Tiny tech, big results: Quantum dot solar cells increase solar conversion efficiency
August 2, 2011 by Stuart Mason Dambrot
Sometimes called artificial atoms, nanoparticles composed of cadmium, zinc, tellurium, selenium, sulfur and other compounds are so miniscule that adding or removing a single electron represents a significant change – a property that makes them suitable not only as components of advanced solar cells, but also in solid state lighting, medical sensors and other applications.
In particular, colloidal quantum dots (CQDs) – synthesized from a three-component system composed of: precursors, organic surfactants, and solvents – can be tuned by changing their size, which in photovoltaic structures allows their spectral response to be tailored as needed. Recently, researchers in the Department of Electrical and Computer Engineering at the University of Toronto have demonstrated the first CQD tandem solar cells (a series of connected solar cell in which adding more devices allows for each device to be optimized to a narrower spectrum giving a higher overall efficiency) using the size-effect tuning of a single CQD material, lead(II) sulfide (PbS). Their ability to tune CQD films may allow tandem and multi-junction solar cells (fabricated by combining CQDs of differing sizes) to raise solar cell conversion limits from its current 31% to 42% 49%, respectively.
http://www.physorg.com/news/2011-08-...s-quantum.html
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