What are OLEDs?
OLEDs (Organic Light-Emitting Diodes) are ultrathin self-emissive devices consisting of a multilayer structure of organic materials between two electrodes: Sandwiched between several charge transporting layers, the central emissive layer makes for the light emission.
Blue. Green. Red.
OLED displays consist of three colors: red, green and blue. They are self-emissive, which means that unlike LCD displays, they do not require a backlight unit. As such, OLED displays have a much simpler structure, which enables thinner display panels.
Advantages of OLEDs
OLED displays also consume less power and offer high contrast ratio and high resolution. Particularly exciting is that OLED displays are fabricated on transparent and flexible surfaces. This enables new form factors, which in turn drives new product designs and new applications.
The power of OLED technology extends beyond amazing viewer experiences. The same technology is enabling a new class of foldable devices. Once the stuff of imagination, these exciting consumer devices are feature-rich yet ultra-light and flexible, with bezel-less screens that expand the viewing space.
Behind the most dazzling displays in the world is OLED technology. Colors are brighter, clarity is pristine, and images are more life-like than ever before. But that’s not all. OLED technology enables displays that are thin to the point of near-transparency, flexible, extraordinarily light and even more power-efficient.
Emitter: The heart of the OLED
The heart of the OLEDs are the emitter materials. These are organic molecules that are able to convert electrical energy into visible light. Depending on their structure, the three colors red, green or blue are generated.
To date, three different technological concepts can be used to generate light: fluorescence, phosphorescence and thermally activated delayed fluorescence (TADF). The main differences between these concepts are their different energy efficiency, which can be explained by quantum mechanics: In an OLED, the electric current leads to an excitation of the emitter molecules and thereby to the creation of singlet and triplet excitons. Due to quantum statistics, for every singlet exciton three triplet excitons are generated. The first generation of emitters, the fluorescent emitters could only convert the singlet excitons and therefore only 25% of all excitons into light. Second and third generation emitters, phosphorescent and TADF emitters, on the other hand, can convert up to 100 percent of the excitation energy into light by using both, the singlet and the triplet excited states.