This is what the website of Nature says:
Cracked your mobile-phone display? In the future, the remedy might be as simple, and cheap, as shining some light on it.
That is according to Christoph Weder, a materials scientist at the University of Fribourg in Switzerland, and his colleagues, who have developed a type of rubbery plastic that 'self heals' when exposed to ultraviolet light. The material might one day be incorporated into varnish, paint or mobile-phone covers.
"Just try to imagine how the lifetime of many items could be improved if damages could be easily fixed," says Weder.