Physicist Isamu Akasaki, a co-winner of the 2014 Nobel Prize in Physics for inventing the world's first efficient blue light-emitting diodes, has died aged 92. He died of pneumonia in Nagoya, Japan, Meijo University said. During the 1980s and 1990s Isamu Akasaki, along with Hiroshi Amano, and Shuji Nakamura used the semiconductor gallium nitride to create efficient blue LEDs.