What Is an Electroluminescent (EL) Display?
An EL display is a new energy-saving, high-luminance display that utilizes organic electroluminescence (EL) technology.
Organic compounds such as diamine and anthracene are molecules that emit light when a voltage is applied. OLED functionality utilizes this property.
Unlike conventional LCDs, OLEDs do not require a backlight, making the display thinner.
OLEDs also have the advantage of being able to display a wider variety of colors than when inorganic phosphors are used.
Uses of EL Displays
EL displays are used in a variety of situations as a new technology to replace conventional LCDs.
The most notable application is in TV displays, which are thin and have high brightness.
Other applications include smartphone displays. The thinness of OLED displays has led to the application of bendable display technology, which was not possible in the past, and as a result, smartphones with new performance and shapes are being commercialized.
Principle of EL Displays
EL Display is a phenomenon in which light is emitted when voltage is applied to organic compounds such as diamine and anthracene.
EL display is a generic term for displays that use this type of EL technology and have the advantages of high luminosity even with low power consumption and of being thinner than conventional LCDs.
Since liquid crystal is a non-luminescent material, it must be backlit from the back to emit light, a factor that hinders thinner displays.
In addition, a color filter is installed in each pixel for color display. On the other hand, EL displays are self-luminescent material that does not require a backlight and can emit light only by applying voltage, which is advantageous for realizing thin displays.
A transparent electrode is used on the side that emits light to the outside, and a reflective electrode is used on the opposite side with the light-emitting layer in between.
Using the transparent electrode as the cathode and the reflective electrode as the anode, a negative voltage is applied to the cathode and a positive voltage to the anode, enabling the injection of electrons from the cathode into the electron injection transport layer and holes from the anode into the hole injection transport layer, respectively.
When the injected electrons and holes reach the light-emitting layer, carrier (electrons and holes) recombination occurs, and the electronic energy levels of the OLED molecules in the emitting layer transition from the ground state to the excited state.
The light-emitting phenomenon derived from this energy is electroluminescence (EL), and this technology, which uses organic compounds as light-emitting materials, is called organic EL or OLED (organic light-emitting diode).
For color display, there are two types of methods: one that uses red (R)/green (G)/blue (B) light-emitting materials in the light-emitting layer of each pixel (three-color light-emitting method) and another that combines a color filter with a colorless (white) light-emitting layer (white + color filter method), as in liquid crystal displays.
In terms of power consumption and response time, they offer significant advantages over conventional LCDs.
In this way, it is now being incorporated as a fundamental technology for a wide variety of displays, including not only flat-panel TVs but also smartphones.