A mobile phone screen is typically made of glass, according to Discovery News. If it is a touch screen, it is usually coated with a special conductive film called ITO, or indium tin oxide.
The glass must be hard to withstand shattering and thin enough so that it's not too heavy. Corning makes a thin, super-strong product called Gorilla glass for some phones, according to CBS News. However, cell phone glass screens are not shatterproof.
ITO can be made into a thin, colourless film with excellent transparency, stability and electrical conductivity. It is used for LCD, plasma and OLED displays and solar cells, as well as touch screens.
Glass is not a costly material, but ITO is quite expensive because it contains rare materials. Future coatings could consist of graphene, which is also very conductive and stronger than ITO, according to Discovery News.