# Organic Solar Concentrators

1. Sep 14, 2008

### Feldoh

1. The problem statement, all variables and given/known data
This is a problem based off of the article published in Science about MIT's organic solar concentrators.

The arrangement that I'm dealing with is a dye layer in a glass window, with the solar cells on the side of the window.

The absorption re-emission efficiency of dye in the concentrator is 15% per μm. A typical dye layer is about 5.8μm thick. The solar cell efficiency is around 20%. The glass is 2mm thick and the refractive index of glass 1.52.

1) How much of the light emitted in the dye reaches the edges of the window?

2) How large would the window have to be, to have the same efficiency, as if you were to expose the photovoltaic cells around the edges of the glass to sunlight directly?

3) Assuming the cost of glass is negligible (in comparison with solar cells) how much more
cost-effective is solar concentration, as opposed to using the solar cells directly, for a window of 1m^2.

2. Relevant equations
Snell's Law maybe
Law of reflection

3. The attempt at a solution
I don't really even know how to begin. I couldn't get the article so I'm not really even sure as to how they actually work. My understanding is that the dye absorbs the light and redirects it somehow into the solar cells? Then a smaller portion of the light that passes through the glass is refracted to the solar cells as well, while the rest just travels through the media.

I'm not even sure if my understanding is right, and I really don't know where to start.

1) There's a 15% efficiency per micrometer, but photons can hit the plate anywhere so I'm not really sure how to calculate this...?

2. Sep 14, 2008

### Feldoh

Anyone? I still can't get it XD

3. Oct 6, 2008

### mheslep

Yes the dye absorbs light one in part of the spectrum, and then emits in another. The glass and dye then acts as a wave guide for light incident upon the face of the glass, from any angle, through the dye with minimal absorption, to the edges with the attached traditional PV.

Abstract of original article:
http://www.sciencemag.org/cgi/content/abstract/321/5886/226