Over the past several decades, light sources have gradually transitioned to light-emitting diodes, or LEDs, and inorganic LEDs are now used across a wide range of applications. In parallel, organic LEDs, or OLEDs, have become widely used in display technologies.
OLEDs in particular offer significant advantages in devices such as smartphones, including higher resolution and lower power consumption. All LEDs operate based on spontaneous emission, which is inherently broadband, and OLEDs in particular produce broad emission spectra.
Narrowing this spontaneous emission toward a monochromatic limit would greatly increase its utility, a goal that has long been a central pursuit in photonics. For example, a narrower emission would achieve more highly saturated colors in LED-based displays.








