Light emitting diodes – How it started

The physical phenomenon of what is now called p–n–luminescence has been known for more than 100 years. However, the effect as such was not understood until 1951 after the invention of the p–n–junction in 1947. The paper presents a brief survey of the development of LEDs in the visible region up to the early 1960s by not only focusing on the history of LEDs but also taking into account material science aspects.