scholarly journals Single emission spectrum measurement enables control of organic LED emission zone giving ultralong device lifetime

2021 ◽  
Author(s):  
Rossa Mac Ciarnáin ◽  
Hin Wai Mo ◽  
Kaori Nagayoshi ◽  
Hiroshi Fujimoto ◽  
Kentaro Harada ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Delayed Fluorescence ◽  
Device Structure ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Spectrum Measurement ◽  
Current Densities ◽  
Device Lifetime ◽  
Single Emission

Abstract Device optimization of light-emitting diodes targets the most efficient conversion of electrically injected charges into emitted light. Where charges recombine and where light is emitted from is known as the emission zone. Determining its form is key to better understanding the physical processes determining device performance. However, a thorough measurement study has not been shown. Here we present an accessible technique to visualize the emission zone in unprecedented detail at all luminescing current densities. Only a single emission spectrum must be measured (at normal direction to the device layers with no additional optics) and compared with the simulated emission spectrum. This method allows physical understanding based, instead of speculative, optimisation of LED device architectures. We demonstrate its impact by examining the device structure – emission zone – lifetime relationships of a thermally activated delayed fluorescence OLED to achieve an ultralong 4500 hour T95 lifetime at 1000 cd/m2 with 20% external quantum efficiency.

Highly Efficient and Stable Blue Organic Light-Emitting Diodes through Selective Quenching of Long-Living Triplet Exciton of Thermally Activated Delayed Fluorescence Emitter

2021 ◽  
Author(s):  
Won Jae Chung ◽  
Jun Yeob Lee
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Triplet Exciton ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Device Lifetime

In the organic light emitting diodes (OLEDs), the achievement of high efficiency and long device lifetime has been a goal due to the short device lifetime of the high efficiency...

scholarly journals Fabrication of a Solution-Processed White Light Emitting Diode Containing a Single Dimeric Copper(I) Emitter Featuring Combined TADF and Phosphorescence

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1500
Author(s):  
Gang Cheng ◽  
Dongling Zhou ◽  
Uwe Monkowius ◽  
Hartmut Yersin
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Device Structure ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light

Luminescent copper(I) complexes showing thermally activated delayed fluorescence (TADF) have developed to attractive emitter materials for organic light emitting diodes (OLEDs). Here, we study the brightly luminescent dimer Cu2Cl2(P∩N)2 (P∩N = diphenylphosphanyl-6-methyl-pyridine), which shows both TADF and phosphorescence at ambient temperature. A solution-processed OLED with a device structure ITO/PEDOT:PSS/PYD2: Cu2Cl2(P∩N)2/DPEPO (10 nm)/TPBi (40 nm)/LiF (1.2 nm)/Al (100 nm) shows warm white emission with moderate external quantum efficiency (EQE). Methods for EQE increase strategies are discussed.

scholarly journals Molecular design of efficient yellow- to red-emissive alkynylgold(iii) complexes for the realization of thermally activated delayed fluorescence (TADF) and their applications in solution-processed organic light-emitting devices

2021 ◽  
Author(s):  
Cathay Chai Au-Yeung ◽  
Lok-Kwan Li ◽  
Man-Chung Tang ◽  
Shiu-Lun Lai ◽  
Wai-Lung Cheung ◽  
...  
Keyword(s):  
Molecular Design ◽  
Delayed Fluorescence ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Thermally Activated ◽  
New Class ◽  
Organic Light ◽  
Tunable Emission

We report the design of a new class of fused heterocyclic alkynyl ligand-containing gold(iii) complexes, which shows tunable emission colors spanning yellow to red region and exhibits thermally activated delayed fluorescence (TADF) properties.

Why Triage the Materials with Low Luminescence Quantum Efficiency: The Use of 35Cbz4BzCN as a Universal Host for Organic Light Emitting Diode through Effective Triplet Energy Transfer

2021 ◽  
Author(s):  
Yi-Mei Huang ◽  
Tse-Ying Chen ◽  
Deng-Gao Chen ◽  
Hsuan-Chi Liang ◽  
Cheng-Ham Wu ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Delayed Fluorescence ◽  
Triplet Energy ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Thermally Activated ◽  
Triplet Energy Transfer ◽  
Triplet Lifetime ◽  
Triplet Excitons

35Cbz4BzCN, a novel universal host with long triplet lifetime, has been developed. The triplet excitons in 35Cbz4BzCN can be effectively harvested by phosphorescence and thermally activated delayed fluorescence emitters. In...

scholarly journals Solution-Processed OLEDs Based on Thermally Activated Delayed Fluorescence Copper(I) Complexes with Intraligand Charge-Transfer Excited State

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1125
Author(s):  
Teng Teng ◽  
Jinfan Xiong ◽  
Gang Cheng ◽  
Changjiang Zhou ◽  
Xialei Lv ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Functional Theory ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Wide Range

A new series of tetrahedral heteroleptic copper(I) complexes exhibiting efficient thermally-activated delayed fluorescence (TADF) in green to orange electromagnetic spectral regions has been developed by using D-A type N^N ligand and P^P ligands. Their structures, electrochemical, photophysical, and electroluminescence properties have been characterized. The complexes exhibit high photoluminescence quantum yields (PLQYs) of up to 0.71 at room temperature in doped film and the lifetimes are in a wide range of 4.3–24.1 μs. Density functional theory (DFT) calculations on the complexes reveal the lowest-lying intraligand charge-transfer excited states that are localized on the N^N ligands. Solution-processed organic light emitting diodes (OLEDs) based on one of the new emitters show a maximum external quantum efficiency (EQE) of 7.96%.

Electrostatic potential dispersing pyrimidine-5-carbonitrile acceptor for high efficiency and long lifetime thermally activated delayed fluorescence organic light-emitting diodes

2019 ◽  
Vol 7 (40) ◽  
pp. 12695-12703 ◽  
Author(s):  
Ji Seon Jang ◽  
Ha Lim Lee ◽  
Kyung Hyung Lee ◽  
Jun Yeob Lee
Keyword(s):  
Electrostatic Potential ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Long Lifetime ◽  
Acceptor Moiety

Pyrimidine-5-carbonitrile was developed as an electrostatic potential managing and strong acceptor moiety of thermally activated delayed fluorescent (TADF) emitters for high efficiency and long lifetime in devices.

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