Polymer light-emitting diodes (PLEDs)

A polymer light-emitting diode (PLED) is a type of light-emitting device in which the active material that produces light is a conductive polymer rather than the small organic molecules used in many other organic LEDs. The light-emitting polymer, sometimes abbreviated LEP, is sandwiched between two electrodes; when current is driven through it, the material emits light by electroluminescence. PLEDs are therefore a subclass of organic light-emitting diode technology, distinguished by their polymer-based emissive layer.

The appeal of polymers lies in how they can be processed. Because suitable polymers can be dissolved and deposited from solution, PLED layers can in principle be applied using printing or coating techniques over large areas, which could make manufacturing cheaper and more scalable than methods that evaporate small molecules in a vacuum. Like other organic emissive displays, PLEDs generate their own light, so they need no backlight and can be made thin and potentially flexible, with wide viewing angles and good contrast.

PLED technology sits alongside small-molecule OLEDs and the active-matrix variants such as AMOLED used in many screens. It is also distinct from the liquid-crystal display, which does not emit light itself but modulates a backlight. Research and development have focused on improving the efficiency, colour range and operating lifetime of the emissive polymers, factors that determine how well the technology competes for use in displays and lighting.

Frequently asked questions

What makes a PLED different from a standard OLED?

A PLED uses a light-emitting polymer as its emissive layer, whereas many OLEDs use small organic molecules. Both produce light by electroluminescence and emit their own light without a backlight.

Why are polymers attractive for displays?

Suitable polymers can be deposited from solution, opening the door to printing or coating over large areas, which can make manufacturing cheaper and more scalable than vacuum-based methods.

Do PLEDs need a backlight?

No. Like other organic light-emitting devices, PLEDs emit their own light, so they require no backlight and can be made thin and potentially flexible.