Engineers have for years been developing solar cells made of inexpensive plastic, but the devices have limitations. For instance, the cells' short lifetimes when exposed to sunlight have prevented these inventions from getting beyond the prototype phase. Now, researchers describe a solar cell made of thin films of inorganic nanocrystals that have several of the advantages of plastic but avoid some of its shortcomings.
Researchers first turned to semiconducting plastics to devise solar cells because such materials are cheaper to produce than silicon, the main ingredient of conventional solar cells, and are more flexible. Plastic formulations also open the possibility of printing solar cells onto various surfaces, much as ink is printed on a newspaper.
Semiconducting plastics, however, break down over time, says Ilan Gur, a graduate student and materials science engineer at Lawrence Berkeley (Calif.) National Laboratory and the University of California, Berkeley. So, he a