Jun Yeob Lee

Recently, great progress has been made in the device performance of deep blue phosphorescent organic light-emitting diodes (PHOLEDs) by developing high triplet energy charge-transport materials, high triplet energy host and deep blue emitting phosphorescent dopant materials. A high quantum efficiency of over 25% and a high power efficiency of over 15 lm/W have already been achieved at 1000 cd m(-2) in the deep blue PHOLEDs with a y color coordinate less than 0.20. In this work, recent developmen

Organic light‐emitting diodes (OLEDs) are increasingly used in displays replacing traditional flat panel displays; e.g., liquid crystal displays. Especially, the paradigm shifts in displays from rigid to flexible types accelerated the market change from liquid crystal displays to OLEDs. However, some critical issues must be resolved for expansion of OLED use, of which blue device performance is one of the most important. Therefore, recent OLED material development has focused on the design, synt

High quantum efficiencies of above 30% in blue phosphorescent organic light emitting diodes are achieved by using novel pyridoindole-based bipolar host materials. A high quantum efficiency of 30.0% is obtained at 100 cd/m(2) by using the new host materials.

Highly efficient deep blue phosphorescent organic light-emitting diodes (PHOLEDs) with external quantum efficiency above 20% are developed using a bipolar-type high-triplet-energy host material and a high-triplet-energy exciton blocking material. Maximum quantum efficiency of 25.1% and low roll-off (still 23.1% at 1000 cd m−2) are achieved in these deep blue PHOLEDs.

Solution processed phosphorescent organic light-emitting diodes (OLEDs) have been actively developed due to merits of high quantum efficiency of phosphorescent materials and simple fabrication processes of solution processed OLEDs. The device performances of the solution processed phosphorescent OLEDs have been greatly improved in the last 10 years and the progress of the device performances was made by the development of small molecule host materials for solution processes. A hybrid host of pol

High quantum efficiency above 18% and extended lifetime three times longer than that of phosphorescent organic light-emitting diodes (OLEDs) are demonstrated in blue thermally activated delayed fluorescent OLEDs.

Abstract Organic emitters have been widely developed since the demonstration of high efficiency in pure organic emitters represented by thermally activated delayed fluorescent (TADF) emitters. Pure organic‐based TADF emitters are found to harvest all singlet and triplet excitons for radiative transition processes, like phosphorescent emitters that utilize all generated excitons for light emission by strong spin–orbit coupling. Red, green, and blue organic emitters are investigated, but major int

Carbazole- and triazine-derived thermally activated delayed fluorescent (TADF) emitters, with three donor units and an even distribution of the highest occupied molecular orbital, achieve high external quantum efficiencies of above 25% in blue and green TADF devices.

High quantum efficiency above 18% in a solution-processed thermally activated delayed-fluorescence device is achieved by modifying a common delayed-fluorescence emitter with a tert-butyl substituent.

A novel blue thermally activated delayed fluorescence (TADF) organic light-emitting diode with an emitting layer made up of a TADF assistant dopant and a pure blue-emitting TADF emitter was developed.

Recently, the external quantum efficiency and lifetime of organic light-emitting diodes (OLEDs) have been dramatically upgraded due to development of organic materials and device structure. In particular, an intramolecular or intermolecular complex based on thermally activated delayed fluorescent (TADF) materials has greatly contributed to improving OLED device performance. Although high external quantum efficiency has been the main objective of the development of TADF materials as hosts and emi

Highly efficient thermally activated delayed fluorescence (TADF) devices are developed by engineering mixed host materials in the emitting layer. Mixed hosts with deep highest occupied molecular orbital and high singlet energy without any exciplex formation are ideal as the host material for the TADF organic light‐emitting diodes. A high external quantum efficiency of 28.6% is achieved in the green TADF organic light‐emitting diodes using a mixed host of 1,3‐bis(N‐carbazolyl)benzene:1,3,5‐tri[(3

High quantum efficiency close to 25% and long lifetime in green thermally activated delayed fluorescent and phosphorescent organic light emitting diodes are achieved using universal 3',5'-di(carbazol-9-yl)-[1,1'-biphenyl]-3,5-dicarbonitrile host material.

Providing adequate lifetimes for organic light‐emitting diodes (OLEDs) has been a challenging issue for a long time because of the naturally weak chemical bonds of organic materials that can be damaged during electrical processes that drive light emission. The lifetime of OLEDs has been dramatically extended to the point where commercialization is feasible due to the development of stable materials and device structures that lessen the damage of the organic materials. However, the lifetime of hi

The external quantum efficiency (EQE) of organic light-emitting diodes (OLEDs) has been dramatically improved by developing highly efficient organic emitters such as phosphorescent emitters and thermally activated delayed fluorescent (TADF) emitters. However, high-EQE OLED technologies suffer from relatively poor device lifetimes in spite of their high EQEs. In particular, the short lifetimes of blue phosphorescent and TADF OLEDs remain a big hurdle to overcome. Therefore, the high-EQE approach