The history of LED technology

3.1 1907: the first recorded observation

At the time, semiconductor physics was poorly understood. Radio researchers used crystal detectors pragmatically, without the band theory and fabrication control that later made solid-state electronics possible.

3.2 Oleg Losev and the light-emitting crystal

During the 1920s, Russian scientist Oleg Vladimirovich Losev investigated light emission from crystal detectors in much greater depth. He published observations, explored the relationship between voltage and light output, and considered communications and signalling applications. His work was technically prescient but did not establish a manufacturing industry.

Losev's story is important because it corrects the idea that the LED arrived fully formed in the 1960s. The device emerged through repeated observations, theoretical advances and improved materials over many decades.

3.3 Semiconductor science and the transistor era

The invention of the transistor at Bell Laboratories in 1947 accelerated investment in semiconductor materials and junction physics. Researchers learned to control conductivity by doping materials and to engineer p-n junctions. Compound semiconductors such as gallium arsenide and gallium phosphide offered direct routes to light emission at useful wavelengths.

Early infrared devices were valuable for communications and sensing, but a visible device was needed for human-readable indicators and displays.

3.4 1962: the practical visible LED

In 1962, Nick Holonyak Jr and his colleagues at General Electric demonstrated a practical visible red LED based on gallium arsenide phosphide. The University of Illinois records the work in its history of the LED, and its account of Holonyak's laboratory demonstration dates the red emission to 9 October 1962.

The early devices were costly and dim by modern standards, but they offered long life, low power use and fast switching. Those attributes made them valuable as indicators and numeric displays.

3.5 Indicators, calculators and alphanumeric displays

Through the late 1960s and 1970s, red LEDs appeared in instruments, calculators, watches and seven-segment displays. Yellow, orange and green variants broadened the palette. LED matrix displays could present simple text and symbols, while sports and transport applications created demand for larger electronic information systems.

These systems were not yet full-colour video displays. Their contribution was to establish reliable packaging, driver circuits, matrix addressing and mass-production methods.

3.6 The missing primary colour

A practical full-colour emissive display needs red, green and blue. Red devices matured first; bright blue remained difficult because the required wide-bandgap materials were challenging to grow and dope with sufficient quality.

Research by Isamu Akasaki and Hiroshi Amano, and later by Shuji Nakamura, established efficient blue light emission from gallium nitride-based structures. The breakthrough also enabled improved green devices and white light through phosphor conversion.

The Nobel Prize's scientific background explains the materials challenge, while the popular account describes the wider impact. Akasaki, Amano and Nakamura received the 2014 Nobel Prize in Physics for the invention of efficient blue light-emitting diodes.

3.7 Why the blue LED changed video displays

Once efficient red, green and blue LEDs could be combined, manufacturers could produce outdoor RGB pixels capable of full-motion colour images. The first systems were coarse by current standards and intended for long viewing distances, but they offered daylight-visible images, modular scale and robust outdoor operation.

The blue-LED milestone did not by itself create the modern industry. Full-colour displays also needed improved packaging, driver integrated circuits, high-speed data transmission, video processing, thermal design, mechanical precision and mass manufacturing. The importance of the blue LED is that it removed the fundamental colour barrier.