Quick question: would you interpret quantum dots as disruptive technology for light absorbing solar energy, or concentrating solar power (CSP)? One is a fairly recent topic in the photovoltaic world, and the other has been around for over one hundred years.
A quantum dot is a nanoparticle in which the excited states (high energy electrons and holes) are “confined” by the very small dimensions of the particle. This leads to increased energy in the excited states (no where to go but up in energy), and has resulted in many new technologies. One proposed technology would use quantum dots as light absorbers for a photovoltaic effect, where one could collect mulitiple electrons (increased photocurrent) or very high energy electrons (increased photovoltage). The up side is that quantum dots sound sooo cool, why not make them into PV devices? The down side is that the rates of charge carrier extraction (collecting the electrons to do work) are still way too high to get much efficiency out of them. A lot of research needs to occur before you start seeing purely quantum dot PV. The disruption appears to be far away.
On the other side, if you concentrate the sun’s power, you can use it effectively for multiple applications, and often you don’t need radical new technologies. Rather, a combination of straight forward technologies in a new way may lead to something disruptive. You can concentrate the sun’s visible light (48% of the suns power, or 656 W/m2) for photovoltaics, OR you can concentrate the sun’s infrared light (45.6% of the total power, or 623 W/m2) and use the thermal heat to do work! Either way, by concentrating you take a diffuse source and, well, concentrate it. Certainly, you would need to cool a PV collector, but what about a thermal collector powering a turbine to generate electricity? In 1878, a solar power collector was exhibited at the World’s Fair in Paris, France. Between 1907 and 1913, an American engineer (F. Shuman) developed solar powered hydraulic pumps with a concentration ratio of about 4.5:1.1
And the kicker, CSP is getting closer and closer to being the first economically viable solar technology–opening the doors to the following technologies? Is this disruption, by opening the possibilities of solar power beyond the single junction photovoltaic device?
1. D. Y. Goswami, F. Kreith, and J. F. Kreider Principles of Solar Engineering 2nd Ed. (2000) Taylor & Francis, Philadelphia, PA.
Hi Jeffrey,
I might say that this post is of great interest for me! I would say that confronting CSP and Quantum Dots (QDs) is a bit unfair for the latter. Huge CSP plants are already working, worldwide companies rush into the industrialization of components for that technology (mirrors, trackers, coated glass tubes). In the other hand, QDs Solar Concentrators technology are just ready for laboratory test but not even for prototype! Am I wrong? Did I miss some more recent development in QDSCs?
What do you really compare QDs integrated into PV cells and QDs into coatings for CSP?
I hope to read you soon.