Plastics and Polymers make up the majority of materials in these products, along with Silicon, some precious metals such as Gold, Tin and Lead from the Solder used, Polycholrinated Biphenyls from the actual electronics boards (PCB Boards), and other metals such as steel, aluminium, copper, etc. The LEDs which create the backlight in most mobile phone screens and the indicator lights for other items contain materials such as the following for different colours: aluminum gallium arsenide (AlGaAs) - red and infrared aluminum gallium phosphide (AlGaP) - green aluminum gallium indium phosphide (AlGaInP) - high-brightness orange-red, orange, yellow, and green gallium arsenide phosphide (GaAsP) - red, orange-red, orange, and yellow gallium phosphide (GaP) - red, yellow and green gallium nitride (GaN) - green, pure green (or emerald green), and blue also white (if it has an AlGaN Quantum Barrier) indium gallium nitride (InGaN) - near ultraviolet, bluish-green and blue silicon carbide (SiC) as substrate — blue silicon (Si) as substrate — blue (under development) sapphire (Al2O3) as substrate — blue zinc selenide (ZnSe) - blue diamond (C) - ultraviolet aluminum nitride (AlN), aluminum gallium nitride (AlGaN) - near to far ultraviolet << Source wikipedia.org >>