Dye sensitized solar cells (or DSSC) are one of the earliest varieties of non-p-n junction solar cells developed. This is also one of the earliest and most well publicized varieties of the advanced solar cell varieties. As a historical note, the concept for these cells was inspired by some of the most ancient photovoltaic devices on the planet: bacteria, algae and plants, via photosynthesis.
The current systems are based on complex surface interactions between a mesoporous titanium dioxide (TiO2) thin film, a monolayer of light-absorbing organometallic dye, and a surrounding electrolyte material that completes the charge transfer system.
The dye absorbs incident photons and uses that energy to make electrochemical charge carriers (e.g.: electrons and holes). The TiO2 and the electrolyte then selectively separate the electrochemical charge carriers, and these carriers diffuse off (largely due to chemical potential) to the positive and negative electrical contacts.
One of the most important contributions of DSSC to the field of photovoltaics was to raise a simple question. Do you need a p-n junction, and the electrostatic field that forms as a result of a p-n junction, to separate charge carriers? As it turns out: no, you don’t.
Ok, if you don’t need an electrostatic field to separate photogenerated charge carriers, then how does the device work? The results of the dye sensitized cell raised this new question. The data gathered from DSSCs has opened up many fundamental questions as to the general science of a photovoltaic device, and a lot of very interesting research is being pursued in this vein now. I will try to present more on these recent findings in the future, as there doesn’t seem to be any one source of information to tie the results together. I believe that these results will also be vital in addressing the important parameters for ETA solar cells, organic polymer solar cells, and third generation photovoltaics in general. We shall see…
