QLED brighter than original 4 times ... ETRI, orig

QLED brighter than original 4 times ... ETRI, original technology development (Google Translation)
2019-04-16 09:29:49

QLED device Quantum dot surface replacement technology to release electron-hole imbalance 4.5 times brightness, 1.7 times current

Korea researchers have succeeded in developing technologies that can dramatically improve the performance of QLEDs, a next-generation display device that follows organic light emitting diodes (OLEDs). Korea Electronics and Telecommunications Research Institute (ETRI) has developed a technology to improve the injection efficiency of QLED (Quantum-dot Light Emitting Diode) to change the molecular structure of the surface of QDED to improve the brightness, current and power efficiency of QLED. Said in a statement. QLED is a display technology using quantum dots that are light emitting semiconductor particles. If OLEDs use organic materials, QLED uses quantum dots instead of organic materials. Recently, demand for display that reproduces colors close to nature has been increasing, so that interest in QLED technology capable of providing the widest color gamut is increasing, but QLED technology has a problem of electron-hole transport imbalance in the light emitting layer. According to the researchers, the devices constituting the QLED display emit electrons and holes injected from both electrodes to emit light at the quantum dots. Electrons are free to move up and down, but in the case of holes, the transfer between the electrode and the quantum dot energy is slow and difficult to move. This electron-hole imbalance problem requires research to reduce the performance of the quantum dot light-emitting diode and to shorten the lifetime of the device.

This time, the ETRI team solved the imbalance problem by replacing the portion of the hole with a material called pyridine, by placing a quantum dot on the light emitting layer that shines brightly on the display.

By replacing pyridine with an organic compound of cyclic structure, the distance between the quantum dots and the hole transport layer is reduced, and the intermediate energy layer is formed, so that holes can be moved easily and quickly.

In addition, the intermediate energy layer makes it possible to transfer the holes more smoothly, thereby enhancing the efficiency in which electrons and holes meet and emit light. Although electrons and holes must be present in one layer at the same time, only electrons can move smoothly and electrons can not follow them. In addition, when the holes are injected further, additional problems arise in addition of voltage. However, the researchers were able to move the holes freely and smoothly without additional voltage, allowing them to emit light at lower voltages, and significantly improved brightness and current efficiency compared to existing devices. "The principle of bright light is that electrons meet a lot of electrons with fast mobility because of fast hole movements even at the same voltage as OLED," he said. "It has 4.5 times the brightness, 1.7 times the current efficiency and 2.3 times the power efficiency Quantum dot light-emitting diodes. " In particular, this technology can be equally applied to quantum dots of all colors of red, green, and blue (RGB), which is expected to be of great help in commercializing QLEDs in the future.

This technology, developed by the team, was selected as a cover paper for the March issue of the Journal of Materials Chemistry, a leading international journal in the field of materials, in recognition of its excellence.

http://www.newsis.com/view/?id=NISX20190415_0000621435