An anonymous reader writes "Following up on earlier work in the field, researchers at MIT are developing a process to print solar cells directly onto many common forms of paper. 'The technique represents a major departure from the systems used until now to create most solar cells, which require exposing the substrates to potentially damaging conditions, either in the form of liquids or high temperatures. The new printing process uses vapors, not liquids, and temperatures less than 120 degrees Celsius. These "gentle" conditions make it possible to use ordinary untreated paper, cloth or plastic as the substrate on which the solar cells can be printed. ... The resilient solar cells still function even when folded up into a paper airplane.'"