The colour that held up the LED

0:00 Red LEDs arrived in the early nineteen

0:03 sixties and green followed quickly,

0:05 but blue took another thirty years,

0:08 and without blue there is no white light and

0:12 no LED bulb.

0:13 The problem was the material.

0:15 Blue needs a wide band gap semiconductor,

0:18 and the obvious candidate, gallium nitride,

0:21 could not be grown as a clean crystal or made

0:24 to conduct properly.

0:25 Most laboratories gave up on it.

0:28 Shuji Nakamura,

0:29 working at a small Japanese chemical company,

0:32 kept going and solved both problems by the

0:35 early nineties.

0:36 The result rewired global lighting and won a

0:39 Nobel Prize in twenty fourteen.

0:41 Every white LED you own is really a blue one

0:45 wearing a yellow coat.