posted on Aug, 5 2007 @ 06:12 AM
This story has been making the rounds - I'm not sure why NJIT is making such a fuss except perhaps just the attention. At any rate, this field of
study isn't new - polymer electronics have been in research labs for about 20 years or so. Solar applications have been getting attention over the
past ten years, perhaps, but neither Mitra nor NJIT are big names in the field nor has this guy presented much of substance here (bulk heterojunction
polymer-fullerene solar cells is my job, btw) .
First - the stuff isn't like paint. It's an organic solution of the plastic and the buckyballs which must be applied in clean, laboratory
conditions to rather exacting tolerances. The substrate onto which you coat the material must be transparent and electrically conductive (a tricky
combination) while the film you deposit must dry to an even thickness on the order of 100 nanometres. On top of this one must also deposit a
top-conductor to complete the circuit. Just painting it on a car is not likely to ever happen.
Second, this guy has ruined these devices. I and all of my colleagues make these every day - simply with polymer and buckyballs they are about 3-4%
efficient. This guy had the great idea of adding nanotubes to increase conductivity (something which has been tried already by others) and ended up
with worse devices (about 0.5% efficient). If anything, Heeger and his group should be the one in the news :
Nature Materials 6, 497 - 500 (2007) [link]
where they showed an increase from 3% to 5.5% in the same cells with a new additive. Much more newsworthy than Mitra press-releasing an ordinary lab
result of dubious promise.
For comparison, at any rate, commercial silicon cell modules are about 16-18% efficient. The big problem for the polymer devices so far is lifetime.
The materials are quite sensitive to moisture and oxygen and degrade after a few thousand hours (at best). Solar panels aren't so hot if they don't
work for more than a month so the research continues. Closer to reality is going to be more like flexible panels (which I'm working on at the
moment) rather than paint - plastic film, rollable, etc, embedded on rucksacks or jackets (charge your phone in your pocket...) that sort of thing.