potential for further improvements in both efficiency and cost by moving to InGaN nanowire materials, since InGaN can be grown as defect-free nanowires on low cost substrates and the substrate does not have to be removed.

Technology Benefits
•Enabling nanowire solar cells
•Growth of high indium content alloys
•Design of other nanowire devices
•Low cost nanowires due to flexible substrate choice and lower defect densities
•Reduces material usage over thin film designs

Solar, photovoltaic manufacturing, Nano technology, metal organic chemical vapor deposition, foundry based manufacturing, semiconductors, optics

To Indicate an Interest or for More Information: 303.444.2111 or Please include a copy of your resume.