Behind the Cover: June 2024

Each month, Physics Today editors explore the research and design choices that inspired the latest cover of the magazine.

Invented in 1927, LEDs took a long time to catch on. Early adoption was limited because of the diodes’ high cost, energy inefficiency, and narrow range of colors. One of the first examples of an LED display was Nintendo’s Virtual Boy in 1995, but the video game console was a commercial failure. More R&D was needed before LEDs would become ubiquitous components in lights and displays.

The development path has been smoother for microLEDs, the inspiration for the cover of the June issue of Physics Today. Created in 2000, they produce light the same way that their larger LED cousins do, but they’re brighter and have a lifetime of around 100 000 hours. Because of their advantages, microLEDs have attracted the interest of the electronics industry, particularly for consumer devices such as augmented- and virtual-reality headsets, watches, and smartphones.

Displays made from microLEDs would make those devices more easily visible in sunny outdoor environments. A single display would need millions of individual microLEDs, and the industry has developed new approaches for efficiently embedding the diodes into displays. In the June cover story , Vikrant Kumar, Keith Behrman, and Ioannis Kymissis discuss microLEDs, their manufacturing challenges, and their applications.

To illustrate microLEDs on the cover, senior designer Jason Keisling suggested the simple design of many individual dots to spell out “MicroLEDs.” His initial cover-design concepts brought to mind the long-popular Lite-Brite toy, with its backlit display of colored plastic pegs. With some input from staff editors, Keisling adjusted the density and brightness of the dots to accentuate the headline.